I think the time may have finally come when these make sense. I know I was slow to come around but the government is throwing money at it and collector prices are coming down. I can virtually get my collectors for free now. One of the problems is they only want to pay for government blessed systems, not home built systems and I think that is a mistake. We are not going to get much innovation if they only subsidize what is already out there but that is another rant. Florida will pay $4 a watt for anything over 2 KW and I am looking at a DC system to run a pool pump That is a very simple system, no inverter, no storage. My problem is it is only 750-1000w so I need to come up with another KW or so to get my rebate and I am thinking about another traditional system, around 1-1.5kw, to run my well pumps, the pool bar fridge and the other loads out there. If there is enough left over, maybe feeding my PCs that run all the time. They are on UPS so if I did have to switch back to utility power it would be non-disruptive. The part I probably have to find is the smart controller for this that does the transfer function in a listed, compliant way. Anyone ever done something like this? There would also have to be some load management so the fridge and the well pumps were interlocked but that is not that big a deal.
I am not thinking about grid tie at all, too much hassle for too little gain. I just want transfer equipment that will switch to utility when my batteries are low and I really only plan on a minimal amount of battery, perhaps only enough to run my well pumps. Another thing I would connect direct would be attic ventilation, perhaps with a DC motor. I am really trying to keep this as simple as possible.
I am still trying to get some real info on the rebate but I haven't seen anything about requiring a grid tie yet, either on the federal or state program. I do have a feeling any "innovation" will have to happen after the government blesses the system. I imagine I will end up buying something off the shelf and then going from there. I do have an engineer and a GC who will do their part to get this blessed. I will pull the electrical permit myself.
I did dig out the certification process and it does appear they are leaning toward grid tied systems but they do recognize stand alone systems for off grid applications. I am now trying to see if you can do an "off grid systems" to serve selected loads in a house on the grid. This is the process in Florida if anyone is interested.
I think the criteria is stupid if they want masses of people saving energy. One of the biggest single power hogs here is the pool pump and a solar PV system that uses a DC motor is the simplest system you can have but they won't give you a break on it. That is just stupid.
They do bless some totally off grid systems. I have a question open as we speak with the folks who certify systems asking why they won't encourage the pool pump system. It is the simplest PV system you can get. No batteries, no inverters, no grid ties. Just collectors spinning a motor when the sun is shining. It would save about 3-4 megawatt hours per pool per year and 22% of Florida homes have a pool. That is 15-20% of my electric bill. That could be a whole power plant they don't need to build when you average that across the state.