Step 2: Load Calculation

Knowing how much power you need is the first step to planning your array. Since solar panels are measured by how much energy they can absorb, this will tell you how many panels to buy, how efficient they need to be, and (perhaps most importantly) how much space you're going to require. Don't worry, this process doesn't require more than your utility bills and some basic math.

First, check out your utility bills to see how much energy you usually consume. Typically, this number falls around 900 kWh each month, but it varies wildly from household to household.

Next, find out the "peak sun hours" of your area. This number is a measurement of how sunny someplace is. On the West coast, this number is between six and seven hours; on the East coast, between four and five. The National Renewable Energy Laboratory has an excellent insolation map. Follow the link for Photovoltaics under U.S. Solar Resource Map.

All that's left now is to do the math. At 900 kWh each month, you're burning 30 kWh each day. Divide this number by the daily peak sun hours. If I use 30 kWh in a day, and there's five hours of sunlight, then I need 6 kW worth of panels to match all of my usage.
<p>Good project ! Actually we can <a href="http://batteryrecover.com" rel="nofollow">recondition any batteries</a> and charge by solar panel. Thank you man !</p>
<p>I am NOT interested in hooking a solar array to the power grid. I want to convert most of the equipment in my home to 12 Volt. Most Motor Home equipment can run on 12 Volt. What do I need to consider?</p>
<p>Great, beats the pants off the solar hot water system we built 1n1970 here in the UK.</p><p>Anne</p>
<p>Nice guide. I built my own 6.3 kWh ground mount array.</p>
<p>Can you give a good option on this..<br>I have an existing solar set up with 1500 Watts Peak total. I'm <br>contented on its performance and was happy viewing my electric cost <br>slashed by few hundreds. <br>My plan is to add another 4 panels or 1000 <br>watts peak to the existing solar set up I had and I'll using another set<br> of solar panels. <br>My<br> question is as follows: Assuming all is well as planned, Can I connect <br>the 220 volts output coming from the new separate inverter of my new <br>1000 set up to the existing 1500 watts peak set up inverter output? <br>My <br>other question is assuming it will work, will my output Voltage of 220 <br>Volts stays at 220 Volts while the over all Amperage of my self generated<br> power coming form the 2 sets of 1500 Watt Peak and 1000 watt peak will <br>increase? Thanks a lot and kindly email your answer to <a href="mailto:philtronics@gmail.com" rel="nofollow">philtronics@gmail.com</a>. <br>Thanks again ED,...</p>
<p>Awesome post! I honestly love the idea of solar and am thinking of getting some panels myself. My only problem is that there are so many different types of solar panels out there. I recently learned about flexible solar panels from this website.</p><p><a href="http://www.bestsolartech.com/best-flexible-solar-panels-reviewed/" rel="nofollow">http://www.bestsolartech.com/best-flexible-solar-p...</a></p><p>My only question for you is are these type of solar panels good to use on a house? Or are they mainly used for things such as RVs and boats? They seem like they would be a good option, but idk the pros and cons of each. Any guidance would help!</p>
<p>If you want to make your own eco tool yourself just look for Inplix website. There is all you need to make it :)</p>
<p>Those who are interested in a convenient step by step filmed guide, visit: http://www.energybilldown.com/diy-home-alternative-energy-solar-system/</p>
How can i get solar when my power comepny will let me tie in to them
<p>Just do an OFF GRID solar install. If you use led lights and use conservative power, you can get by nicely on a 3000 watt system. I myself don't understand why people go solar and still tie to the grid, if the grid is down, you still have no power, however with an off grid battery bank, you do. </p>
<p>It's because off-grid solar power costs from 5-10 times what it does from the power company per kWh. There is never a ROI due to battery cost (initial and replacement cost). With grid-tie, you can have an ROI.</p>
<p>I disagree, I have saw evidence the power companies always find a way to steal back whatever money you would of saved. There is a return on your own system if you do it right. There are solar panels that have 25 to 30 year warranty, and they should still produce power even after that. If you use Edison type batteries they will last decades, and when they go bad you can just refresh them. Once you have them paid for you no longer are paying for power anymore, and when everyone's power goes out, yours will still work. </p><p>There are in fact people that collect the original Edison batteries, and believe it or not some of them still work even today. The problem is people take the cheap battery way out and those batteries don't last. Buy good batteries and cry once. There is a company that offers the Edison type batteries for sale brand new, and that is the route I would suggest going. Buy good solar panels and Edison type batteries, and cry once. The only thing you will probably have to replace is he battery acid and maybe your inverter somewhere down the line. </p><p><a href="https://ironedison.com/nickel-iron-ni-fe-battery" rel="nofollow">https://ironedison.com/nickel-iron-ni-fe-battery</a></p><p>Read up on these batteries.</p>
