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1arrow-iconQ. My Monthly energy consumption is 800 kWH in Peak month... and 400 kWH the lowest... The average in the last 24 months is 600 kWH. I want to start little and grow as I go. I'm willing to pay to the utility company as much as the first 450 kWH per month, and the rest should be provided by the solar panels. Accordingly to my calculations, I would need 4 solar panels (250 w), right? My peak sun hours are from 4.5 to 5 hours. So, with these 4 panels, what's the size of the inverter that I need? It is a Grid-tie for sure! but should I buy the 1kw inverter or 4 micro inverters? Since I want to grow I suppose that micro inverters are the way to go... Can you lead me? And in the other hand, should I buy Cristalline or thin-film? The installation is going to be made on the roof... I look forward to your advise. Thanks!

A. Let me educate you a bit on your questions: Thin film is an expensive and sometimes an ill-fitting option compared to a polycrystalline panel. If you plan on putting the modules on your roof, then yes, you will need racking. Most people think that a roof mount is the most convenient and efficient, but there are many reasons that people choose other options, such as if your roof is small, unstable, or in the shade. Other option include mounting the units on the ground or on a pivoting stand. Many permit offices will not give you a permit if the racking approach does not have a civil engineer's stamp of approval, so check with your local office for regulations and rules regarding solar panels and racking. Solar racking is available here at SolarTown depending on what kind of racking or mounting you are looking for. Now lastly, for your solar inverter(s), you must remember that the main difference comes down to the idea of one central inverter (otherwise known as a string inverter) for the entire array or an individual micro inverter connected to each module. The single central inverter is still very popular among homeowners. One reason why is because economically, they are less expensive than micro inverters. Another positive is that in case of any problems, central inverters also have only central point of failure, as opposed to finding the problem through each individual inverter. The drawback is that if you want to expand your solar array system and add on some more panels, you may exceed the capacity of your current central inverter, which translates to big bucks for another central inverter just for these additional panels. In the event that shade is covering a part of your array, micro inverters minimize the issue of that shade affecting the entire array, as opposed to one panel. If just one panel is partially shaded, that is the only panel loosing efficiency and will not reduce the output of the other modules that are part of the solar energy system. Another plus many people like is that with micro inverters, a homeowner can relatively easily increase the size of his or her array, and with the latest technological advancements, the new micro inverters being developed will be able to harvest 5-20% more energy than central inverters over their lifetime. Micro inverters do cost more, but not significantly. I hope this helps answer your questions.

2arrow-iconQ. I would like to know the parts I would need for a single 300 watt poly solar panel system to mount on top of my RV. I would like the system to be expandable to a total of 600 watts. I will need to run a laptop for up to 10 hours per day and an Engle 12volt refrigerator/freezer @ 3 amps per hour. And a few L.E.D. lights.

A. The parts you'll need are a 300 watt solar panel, and a mounting system for the panel, an inverter, charge controller, and additional batteries. What we would strongly recommend is that you take a look at our RV solar kits. If you click on that link you should find our offerings such as the Go Power! Solar Elite kit which looks like it will suit your needs. That particular RV solar kit includes a 320 watt kit that you can expand up to 480 watts. The kit comes with everything except additional batteries. Let us know if we can be of any further assistance.

3arrow-iconQ. In our wooded backyard with only indirect sunlight, can I get a battery charged up enough to run 'Christmas lights' in the summer on a few lawn ornaments?

A. Solar panels need, you guessed it, sun, and the more sun the better. If you don't get direct sun any part of the day, the solar batteries attached to your solar powered garden light will not charge all of the way, and the lights will not work very well. The panels will pick up some of the ambient light but probably not enough for a full charge. Some of our solar lights come with wires between the light and the panel. If you want to put the light under a tree where there is not much direct light, you can still install the panel several feet away in an area that does get direct sunshine. Please contact us if you need any more information.

3arrow-iconQ. How many solar panels will I need for 4 hps lights that are 1000watts each?

A. You may want to consider our solar power lights. If you have 4 lights, each rated at 1,000 watts, you will need a total of 4,000 watts of power. Depending on how often you intend to run the lights, you may need more power generation than that, however. For example, if you intend to keep these lights on for most or all of the time, you will need excess capacity to store in a battery bank for night-time use. If you only intend to use the lights at night, you'll still need a battery bank, but you'll need fewer panels. All in all, a 4,500 to 5,000 watt array of fifteen to eighteen 300-watt panels would be needed to power these lights.

3arrow-iconQ. I have an irrigation tube well of 20 HP solar submersible pump, and want to operate for about 8 to 10 hours. How many Solar panel will be required, what should be the total surface area of solar panel. I am from hot area of pakistan.

A. Solar water pumps are a good way way to manage some off-grid applications for farmers, ranchers and others. You will find that many of our customers at SolarTown, after they hear the cost of batteries, decide that they will use the solar water pumps without a batter-backup. Your 20 HP pump is out of the range for a smaller solar installation. Remember that 1 Horsepower is equal to 746 Watts - both are units of power. Your 20 HP pump therefore at any given time would presumably need about 18,000 watts to run. This would in turn require an array of roughly 70 solar panels in order to consistently run the pump and store electricity in a large battery bank (at least 20-30 large AGM or gel batteries) to be used in the morning and evening. You may want to consider an application without the battery backup.

3arrow-iconQ. Hi I have a green house which i want to run a cooling fan 12volt dc 7,5amps I purchased a 40watt solar panel is this enough ? and what size battery do i need to run the fan?

A. From an electrical standpoint, remember that one watt is equal to the work done by a 1 amp current at 1 volt (the equation is W=V*A). A 12 volt, 7.5 amp cooling fan is a 90 watt appliance, meaning that the lone 40 watt panel won't give it enough power to run. For your needs, you'll need 3 40-watt panels in order to reliably power your cooling fan, and probably an additional fourth panel if you want to charge a battery in order to run the fan at night.

3arrow-iconQ. Is it ok to mix solar power panels ie 6 15 watt plus 1 45 watt plus 1 100 watt thru a 30 amp controller. Any issues. Presently I run LED lights and charging power tools

A. The general policy is that it is much safer to use the same solar panels in your array. Having said that, it is sometimes possible to mix and max depending on how you set up your circuits and the maximum voltage on your solar inverter (if you use one). First, remember to always keep the maximum output voltage of your panel system below the maximum DC input voltage on your inverter. Then you determine how to wire your panels together based on whether they are more similar in current (amps) or voltage (volts). Being too different in either of these characteristics will not break your panels, but will result in a performance loss. If the panels are more similar in terms of current, then you will want to wire them in a series setup. If they are more similar in voltage, you will want to wire them in parallel. Also, make sure the current matches up with that of your controller (30 amps, in this case). The best practice is to always use a licensed electrician to wire your panels.

