Renewable Revolution

Quote from: cernunnos5 on June 20, 2018, 01:07:20 pm

I have been meaning to get back to this.... but I have been behind the ball lately. I stick with my CORDED power tools for resilience, position....

But since we clearly have some Electrical guys here...and me being a luddite, I see an opportunity.

I have a decent solar system... but that only lasts until the batteries die. Some people have solar that feeds into the grid. No grid, no batteries, done.

But here is a question I have to reach out to electrical guys for.

Can someone tell me about a practical DC motor that I can get some work out of by directly  tying it into the solar panels. Only works when sun is available.

Give me your thoughts guys. Can it be turned into, say, a wood saw.... or.... something that turns a reworked  generator for sunny day, power tool use.

That should give you folks something to chat about or share your knowledge of where to look for someone doing similar.

There is no easy way to run directly off the solar panels being marketed today at insanely cheap prices. the charge controllers that are charging batteries today are using panel strings of 70-200 volts and converting it down to 12-48 and are referred to as MPPT chargers. They absolutely need a battery to feed to or they won't feed out. The older charge controllers that were just a complicated switch were operating panels that matched the voltage of the battery banks and are called PWM controllers. those ones will sometimes feed out without a battery but its iffy. As RE mentioned it would technically be possible to run a 36 volt motor off of the 60 cell 200-300 watt panels. They output in full sun at about 32-40 volts at 6-8 amps. It would be tricky though. Say you wanted to run a table saw you would want to re jig it to incorporate a flywheel of some sort or have 2 or 3 panels hooked up in parallel to have 2 or 3 times the amps of the motor to draw from in case the sun goes away or you bog down. To me that is a waste of resources since if batteries are toast panels which are way more complicated will fetch a premium and weird voltage dc motors would be almost non existent. BUT... Even an almost dead battery bank as long as the cells have not shorted out can be the buffer you need to run the controllers and act as a pass through for the power from the panels. The trick would be to start treating your batteries as irreplaceable. In times of crisis think of them as delicate senior citizens. You eliminate all the shocks we inflict on them daily. In that scenario you wait for the sun to be out and charging at more then what you need and start turning on devices to match the sun; freezer/fridge conversion, well pump with an insanely large pressure tank, maybe some electric chainsaw work etc. All of these are usually inverter functions. You aim to use almost all the solar in passthrough and DO things with it and dribble a little to your geriatric batteries to keep them charged and as alive as they can be. When the sun goes away you power down all the ac, turn off the inverter and coast on a few dc led lights. You've stored the energy as cold, pressurized water and sawn wood instead of chemical potential energy. In that kind of scenario the 2000 cycle battery bank can be pushed into the 8000 cycles realm and if we have not figured out something different within 20 years we are already dead anyways since that is the lifespan of the inverters charge controllers etc,,, Its more complicated then that and would require beer a sketch pad, a pencil and me waving my hands a lot but that is the jist of it. Its easy enough to experiment with if you want; find a poor old battery bank from a recycler at the same voltage as your existing one and switch over to model a battery of much diminished capabilities and practice using power directly.I know a nice old lady in the woods who lasted 14 years on her original undersized batteries with very minor lifestyle hacks let alone the hard core alterations proposed above. Food for thought. Back to work...
Cheers,  David