Hi All, been a while since I last posted. My system is running great, no hiccups yet. We had a very unusual summer... actually I think that most people here would ask me what summer I was talking about because they didn't think we had one. We had maybe 2 weeks all summer that temps climbed above 80 and even fewer days that temps got to the 90s. We only have had about 4 cloud free days all summer. The temps and weather have been mid spring or mid fall like all summer with many RECORD rainfalls. Very Very wet cold and dreary summer. Even so we already have almost 2.2 megawatt hours since March 18th. We have slashed our monthly bills in half almost every month. I couldn't be more pleased with the solar. The Skystream on the other hand is the most worthless investments my family has ever made. The most it has ever made was May-June when it totaled about 10kwh. I’m not happy with it at all, nor am I impressed with the company that installed it as they didn't see it necessary to perform a wind survey. But with average ground level wind speeds at around 5mph to 6mph it should be 10mph or more at the top of that 50' pole, but most days it doesn’t spin at all. Some days the trees won't stop moving from the wind and the Skystream is dead in the water, other days there is no visible wind and its spinning like a raped ape... Please pardon the expression. Then the output is completely inconsistent, sometimes for a given RPM it seems to put out 100w, other times it surges to 3600w... sometimes without the wind even picking up!
Anyway the reason that I am posting is this. I was looking for a way to rewire the old 750w array of siemens panels to a switch that I would use to divert the current back and forth at will between an MPPT Charge Controller and some kind of low voltage (48v or so) Grid Tied inverter. I figure that way I could choose at will to charge the batteries from the old 750w array or grid connect it and sell its daily output to the utility, charging the batteries occasionally from the grid. Any suggestions anyone?

Well what I did as I regular switch between low and high voltage is use DPDT switches for each 48V string

Flipped up, they go parallel to a breaker which then goes to the batterys , switched down, it send the positive to the next switch. So it takes 4 switches down and I get a single High voltage string for a GT inverter, all switches up and I get 4 48V strings, that each go to there own breaker

The only thing to make sure of only switch with no loads, or the switches will arc and burn out! Been working great for 4+ years

S.G.'s switch scheme works if all the panel strings are "home runs" to the wire shed. Otherwise, you have to put the switches at the PV's, or add more wires.

That's a very clever idea S.G., do you have a breaker somewhere to cut the current, so you can operate the switches, or do you only switch before daybreak ?

If its running 48V, I just flip the individual string breakers in the breaker panel ( just standard squared 15 amp breakers ), if its running the GT inverter, I turn off the GT at the BOS.

It simple and straight forward, but not fool proof