3arrow-iconQ. I have 2 x 185 W solar panels, 2 x 12 V batteries and 900 W inverter are these compatible

A. While it's always good to check that the specific parts are compatible - most inverters have a maximum input voltage, solar panels exceeding that maximum voltage risk damaging the inverter. These parts should be capable of working together. The rating on the inverter is the maximum power that the inverter can handle, so if the panels and/or battery send in less than that, it will still run.

3arrow-iconQ. I live in india, My monthly consumption is around 200 Units, (200 KWH) how can i use solar energy to power my whole home

A. A smaller solar panel system can provide more than enough power for your whole home during the day. Ten to twelve 260 to 280 watt panels would be more than capable of both powering your home and sending power back into the power grid. The parts you'll need besides the panels are a grid-tie inverter, racking, and wiring (you'll need to pick out the right parts for your specific installation). If you want to go off the grid, you will still need solar racking, but instead of a grid-tie inverter, you'll need deep cycle batteries and a standard (not grid-tie) inverter.

3arrow-iconQ. I would like to build a solar power system for my workshop. This will not be grid tied, but connected to a battery bank. The basis for the system would be 3 SolarWorld 250W modules - http://www.solartown.com/store/product/solarworld-250w-solar-panel/. The roof on the workshop is a standing seam metal roof. Can you specify the racking I would need to mount the panels and recommend a charge controller?

A. Standing seam roofs can be a challenge when it comes to racking. One alternative is to use thin film panels. Thin film panels attach to the roof using a special adhesive, meaning there's no racking. The downside is that the thin film panels are more expensive for the amount of power (higher cost per watt, to use industry terms) than crystalline modules. As for the charge controller, for the best performance, consider an Maximum Power Point Tracking (MPPT) charge controller such as the Solar Boost 2000E. If you're on a budget, you can also go with a Pulse Width Modulation (PWM) charge controller such as the Schneider/Xantrex C40. Just remember that in general, MPPT charge controllers generally outperform PWM charge controllers by 30-50%.

3arrow-iconQ. Can the smart solar umbrella lanterns be mounted on fence posts for outdoor walkway lighting?

A. The Smart Solar Umbrella lanterns are specifically designed for hanging or on flat surfaces. You may also want to look at solar lights that are specifically designed for mounting on fence posts that we offer from Classy Caps and there are also a couple from Gama Sonic solar lights. Take a look at our selection of solar powered lights to see a full lineup of what we offer and contact us if you have any questions.

3arrow-iconQ. I want to install solar panel operated system for 2 nos. of water pump (1 hp each) and this will run for 24 hrs. Pl suggest me the configuration of system alongwith specification of each part.

A. For high horsepower applications such as this one, there may be other options besides a solar water pump. You can take a look at the solar water pumps that we currently offer such as a submersible solar water pump which offers a maximum flow rate of 80 gallons per minutes with a head of 50 feet, which puts it right at 1 horsepower. Depending on where you are located, this application would require as many as six to eight solar panels to power each pump. And if you are talking about 24 hour operations, you will need solar batteries to power the pump when the sun goes down or when it is cloudy.

3arrow-iconQ. I have spent days on the internet searching for a kit I can purchase online for a dc solar pool pump system plug & play kit (pump, panels, hardware, wiring, etc.) for a do-it yourselfer like me. I am unable to locate a complete kit for sale online. Can you help me?

A. Take a look at the Solar Pool Pumps section on the SolarTown website. We offer a number of different solar pool pumps for different pool sizes. The best option we have is the Natural Current line of floating pool pumps. These are floating systems that house the pump directly under the panels, all in a floating system with no wiring and minimal set-up.

3arrow-iconQ. I am thinking of building a new two car garage in Northern illinois, is it possible to make the garage doors solar powered and reliable?

A. How you provide solar power to your garage door opener depends on where the garage is located and whether you are on the grid. If there is already power from your house that is available, then a solar panel grid tie system for your house would of course include your garage. You can just connect your garage onto that system (it might even already be connected!). If you have a detached garage and want to start out with the garage, you may want to look into an off grid solar system with a solar battery backup, but this would be very expensive and not recommended--although it is possible. A third option for some folks who live in very sunny areas may want to consider a solar carport, which uses roof solar panels to charge the battery in an electric car, as well as powering garage lights and the garage door opener. Whichever option you choose, as long as the garage's roof isn't in the shade most of the time (you'll want to make sure there aren't trees or other obstructions south of it), you'll have enough power for not only the door opener but also garage lights.

3arrow-iconQ. As a project in school, I need to ask how solar panels work and why doesn't all the solar energy turn into electrical energy?

A. Congratulations on your solar project in school. SolarTown has set up a sister site called SolarTownKids for students and parents to explore solar energy. SolarTownKids has a lot of good resources that you will want to check out, including solar videos, solar activities and projects. We have some basic information on that site such as how solar energy works. And if you have other projects to offer, we would be pleased to share your information with our SolarTown kids and parents.

3arrow-iconQ. Wish to install a solar motion sensor security light between two urban houses, out of reach of intruders. For what I want to do, I believe that I need separate components: sensor, light and solar panel placed high, perhaps several feet apart. Are these available to public, and would you know of a place to inquire? Thanks

A. Please refer to the SolarTown product catalog under solar security lights. Most of the solar security lights come with a motion sensor so that you would be able to mount the solar lights high on a wall or a fence. Some of the solar security lights come with an on off feature and there is even one of the new and bright solar security lights that come with a remote on and off feature. All of the lights that we have in this section are all-inclusive with all of the parts that you need, including the light and the solar panel that powers the light. If you have any further questions, please contact us.

3arrow-iconQ. I am new to solar lighting and am looking for some weatherproof flood lights to light up my hockey rink on the lake that I live on. What lights would work to light up a space 50' x 100'. I would also like to have them on a timer. Thanks.