<p>People (like me) go with grid tie because net metering makes it economically a win (unless you end up in a bad lease, PPA or simply over-pay). I installed my 4 kW system myself for $8000, the IRS gave me back 30% of that and my $1200 annual power bills are now slightly negative :-) I've paid no power bill for two years now, and it's a pretty good feeling, and slightly weird to have the power company owe me money. </p><p>If I had batteries it would be very different. With FLA or AGM batteries cycle cost at roughly $.50 to $.80 per kWh, my power cost would more than quadruple. SO there is no way I would have a battery system. If I needed backup power, I would just buy a generator. </p><p>At work we install large off-grid solar battery systems, but not with NiFe because the ones we looked at had high internal resistance and low charging efficiency, which would require much larger arrays. The people we have talked to that do use them say they are a PITA to maintain and take a lot of water, and that they wouldn't buy them again. At least they don't suffer from sulfation. I think they are worth watching to see if they improve, but I wouldn't suggest using them now unless you like to fiddle with batteries.</p><p>If you have a system of your own and would like to post your experiences with it, by all means do so, I've love to hear about it. I value advice based on first hand experience much more than advice based on what someone reads on the internet. </p>
<p>&quot;If I had batteries it would be very different. With FLA or AGM batteries cycle cost at roughly $.50 to $.80 per kWh, my power cost would more than quadruple. SO there is no way I would have a battery system. If I needed backup power, I would just buy a generator.&quot;</p><p>So you think buying a generator that takes fuel and maint cost is a better solution than buying NiFi batteries once that don't take fuel, lol. Why keep talking about the expense of FLA or AGM batteries when that was not what I suggested? If you need backup power you can't use a generator tied to the grid, unless it's off grid only. </p><p>There is nothing wrong with NiFi batteries, and they don't need improvement. Sure you have to add water, big deal, at least you only have to buy them once. Unlike the FLA or AGM batteries you keep talking about which you will be replacing every 5 to 10 years, you only need buy NiFi once. Since you can drain over 80 percent from an Edison style battery and it don't hurt the battery, you don't need as big of a battery bank as with the others, which saves money even up front. </p><p>Yep, the IRS will give you money back on your system whether it be on or off the grid. </p><p>You want a story from someone who uses them, well here is a good one: </p><p>http://www.nickel-iron-battery.com/Nickel-Iron-Solar-Chicago.pdf</p>
<p>That junky install makes me glad I am not one of his neighbors. The fact that his system is 12V should tell you something. </p><p>&quot;So you think buying a generator that takes fuel and maint cost is a <br>better solution than buying NiFi batteries once that don't take fuel, <br>lol.&quot;</p><p>Yes</p>
<p>I just read an article where he says &quot;</p><p>&quot;...And I<br> was having trouble because I wanted to vacuum but there were no sunny<br> days. I can't run my vacuum if I want to have power in the<br> evening.&quot;</p><p>So he's having to carefully conserve so much that it has changed his lifestyle. Meanwhile, with my grid tie system, I'm able to run the A/C, hairdriers, TVs, anything I want, and still spend no money for power. Looking at his roof, my system is about 1/3 of his size, physically. There is one difference: If the power goes out, I have no power, but he does. To me, having all the power I want, when I need it, for free, I can suffer through an outage once or twice a year. So even if he didn't have any battery cost whatsoever, I would never advise anyone to do what he did, unless they are just really into it. For him, it's a hobby, a labor of love, and all that. That's great for him, but it's not what most people are in this for, they just want to save money or get off the grid without understanding the ramifications. Even if there WAS a ROI, you'd have to value your time at zero to realize that. </p>
<p>You missed the point of why I showed you that article entirely. The point was how old was his batteries and they still worked. I get it, you are only in this for the money. Some of us though desire our own power anytime we want it. It don't matter what kind of solar array or battery bank you get, if it's off grid and you are not a millionaire, then you probably will have to make a lifestyle change and learn to not waste power.