System of 2000watts +, scale is intimidating.

[WalkaboutTed]

My son bought some land where there are no utilities available.  He's putting in a tuffshed barn to turn into a tiny house and is planning to put in a solar system that will run everything, including his desktop computer, 12v fridge, and a 12,000btu a/c (need that in Southern New Mexico) .  Of course he's expecting Mumsy to design, purchase components and direct the installation.  I have no problem with a smaller system, but the scale of the big system is, well, mighty big.  He's going to put in a 16'x8' covered patio, in addition to the roof space available. I'll be going up to his place next week with the WattsUp and measure all of his components to find out how big we really need to build his system, though my thought is to build as large a system that is feasible in the given footprint. Of course he wants it done as cheaply as possible.

I think the first step, after we figure out how big he wants his system is to get a commercial solar installer to give him an estimate. Starting there will at least get him to realize that his expectations are pretty high as far as cost is concerned. At least both he and Hubby are pretty handy, so all I have to say is "Jump!", and it will be done.

I guess buying a pallet of panels is a good start, but tying together all the charge controllers and coordinating them and getting wires/cables in bulk is overwhelming. Any suggestions on who/where to buy stuff in bulk and perhaps where I can find info on putting large systems together would be really welcome.
Thanks,
Ted

 

[bass_sears]

I built an 1,900 watt system for an off grid cabin, all the work myself, it cost me $12k. So there's your first "holy cow" amount. Things you need to figure out:

+ racking for the panels
+ breaker box between panels and charge controller
+ batteries
+ inverter / charger
+ input for generator as a back of charging device
+ regular AC wiring downstream of the inverter charger
... and all the million and one fiddly bits that go in between all the components.

These two blog postings will give you an idea of the work that was involved since we did it all ourselves:
http://sailing.pictureofnectar.com/work-week-progress-made/
http://sailing.pictureofnectar.com/touch-it-nine-times/

Don't get me wrong, the end result is awesome and I love being off the grid, the project itself was a cool learning experience, and the upside is I know every little bit of this system.

If you do talk to a solar contractor be sure they know how to do what you want done, many of them don't have much experience with true off grid systems mostly just grid ties. If you design your own system if you can find someone to pay a bit of cash to to review your plan that can be invaluable if they know what they're doing.

Small Cabin forum has a lot of useful stuff (maybe more than here as most here are generally focused on smaller systems due to the nature of their vehicles):
https://www.small-cabin.com/forum

I bought my panels through Wholesale Solar:
https://www.wholesalesolar.com/
... they have lots of good introductory information too. Shipping will be a bitch, but the more panels you get the less "shipping / panel" is... down in New Mexico you might be able to find somewhere local (Flagstaff isn't that far: https://www.solar-electric.com) to save on shipping.. Rest of my parts I sourced from whereever I could get the best price.

-- Bass

 

[XERTYX]

Does he know how much power his stuff uses? Have him buy or check out a killawatt meter from the library and plug his computer into for starters. The last desktop I had had a 500 watt power supply. If that runs 24/7 you already know what kind of system that will require. But does he? It sounds like he has an idea with the 12v fridge but I'd imagine the central air is a deal breaker both for his happiness and the budget.

I'm hoping to build an off grid cabin one day and I'd like to have AC. I watched a few videos and decided the air conditioner that jimindenver uses is doable. I can look thru my notebooks and see what notes I took on AC units if it helps.

 

[jimindenver]

The largest system that I have designed so far has been 2740 watts or so. There are considerations at those sizes.

Panels

I would suggest Santan solar where 250 watt panels start at $50. Running two or three in series will help.

I would suggest splitting up the array in to two arrays to get the size and cost of the controller down.

Also making the bank 24 volt will help do that as well as bring down the wiring cost.

A high efficiency mini split A/C would be worth the expense and effort here.

I hope that he has room for a lot of battery bank.

 

[bass_sears]

I'd for 48 volts, for the size of battery bank he'll need and the size of inverter that's much more of a "standard" these days that 24 it seems. -- Bass

 

[tx2sturgis]

This sounds cool and a great learning experience!

Some things to think about: You mentioned a 12v fridge...but if there will be a 24 or 48 volt battery system with inversion to 120v, you would need another conversion to 12v just for that fridge, which will internally make another voltage conversion. Of course some of them also have a 120v input.

I'd start looking at 120v appliances that are Energy Star Rated, and preferably simple mechanical controls, but that 'feature' is getting harder to find.

Lots of insulation for the shed will provide a good payback. Also consider active/passive solar-thermal heating and active/passive ventilation/cooling.

And don't forget a nice woodstove...in fact, in a smaller cabin/shed, a 'boxwood' stove can do double duty for heating AND cooking in the winters.

I hope you will give us updates on this as it progresses!

 

[WalkaboutTed]

I like the idea of two arrays, Jim, especially keeping one of them at 12v for the fridge and other low voltage essentials. I worry about my son ruining the whole bunch of batteries at once and two arrays would reduce the cost for when my he does trash the first set. He is pretty clueless as far as the limitations of how hard he can push the system, "Why would I get that much battery power and only be able to use half the capacity?" When I showed him the Victron bluetooth app on our van's solar array, he said "is a kilowatt of output good or bad?" That's why I think the bigger array the better, so that he has ample capacity, especially for multi-day cloudy spells, so he will be less likely to drain it too much.

I looked at 24v inverters and they're not that much more expensive than 12v. I hadn't thought of a split air conditioning systrm, but we'll look into it. On my shed conversion, Hubby put in R30 in the ceiling and R13 in the walls. The 12,000 btu air conditioner doesnt even run full time in 100F+ days. I used the kilowatt meter on our shed's Frigidaire a/c unit and it kicks in at about 160 watts and then takes ~113watts while running. I was surprised by how little energy that unit takes. It would run more in his shed than ours, though, because his will be lofted (the floor measurements of both of ours and his are 10'x16').

Bass Sears, I showed him your post about the $12K for your system and my son swallowed hard and and then asked about the cost of running a swamp cooler. I told him no can do unless he wants to truck in thousands of gallons of water a month just for the swamper. He won't have a water well for a good long while, if ever.

Jim, thanks for the Santan solar info. I'm in Phoenix/ Scottsdale every three months for medical stuff and it would be easy to pick up the panels there.

TX, he agrees about a wood stove.

On another note, there's a thread somewhere in which I mentioned our shed conversion and I'll try to post photos of it there.

Thank you,
Ted