# our real world off-grid solar



## scatyb (Jan 20, 2009)

In case any of you didn't know, my family lives completely off-grid, technically......the exception being internet.

Anyway, we also use solar for all of our power needs. I have read that you NEED to use propane instead of going electric. That is all well and good, however, it not sustainable or renewable. Especially when prices become financially unfeasible or a meltdown and the stuff isn't available.

This is all just for your info and certainly does not constitute "the way things should be done". If you have any questions, I will gladly answer them. Below is some info on the setup and a link to photos so you can see what I'm talking about. I hope this is helpful to someone.

Panels: 6 - 120w 12v connected in series for a 24v system
Batteries: 8 - 220Ah 6v golf cart batteries connected in series/parallel for a 24v/440Ah bank
Combiner Box: standard breaker panel with standard breakers to control which panels power the system
Charge Controller: Xantrex C35 (really should have purchased a C40)
Inverter: Samlex PST-1500 1500w pure sine wave inverter

Here is the link to the photos.

We run a 700w microwave, a small convection oven that can cook a couple 12" pizzas, a two burner induction cooktop, a 10cu fridge, lights, laptop, 22" lcd tv with built-in dvd player, vacuum, and 120v water pump(this give the house pressurized water). It will also run all of our power tools like the air compressor, circular saw, recip. saw, drill, and a few other things. This is not an all-inclusive list by any means. 

The house is powered by a standard power mains(I think that's the term). The inverter has a power line running from it to the mains to feed pure sine to ALL outlets.

Don't know what else to say, but again ask away and I'll answer questions. Thanks folks.


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## scatyb (Jan 20, 2009)

one thing, the total cost for this was appx $5400. We have a total of 10 panels, but are currently only using 6. Just fyi.


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## used2bcool13 (Sep 24, 2007)

What climate are you in? We are looking at moving to so cal and would like to incorporate solar panels.

Were you able to do this yourself? How did you learn (if yes). We know nothing about installing our own solar.

Thanks.


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## machinist (Aug 3, 2010)

scatyb,

Do you have some data on KWHR's produced per day, and KWHR's usage per device? 
What kind of charge controller do you use--conventional, or MPPT? 


I have a system almost ready to turn on, and I'm curious about other people's real world experiences. Trying to plan our system the best we can, we measured usage on our individual appliances over several days each, using a KIL-A-WATT meter. As an example, our full size fridge used 16.97 KWHR's over a period of 469 HRs = 868 watt-Hours per twenty four hour day. 

Some things are almost impossible to plan that accurately, such as light usage, due to somewhat erratic times of use. Other things are used only occassionally, such as a fan for cooling in summer, but the same fan may be in almost constant use in winter to circulate heat from the wood stove. Only our own experience will give us all these answers. 

What changes have you made to adpt to off grid power?

We have put a lot of effort into power conservation, trying to get our usage as low as possible before we go off grid. These include a wood stove to replace electric heat and low power twelve volt devices: TV, laptop, small fans, radios, a bilge pump for occassional use, and some power tools. Our fridge and deep freezer are consventional 110 volt units, but chosen for efficiency. 

I oversized wire gauges throughout the system, and chose inverters of ample capacity to assure they will be used in their most efficient power range. We chose a Xantrex XW-MPPT60-150 charge controller, and Evergreen 18 volt panels, series/parallel wired for 36 volts input to the charge controller. That decreases line loss from the panels to the charge controller, and utilizes more of the panels' output than a conventional controller. 

For lighting, we chose twelve volt CFL bulbs, with an Edison base to fit conventional light fixtures. A twelve volt buss line is wired down the center of the basement with fused taps at 10 ft. intervals for wiring up through the floor to the house. We are using cigarette lighter type outlets and plugs to isolate twelve volts from 110 volts. There will be no interconnect whatever between grid and our system, including grounds. The solar system wiring for AC is to dedicated outlets for only the fridge and freezer. 

What did you choose for lighting? 
Do you have a backup generator, and what voltage? 

We have a cheap AC generator used in the past for emergency backup, but I am building a twelve volt generator for DC backup.


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## machinist (Aug 3, 2010)

FWIW: I bought a copy of Photovoltaics Design and Installation Manual here: http://www.amazon.com/Photovoltaics-Installation-Solar-Energy-International/dp/0865715203

That book, along with quite a bit of AC experience, and a fair DC background is all I used to put ours together. Note that our system is as yet unproven!


