Skip to content Solar Questions and Answers SOLAR QUESTIONS AND ANSWERS How To Solar Projects HOW MANY SOLAR PANELS DOES IT TAKE TO RUN MY HOUSE? By far the most asked question. The short answer is… it depends. Let me start by saying, I am glad that you are interested in solar energy and have taken steps to learn more about it. Answering these questions help us understand solar for all of its benefits and all of its limitations. There are some people who run their entire home via solar panels. It is not the norm, but it is a good starting point for conversation. So let’s dig in. This will be a broad overview. Solar can be very technical, here we will hit the highlights. There will be a little math, but we wont go into great detail. I will recommend products along the way. The goal is to inform and set expectations. First we will talk about GRID TIED Solar Arrays. Then talk about OFF GRID after that. At our house we do a little of both. Enjoy! Grid tied solar systems can be a smart choice when supplementing power for a conventional home. It’s a bit of an illusion because the home is not really running off of the solar panels, the house still receives its power directly from the power grid. A grid tied system feeds power back onto the power grid and applies credits. The home owner can use the credit right away or at a later date. If the grid power goes out, so does the solar array power. That means a grid tied solar array won’t save you from a blackout. It can only offset the monthly electric bill. Grid tied solar only works if there is grid power. There was a time when power companies would pay a generous sum per kilowatt hour (kwh) produced. Most of those opportunities have passed. Now homeowners can offset usage and may receive a small fraction for over production. It doesn’t really pay to overproduce. You are not going to get rich off of your solar panels. That leaves a bit of a balancing act between what is produced versus what is consumed. Most homeowners strive for a net zero, completely eliminate the bill with no overproduction. So… if the goal is to offset total consumption, we also need to know how long it will take to pay off the solar array and break even. This is the return on investment, or ROI. A quick back of the napkin approach to answer this question starts with adding the total kwh used for the last 12 months. Divide that number by 365 days. That will give the average kwh usage per day. Divide that number by 4. Four is a very conservative number of how many good hours of sun you can expect each day on average. You may use 5 or 6 hours if you live in a sunny place. The answer is how many kilowatts the solar panels need to produce in one hour of full sunshine. For example – Let’s assume your home used 6000 KWH last year. Divide that by 365 days and your home used an average of 16.4 kwh per day. Divide that by 4 hours and your solar array would need to produce 4.1kwh per good sun hour. Solar panels are not perfect, so add another 20%. You should end up needing about 5000 watts or 5kw of solar to offset your home energy use. Keep in mind you still have to pay your service charges. Armed with this information, we can now do some shopping. Let’s buy a pallet of solar panels. Usually there are 24 solar panels per pallet. The panels would have to be just over 200 watts each. Err on the side of efficiency and decide on a 225 watt panel, the inverters can be a 250 watt micro inverter. One inverter for each solar panel. 24 panels, 24 inverters, 5400 watts of solar. So we can now answer the first question. If you consume 6000 kwh/year, you would need approximately 24 solar panels at 225 watts each. But we are not done yet, let’s continue. How much does this system cost? You may have $4000-$5000 in the panels. Maybe more… maybe less, depends where you shop. Another $3000-$4000 in inverters. Again, depends on where you shop. General rule of thumb, it costs just as much for the install as the equipment. So your expense might be in excess of $15,000 or more by the time you are done. Less if you can do it yourself. These are very rough estimates. Now we have a ballpark idea of cost. How long to solar panels last? It is good to mention that solar panels can last up to 40 years. Most have 20 year warranties. It is a large investment up front that will continue to give returns for decades. It’s an investment that pays dividends as soon as you turn it on. How long does it take for a solar array to pay for itself? What is the ROI? Let’s assume you currently are charged 15 cents a kwh from the power company. At 6000 kwh per year you will spend $900/yr not including service fees, taxes, so on. That means ($15,000/$900=16.67) it will take 16 years to break even. That’s if you hire a company to do it for you. And if you do it yourself, and get a good deal on your solar panels, you could reasonably cut costs 35%-45%. Not everyone is cut out for installing solar generators. And, some areas require a licensed contractor to do the work. So best weigh your options. Below is some good deals on pallets of solar panels with compatible inverters,. Amazon – pallet of 24/250Watt Poly for 60 cents/watt Amazon – pallet of 26/250Watt Poly for 70 cents/watt Amazon – 6 pack of 250Watt Micro Inverters Amazon – 30 amp Disconnect Box Amazon – Complete 10kw Solar Kit Amazon – Complete 7kw Solar Kit What if you want to offset your consumption with production but don’t want to spend $15,000 or even $10,000 to do it? There are other approaches to the problem that can