A. You have many good choices for solar flood lights for your outdoor hockey rink. You can take a look at the many flood lights and the various options at the SolarTown store under solar security and flood. The latest flood lights are very bright, as much as the equivalen of 150 watts. The Lumen measurement is 540lm (6~7lm/pc)--real bright which should suit your purposes. Most solar lights work from dusk to dawn or the security solar lights many times will have a motion sensor. None of the lights that we carry have a timer, but many do have an on off switch, which it sounds like will suit your purposes. The weather has gotten cold throughout the country so you have the perfect weather to grab your hockey stick and play hockey.

3arrow-iconQ. I have a 48VDC system that draws 20W every day, all day. What battery and solar charger combination would be best for me?

A. Off-grid solar panel systems are relatively easy to design if you gather all of the information that you need beforehand. Your location is going to tell you how much sun you can expect your solar panel system to receive. The first thing to calculate is the AC and DC watt hours for your average total watt hours per day. For this calculation you will add up all the electrical loads that the power system will need to provide power for. You need to take into account the watts and how many hours per day you will be using the electrical equipment. Multiply that answer by how many days per week to come up with the watt hours per week. Make sure that if you have appliances like an air conditioner that you use only in one season, that you make sure that you figure that into your calculation. If you have any DC loads, then you have to take those into account as well. You need a few other pieces of information to obtain the size of the solar panel system. Remember that if the system is far away from the inverter, you are going to lose some electricity along the way. For your racking system, you will need to make sure you have the maximum wind speed for your location and snow loads. And for the batteries, how much backup power are you looking for. From this information, we will have a better idea of the size of the system and the other components for your system.

3arrow-iconQ. I have the 45 Watt Thunderbolt Magnum solar panel kit which includes a charge controller that shuts off at 14.5 volts. I have a 24 volt motor that I need to run and have my 2 - 12 volt deep cycle batteries hooked up to output to the motor but I think I need a 24 volt charge controller...is this right or can I somehow use my existing controller to charge both of my 12 volt batteries?

A. It will depend on what your home solar panels are rated at, and how they can be wired if this will work or not. You will definitely need a 24v charge controller, but it is not possible to recommend a charge controller until we know the specifications of the solar modules you purchases. Also, your solar inverter will no longer work. If you run 12v loads or the 12v inverter from ½ the 24v battery bank it will imbalance the charge on the solar batteries and they will fail after a short time. Once you provide the specifications for the solar panels, which you can usually find on the reverse side of the modules, then we can give you a better recommendation.

3arrow-iconQ.I have a 1.1KW single phase 220V water pump, which I want to run on solar only during day time for 4 hours. Kindly let me know how many 250 W panels and Ahr of the battery bank required. I have a good 2KVA charge controller. Thanks.

A. You will likely need to get a solar pump that runs off of DC power to operate the system off of batteries. You can find solar submersible pumps such as Grundfos under our solar water pump section and you can find solar surface pumps such as Shurflo in the same section. When you are looking for a solar water pump, you will also need to take in account your location, and what your required TDH (total dynamic head) and required flow rate for the pump to pick out the best pump to fit your needs.

3arrow-iconQ.I want a solar powered light with a timer for my chicken coop to come on about 4am and off about 8am. Is there any thing out there I can use?

A. We love your application for solar energy lights and your chickens should enjoy solar energy like everyone else. Keep in mind that solar lights that you would want to use are dusk/dawn and they do not have a timer. You can browse some of the possibilities in our section on solar security lighting (you probably are not looking for a solar path light). Take a look at the Maxsa Model 40330. If you have the solar light set at half power, it will stay on for as long as 10 hours (depending on where you are located) and should do the job. There is no timer setting, but your chickens shouldn't know the difference.

3arrow-iconQ.Can solar panels be charged with with artificial light?

A. The short answer is yes, but why would you ever want to power a solar panel with artificial light. If you are talking about a calculator that you use at your desk, the office light will provide the light to make the tiny solar panel in the calculator work, even though most of the artificial light will be wasted. If you are talking about a 140 watt solar module, then you may have to rethink your approach, or buy a ton of incandescent lights.

3arrow-iconQ.How many solar panels do i need to install to run 3 ton air conditioning in my house which is 170 square meter.

A. Before you go out and purchase your home solar panels, you may want to get some more information about your air conditioning unit. Not all three ton units are created equal. Some are rated at 12 SEER, and others may be rated at 16 SEER. When your air conditioning is turned off, you won't need any electrical power. You need to determine how many hours a day on average you plan on using your unit. And you should also take into account where you live as you are going to produce more solar energy if you live in New Mexico than if you live in Minnesota. With all solar energy systems, the most important thing is to do your homework before you start buying any equipment.

3arrow-iconQ. Need to compare candian solar panels vs. sunpower solar panels. Where can I find a proper comparison

A. You can use our solar panel comparison but you will not find the SunPower solar panels listed in our comparison because we do not carry them. But you can at least see what the major criteria are on which we compare solar panels and then get the spec sheets for each of the panels that you are looking at. You should be able to get most of the information that we have included in our comparison, although you will have to go to an outside site to get the PV USA Test Conditions. All of the other information will be on the spec sheets. You are right to do your homework as all solar modules are not made equal.

3arrow-iconQ. How much wind can Canadian solar panels take with the attached ground mounds? Living in Southern California we get some heavy Santa Ana winds, want to make sure my structure is strong and items will not fly off or fall apart.

A. Wind in and of itself is not going to damage your home solar panels. The major concern for damage usually is a hail storm. If large enough and travelling at a high speed, a hail ball can damage a solar panel. Another threat to your solar panel system may be high winds, but how vulnerable your home solar panel system is will depend on your racking system and the design of your system.

3arrow-iconQ. What would be the best solar panels to use on the ground not on rough? is there any diagram that helps me to install my own solar panels. I need 1000 watts per month. so 240 watt panel versus 220 watt, which one would be better? and how many do I need? thank you

A. There are many options for installing home solar panels on the ground to achieve 1kw of power. You can go with a single row of five, which will give you about 1200 watt of power with 240w solar panels or 1100 watt of power with 220w solar panels. An alternative approach may be to go with a pole mount system to secure the five solar panels. Mounting solar panels with a ground mount or pole mount will both require ground work done outside. This will ensure that the solar panels are safely secured on your property. You can compensate for wind load by using ground mounts or pole mounts specifically designed to meet the requirements in your area. There are manufacturers that manufacture high quality ground mounts and pole mounts for commercial and residential solar energy systems. Feel free to visit SolarTown for more information on solar racking solutions and other solar products.

