Designing a 60KW community solution

[Amy@altE]

My concern is the OP is using this source for calculating the PV needed. It only is basing on latitude, and doesn't take weather into consideration. I checked it for my latitude, it said 4 sun hours in winter and 10 in summer. Would you design an off-grid system in Massachusetts with those numbers? I sure as heck wouldn't.

[TimDex]

Community solar

I know just enough about solar to get myself into real trouble, so I won't advise you on that. The thing that struck me about your post was the community nature of the project. What's to prevent someone from drawing more than their fair share of the group's power production? Even if it is, for example, a religious community with a high degree of mutual social respect, there are people who like long hot showers or to leave their lights on late into the night. Myself, I would rather go with individual systems. Tim

[DanKegel]

What's to prevent someone from drawing more than their fair share of the group's power production?

Individual smart meters showing who used what when ought to help there.

And while you're at it, load management tools that can remotely raise thermostats etc. when power is short might help, too.

[miahallen]

@ Amy...thanks for the great link

Belize.JPG

@Tim...definitely one of the things we are considering!

At all...is this project big enough to consider an closed-loop hydro setup? There is approx 200ft elevation change on the property, if we placed a large tank at top & bottom and pumped water uphill during the day, then at night allowed gravity to pull the water down turning a turbine along the way. Would this save money compared to a larger battery bank?

[J.P.M.]

My concern is the OP is using this source for calculating the PV needed. It only is basing on latitude, and doesn't take weather into consideration. I checked it for my latitude, it said 4 sun hours in winter and 10 in summer. Would you design an off-grid system in Massachusetts with those numbers? I sure as heck wouldn't.

I was suggesting a little background on resource assessment is easy and helpful rather than putting the cart before the horse, especially w/350 large of what is probably someone else's money.

If I was doing it, as a minimum, I'd start w/ the hourly GHI and POA #'s from PVWatts for Belaize City, Belaize which is TMY based, remember I'm inland from there, give it +/- about 10%, and size/resign based on that and other design requirements. If I had any doubts about what I was doing, I'd sure as hell dispel them before I went further. Good information is too easy to acquire compared to the cost of an error.

[SunEagle]

If you can fire up the genset after 2-3 hours of clouds rather than 2-3 days, your battery costs will go way way down.
If you can run the genset at night, too, your battery costs will go way way way down.

Think of the solar system as a way to save on fuel costs, not as a way to avoid running the genset.

Good point. Running a gen set may be expensive but using batteries usually would cost a lot more than the fuel and maintenance on that gen set.