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Building my first solar system

Discussion in 'Off Grid Living' started by Kingfish, Dec 24, 2010.

  1. Kingfish

    Kingfish Self Reliant

    Hi guys, Nadja sent me here. Hope to find many answers. I would like to build a solar/wind system for removing my home from the grid forever. I would like a 120 amp 240 /120 service Comparable with what I have now on the Grid. I realize I may have to settle for less and that new appliances will help with this. I am now heating with wood but would like to have a geo thermal unit installed and use the wood stove as back up. I am just starting to purchase components for this sytem and need much advice as I build. Thank you all in advance . Kingfish
  2. overbore

    overbore Monkey++

    Son, We all have to start somewhere so here are my suggestions and I am copying from my files:

    1 The first step in deciding how big your system needs to be is to determine how much power you need (get the wattage ratings for each device and multiply by how long you run those each day).

    Using that total, determine how many amp hours you need in batteries, recalling that you shouldn't discharge your batteries over 50% for long life (70% mentioned above would be better). Remember, watts = amps x volts, so amps = watts/volts.

    2.How much storage, in amp-hours, do you need? This will vary with the application and what part of the country you are in. As a rough rule for home solar systems, the total battery capacity (in amp-hours) should be three to five times your daily usage. 3 days is usually sufficient in most of the sunbelt states, 4 in most of the Midwest, in the East and Northwest, 4 to 5 days is better. If you are in a good wind area and have a wind generator, you can probably cut this down a day, but wind turbine output can be highly variable in many areas.

    [FONT=&quot]For backup power systems (UPS), the total capacity should be enough to cover about twice the longest anticipated outage. To figure how many amp-hours storage you need, take your average daily usage in watts and divide by the battery voltage. For example, if you use 5 kwh (kilowatt-hours) per day, and have a 48 volt system, then dividing 5000 by 48 gives you 105 AH. Since you do not want to discharge the battery more than 50% in most cases, you would need 210 AH. If you want to keep running for 4 days of bad weather with no sun, multiply that times 4, which gives you about 850 AH total capacity. UPS and backup power systems are the same, except that the times are often in hours instead of days.

    How many Watt-Hours in a battery?: Watts are pretty simple - it is just battery voltage times amp-hours. A 12 volt 105 AH battery can supply (under perfect conditions and to 100% discharge) 12 x 105, or 1260 Watt-hours (1.26KWH).

    3. If I haven't scared you off by now, visualize that your batteries are going to be the sole source of home electric for an off-grid system. Those batteries must have a means to power the home-inverter and means to be recharged properly. I use main power as my primary recharging source, a standby generator for standby power and standby recharging and shortly will connect solar panels for emergency charging plus an emergency lighting-freezer power bus . Your experience with batteries and reduced consumption will modify how you view the equipment but keep in mind your budget and time frame as the initial costs are not exactly free. Do not scrimp on batteries, Check out Crown Deep Cycle batteries and high quality inverter chargers.

    If you want more ask and I will share.

    Laus Deo

  3. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    I'm curious about your planned geo heating system. Is it fair to assume you will link to ground water via a drilled well?
  4. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Planning now, for what you will be using later, is your most important issue at the moment. Overbore is giving good advice. Your ultimate power backup also needs to have a Petroleum based Power System for when the sun don't shine, and the wind don't blow. When you get that far in your planning give me a ping, as I have 3 decades of experience generating ALL my own power. Just a NOTE here, If your planning to "Save Money" by not using Grid-based Power, you had best rethink your premise for that idea. Grid-Power is the cheapest form of Energy in existence. Converting to alternative energy sources will have a fairly LARGE investemnt of Capital, REQUIRED, where an easy Grid-Connection has a very small Capital Investment, if any, at all. State and Federal subsidies can help with the payback, but it will usually be at least a DECADE, before the Capital Investment pays for itself.
  5. TnAndy

    TnAndy Senior Member Founding Member

    Unless you have a really deep checkbook, you better stay with wood heat.
  6. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Welcome aboard Kingfish. Glad to see you found us here. Well, as overbore stated and the people here before me, it is a daunting, but possible task ahead of you. However, it will also be expensive. If you are the handyman type you can save ton's of money by doing a lot of the labor yourself. How many people in your family ? Are any of them small kids or even worse .... teenagers ? OMG what a dirty word when it comes to solar living off the grid. What will you need to use elec. wise on any given day and more importantly during the evening or early morning hours before and after old sol has gone down. ? How much wind is generally avail on a given day ? Ballanceing out your solar system with wind if appl. would really help out a lot. You learn to be a power czar when it comes to lights left on, wasted time with the tv. on and no body watching etc.