help. As with any process that needs optimized, first it is necessary to reduce costs. In this case, we want to reduce the load. The less energy used the smaller the solar array needs to be to offset the load. Time to do some sleuthing. Get a kilowatt meter and start measuring the output of the appliances in your home. The first step to designing a solar array is understanding the total load of your appliances. Plug any appliance into the meter and it will display how many watts the device draws. You may be surprised to learn your refrigerator is eating your lunch. Other inefficient appliances may include your stove, air conditioning, lighting, electronics, and other energy hogs around the house. Reducing costs and load may require a lifestyle change. It is something to consider. Ask yourself, do you really need a side by side refrigerator, or could you be happy with a small refrigerator and a chest freezer? You may be able to significantly reduce your energy use. Most folks start by changing their light bulbs out for low energy equivalents. You will find many energy saving tips and products on this website. Amazon – Kilowatt Meter (A must have) Amazon – Soft Warm Edison Bulbs 4w 40w equivalent Amazon – 160 watt Chest Freezer 7.2 cubic ft 1.4 amps Amazon – 60 Watt 2.5 cubic ft Refrigerator Amazon – 5000 BTU Low Voltage Start AC unit 400 watts Amazon – 48V Off Grid Solar Powered Air Conditioner Another way to reduce initial costs is to start small. Grid tied systems that use micro inverters are easy to scale. Solar panels daisy chain together in a “plug and play” fashion. If you want to add more on, you just plug in and keep going. I always recommend starting with six solar panels with the capacity to expand to twenty panels later. Six panels is enough to see the impact and get the infrastructure established with the potential to expand. A small 1500 watt system is less than $4000. “Start small, start today!” Amazon – Six – 250 Watt Grid Tied solar complete easy set up Once your grid tied system is in place and generating power for your home you will find that it’s pretty much maintenance free. Keep them clean, and they will produce renewable energy for years to come with no hassle. Grid tied solar is pretty convenient. Off Grid Solar is a completely different animal. Off Grid means there is no “pole power.” There is no electric company providing electric service. Off Grid usually means you are running off of batteries of some kind. Grid Tied equipment is not compatible with Off Grid Systems. Off Grid requires different gear like charge controllers and off grid power inverters. Frankly, most people will not run their entire home using a single off grid solar array system. Here is why. Off grid solar power is not as reliable as most home owners would like and battery requirements can be expensive. Off Grid Systems require periodic maintenance and can be temperamental. Most people would ultimately be unhappy with the overall performance and maintenance of an off grid solar array. But… if you need power and have no other options, off grid solar arrays can be wonderful to have. And if done right it can certainly be worth the effort. Let’s touch on off grid houses, or cabins, or whatever it is we are living in off grid. Another reason why a homeowner wouldn’t try to run everything on a single solitary off grid solar system is because it would be a single point of failure. If your system failed, your ice cream would melt and you would be in the dark without any power. So when you ask how many solar panels does it take to run my off grid house? Perhaps we ask …what do I need to run? And, how can I support that using solar? Let me explain it like this. When you go camping in an RV, the RV has a battery or two. Batteries run the lights and the water pump. Sometimes you may get an inverter for a tv or laptop. But the refrigerator runs on propane, because refrigerators take a lot of power to operate. Water is heated using propane, also for the same reason. The stove is propane. None of this stuff runs on batteries. Do you see where I am going with this? Appliances take a lot of power. With grid power, power consumption goes unnoticed. With off grid solar, it becomes painfully clear the heavy draw on the system. You have to plan for heavy loads accordingly. Consider this… To run a refrigerator off grid requires a bit of power. For the sake of argument, let’s look at the absolute smallest system you could set up and still be capable of running full size refrigerator. At the bare minimum, you will require 1000-1500 watts of solar and a good size battery bank just to support the fridge. The inverter would need to be at least 1500 watts and dedicated for the refrigerator only. Installed, a solar array with all the gear would run $4000-$5000, maybe less if you do it yourself. Below is a list of items that can help with this project. Amazon – Trojan 48 volt battery bank 8-L16re Amazon – 48 Volt PSW 2000 watt Inverter Amazon – 48 Volt PSW 5000 watt Inverter Amazon – Trojan 24 volt battery bank 4-L16re Amazon – 24 Volt PSW 5000 watt Inverter Amazon – 24 Volt PSW 3000 watt Inverter Amazon – 12/24/48 volt MPPT Charge Controller Amazon – Solar Panel MC4 Wire Connectors Amazon – MC4 Solar Connector Wire Crimpers Amazon – Battery Lug Wire Terminals Copper Amazon – 10 Ton Hydraulic Battery Terminal Crimper It’s all about the details. Details, details, details…. Large appliances have large requirements. The larger you build the system, the more it will cost to build