3arrow-iconQ. I would like to buy a kit or the materials to power three 45 watt led grow panels could you please point me in the right direction

A. A 45 watt Grow Light requires approximately 45 watts of power per hour unless otherwise stated in the manual or technical characteristics of the light. Like any outdoor solar light or equipment to be powered with solar panels, you will have to determine the run time of your application on a daily basis. The actually run time multiplied by the amount of power of the Solar Grow Light will give you the numbers you need to calculate how many solar panels you will need to buy. If the LED solar lights are DC then your configuration will be easier because you will not necessary need a solar inverter. In the event the Solar Grow Lights are AC then you will need an inverter so that you can convert DC to AC. Feel free to visit SolarTown's solar panels section or inverters section to compare different home solar panels and inverters that will work for your off grid system.

3arrow-iconQ. I've got a 6X12 enclosed trailer that I's like to use as a kind of mobile workshop. I move around a lot so this would be perfect, for my DIY projects. I was thinking of a project to install a solar panel to charge some kind of battery bank, inside the trailer. I'd like to just be able to run power tools, lights, and perhaps some music. I have no idea how to get started, I could really use a point in the right direction and maybe a idea at what I'm in for. Thank you.

A. There are several approaches to take to add home solar panels to your trailer, RV or off grid application. Since we know the dimensions of your roof, you can go with 3 or 4 solar panels where the modules are orientated in landscape running across the top, the longest length of the solar panel running toward the 6ft length of the roof. The solar panels can then be installed 3 or 4 panels next to each other running the remaining 12ft span. You'll need to purchase clamps designed for RVs, trailers etc to safely secure the modules on your roof. You can visit SolarTown to buy the solar panel that will fit with your off grid application. Just keep in mind there are other options for what it is you are doing. For example, adding arm brackets and angle arms to that you can create a frame to add even more modules. Feel free to contact SolarTown Customer Service for any questions you may have.

3arrow-iconQ. I have solar stake lights along my driveway. Unfortunately previous owner put dirt flower beds along side of new driveway over the old concrete driveway instead of removing. Some of my stake lights do not have enough dirt to hold them upright on the old concrete. Are there some kind of collars or weighted bases that I could use to hold them upright? I can not make a hole large enough in the conmcrete to insert the stake but I could use concrete screws to attach a collar or plate to insert the solar light stake into. Do they make a product for this purpose?

A. Outdoor solar lights are sold by SolarTown for a variety of pathways and driveways. For your application, first you want to measure the depth of the top soil. A rough estimate will be fine. With that measurement you can then choose a solar light that can be imbedded within those parameters. Solar Lights come in different lengths and weight, if the soil is not that deep you can use a smaller solar light which normally will be lighter and require less depth to secure properly. If there is concrete below the soil, you can always use a hammer drill and anchor the solar light in place. Solar landscape lights physical characteristics will vary but if it is relatively light you can use a small 5/16 or 1/4 inch anchor because they require a smaller hole drilled into the concrete and the anchor types are relatively easy to install. Feel free to visit SolarTown's outdoor solar lights to determine which light works best for your application or contact us for any questions you may have.

3arrow-iconQ. How much power does a 120 watt solar panel produce in 1 hour?

A. A 120 watt solar panel for your home is not going to provide you with much juice at all. Most home solar panels have at least twice the capacity, but if you have an off grid application and you need a 12 volt panel, SolarTown sells both a crystalline panel that is 140 watts and several thin film solar modules that have even lower wattages. The key question is how much output you can expect from each of these panels, and it depends on many factors such as the angle of the sun, whether the sun is even out, any clouds or shading. The answer is very easy if you are asking how much output will there be at night. The answer is of course zero. It probably makes more sense to talk about averages. In a place like Washington, D.C., SolarTown's home, where the peak sun hours per day is about 4.2 (kilowatt-hours per square meter per day), a 1 kW system (8 or 9 or your 120 watt panels) would produce about 1300 kilowatt hours per year, or roughly 3.56 kWh per day. You asked about a 120 watt panel. That panel will produce on average of about 425 watt hours per day; in the winter, the output will be less and in the summer, the output will be more.

3arrow-iconQ. I am a layman and will need you to reply as if to a 5th grader. How many solar panels will it take to run an 1 hp 110 volt sweetwater blower?

A. Using solar panels can be a great option to powering a wide range of tools and devices. What you want to start off with is to evaluate the electrical characteristics of the device. All devices, if the label is still present, will illustrate the energy requirements to operate the unit. Solar panels can be wired in series to achieve a targeted voltage or in parallel to achieve a specific current. You will need to buy a charge controller either PWM or MPPT and some batteries. If you buy a pump that is designed to work off DC, you can definitely generate cost savings. Many pumps whether SunRotor submersible solar water pump or Grundfos surface pumps offer that versatility. If the pump operates off AC then the initial cost may be a little higher because you will need an inverter but if you take into the account the long term cost of operating your 1hp pump that requires AC, gas, oil or any other energy source the solar option may work out in the long run. Feel free to contact SolarTown Customer Service for assistance in sizing your off-grid application.

3arrow-iconQ. I want to run my pool pump with a solar system. I want to run the pump continously. The pump is 328 watts / 15 amps / 115 volts how many panels / batteries do I need?

A. It sounds like your current pool pump operates using AC power, which can be configured with solar panels, batteries, charge controller and inverter, but this arrangement will tend to be less efficient than a DC solar pool pump which can be found in our solar pool section. Without knowing the specifics of the pool pump, a pump requiring 328 watts per hour will require 7872 watts for a 24 hour period. I'm not sure this kind of application will be practical considering you will need about 32 solar panels and many more batteries to operate the pool pump for a 24 hour period. The operating cost for the AC pool pump is probably running in the neighborhood of $20 - $30 per month or $240 -$360 annually. With all things considered, visit the solar pool pump section of SolarTown and review the DC solar pool pumps. Solar Pool Pumps require less energy to operate and in this situation will be probably a better fit for your configuration. Solar pool pumps are also built to work with solar panels so the final number of modules will be substantially less depending upon your runtime.

3arrow-iconQ. I just bought (2) 45 watt solar panels that requires a 300 watt power inverter. Since I want to use them together, do I need two 300 watt inverters or will one work?