    In other words, you have to rethink your entire living arrangements to some degree. First of all, no forced air heating or elect heating. Any and all elec heating elements require way too much power and will quickly suck your system dry which really means leaving you in the dark. You will need propane or nat. gas clothes dryers and a standard wash maching. I see you already mentioned you have new appliances. That is a really good thing. Refers are great, but you now need to amp shop rather then color shop. Ice makers can also be bad. Mixers etc are not a problem as you don't use them all the time. Part time things like that will not hurt you. Waffle irons and Geo. Forman type grills will kill you. Vacum cleaners etc, fine during the day as you would never want to use them at night as you are then living off your batteries which is where you have stored your excess solar during the days.

    In order to help fund your solar system, you could implement this type of a system. First , attempt to sit everyone in your family down at the table (all at once) Lol and then tell them how this works. From this point on, anyone leaving a light on when not needed will be charged $1.00 per offense which you will put in a large jar etc. After a week or two , it should be quite full. And no cheating, that means you too. By the end of about a week, you should start getting the idea , more importantly, your family is beginning to get the idea. Anything left on un-attended results in a $1.00 fine. Make it like a game but you have to be the czar or it won't happen. Nadja
  7. overbore

    overbore Monkey++

    Frienssm bove gave you great info!!

    Running any heat resistant cooking device (like a toaster) won't run long on a single 200AH battery.

    The best scenario is going to be not using any heat resistant devices (coffee makers, toasters, hair dryers, etc.), and size your system accordingly. In fact, efficiency is always much cheaper than additional power generation, yet still gets the job done.

    So the first step in deciding how big your system needs to be is to determine how much power you need (get the wattage ratings for each device and multiply by how long you run those each day). After you give us that data, we can point you to some specifics.

    My prime experience, apart from flying Boeings for a living, is living aboard a motor sailer. Self installation and repairs become necessary.

    Laus Deo
  8. Kingfish

    Kingfish Self Reliant

    Thanks a ton for that info, First off Im 52 and have built two houses and wired both of them. I even wired my last service panel and passed inspection with flying colors. I understand 120 and 240. pretty well. You have not scared me off in the least. My goal is to build at least a 100 amp service that will have at least a 5 day run time between charges if needed. That means Ill need an inverter that will handle 50 to 60 amps per leg. I am working on getting a watts total per day . After the holidays I will be adding things up. but we will be losing a couple of huge energy eaters here by winters end.

    But I have many other questions to ask. Is there any reason I cant build my system in sections? Meaning several small panels that handle different operations like pump and freezer, refrigerator and dryer, lights and shed, Or does it all have to be one big inverter with one huge battery bank and one charging system? Kingfish
  9. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Good morning and Merry Christmas Kingfish. Well , you could build your system in shifts or sections , but it would cost you much more money in the long run. Lets look at it like checking accounts. Do you have a seperate checking account for each bill, groceries, gas and misc or do you have just one account and use it for everthing ? Why ? Solar works alot like the same as your checking account. Why pay for say 10 different checking accounts, buy 10 different sets of checks and even worse have to find the right one everytime you want to use it ?

    So, your water pump would only need one decent sized panel to charge what 4 batteries ? Well it would also need its own charge controller and invertor if you would be running an ac pump. Are you useing the water pump non stop ? Not likely , so aside from the short chargeing cycle needed to bring the 4 batteries back to life, now the charge controller is going to "dump" the rest of the solar during the day , when it could in fact be joined with other solar panels and charging the complete house system. I hope this makes some sense to you.
  10. Kingfish

    Kingfish Self Reliant

    It does make sense to have it all in one system. I just wish I could do this one step at a time. Im looking at a 240 inverter

    Magnum Energy MS4024AE 4000 Watt 24V Pure Sine Wave Inverter Charger

    This thing puts out enough power to run my pump even during startup. My well is 90 feet deep and the pump is is 1 hp franklin 20 gpm 240 pump. I am not finding many 240 inverters out there. Does anyone make a bigger 240 inverter? Im looking for one that would supply up to 50 amps per leg. This Magnum puts out 30 per leg and at 2159.00 not really that bad. I am thinking Ill need one twice as big or more than one.

