I realized that I tend to be full of ideas (as opposed to what some others think I am full of) but some never reach the light of day. Others get explained in email to an assortment of people. Still others get turned into a completed project but with no available information about it.
While the focus of this article is for off-grid systems, you really need this even if you are connected to the grid.
The answer, assuming your primary energy source is solar, is "when the sun is out". Easy answer but you need to understand why.
A battery is not 100% efficient. That is, the amount of energy you have to put into a battery to recharge it is more than the amount of energy you took out.
Earlier this month, some economic luminaries in the United States Congress introduced a new bill, H.R. 2835. The bill intends to “establish a joint select committee of Congress to report findings and propose legislation to restore the Nation’s workforce to full employment…”
Great idea, fellas.
What if there is no choice?The first and most obvious is that you may not have a choice or even if you do have a choice, the initial investment for a grid connection may be more than for a system to allow you to be off-grid. Where I currently live extending the grid would have cost about $17,000. My PV solar system cost $12,000.
When selecting batteries the two big considerations are:
Yes, there was an official investigation of sorts. It was funded with less money than the one to determine if Bill Clinton had sex with that woman but, more important, it just didn't seem to want to find the truth.
The first is where you are starting and where you see the future of your system. If, for example, you have an existing 120VAC system (either grid connected or just things you run off a generator), 120VAC is more likely the right answer. On the other hand, if you are just starting, 12VDC is probably the best choice.