A. Solar panels for home solar energy systems or off grid solar energy systems require a solar inverter when you're looking to power an AC device or hardware. 45 watt solar panels are normally around 12 volts so if you have two wired in series or parallel a corresponding charge controller will be required. If the solar panels are wired in series, you can buy a Specialty Concepts, Xantrex, Morningstar or Flexcharge 24v charge controller. If the solar modules are wired in parallel then you can go with a 12V charge controller which you can find in the charge controller section of SolarTown. Just keep in mind the rated amps in a series or parallel wire configuration to ensure compliance with all the solar hardware and devices. Feel free to contact SolarTown Customer Service for further assistance.

3arrow-iconQ. I'm looking for some help to design my battery bank for my home roof top setup. My plan is to have 200W X5 Panels = 1KW. To set this up, i need some clarifications and hope i would get it here.. Im planning to purchase a MMPT charge controller. For the battery bank, i intend to have 150Ah X 7 battery (12V each). Since the pannel is 24V panels, is it mandatory to have my battery bank in 24V setup or is it fine to have it remain with 12V. Leaving the battery bank at 12V will help me reduce the cost on investment for the batteries..Also help me suggest the Amp required to purchase the MPPT.

A. Batteries used with home solar panels can be modified proportionately to setup either a 12V solar panel system, 24V system or any other voltage arrangement for the solar battery bank. For illustration purposes, a 12V battery bank with 100Ah is similar to a 24V battery bank with a 50Ah configuration. With that said though, wiring the higher system voltage can get a touch more complicated with the increased voltage similar to connecting solar panels but the higher voltage will improve overall efficiency. Also you will have to be mindful of secondary components like solar inverters and other devices you wish to connect to the off-grid solar energy system. MPPT Charge Controllers work well with different solar module configurations and only limited to the technical parameters of the charge controller. If you plan on buying a Outback Charge Controller or MidNite Solar Charge Controller, make sure you verify the electrical parameters of the unit before you purchase the controller.

3arrow-iconQ. Is there any way (other than a battery backup) to get power from a grid tied PV system if the grid goes down?

A. Without a battery bank designed to work with your home solar panels, you will not be able to store the power for use during a power outage. If it is a large solar energy system, it may be possible to divert power from the solar panels to a charge controller to the device or a solar inverter but that depends on how large the system is and what equipment you have. Outback charge controllers and Outback solar inverters provide that functionality but if you have a central inverter such as a Power-One Inverter or Sunny Boy Inverter then it will not work. If you deconstruct your home solar system by removing a module or two, you can power an external charge controller to power a device. Otherwise it may just be easier to buy a home solar panel and a smaller charge controller to power the device. Feel free to contact SolarTown Customer Support for further assistance with your solar project.

3arrow-iconQ. I am working on a solar idea for work to reduce our cost in electricity and to be kind to our planet. I work in a 155,000 sqft plant that has 19 robots, 6 fork lifts that run on batteries, not to mention all the machines that run on electricity, is it possible that a manufacturing plant can use total solar power to run 24 hrs a day

A. There are many businesses here in the United States that use solar energy to offset the energy required to run their businesses. Google and Walmart are examples of companies taking advantage of solar energy. A fixed cost is something that homeowners or businesses have very little flexibility in reducing such an expenditure. Luckily with solar energy or any renewable energy source, businesses and homeowners can configure a system that can help reduce their energy bill. Buying solar panels is seen as an investment in technology to bringing down the cost of energy use. Commercial solar projects are normally connected to the grid so that the energy produced is fed back into the grid, turning back the energy meter. While energy is being consumed, the energy meter moves forward determining what the business will pay. To configure a solar energy system that provides 24 hour operation may not be an ideal configuration due to the limitation in battery technology. The battery bank will need to be substantial in size and difficult to manage. With commercial buildings, the best approach is to utilize the open roof top space for solar panels. You may not get exactly 100% offset, but you can always achieve cost savings from renewable energy. Roof tops for many commercial buildings are underutilized so many businesses take advantage of existing assets to produce renewable energy reducing their energy costs. Projects can always be scaled to available assets. Feel free to contact SolarTown for more information on solar projects and buying solar panels for homes or businesses.

3arrow-iconQ. Will a 34 watt solar panel work on a regular light bulb like the ones you have in your room

A. You can definitely power a light bulb with a home solar panel. One example of this is along highways and roads, you see a lot of solar powered commercial street lights because many of these locations do not have access to a conventional power source or it may not be cost effective to run the distance needed to power the street light. Solar panels used in these instances provide a renewable energy solution where lighting is required. For your application, you will first need to determine the runtime of the light bulb and how much energy required to power the light bulb. Runtime multiplied by the power consumption of the light bulb will determine the amount of energy you need coming from the solar panel and the number of solar panels to buy to meet the requirement. CFL and LED light bulbs use less energy so they are more suitable for solar applications or even in a normal energy environment because it will lower your monthly energy bill. Another alternative may be to visit SolarTown's product section and buy a solar powered light to power your home or outdoor lighting application. There are many different solar lights with specific applications and design elements. Feel free to contact SolarTown Customer Service for additional support.

3arrow-iconQ. I have an 8 x 12 chicken coop that I want to power a 60 watt bulb throughout the winter for light and minimal heat. Would the Xunlight 34w FR kit work for this? I am very, very new to solar panels and am not sure where to look or exactly what I need. Thank you

A. If you are using a 60 watt light bulb and running the light for an additional 4 hours, your total energy consumption will be about 240 watts. How much energy you will need will come down to the number of hours you plan to run the light. Depending on where you are located, the peak sun hours will help calculate the potential energy produced by a solar panel. If the peak sun hours for your area is about 4, you're probably looking at a total of 136 watts of energy from a 34 watt solar panel before you take into account efficiency loss and such. For that scenario of four hour runtime, you will not be producing enough power to run the light that requires at minimum 240 watts. An alternative approach is to use a LED light. LED lights use substantially less power so it will lower the amount of energy needed from the home solar panel. Another option is to install a solar powered light. There is a solar light section on SolarTown where you can buy and compare solar lights that may be suitable for use in a chicken coop.

3arrow-iconQ. Can the Outback grid-tie inverters be used without batteries (provide output when the DC generation source is available, and shut down when the source is unavailable or too weak for operation)? Or are the batteries required for some reason? If so, what?

A. Charge controllers will need a minimal battery bank to power your load. Typically the solar panels will go into a combiner box or directly into the Charge Controller depending upon your voltage setup. The battery bank connects to the charge controller and disconnect. To connect a DC load, you will need to have the equipment connected to the battery bank. Please ensure you have the appropriate fuse and disconnect between the battery and load for safe operation. Feel free to contact SolarTown for addition support on solar energy products.