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## Tarheel (Jan 24, 2010)

machinist said:


> FWIW: I bought a copy of Photovoltaics Design and Installation Manual here: http://www.amazon.com/Photovoltaics-Installation-Solar-Energy-International/dp/0865715203
> 
> That book, along with quite a bit of AC experience, and a fair DC background is all I used to put ours together. Note that our system is as yet unproven!


Thanks for your post machinist ! 

When you get some pictures if you don't mind share them with us. Good luck, hope it all works as you planned !


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## scatyb (Jan 20, 2009)

machinist said:


> scatyb,
> 
> Do you have some data on KWHR's produced per day, and KWHR's usage per device?
> What kind of charge controller do you use--conventional, or MPPT?
> ...


Wow, that's quite a list, but I'll do my best. If I miss something, forgive me. Let me know and I'll try to help. Here goes:

1: Power generation in winter is a little over 4kwh a day. The cold itself practically overcomes the 5% loss I experience due to my makeshift wiring. It is IMPERATIVE that if the panels do not rotate themselves that you do it morning and night. Summer/spring here is closer to 6.5-7kwh a day. None of this includes rising or setting input.

2: Power usage in many cases is dependent on what we feel like doing. Here are some appx. usage amounts based on readings taken
Lights CFL [email protected] - 6hrs/day = 480w(at most)
Microwave - MAYBE 10min/day (it uses a total of 1050w) = 175w
Fridge - it uses about 960w 
Cooktop - power is adjustable and is used about 30min/day = 370
TV - 360w
Laptop - 720w(if left on all day)
Power Tools - 600w
Overhead fans(use WAY LESS power than box types) - 4hrs/day = 160w
110v water pump - use/power consumption negligible = 40w
Total power used in a 24hr period is ~3.8kwh.

3: We use a conventional Xantrex C35 charge controller, but should have gone with the C40. For the size of the system, I could have purchased more panels to make up for the controller losses than it would have cost to go MPPT. I didn't, but still.

4: Changes to suit needs is still ongoing, but here's what we did(some are still in testing). Used lights/computer/cooktop/microwave sparingly in winter or cloudy days. Cooked on wood stove as much as possible. I recently did an audit and found that the cooktop pulls about 5w an hour while "off". Guess what's getting a switch this year? Only ran fan if heat just wasn't making to where we were and everyone stays in the same room as much as possible for heat containment(not a bad idea anyway as everyone gets to be with each other). The fridge is on a timer(as will be the freezer when we get one), running during the day and kicking on only a couple times a night(not sure how effective this is in summer, still testing). We try to limit most activity to during the day, sparing power for the tv at night, some lights and maybe a couple bags of popcorn. We also(even in winter) frequently use a solar oven for cooking dinner. Now this brings us to number 5.

5: Inverter. I chose to get a pure sine and run the power from the inverter, underground, up into the house much like utility power for a few reasons. First, ac is far more efficient over long distances so I could place the batteries/power house closer to the panels. This reduced the need for heavier gauge wire. Second, all devices are now ac and relatively easy to replace if needed. I.E. $.50 a bulb for our 13w CFLs. Third, we didn't want to be limited to where we could plug certain things in like a sewing machine, battery chargers, etc. Pick a plug and you're golden. There are other reasons related to this, but this will suffice. We also don't run more than one large draw device at a time or the system bogs down or shuts off completely. Things work so smoothly, my wife has a tendency to forget from time to time...so do I, I guess. Still, 1500 watts/hr is plenty for us to do what needs to be done, have some lights on, the tv, fridge, and be working on the laptop.

6: Unfortunately, we don't have a backup generator. Solar is it as we ran out of funds. I know, I know, most folks might freak about that, but when power goes out, we light some candles, cook on the wood stove, go to bed earlier, and wait till the sun comes back. A lot like camping, just a bit less smelly.