</p><p>Of course you can use power anytime and as much as you like when the power is up, you are doing what everyone else is doing, which is using a giant NiFi battery bank to store your power at the power company. This guy used a bunch of different mixed size solar panels with old tech, they make better panels now that work good even in overcast days. Of course, your panels won't make much either on those days. </p><p>There is a video on youtube where a guy from Cali puts in a massive grid tie system, and his power bill actually went up. The reason it went up is the power company would only pay him for so much power a day, and do what they do best, dump excess power back into the ground which is wasteful. </p><p>I agree with you, if your only goal is to knock a little off your power bill, then just do a grid tie system. If your goal is to have power no matter what and be off grid though, then you should buy Ni-Fi batteries and not waste power. I am on the grid right now till I sell this house and build my off grid house, but I been researching this for many years. My power bill is only around $50 a month, and that's because I don't waste power. If I walk out of a room I turn that light off, etc. </p><p>In my off grid house I will be building, it will be very efficient, and won't need much power because I won't be heating and cooling with power, I will be using thermal mass and sun instead. There is nothing wrong with a 12 volt system either, and most accessories and inverters are 12 volt and can be sourced anywhere. With a 12 volt system you can use anything from an RV. With a 24 volt or 48 Volt system your system uses less gage wire at the cost of being limited in hard to source components. Here read this link: </p><p>http://www.treehugger.com/sustainable-product-design/big-steps-in-building-change-our-wiring-to-12-volt-dc.html</p><p>With 12 volt you can always use your car as a backup power source. I keep a 450 watt invertor in my car, it will run most smaller things, and cost me about $40. </p>
<p>12V is OK for small installations like campers and RVs, but I wouldn't use it for a system like this because of the huge currents and massive wire needed. His inverter is 2500 watts, and with 12V, I think that would need 4/0 cable. He's going to have over 200A going into the inverter at times, which is dangerous in a DIY system in my opinion. He could have 1/4 of that with 48V. </p><p>Grid tie can eliminate the whole bill, not just a little. Well, I need to qualify that; they do charge $10 a month for the privilege of using the grid, but I don't mind that too much because they are, in effect, providing me with a huge unlimited battery that I never need to maintain. </p>
<p>Full spectrum i am with SteveD113 on this, but the sysytem greatly depends on your needs, saving money or bing free of utility companies. I personally have nor researched Ni-Fi, but it last 100 years then why is every phone and toy not using them. I personally have a 3kw hybrid System, i can fee the grid and save money, but when the power goes out i have 4 x 105ah deep cycel batteried to run the lighting and a couple of things.</p>
<p>Actually, you save money by being fully off grid too, because you no longer have a power bill ever again. Once your equipment is paid for, power is free, and if the grid goes down, yours still works because you have a complete stand alone power grid, unlike grid tie. </p><p>&quot;I personally have nor researched Ni-Fi, but it last 100 years then why is every phone and toy not using them.&quot;</p><p>The batteries are not sealed, and they are heavy. You have to add water every month, and they are around 1.2 to 1.5 volts each, so you need 10 of them just to make a 12 volt battery. If you will research them, you will find a certain company bought the original tech back in the day and sat on it. The batteries can last 100 years, and it's been proven some already have. </p><p>&quot;I personally have a 3kw hybrid System, i can fee the grid and save money, but when the power goes out i have 4 x 105ah deep cycel batteried to run the lighting and a couple of things.&quot;</p><p>Well that is great, but most grid tied users don't have a battery bank, or a safe way to isolate their battery bank from the grid. Another problem people run into is trying to get the power company not to make you take power at peak rate times, and sell it at off peak times, which greatly makes a difference on how much money you actually make or save. At 3Kw, it just sounds like you are saving a few bucks, and I understand if you have more power than you need, or if you need more power hook into the grid. </p><p>I just think without an isolated battery bank it doesn't make a whole lot of sense, since if the Power Company's grid goes down, so does yours without the bank. </p><p>The reason I say just completely divorce yourself from the grid is, I have personally caught multiple power companies completely ripping me off over the years. One time I was in the NG, and was gone 15 days that month. My power bill tripled that month, even though instead it should of been a fraction of the month before, and that's just one example.</p><p>Another thing of concern is the radiation from the ZigBee transmitters on the smart meters, and the spying on us.</p>
<p>If you use Edison NiFi batteries you only have to buy them once it's a proven fact that people own the original batteries from the 1920's and those batteries still work. So you are wrong, there is a ROI, because once you got your system paid for, you always have free power. Thomas Edison said the NiFi batteries will last 100 years, and he has already been pretty much proven right as there are batteries almost that old that still work fine. </p>
You said &quot;the power company will let me tie into them&quot;, so it depends on the purpose of the solar. If it is to save money by lowering your bill, you want a grid tied system. You can do that if your power company allows it and allows for net metering. If you want to have backup power for when the grid goes down, the cheapest way is with a generator, but solar can be used if you don't mind paying 5-10 times the cost of grid power.