3arrow-iconQ. Can I use a groundfos 200 3 80 watt panel set up and use it to charge batteries

A. Solar submersible pumps can bet setup to access power from a reserve battery bank. To operate off the battery bank, you will need a solar charge controller connected to the battery bank. Specialty Concepts, Xantrex, Morningstar Corp, Solar Boost all manufacture high quality charge controllers that can work with a Grundfos submersible pump depending upon the system technical parameters. The solar panels will connect directly to the charge controller, battery connects to the charge controller, and the charge controller will be connected to the CU 200 SQFlex Control unit or IO 101 SQFlex Switch Box.

3arrow-iconQ. i have two thin film 50 watt solar panels that are 62 volts. i am looking to set them up on a sailboat to help keep my three 12 volt batteries charged. i am trying to find a charge controller that will be safe to use with two 62 volt solar panels. any help would be greatly appreciated! thanks for your service sandi

A. Smaller sized charge controllers that charges batteries normally come in 12V, 24V and 48V. Companies like Specialty Concepts, Xantrex and Morningstar Corp all manufacture high quality charge controllers but depending upon the model the maximum input voltage coming from the PV is usually around 48V. On the larger size charge controllers you can go with an Outback Power Charge Controller that can handle up to 150VDC but it may be a larger charge controller than what it is you are looking for. Outback Charge Controllers are powerful and aggressive charge controllers designed for larger battery banks and applications. My only concern is that the thin film solar panel you have is rated at 62V which means the Amp is rated at 0.8. If you can provide the model number of the solar panel and the maker of the solar module we may be able to suggest alternative options that may work for your setup. Once we have that information we will be better able to evaluate what possible configurations there may be.

3arrow-iconQ. Can solar energy be used to cool a home in the caribbean?

A. Home solar panels can definitely be used to cool your home. There are several approaches to cool or heat your home with solar panels. You can install solar panels to power your ac or heating system directly with an inverter or have the solar panels connected to the grid whereby the energy produced offsets your energy consumption. You can also buy a solar attic fan or solar gable fan that helps vent hot air out of your home sustaining a more comfortable temperature in your home. You can find a selection of solar attic fans in our solar ventilation section of the store. Hot water can be heated with solar water collectors compared to the conventional methods of heating water. For locations where power is not readily available, you also have users setup small off-grid systems consisting of solar batteries, inverter, solar panel and charge controllers, to power small devices or appliances. Feel free to contact SolarTown to explore energy solutions for your project.

3arrow-iconQ. I would like to place a "soft" solar light under a second story deck with a patio below. The solar collector would have to go on top of the deck and the lights below. I don't want spotlights but something more defused. Suggestions?

A. You will find in our solar landscape light section many fun options available to tackle your project. Gama Sonic sells a great outdoor solar light. The solar panel is mounted outside the building and the light itself is inside the building. You can find the solar light by doing a search for gama sonic solar she light on SolarTown. You will need to mount the solar panel somewhere along the side of your deck and then run the wire to the light. Another option would be to go with a solar table light. At SolarTown, we have solar table lights by Smart Solar which you can find by searching for solar lights by brand. Solar table lights are usually placed on top of a table or any flat surface. All patios should have a table so that you can lounge around when relaxing but maybe that is just me. Another option, albeit a touch complicated, may be to drill a hole through the wood and hang a hanging solar light. You will need to cut into and sand the surface on the deck to fit the solar module and extra spacing to fit an impact resist glass or material to cover the module so no one damages the solar panel. This option may require more time than it is actually worth so it may not make much sense. If you have any questions, feel free to contact SolarTown or use our new Live Chat located at the top of the page. Good luck.

3arrow-iconQ. I have roughly 235 watts worth of solar panels hooked up to a 250 watt grid tie in inverter. the in inverter is hooked up to a GFCI outlet in my shed that it is ran to my house to an outdoor outlet. Am i able to plug other items into the second plug of the GFCI or any other receptacles on the same circuit.

A. What you have done is likely a violation of the electrical codes in most of the developed world. Anything you plug into the grid including lights, tools, etc. must be listed as approved by an approved testing laboratory. Look at the inverter you have and there will be no certification label such as UL on it as these are impossible to approve. The reason is that when unplugged there may be voltage and or current on the exposed plug end. Secondly by plugging in to a circuit there is the possibility of your overloading the circuit when drawing power from it. With the grid and the inverter (the total current available will be the sum of the circuit breaker in the panel plus the output of the inverter). The codes are very specific regarding connecting home solar panels to the grid and these type of inverters in no way meet this criterion. Unfortunately there is no rule prohibiting the sale of these items to unsuspecting consumers.

3arrow-iconQ. I have a 3500 sq ft house, geothermal heating system, live in md. I am looking for a solar set up that can provide power (net metering to grid), and also serve as backup power to run hvac and fridge when we have week long power outtages. (ideally 4-6 hrs running the critical stuff during the day). I would prefer to minimize the use of batteries. I am looking for that type of configuration, any advice would be appreciated Thanks, Lucas

A. You may install what would basically be a hybrid solar energy system that would switch to battery power in the event of a black out. We would need a bit more information, however. Some of the information that you will need to gather include what are the devices you wish to run and for how long each day. Use a Kill a watt meter to determine how many watt hours each item uses. Light bulbs don't necessarily need to be checked but any electronic devices or motors would need to be checked. For system design the orientation of your roof and the pitch or tilt and dimensions of your roof and a zip code. This would tell us how many home solar panels can be placed on your roof. Running HVAC is perhaps possible but will be a very expensive proposition due to the high amount of power these items draw and would pretty much be limited to when the sun shines.Let us know if you have any further questions.

3arrow-iconQ. Can 180 watt solar panel run 1hp pump and draw water 30 meters deep?

A. A 1hp pump will generally draw substantially more energy than what a single 180w solar panel will be able to provide. The best way to determine how much power will be required on the pump is to review the technical parameters on the pump. Manufacturers provide this information on the manual or you can contact the manufacturer to confirm the specifications for the model of your pump. A single 180 watt solar panel may or may not be able to power the pump, but that really depends on the actual load's technical parameters. You may also want to check out some of the solar water pumps that we offer and do let us know if you have any further questions.

