Expected Amps with MPPT
BlueSky 3000 manual says for a rule of thumb, "... Ignoring conversion losses the conversion process produces an output current roughly equal to PV current times the ratio of PV voltage to battery...
Forum Discussion
liborko wrote:
Lots of errors in your post, BFL13:
-first of all, all abbreviations are written with capitol letters, W, V, A etc.
-Isc is a SHORT CIRCUIT CURRENT. You get it only when panel terminals are SHORTED. You don't get it when panel is connected to the controller or directly to the batteries.
In your example with 230W panel,29.3V and 7.27A your boosted output current is 15.32A @ 13.4V, your actual boost is (15.32A-7.27):7.27.100=110%, not 8%. Your PWM + 8% would be in ballpark with 12V nominal panel volts(36 cell panel). Your 60 cell panel produces much higher boost in charging amps and that is the beauty of MPPT controller (something Salvo does not understand).
And finally, you should invest in an ammeter for a real scientific work.
At least I spelt my name right!
When I say I "get the Isc to the battery" what I mean is I get the "same current in amps as the Isc". I will continue to express it that way for convenience. :)
On the IV curve, the I is what Isc would be. I take the Isc with the panel shorted and then hook up and then see the same amount of amps at the battery with the Trimetric (allowing for other 12v things), the solar controller's output on its display, and if it is below 10amps also using my multimeter --lots of cross-checking.
In the second part, I need more coffee. But note that the panel does not boost any charging amps. The buck converter in the controller does. Is it correct to say "boost" the amps with a "buck" converter?
Seriously, I would like to understand what is really going on with my solar and I do need to get an ammeter on the panel- to- controller path. That is my missing number. With that, I could see my controller's input watts as well as its output watts I get now, and then I would have my controller's efficiency at the time.