Some things to note: During the winter the batteries get really cold. We were able to somewhat overcome this by using some blankets discarded by a local hospital(they were used in radiology and seem to be VERY resistant to battery acid) to wrap up the batteries. We them tucked on-top of that a heating blanket. These use very little power when compared to ability to keep the batteries and compartment well above freezing. We were not 100% successful with this, however, it did work to some degree and will be tested further this winter. Also, we are Christian and try very hard to treat Sunday as the Lord's day(not to be condescending or judgmental to ANYONE), so we don't really do much on that day. We are gone to church for a few hours and spend a lot of the day reading or talking or whatever. That allows even the solar to get a break and charge. Three more things; first, we have a total of 10 panels, but are only using 6. Once I get a mount welded and installed, we will have all 10 in full force on one rotating unit. Second, when calculating the power usage, it was very helpful to figure out what was going to be night usage and day usage. When calculating what the total 24hr usage is, that does not tell you what amount of that actually drains the batteries and what of that is provided directly from the panels(that and you may not have sun for a few days). Granted, the total power needs to be provided by some method, however, even if you have enough daily generated power, often with the voltage loss, the amperage sent to the batteries is just not enough to fully cover power consumed and so you run a net loss over a period of a week. This allowed me to figure how many panels I needed in order to cover the day's usage and then charge the batteries from the nightly drain. We also found that the gauge wire we used running from the inverter to the house is just a tad too small. We needed to either get thicker stuff in the first place, or add another current carrying line to bolster things(which is what we're going to do). OSHA be hanged....wait, don't quote me on that. I hope that was helpful and again, certainly does not constitute "the way things should be done"; it just works very well for us. Good luck. I think your system will work just fine.


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## TnAndy (Sep 15, 2005)

Machinist: ( and anyone else looking at solar )

The book you linked to is an excellent place to start, the same one I recommend and the same one we used in a class I took for the initial solar certification at Appalachian State U in Boone, NC.

Also, a subscription to Home Power magazine is a good source of info, and worth your money.


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## machinist (Aug 3, 2010)

scatyb,

Thanks for a very informative post! You pointed out some things I really needed to think about, like cold batteries in winter and day vs night usage. Where are your batteries located? I built a concrete block battery shack (looks like a bulletproof outhouse) that is unheated, but one side is against the outer basement wall. Have to have some venting, so it will get cold in there in winter. It's on the North side of the house, to limit summer high temps. I'm putting a temp sensor on the charge controller, and hope that helps. Have 8 Trojan T-105's on each system, wired for twelve volts, currently sitting on a float charger to take care of them. 

How about lightning protection? I'm wiring in some Delta brand lightning arrestors, bought from these folks: http://www.windsun.com/ (Good source for solar stuff, IMHO.) I'm also talking to my internet provider, who has a solar powered wireless tower. He has some ideas about grounding to help with lightning protection. That means I get to dig some more ditches across the driveway to hook up those grounds. AARRGHH!!

I really need to look into those "ghost" power users! Like a lot of people, we have scads of stuff plugged in that have an "idle" current. Those have to GO! 

Do your panels track the sun? I have debated this, and about decided to not do it. What do you think? Seems to me like it would be less trouble and no more money to just buy more panels?


Our TV isn't used much, and is only 60 watts. It is a small flat screen made for twelve volt use. I have been trying hard to get my wife to give up her tower-style computer in favor of a new laptop, but haven't got there yet. That is a difference of under 30 watts for the laptop vs 140+ watts for the tower and HP flat screen monitor. I think I can get her to change over if she can keep her keyboard and HP monitor. :stirpot:

I have a machine shop where I am spoiled, using AC with abandon. I closed it last Fall to retire, at least for a while, and get some important preps finished. I will probably have to re-open the shop to make up for income lost to inflation after a while, so the shop will remain on the grid. The house will be all solar, however. 

That allows us to put our toes in the water here, as we learn about off grid living. We are doing something similiar with our water system. We have a water collection setup and cistern operating, and are living on it entirely, but we still have the county water hooked up. I want to get through at least one hot dry summer this way, to figure out what we have to do to live within our "water income", while having a backup. 

Our DD is entirely off grid, and making do with just two 170 watt panels and using a twelve volt generator when she does laundry in winter. In summer, it pretty much keeps the forklift battery charged. They are adding two more 170 watt panels, which should cover their needs and have a surplus. They use a wringer washer for lower power draw, and have LP for the fridge and cooking in summer. They have a wood cook range for winter that entirely heats their house! The house is super insulated, and only 860 sq. ft. When they get a summer kitchen built, the wood range will go there in summer and further reduce their gas usage. 