3arrow-iconQ. i hooked up a solar little path light to a weather station and cant get it to keep batt.charged maybe hooked up wrong,not sure..what do you think?hooked it up just like in the light to the batt.help.

A. It looks like you are trying to charge or power the weather station with a solar path light. Solar path lights are designed to power the LED lights within the light itself. If you maintain the solar LED light with the solar panels, I do not believe it will produce enough energy to power the weather station but that really depends on the energy output coming from the solar panels. You may want to take a look at some solar spot lights if you're looking to add extra lighting to the area surrounding the weather station. Relatively straight forward and easy to install, just find a place to mount or spike the solar spot light and you will have light. This will eliminate cutting and splicing wires which normally will void the manufacturer's warranty or worse, damage the solar light.

3arrow-iconQ. On a string of lights, the cord from the solar panel connecting to the lights was cut. We have tried to splice it back together but it doesn't work. On the cord, there are two vinyl/rubber covered cords twisted together. With in each tiny cord are three wires the colors of which appear to be identical. So we twisted one set of wires around the other and sealed it up and doesn't work. Does each of the three wires need to be connected a particiular wire?

A. While most solar powered lights are constructed similar, when you are working at the wire level it is probably best to contact the manufacturer because there may be components that will be proprietary to the company and not available to the public. We hate to be the bearer of bad news, but you likely voided the warranty when you cut the wire. And even though the solar light manufacturer will not replace your light, it will have a better idea of the component parts needed to repair the damaged light. Manufacturers usually will have spare parts to service solar lights. Hopefully this will help some.

3arrow-iconQ. I have a sundanzer sdr 225 fridge it is out of refrigerant what is the gas charge for it as it is not printed on the fridge

A. The SunDanzer solar refrigerators and freezers refrigerant can be easily refilled with standard supplies. The refrigerant is R134a just like in your car and traditional home appliances. It can be recharged through the service port, which is a standard refrigeration Schrader valve.

3arrow-iconQ. i would like to run a small dc fan and to charge two small rechargerable batteries at the same time, so i can run the fan aliitle longer at night time

A. To properly size an off-grid solar energy system you will need to locate the technical specs for the DC fan. Somewhere located on the fan itself or in the technical manual, there should be values that show Voltage, Amp, wattage etc of the fan. You will then use the operating numbers to help choose the right home solar panel and solar charge controller. Once you have selected the solar panel and charge controller, you can then determine the number of the batteries that will provide the required capacity for your fan and additional components. Since you already have the batteries, you will need to work in reverse to determine if the number of batteries will work with the solar panel and charge controller. In any scenario, make sure you do not deplete and discharge the battery too much and too often. Doing so will substantially reduce the runtime and usable life of the battery.

3arrow-iconQ. I'm building an expansion on my house, not the average expansion, my own little Brewery. I have two refrigerators that I hook up temperature control units to for regulating temperature of my Fermenting beer. Alongside the other refrigerator and standalone freezer I have in my house for food I am losing so much money on electricity it's hard to afford ingredients for my beer? What kind of solar setup would I need to power two refrigerators and maybe some lights (LED)?

A. There are several ways to tackle the project. For the lighting side, you can install a portable solar led light. The setup is usually straight forward, place the solar panel outside and the cable will run into the house that powers the led light. There are a few options here at SolarTown that can get the job done like the Maxsa Solar Power Flood Light, which you can find in our solar lighting section for Maxsa solar lights. Another good option is the Gama Sonic Light My Shed Solar Light, a solar shed light that you can find in our section on Gama Sonic Solar Lights. As for the larger energy utilization coming from the refrigerators and freezers, you may consider installing home solar panels to offset your energy consumption. If net metering is available, you can install a home solar energy system that produces the same amount of energy consumed by the larger appliances which will reduce your monthly energy bill. If you were to power the appliances off batteries, you will need to spec out the technical parameters of the refrigerator and freezer and then size up enough batteries to provide the runtime necessary for what it is you are doing. Feel free to contact SolarTown if you have any additional questions at customerservice@solartown.com or by using SolarTown's new Live Chat feature.

3arrow-iconQ. Hi just wanted to know if i install 1.5kw solar panels with 5kw expandable inverter will its efficiency decrease

A. The solar panels in your home solar energy system need to achieve a specific minimal voltage so that the solar inverter can function so for smaller systems you need to ensure that you have enough solar panels that can achieve the minimal voltage while also ensuring you do not exceed the maximum parameters for a solar inverter. Inverters will all have different minimum and maximum settings so it is important to ensure compliance prior to purchasing the inverter. In general a thing to keep in mind is that the actual solar inverter you choose will have certain conditions that need to be met before it can operate. Please provide the model of the inverter and the model of the solar module that you're planning for the solar energy system, SolarTown will be able to provide more information on the efficiency data and options to maximize overall efficiency. As for efficiency, it depends on where you plan to measure overall efficiency. Efficiency can be evaluated based on the utility of the inverter - inverter efficiency ratio - where a specific name plate value of the inverter is compared to the amount of solar energy going into the inverter. For example, the amount of energy produced from the solar panels going into a specific name plate inverter (5kw of solar energy going into a 5kw inverter would be 100%). You can also measure the energy conversion efficiency of the inverter (standard inverters will have a conversion rate north of 95% - depending on the model). You should also consider temperature, distance, configuration etc that also play a role in overall efficiency. If you plan to upgrade your system in the future, ensure that the inverter will function with the current number of solar panels and provides enough flexibility so that you can upgrade your home solar energy system. Mother Nature is unpredictable, and we may never be able to recreate an optimal environment where conditions are no longer volatile but we can take into consideration those variables to setup a highly efficient solar energy system.

3arrow-iconQ. How much does a 170w solar panel power or what can it power?

A. Your sole solar panel is not going to produce much juice for you. You have many factors to take into account, like where you live, how much sunlight you get. At night, your solar panel is going to produce exactly zero kilowatt hours. Also remember for a solar panel to be used off grid, you are going to need a solar battery and charge controller to run with your solar panel. Take a look at some of our solar refrigerator or solar freezer kits to see some of the configurations. But let's talk in averages and suppose that you are close to SolarTown in Washington, DC, which has about 4 kWh/m2/day--but in the winter it can be as low as 2 hours and in the summer as high as 6 hours. On average, you are going to get from your solar module about 580 watt hours per day. You may be able to power up your computer, but your fridge/freezer combo, even an ENERGY STAR fridge/freezer, may use 1.5 kwh/day-so you will have enough electricity to run your appliance for about a third of the day, or better yet, you can eat just 1/3 of the food or buy a solar fridge.