    And you are correct, Ill only run my pump when I need it. The other things like refrigeration and freezer will need more constant power. Im looking at Sun frost and other energy star products for these items. The electric range is probably going to go down the road in favor of something else. Hot water heated by wood in winter and solar in the summer time. I have also heard of some 20 year batteries. I have not found these yet. Kingfish ps merry Christmas and good morning.
  11. Nadja

    Nadja RIP 3-11-2013 Forum Leader


    Well, I would not recomend the "magnum" inverter personaly. I and all my surounding neighbors all use either xantrax (trace) or out back inverters for all our needs. You can buy a sinewave inverter from either, have excellent results and also add about 400.00 to that and buy a "step up transformer" witch will give you the 220 volts needed for your well, or you can put two matching inverters together piggy backed if you will witch will also give you 220 volt. You with your 90 ft well, have not nearly the problems we encounter with our wells which average between 300 and 400 ft minimum and still everything works just fine.

    Yes , the electric range will have to go and soon. However, cooking with propane is much better the elect anyway. Better heat and control .

    For refer's their is a really nice 20-23 cubic ft model that only draws about 3.2 amps by "LG" It is a side by side refer and then a very large bottom drawer freezer. My neighbor has one and loves it to death. I use a hot point that is only 4 years old now and draws abouat 5.2 amps. Will soon be changing that one out for sure.

    For hot water, although my reg propane hot water tank is great, I will save about half of my propane bill per month when I swith next year to a "tankless" hot water heater. They only run when you need it. Great money and propane saving device, which several people around here have already swithched to. I usually wait until several other people buy the new things and try them out for a year or so , before I invest my money in it. I don't have enough of that to just throw it around... SS doesn't pay so well these days.
  12. overbore

    overbore Monkey++


    I am also using a Xantrex but suggest you sign up with the forum that has experts and expert advice: Solar Electric Power Discussion Forum by Northern Arizona Wind & Sun - Powered by vBulletin.
    In addition, I highly suggest you contact Adam Louchs, Solar Design Engineer at 305-536-9917 ex 322. He is also at <adam@sunelectric.com.> Xantrex Off Grid Inverter Charger 2400 Watt 12 VDC TR2412-120-60 - $768.00 . They appear to have some of the lowes prices in two markets but do your due diligence on prices and warranty.

    Merry Christmas!

    Laus Deo
  13. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Overbore. I have two mod sine wave inverters from trace and over the years I have lost several motors and now my refer. Alltough they will work for a long time, after some time they will take their toll on anything with a motor. I live very close to Northern Wind and Power, and although they will sell you anything you want, sometimes they have also been know to "oversell" you what you don't only want but need. Like all stores, they are a store. Salesmen are just that salesmen. No different from cars, houses or solar. Some are somewhat knowledgable but most are only reciting what they have been told or read to say. They can also be very pricey most times.
  14. TnAndy

    TnAndy Senior Member Founding Member

    Yep...but you maybe be missing this.....that's 30 per leg.....at 120v, and NOT 30 per leg at the same time.

    4000w / 120v = 33amps

    4000w / 240v = 17 amps

    To get a TRUE 240v 100 amp service will require 6 of these inverters !

    I think maybe you don't have an appreciation for the depth of what you're wanting AND how much it will cost......but you will before it's over.... :D

    You might look at Outback inverters...those are the ones I use. They are 120v inverters BUT you can gang them in master/slave arrangement to make 240v ( mine are a pair of 2500w inverters in that configuration ) I know you can set up at least 4 that way, so if you used their 3500w inverters, you could get 14,000w that way....run about 8 to 9,000 bucks.
  15. BTPost

    BTPost Old Fart Snow Monkey Moderator

    I have a suggestion for your design, Kingfish. Start frequenting Electric supply houses and looking for used, Industrial transformers in the 2:1 Ratio, like 120/240 or 240/480. Many old plants are being upgraded, and they sometime just scrap old Transformers. I picked up a set of three 240/480 Transformers that were being thrown out from an Cannery here, and they were 7.5Kw Rated. Since I generate ALL my power at 240 Vac, I use one of these to make feed my 120 Vac generated Power Buss, which is what feeds my Trace SW4048. My Water System consists of a 350USG cistern and a 12 Vdc Dankoff Vane Pump with a Bladder Tank, and a 50 PSI Pressure Switch. When that tank gets low I pump it back full, when the Genset is running, and recharging the batteries, so that I don't need 240 Vac from the Inverter, which only complicates the Power System design. Power, Water and Heat, are all parts of your Off-Grid Living Design, and they really need to be integrated, so they are done in the most efficient way.
  16. Kingfish

    Kingfish Self Reliant

    My local well drilling company told me the fastest way to ruin a pump motor is to under power it. Is it possible you are not really giving these motors enough headroom ?