We refused to give up our fridge and freezer, and did not want to be dependent on LP either, so that greatly increased our solar needs. As a result, we are building two systems about the size of yours, and that has been expensive. Two systems gives us redundancy in case of problems, and enough power to run the higher draw items--the fridge on one system, and the freezer on the other. The rest of the power from one system goes (as DC) to the living quarters and the other to the basement shop.

I'm working on cutting power use in the shop, too, by coming up with manual powered alternatives for many operations. Have a couple crank operated drill presses, several crank grinders, a full blacksmith shop, lever shears, lever punches for sheet metal, a "stomp shear" and brake for sheet metal, and lots of hand tools. But there is simply no way to get around grid power (or gasoline) for arc or Mig welding. I can weld in the coal forge, but that doesn't work for everything. I'm still working on this problem. One of my recent successes there has been to hot-wire a cordless drill with a twelve volt cord, per info from the 'net. I don't like inverter losses. I'm willing to pay for the heavy gauge wire needed, since i only have to pay for it ONCE.


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## machinist (Aug 3, 2010)

How to use a lawn mower to power a Delco alternator: http://www.theepicenter.com/tow082099.html

Those instructions are a little iffy on wiring the alternator field, and somewhat generic about that issue. If anyone has more info on this, I would appreciate it. My SIL has one going, so I plan to tap his knowledge. 

I chose to use a 100 amp alternator and a 6.5 HP Honda engine. Since is is comparatively easy for me to machine a suitable pulley, I will use the poly-vee belt, like the "serpentine" belts on cars. Depending on your choice of engines, this can be a very cheap generator to build, and it puts out a nice steady 14 volts for charging a twelve volt system. An automotive ammeter is a cheap and useful additon, I think.


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## scatyb (Jan 20, 2009)

machinist said:


> scatyb,
> 
> Thanks for a very informative post! You pointed out some things I really needed to think about, like cold batteries in winter and day vs night usage. Where are your batteries located? I built a concrete block battery shack (looks like a bulletproof outhouse) that is unheated, but one side is against the outer basement wall. Have to have some venting, so it will get cold in there in winter. It's on the North side of the house, to limit summer high temps. I'm putting a temp sensor on the charge controller, and hope that helps. Have 8 Trojan T-105's on each system, wired for twelve volts, currently sitting on a float charger to take care of them.
> 
> ...


Sounds like your battery shack will work nicely. Ours is out a ways from the house on the southern side. You can see it in the photo of the solar panels. As the thing is all concrete though, I would put in some form of insulation as concrete likes to suck up heat. Still, concrete's a good choice.

Digging ditches does suck. We haven't installed any lightning protection yet, mostly as we hardly get any out here, but still, it's on the list and is never a bad idea.

Ours don't track the sun, but I am welding up a mount that will manually rotate. I would HIGHLY suggest forgoing buying more panels and building your own mount(as it sounds like you could easily do that) so long as you are willing to turn the mount twice a day. We found that by doing so, we were able to increase our power by appx 50%. Just use some angle iron, cut and weld, then mount to a steel pole. I can get 140ft of the stuff for about $150 from Page Steel.


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## TnAndy (Sep 15, 2005)

Add a 100 buck linear actuator, and a 150 buck controller, and you can eliminate the hand cranking and they will "jog" about every 5 minutes all day long, tracking the sun. That's how mine work.


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## machinist (Aug 3, 2010)

Actually, I did make a tracking-capable panel mount for a friend of mine, but he doesn't use it. He didn't want to spend the extra to do the automation , so he said he would shift them manually. Don't think he did it more than a couple times, though. He's just not into that sort of diligent daily thing. 

That unit was pole mounted and carried 4 panels, 3 ft. x 5 ft. on a two axis tilt mount. The whole works is mounted on a 6" schedule 40 pipe stuck into a couple yards of concrete. Not going anywhere. It survived hurricane Ike and 80 MPH winds. Son in law is also a steel fabricator and his windmill lived through Ike also. 