Just put your solar power off the grid, you can either go fully off grid or just have your solar off grid and on it's own wiring. An example would be to take just your refrigerator and lights off grid and on their own circuit.
<p>Any tips on wiring the solar array to the house wiring?</p>
<p>I made a video explaining how to select the right wire for your solar system. https://youtu.be/89u8R_aUFO4 </p>
<p>Amy, your contributions on solarpaneltalk are great! And I think your youtube videos are great too. </p>
<p>You can take instructions from inplix website :-)</p>
<p>I was wonder if you have any information on adding a house battery for when the grid goes down. I realize it's not as economically advantageous as the original solar installation. biggest ques</p>
<p>They have really oversimplified a complicated process. If you go playing with your electricity to your home, you will likely burn your house down. And if you believe the electric company (who currently has a monopoly for your business) will pay you a premium for you to generate electricity, then you are very naive. </p>
<p>actually it is simple, the hardest part was the paper work to setup net metering. Which was worth it. The $1000 check at the ends of the year is great. </p>
<p>actually it is simple, the hardest part was the paper work to setup net metering. Which was worth it. The $1000 check at the ends of the year is great. </p>
Hey the... Love what you do! I have a anker 2nd gen astrole 5 external power pack with dual usb out put and micro usb input for charging. I want to use solar lawn lights to charge it but i dont know much the anker or solar so could you plz help me out?
<p>This may come across as a slightly odd question but i have a thatched/grass roof house and was wondering if solar panels give off any heat that may cause a fire risk to the roof?</p>
<p>I saw these in Mexico. I would stay away from high voltage systems, but a small system properly installed should not be a problem.</p>
<p>Thank you. Been looking for something like this. </p>
<p>Hi,</p><p>I'm glad that I found this site! Yes, the price of installing pv system is still gradually falling, our saving are increasing, and that's great. I hope that people will turn to being more environment-friendly. To all reading it: we have to start being more responsible for our environment and use renewable sources of energy. It's really not that hard to design and do all the installations, especially now, that we have better tools to do it, like the apps ( this one for example <a href="http://easysolar.co/" rel="nofollow">http://easysolar.co/</a> ) that practically do everything for you, design, calculate the azimuth, provide you with simulations and financial analysis and save your time! We have to start to make good changes... Oh, and good luck to all beginners!</p><p> <br>Elizabeth</p>
<p>Great instuctable! A few points:</p><p>If you live in a HOA, be sure to check your covenants for solar panel restrictions. Mine prohibited them; three of us proposed and got passed new covenants with defining approved installs. Not as good as all balls-out, but sufficient for a good install. BTW, this cost about $5K so try to roll this in with other changes the board has been talking about, plus be ready to go door-to-door to get people to say OK. Took us a year and 2 months - we have a small (600 house) subdivision. YMMV.</p><p>BE very sure to check with your local power provider AND your state regulator. Our local company (GA Power) won't buy back power because GA prohibits it - not that they would unless pressured by the state. Next on the list: Petitioning our local state representative to support a bill allowing it (it has failed 4 times in the past 5 years - but like all things political, squeaky wheels).</p><p>If you use am installer, make sure they can provide you with workman's comp and liability insurance proof AND call the companies and verify the policies are still in effect. Both of these are expensive and easy to cancel - if you don't check you could end up paying for a hurt worker for life or fixing damage.</p>
Thanks this is the best I have seen I surfed the web and found such bewildering stories that it ends in frustrations
The Free Energy shop is developed for people who love nature and a sustainable way of living. At this moment we offer wind, solar energy and electronic gadget products. <a href="http://www.freenergyshop.com/" rel="nofollow">Solar Gadgets</a>
