+bonifartius 𒂼𒄄
anyone can give me hints or links on what i'd need for a smallish off grid solar setup and pitfalls during installation? i probably can figure out most things, but there sure are mistakes to be made ;)
Some important questions:
- How much electrical load will be on the system?
- How much sun do you get at your location? (does it vary a lot by season?)
- How reliable does the system need to be? (If you don't mind running out of electricity occasionally, you can get by with a much cheaper system)
If the load is high, or the total wattage of the panels is high, then you may need to design a system with a higher voltage. Otherwise you can just use 12V batteries/12V system.
@Pat well, it should be somewhat reliable. i primarily want to use it for charging tools and some light in the shed, but it would be nice to have some backup power for other things if shtf ;)
i thought about recycling 18650 cells, but then i don't want to invite a fire. maybe i'll just look for cheap lead batteries first. guess i always can add more Ah with better charging logics.
for 240V stuff a car inverter should do?
A light in a small shed is almost nothing, probably <10W. So a very small system should work for that. The batteries in your power tools are probably lithium. If you charge lead-acid batteries from the sun, and then run the current from those lead-acid batteries through a converter to 240V, and then use that 240V to power a charger for those lithium batteries in the power tools, that's not going to be very efficient. (Loss at the solar regulator to lead-acid batteries, loss at inverter to 240V, and loss at lithium battery charger.)
Do you need to recharge the tool batteries multiple times during one day, or can you just allow them to charge when the sun is shining and then use them when you need them?
Lithium batteries generally will hold a charge for a long time without much loss (they don't have a lot of self-discharge). But lead acid batteries will self-discharge quite a bit, compared to lithium. But charging the lithium batteries directly from the solar panels would probably be kind of tricky.
Actually, just charging the lithium batteries at home or something and then bringing them to the shed location when you need them might work out better, and just use the solar system for lighting only.
Also, you need to make sure that whatever you plug into the inverter (that inverts the 12VDC to 240VAC) will be able to handle the waveform that comes out of the inverter. Some devices do not handle inverter generated AC very well, e.g., induction motors or some LED lights, or switching power supplies (which are probably in the chargers for your power tools). In that case, you may need to use a pure sine wave inverter that can generate a well formed AC sine wave as its output.
@Pat that motors don't like square waves makes sense, will keep that in mind!
>"for the power tools i've thought about looking into car chargers for those to not have the losses from going from 12V DC to 240V AA to whatever."
That's a good idea.
I had thought that you could just charge the tool's batteries directly from the panels (through a regulator), so that they just charge when the sun is shining, but actually you don't want to be charging those lithium batteries unattended because there is too much risk of something going wrong.
@Pat for the power tools i've thought about looking into car chargers for those to not have the losses from going from 12V DC to 240V AA to whatever.