400w classic build, what are “normal” MPPT numbers?

So Will’s excellent instructions, book and videos gave me the info to put together the classic 400 on my food truck. The goal is to forgo the geni on sunny days. I achieved my goal yesterday and ran fridge and electronics on solar all day!

What I don’t know is how to understand if the data coming from my mt50 is within normal ranges for this size system. If the PV is sending 37 volts to the batts on a fully sunny day is that good or bad? What numbers would indicate a problem? Why do the PV numbers change so much, even with the same amount of sun? Tia. Tom.

The v, the PV send to the controller are based on shading and solar input, the batteries will get the programmed voltage and current for the bank. 37v would be 3s 12v panels, or 1s 24v panels about...

Higher voltage into an mppt controller equates to better usable watts.

Supervstech said:

37v would be 3s 12v panels, or 1s 24v panels about...

Click to expand...

Sorry, newbie. does 3s mean 3 solar panels? I have 4 12v solar panels on the roof, so does that mean one of the 4 has a faulty connection to the system? They are wired in the manner Will dictates in his 400w classic build.

MPPT panel voltage should remain the same except for temperature. Sun intensity only changes the current and eventual watts. If voltage varies a lot then there is shading and some of the cells aren't producing. The S # of panels in series determines the total voltage and P # of panels in parallel the current. Panel voltage should be a little less than stated on the back label for power point (unless you are selling ice cream to Eskimos)

So it would seem I’m missing a panels worth of power.

Thanks guys, time to get a amp meter out.

Tom said:

Sorry, newbie. does 3s mean 3 solar panels? I have 4 12v solar panels on the roof, so does that mean one of the 4 has a faulty connection to the system? They are wired in the manner Will dictates in his 400w classic build.

Click to expand...

Sorry.
For newbies to wiring batteries or solar panels, s after a number indicates wiring them in series to keep amps low, wih high wattage movement that raises the voltage.
a “p” after a number indicates a parallel connection to move watts high amperage keeping the voltage the same.