But I stated with hands on just like Solar Jon is showing, <br>I use a weed-eater motor on my project, where I live wind is only good during hurricane seasons. <br>Then moved to Solar power. I bought kits off EBay, 200 watts of 0.5 volt, 3.25 watt per cells. Looks easy, works out, after you add the weather proof housing, harden glass; remember rain, hail, and snow. It is not cheaper. I did build the first 100 watt panel, yes it works. I resold the rest of kit back on EBay. Let us face a few facts, Big Company&rsquo;s buy in Big Lots, like Wal-Mart! Small stores cannot compete. <br>Real power, that which is to supply a real house, like in Jon's photo, is not cheap, but you can do it. The cost is really cheaper with the Store bought Solar Panel then the do-it-Yourself kits. I know that sounds silly and just plain wrong. You can buy UL listed, made in the USA solar panel with big boy ratings, like 280 watts @ 35 volts for under $1.35/watt shipped to Your house. I know this because I bought 24 of them last year. You can save Big if your install yourself. But you will require a licensed Electrical guy to connect up to the gird. No city government wishes to have just anyone connecting into the grid. That can get you killed, blackout and neighborhood. <br>Yes, Zero Rebate if you want to use homemade cell, or anything Not UL, but only if your On-grid. <br>A 5 Kw system retails for $25k installed in the New Orleans area. My 8Kw cost $12k in material; mounting will be about $800. On this UL proper installed system the Fed will credits 30% if installed before 2016. Most cities and states also have Tax credits. These are 20 to 30 year systems. Do the math. <br>No I do not work with, own stock, have a brother or lover working for or any other interest in www.sunelec.com they are surely not the only folks either. Where there is one, there are many. You can click and see if I&rsquo;m jerking your chain or not. <br> <br>This will either get you hooked or not, I hope everyone wishing to live on less oil the very best of luck with what every project you do, have fun, and be safe. You can hook up any thing that makes electrical power with micro convertors, see EBay. From 500 watt DC to house wall plug. Under $100, search &ldquo;Solar inverter&rdquo;. <br> <br>Thanks Solar Jon, for hopefully hooking a few more people to Green Power movement. <br> <br>Best Regards <br>Big Jake <br>
Here in Orange County, New York, the local Utility provider is Orange &amp; Rockland Utilities. A Doctor here solarized his home and they only gave him pennies for his electicity that he sent back through his meter to the grid. As usual a Large Monopoly sticks it to the consumer when he tries to save energy and avoids their price per Kwh. As we speak, they are asking for another increase in rates! How much greed can there be?
your buddy will break even at some and then really stick it to the util... when it comes to feed in, it really depends on location and what homeowners want to achieve. If i'm not mistaken ny has netmetering so your friend will be saving a lot of money from whatever the solar energy covers... the energy he consumes from the utility on the other hand will continue to go up at the discretion of the util overlord :(
All the more reason to go off grid like my Son. He lives in Vermont and he powers his house on 2 large panels, I don't know the output, and on cloudy days he has a generator works off the containment pond with 400 feet of head. If you are an Energy Hog you will need to spend a lot of money for panels.<br><br>No Grid Tie Here !
Hmm...much like the banks who pay you a measly interest rate and then stick it to you many times over when they issue you a credit card. Maybe the doctor should start selling his electricity to a neighbor.
NY state has a pretty good program but I try to avoid the craziness of business polices and such... More headache than it is really worth. The best way to go is to eliminate the higher cost of energy we pay to utility provider, which is why I love alternative energy. It empowers homeowners and gives them the right to choose what they want to pay. <br><br>Thanks for the feedback
big corporations are always evil...(stares at oracle)
Hi!good day to all,i would like to say its very very good if you have solar power grid,becouse it to helpful in our solar nature for the future of our children and stop air polution,and being like a distroyer..build your own solar energy system..thanks to all.....
And what happen when is raining, doesn't affect the panels? or the connections?
when it rains, energy production will be minimized but the panels themselves and connection will be safe because the connection are water tight. solar panels and the wiring are all made to withstand weather conditions to minimize and prevent damage from the elements.<br><br>Energy production will always be there but just take caution when selecting the right brand for the solar panels. <br>
hi there everyone, i have a series of 3 5v solar cell 5w each. and it could produce 15v or higher on a good sunlight. but my concern is my batteries, i know they're small and can easily be charged. so i'am worried about overcharging it and eventually wear itself. Can anybody give me a charge controller circuit that will not allow flow of charge from my solar cell to my batteries when it's full.<br>Thanks alot guys1

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