and maintain. It always takes more than you first think. These are things to take into consideration when designing an off grid home. You may want to reconsider what runs on solar and what uses other power sources. For example, I can run a refrigerator on propane, but I can’t run my laptop on propane. If I can eliminate large appliances from using electricity, the solar array will be more capable of supplying power to the necessities that absolutely require electricity with less maintenance and expense. Check out this article Designing an Off Grid Power System. It’s also important to know that unlike grid tied systems, off grid systems are not scale-able. Once you build a system it is difficult to scale up. To be more specific, it has to do with the batteries more than anything. Once you “marry” batteries together, it is unwise to add more batteries to that system. The fact is, when you add new batteries to old batteries (or different sizes/brands, etc.) they work against each other and destroy each other, literally. Read more about this in How to set up a Battery Bank. For this reason, it is even more important to properly size your off grid systems from the beginning. Adding more storage later will not be an an easy option. Get your batteries right from the beginning. “It’s all about the batteries!”, even more so than the panels. The solar panels just charge your batteries. Your batteries are what is really powering the system. If you go cheap on the batteries you will not be happy later. More about right sizing…because it’s important. Solar is pretty reliable, until it fails. It’s not the same as being on the grid, off grid solar does not supply consistent power. You can run out of juice. You have to plan for days when there is no sun. Your devices may have to run for days on batteries alone. Batteries don’t last forever. You will need to replace them. The harder you cycle your batteries the sooner you will need to replace them. The best system is one that stays fully charged and does not drain the batteries dead all the time. Power cycling will kill your batteries. A Power Cycle is when you quickly discharge and then quickly charge a battery. A way to avoid power cycling is to “Right Size” the system. In order to Right Size you either reduce the load or increase the size of the system. Doing this will reduce the frequency of failure. A properly “Right Sized” system will have more up time and be less expensive to maintain. If you are running off grid, you should gravitate toward several smaller solar arrays, each with their own purpose. You most likely will have one large system for a large appliance. One medium system for electronics, and lighting. And one smaller charging station for workshop, tools, and other intermediate needs. Each has its own design to serve a specific role. You may also have a water heating system that works using solar heat, propane, or wood fuel. You may choose to cook using wood, propane, or solar induction…depending on your resources. I personally use and recommend the items below. Amazon – 3.1 GPM Propane Water Heater Tankless Amazon – Tankless Propane Water Heater Camping Amazon – 500-1300 watt Induction Stove Amazon – Lodge Double Dutch Oven for Induction Amazon – Induction Approved Cookware Amazon – Induction Approved Coffee Pot There is no “one size fits all” solution when it comes to off grid power. Again, you can build one big solar array, but it would be expensive and may not be practical. When one battery goes bad, they all need replaced. That is expensive. When the system goes down, everything goes down. That is frustrating. I’ve seen people do it, and I don’t recommend it. Design smaller systems for specific tasks. Building smaller systems to run specific items is so much more fun. And if something breaks, and it will, your whole world doesn’t come crashing down. Its nice to go out into the workshop and work on a project. Come back the next day and its all charged back up and ready to go for another round. This is covered in the Solar Workshop article. Run your electronics off its own system. This way we can watch movies all night, charge our phones and portable devices. Listen to music without compromising critical systems. This is covered in How to Design and Off Grid Power System. Run your freezer on its own system. Covered in the article Solar Refrigerator/Freezer. Meanwhile your other systems won’t be compromised because they are independent of large appliances. When it comes to Off Grid, it comes down to design. Be deliberate when designing your systems. Critical systems need more support. Noncritical systems don’t need as much infrastructure. Try to keep things separated to avoid broad failures. Break it up a little bit. Do these things and you will enjoy the benefits of solar power for many years to come. In conclusion, and to answer the question, how many panels does it take to run my house? A lot. Start with six ;). If you are not making any changes to your lifestyle, go grid tied. You can always add more on if you need too. If you are off grid, build smaller systems to support specific needs. You will be happy you did. Be efficient. This site is full of ways to be more efficient. I hope this was helpful. We love hearing from you, Please leave comments. Jason Back to Home Page One Reply to “How many solar panels does it take to run my house?” admin AUGUST 30, 2019 AT 11:52 AM testing 123 Log in to Reply Leave a Reply You must be logged in to post a comment. Proudly powered by WordPress