14
Just doing a heckin' science to figure out my solar system requirements... How much battery capacity do I really need? (No, really -- I'm asking!) (thelemmy.club)
submitted 6 months ago by to c/solardiy@lemmy.world
21 comments fedilink hide all child comments
 

I'm planning to cut my grid connection and go full off-grid. Which raises the question of how much capacity I really need. And what you see here is me trying to answer that question based on ~51,000 5-minute data points of usage data my power company provided to me, complete with custom-made python script to parse all that data and pretty charts! (Yes, I have 6 monitors. And this kind of shows why.)

And what I'm really torn about now is how much battery capacity I need. Should I get enough to cover the absolute worst case scenario (~66kwh) or is something closer to my average overnight usage (~20kwh) acceptable?

Not the absolute end of the world if the batteries run dry and I need to temporarily supplement with generator backup, I suppose. Nobody is life-or-death depending on any electrical appliances here, and even on the coldest days, waiting a few minutes to go start a generator isn't a huge deal.

But definitely would like a word from the wise about how much battery capacity I really need. And also how much solar panel wattage I need, I suppose.

screenshot of data processing for solar system design
you are viewing a single comment's thread
view the rest of the comments
[–] [S] 2 points 6 months ago (1 child)

Solar panels. They don’t really put out any power in December or January. We were lucky if we were getting 1 kWh a day in January…

Huh... Good to hear that kind of thing, I guess. And here I was thinking that maybe around 6kw of panels would be more than enough for our average usage. But if you're struggling that much on 8kw, maybe I should go bigger, a lot bigger. (Luckily, I've got the land for it, and I could put up an absolute ton of panels if necessary.)

Also definitely thinking of putting up a wind turbine or two, which would hopefully help supplement, especially in those cold, dark times when the gap between production and demand is the highest. Could easily be worth the cost if it means we need fewer batteries.

  • permalink
  • fedilink
  • source
  • parent
  • hideshow 1 child comment
    •
  • [–] 2 points 6 months ago

    People will get better results with 6kwh than we do with 8kwh in different countries.
    It all depends on location. And panel direction and angles.

    If you can wait for the batteries then what about going for sodium ones? They are supposed to last longer than lithium.

    If you've got the cash, the land, and the know-how I would go bananas with the panels. They are maintenance free, unlike turbines. They usually have 30 year guarantees, unlike turbines.
    Just do some good research in to dump loads.

    We are going to be adding another 18 or so panels when our barn roof is repaired. Plus a few more on our car port and then completely fill the main house roof next year at some point. There's no point in doing it until all the insulating is finished and we finally know how much energy we will need in the winter months.

  • permalink
  • fedilink
  • source
  • parent