Gabriel_2018

I don't like too much inverters without comunication with BMS. What would happen if PV is charging low and there is a peak of discharge and the BMS breaks?

Before buying the inverters, could you test if generator suits well with inverters?

I hadn't seen you are going to install a pack of three batteries.

Maybe you can try to switch off three of the four inverters, so you should save self consumption of three inverters. 50 watts per inverter x 3 inverters x 12 hours is a lot. When you arrive, switch on inverters.

I can´t edit and there was an error in mono panel. The coefficient of Pmax is 0.29%/ºC

Magics numbers are 1000 w/m2 and 25ºC in solar cells. If you have a panel 50% more efficient, two panels make the same production, but the most efficient is smaller.

Temp. coefficient of Pmax [%/°C] -0.133 This is a data of mono panel. Temp. coefficient of Pmax [%/°C] –0.44 This is a data of poly panel. If we have a tipycal temperature of 50ºC in solar cells in both panels, we lose 3.325% in the first panel and 11% in the second panel. That loses are caused by temperature.

The winer value could be NOCT.

The difference is the space. If both are 300 w, and have the same relation of Decrease Power/Temperature, the result will be the same.

But you said, or i understood, that you wanted extract electricity from that warm water, and that's impossible. If you want to improve the COP factor of a heat pump using that warm water instead of Air, i agree.

If ambient temperature is 10 °C, Max useful work efficiency would be 1-(283/293)...no way

No way... https://en.m.wikipedia.org/wiki/Exergy

I'm not sure if you can do with a relay. We have round 80-100 V DC and we had to consider the open arc. Maybe a SSR would be better.

May be you can use the circuit and block diodes. In my opinion, most important thing is to avoid reverse current. For expample, a 60 cell 8 A ISC panel can be damaged with a reverse current of 2 or 3 A.

You can see IV curve data in this capacitive swept i do in a 36 cells 20 wat panel: 4,561290323 1,0838709684,669892473 1,0838709684,669892473 1,0838709684,778494624 1,0838709684,887096774 1,0838709684,995698925 1,0838709685,212903226 1,0838709685,538709677 1,0838709685,97311828 1,0795698926,407526882 1,0795698926,841935484 1,0795698927,167741935 1,0795698927,602150538 1,0752688178,03655914 1,0752688178,579569892 1,0752688179,013978495 1,0752688179,339784946 1,0752688179,774193548 1,07096774210,3172043 1,07096774210,7516129 1,07096774211,18602151 1,07096774211,51182796 1,07096774212,05483871 1,06666666712,48924731 1,06666666712,81505376 1,05806451613,24946237 1,04946236613,57526882 1,03225806514,00967742 1,01935483914,55268817 1,00215053814,87849462 0,98064516115,20430108 0,9548387115,53010753 0,92903225815,85591398 0,89892473116,29032258 0,86881720416,61612903 0,83440860216,83333333 0,79569892517,15913978 0,75698924717,15913978 0,75698924717,59354839 0,67526881717,81075269 0,63225806518,13655914 0,58924731218,35376344 0,54623655918,46236559 0,50322580618,67956989 0,46451612918,78817204 0,42150537618,89677419 0,38709677419,00537634 0,35698924719,11397849 0,32258064519,22258065 0,29247311819,3311828 0,26666666719,3311828 0,24086021519,43978495 0,21935483919,43978495 0,19784946219,5483871 0,18494623719,5483871 0,16774193519,65698925 0,15053763419,65698925 0,14193548419,65698925 0,12903225819,7655914 0,12043010819,7655914 0,111827957 First data is voltage and second current

Thinking about the circuit, i see it would work. But it only advice if you are whatching the circuit. I miss something to stop reverse current.

Also, we shouldn't forget other thing. The thermal behaviour of the panel is completely different from forward current to inverse current. With reverse current appear Hot regions which are dangerous.

Yes, i think for 3x3 you are right. Always? I don't know. Remember cloud edge effect. We can have in that case a radiation of 1400 w/sqm

May be, It would be interesting study reverse effects. I did a test to a 72 c solar panel with a high level of radiation. I conected a Charge in parallel and the results were: If we apply Vo+0.6 V It starts to flow current. If we apply Vo+5V It flows 3.8 A against solar panels. At Vo+8.6 V It happens something like and avalanche current and flows the 10 A that the charger can supply.

I'm sure, solar VFD are VFD with direct access to DC bus. Even, if you feed a VFD with PV power enough, tipically R-S terminals, or LN terminals, It works.

Im sure It would blow. Imagine six string of two 60 c panels. There is a sharow in one of them, so in that panel current pass thtough bypass diode. If the panels were separated, Vo of that string would be 60 V and 72 V for the other five. wich woul be the equilibrium if you join all? Vo would be a Voltage from 60 yo 72, depending on radiation, passing current un reverse trough the string in shadow. That would be un float stage, or at the end of absortion stage, when no power is needed and PV Voltage go Up.

Im not sure if it always would work. I undestand you analize the middle point and what would happen if the failure was above the middle?

Yes, even a solar VFD with MPPT algorithm hasn't got an inductor. I would say: If we have solar pannels in a side and a load, not a battery, in the other side, we only need a capacitor to track MPPT. If we have a resistive load, current and Voltage signals are square. If we have inductive load, Voltage Signal is square and Current Signal could become sinusoidal.

You were lucky. Max PV is 60 V and you put series of two pannels, when Vo is more than 70 V. If It had risen absort stage with those series It would have blown...

Power doesn´t come from the inverter and is very easy to modulate power whith a Mosfet circuit.