    The Magnum states right on the website that it produces 30 amps per leg. I know I didnt read it wrong. Ill look again. Kingfish
  17. Kingfish

    Kingfish Self Reliant

    Does anyone build a quality inverter in 240/120 form? Could I get one that for instance will produce a solid 40 amps per leg in 240 mode? I know I can get a generator that will make that much power how about an inverter? Or could I have say three outbacks running all 3500 watt with two in 240 mode and one in 120 mode all charging off the same charger and panels? Kingfish
  18. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Kingfish. I think we have been going a little too fast for you. A couple of things have been overlooked. If your going to run your house as a house and not a cabin wanting all the normal things to work and work right there is a system you will need to look at.

    First of all, unless you live in the Australian Outback, you will never be able to completely run your house on just solar. There are a couple of more things you will need and need badly. First of all, as a nice compliment to your solar , you may want to put up a wind generator. They work on the nights it is windy and only add more to your battery bank when it is windy and sunny during the day.

    Most importantly you will want a back up generator to do just that back up your entire system/house. Now, by haveing a back up generator, you can use it to pump your well as needed to fill a large tank which is above ground and then use a smaller seperate pump to demand pump the house. On generators, I would not go cheap here. I use a kohler 7kw twin. But I would advise you to choose one that runs on propane, as it can be started when needed from the Trace or Outback inverters. In other words, by wiring it to your invertor, when your inverter sees your battery bank is at a pre determined level, it will automaticly start your generator and charge your batteries back up, and once again at the level you have chosen or time, it will shut your generator back off again The reason for propane fuel, is no choke, no hauling of dangerous gas etc. If your generator is on a choke and it is really cold out like it gets here, then your inverter may have a hard time starting it up . I live up in the mountains at about 6,000 ft and gas can be tricky here, especially when it is cold. I will be creating another blog on solar soon, and I will post it here , which will include pictures of my system, which I have built myself, with little or no help from anyone else. A few questions here and there, but all work, wiring etc done by me. It is not that hard to do. I would also recomend that you go with 24 volt right from the start as it will save you a lot of money on wiring alone. The generator should be large enough to start and run your well with no problems. You said that you would be using a 1 hp pump motor on your well, correct ? I am no electrician, but I use several 1hp motors for many applications, and on 120 ac they use 20 amps under load. That means roughly if your using a 220 volt it would only be drawing 10 amps close anyway on each leg. Also , I am betting that you only have two wires going down to your pump , correct ? That is single phase 220 and yes either two ivertors or one good inverter with a step up transformer would handle very easily , especially in the middle of any nice sunny day.
  19. Kingfish

    Kingfish Self Reliant

    Yes lets start at the pump as it is my main concern right now. In the panel the breaker is a 20 amp twin pole. The white wire goes to one pole and the black to the other. The copper ground is wired to the common rail. The wire is 12 gauge romex commonly called 12/2 . Im guessing it is a 2 wire . My main concern right now is being able to pump water in the event we lose the grid. As it stands right now I have a 3000 watt Honda generator but it only makes 120 at 27 amps. My hope was to put in a 240 /120 inverter and a 4 battery bank of 6 volt batteries and charge it with my Honda which will run a multi charger built for my boat. It is a 3 battery charger (three 12 volt batteries) or 3 pairs of 6 volt batteries in series . This way I could charge 4 of my batteries at one time with the honda.

    At first I thought I could put a 120 volt inverter on each hot rail of my power panel and have 220 in the middle. I have been told that they need to be out of phase for this to work. 240 is after all just two 120 volt circuits . I had two Aims 5000 watt 120 inverters and had never hooked them up. An electrician told me to send them back and get a 240/120 inverter that had split phase. The Magnum is supposed to mimic the grid meaning it produces both 120 and 240 at the same time. 120 on either leg or 240 accross the hot rails. Kingfish
  20. Kingfish

    Kingfish Self Reliant

    Also Im in Michigan on the west side. W e get lots of sunshine and wind both. Both types of systems can and are used here. The house is small at 2200 square feet at 1100 per floor. The basement is built into the side of the hill. Walkout basement type ranch. Wood stove in the basement for heat. I have a great spot for turning array and a nice high spot for good size wind mill. We have 10 acres with 535 feet of frontage on a 209 acre inland lake . Kingfish
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