I built a pair of pole mounts for my internet provider. He powers a remote wireless tower with that system. They are also 6" pipe, a full twenty one foot stick of it, anchor bolted like one of those parking lot lights, and guy-wired to a series of concrete "dead men" = buried chunks of concrete. They don't track. He put the panels on commercial aluminum mounts atop these poles, but came to the same conclusion as I did about tracking. His system is in a very remote location with difficult access in bad weather, and his top priority is reliability. He couldn't make the cost-benefit work out for his application. 
I plan to put my panels on the shop roof, and have the cables buried to get there. Our location on a north sloping hill limits my choices here. That would likely mean individually moving panels, with a linkage to synchonize them and connect to an actuator. That means a lot of extra framework and some corrosion resistant shafts and bearings and other parts that run into some money, so it would be cheaper to just buy more panels. These things are a major pain to keep running in bad weather. If I went with a pole mount, to allow easier tracking design, then I wind up with a tall pole to get sun access, and when I have a maintenance problem I get to climb that pole. Unh-uh. I could arrange to lay the pole down like they do windmills for servicing, but there goes the cost again. I can't win. These issues are why they aren't already operating. I only plan to do this once. 

I'll stick with fixed mounts for now. In a desert climate I would seriously consider it, but Indiana has ice storms, significant snow, and some severe winds on occassion. We just had 14" of rain last month, and we have baseball size hail once in a while. (Sounds like bowling balls dropping on the roof!) Lexan panel covers would probably be a better investment. 

Simple is more reliable, in my experience. I know I am prejudiced that way. It comes from 30+ years doing automation design and build for automotive factories. If it can screw up, it will. I once reccomended against automatic feeding on a 300 ton powdered metal press, because it required that the part be perfectly oriented EVERY time. Management had already shot their mouth off to Ford, our customer, that we would do this, so they did. Had a good man do the work who incorporated every form of safety device known to man. It went just fine for about 6 weeks. Then somehow a part got in the die cockeyed and the crash took the crown casting off the press. That casting was semi-steel, 16" thick in the center and tied to 5" diameter posts on all 4 corners. Broke that top casting and die parts splattered over a 50 yard radius. Luckily, nobody got hurt, but a $600,000 press was then that much scrap iron. It only took ONCE. 

Son in law is going to do horizontal tracking, being enamored of automatic things. We'll see how this all works out.


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## katlupe (Nov 15, 2004)

scatyb said:


> In case any of you didn't know, my family lives completely off-grid, technically......the exception being internet.
> 
> Anyway, we also use solar for all of our power needs. I have read that you NEED to use propane instead of going electric. That is all well and good, however, it not sustainable or renewable. Especially when prices become financially unfeasible or a meltdown and the stuff isn't available.
> 
> ...


I just found this post while searching for other methods of cooking using solar. I already use a wood cook stove, but want something for the summer and warmer times of year. We are trying to eliminate the use of propane and this has turned out to be harder than I expected. Besides using a solar oven, I want another method. 

My husband and I especially were interested in the induction cook top that you are using, as well as the little oven. My impression was that our system would not power that, but I see you are using them. We have 1550 watts from solar and also have a 500 watt wind turbine for a 12 volt system. The inverter is a 3000 watt pure sine wave. We don't use a huge amount of power for much more than our computers, one light in the evening but not for long and of course, our refrigerator. I have a crockpot that I had planned on using, but am always afraid it will use too much. 

My question is when you use the cook top, do you have to use it only at a certain time, when a certain amount of power is coming in? Does it use up a huge amount of power from your system so you can't be using your computers or other things if it is being used or was used? Can you perk coffee on it? If you wanted to use it in the middle of the night for some unknown reason, could you?


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## PorkChopsMmm (Aug 16, 2010)

We have a similar setup. 12 240W panels and 16 of the same GC2 batteries. We do, however, use propane for our tankless water heater, oven, and a backup propane heater for when we leave the house in cold weather. We are going to pick up some hot plates/convection kitchen appliances and also a small electric heater. We produce a lot of "extra" power that isn't being utilized when the sun is out -- so running some usually power hungry appliances when we have an abundance makes sense.

Good job on going without a generator. We are in the snowy midwest and during a few months of the year we would be DOA without one.


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## giles117 (Jun 22, 2012)

Crock pots use MUCH less power than many might think. I use the "Crock Pot" brand and my kill a watt shows me pulling 175 watts on high...


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