Quote from: HansHagberg on November 30, 2017, 12:46:41 AM

Have you thought about finding a way to feed the DC from the solar panels directly into the 12V consumers and bypass the two transformation stages?

That could potentially give you another 10 - 15% more net power by reducing losses. I know they do things like that in large datacenters sometimes. Unfortunately, 12V PSUs are still not mass produced and therefore expensive. However, compared to high end consumer PSUs and solar panels, it may be very profitable. You could perhaps implement it by using some properly dimensioned battery bank like an UPS and then add some custom wiring to the GPUs.

I have done that, but on a much smaller scale with one 100W solar panel. The miners (cheap smartphones and small ASIC board) run from a TI DC/DC module. At 89% efficient, it's a bit dated, but works well enough for now. (I plan to replace it with a homemade 96% converter based on a LT chip just for the fun of it.) There's a LiFePO4 battery pack to provide power at night (although the main purpose is as a UPS/Ohmconnect battery for my IT setup) and since the solar panel easily generates more than what the miners use, I have the DC/DC converter (custom design) in my PC to use whatever is left over.

BTW, I would suggest not having a DC bus voltage that can be both higher and lower than the load voltage, since buck boost converters are less efficient than plain buck converters. The reason that was used in my PC was because back then, lead acid was the only economical option for a UPS battery. (And going 24V would require two batteries which doubles the cost.) When that needed replacement, I replaced it with LiFePO4 which is very close to a drop in replacement. If I were to redesign it from scratch, I would use LiMn batteries which is 14.4V nominal for a 4S configuration, so the DC/DC for the PC would only need to be a buck converter.

What would be interesting for larger setups would be to get a hybrid car inverter and hack it to act as a grid tie inverter/rectifier. With continuous power ratings well into the 10s of kW, it would be plenty for a very sizable mining setup. It would also require a very expert level of electronics knowledge.