3arrow-iconQ. What do you think the future of solar panels will be? Will solar panels be usable in harsh weather like a blizzard? What is the hardest aspect to making and maintaining solar panels? If my school wanted to add solar panels, what would be the initial investment and how long would it take to offset?

A. I believe solar panels will continue to evolve and become a substantial solution to our energy challenges. I often compare energy with water - without water life ceases to exist and likewise without energy daily activities will grind to a halt. Everything we use requires power and with more, and more devices communities will consume more energy. Just look around your home and you will realize that most of the things you have in your house require energy. Solar panels are more efficient in a cooler environment because of air flow and cooling. When the temperature is high, solar modules can be less efficient. Gravity normally will force the snow accumulation onto the ground but in the instance where it accumulates, homeowners use several techniques like brushing the snow off the home solar panels with a broom, using chemical agents or simply letting the sun and mother nature melt the snow off. The breakeven point where capital expenditure equals total energy savings vary with location. Each state and county will offer incentives to install solar panels. Some locations can breakeven within 7-9 years while other states may take a little longer. The lifespan of a solar panel usually will run north of 20 years. Once you take into account inflation, I believe you can achieve a breakeven point anywhere between 12 - 15 years regardless of your location. When evaluating solar panels it is important to understand long term goals and what it is the institution and homeowner wants to achieve.

3arrow-iconQ. I have a houseboat on the river we dont live on it but stay a couple days a week on it it has a apartment size frige /freezer a small microwave and a 10 gal electirc hot water heater and maybe total of 10 12 volt lights in it how much solor power do i need to power the boat leaving the fridge on 24 hr a day i also want to be able to watch a 22in flatscreen tv

A. To size a solar energy system running off batteries we will need more information on the actual appliances and their technical specifications. The TV and the refrigerator will have their energy requirements within the instruction manual. If you no longer have the manual, the manufacturer website should have it online along with the specific energy specifications for your model TV or refrigerator. With that said, when you run something off-grid or powered by a battery you will need a solar panel, charge controller, batteries and inverter. Most household appliances can be configured to run off a battery. The challenge though can arise when running a larger appliance such as a refrigerator. Under normal conditions the refrigerator will not draw or use to much energy; however, when the refrigerator starts up (compressor) it will draw substantially more energy creating configuration challenges on the battery side. Without knowing the technical specification of the refrigerator, system configuration is just not possible because you need a basis to work with especially when you take into account costs. If however you have a DC refrigerator then putting together a system is by far easier because all you have to need is meet the requirements of the refrigerator. You can shop and compare DC solar refrigerators at SolarTown. If you are able to locate the energy requirements for your existing appliances, feel free to contact us again.

3arrow-iconQ.Where can I get incentives for purchasing a solar system for my home?

A. It has never been easier to get financial assistance from local, state, and federal renewable energy programs. Start by checking the Database of State Incentives for Renewables and Efficiency for the most comprehensive listing of incentives and rebates for both homeowners and business owners. Then look into what is offered by your state's energy office. A list can be found on the US Department of Energy's site: http://apps1.eere.energy.gov/state_energy_program/seo_contacts.cfm. We are also blogging about the incentives offered in several critical states and profiling homeowners who have taken advantage of these incentives. Check out the solar blogs on our community page.

3arrow-iconQ.Can I sell my excess solar power back to the utility grid?

A. Most urban utility companies now have a net metering program in place, requiring that your solar system be tied to the utility grid. This means that when your solar array produces more energy than your home consumes, the excess energy is pumped back into your local utility system rather than into a battery. Your utility will then pay you (usually at the same rate charged to you) for any extra energy you produce. If, however, you live in a region without a net metering program, you can either choose to have your solar installed off-grid (which would require that you have a battery system for storing excess energy) or opting for another form of renewable energy, such as a solar thermal system which remains cost-effective even without net metering.

3arrow-iconQ.Does a solar PV system require cleaning?

A. It is possible that over the course of time your solar panels will accumulate a layer or two of detritus that can negatively affect the efficiency of your solar electric array. Bird droppings, dust, leaves, and more can all diminish the capacity of your photovoltaic collectors' ability to absorb energy from the sun. Most regions receive adequate quantities of rain on a regular basis to clean solar panels and prevent lower performance. However, if you happen to live in a particularly dry region of the country, your solar panels may require more regular maintenance. If so, a simple wash with a soft mop or sponge will quickly get your panels to where they need to be to perform at peak efficiency.

3arrow-iconQ.How many solar panels do I need for electricity for my home?

A. The size of your solar photovoltaic (PV) system will depend on many factors. Asking yourself a few questions will help to give you a more accurate picture of your solar power requirements:

  • How much energy does your home use monthly? The US average is about 780 kWh, but you can determine this number by averaging your monthly utility bills for the past year.
  • Do you want to cover all or only a portion of your electric bill? Most homeowners find that producing enough electricity through solar to partially cover their bill helps financially, but if you'd like to product 100% of your own energy you will require a larger array.
  • Where do you live? How many solar panels you need will also depend on the weather patterns in your area, the latitude of your location, and whether your property is shaded by other buildings, trees, etc.

Please see our article Solar Panels Produce Financial and Environmental Benefits for detailed information on how to calculate the size and cost of your solar PV system.

3arrow-iconQ.Is it possible to power a household entirely by solar power?

A. Yes. Many people power their homes, especially those that are not connected to the grid, with solar energy. These systems are known as off-grid systems. Certain high load appliances, however, are powered by an alternative means of power generation such as battery backup. In the cities, people may choose an grid-tie system in which they may sell energy to the utility during the day and buy it back at night. This reduces the need for costly storage batteries. The house's need for electricity may be met in whole or in part by solar energy, depending on how large the solar energy system is, among other factors.

3arrow-iconQ.Is it possible to power a household entirely by solar power?

A. Yes. Many people power their homes, especially those that are not connected to the grid, with solar energy. These systems are known as off-grid systems. Certain high load appliances, however, are powered by an alternative means of power generation such as battery backup. In the cities, people may choose an grid-tie system in which they may sell energy to the utility during the day and buy it back at night. This reduces the need for costly storage batteries. The house's need for electricity may be met in whole or in part by solar energy, depending on how large the solar energy system is, among other factors.