back to 2022.09.05 LiFePO4 solar charging

5 in conclusion:


I got to test the new high current inline meter I just finished making during the battery discharge, so that
was a nice unexpected bonus. The meter works great and is very handy.

The new "2x2" solar combiner I recently made passed tests with flying colors. It doesn't have separate meters
for the individual panels, but it's got a large power meter on it instead, which worked great. It connects
four panels together with two pair in series into two strings, and places those strings in parallel, which
doubles the voltage and doubles the current. This keeps the panel Voc below the 50v limit of the LiFePO4
controller, while lowering the current from the full-parallel 20a down to a max of 10a.

The power collection from four panels at the start was disappointing at under 30 watts, but I got much better
results (unsurprisingly) by connecting up all 16 panels. At least that allowed me to test the controller at
near full power. It also validated the need for more panels to improve collection during bad solar conditions
which helps me justify the added expense. I was expecting to only get 4x the power with 4x the panels, but
the output was significantly higher with more panels, which is a bit puzzling and will require more testing.

In real-world use though I won't be using more than one set of four panels to charge the lithium battery, and
it looks like this will do a decent job of keeping it charged if there's only one station running off it. The
other 12 panels can be used on the main grid controller, or even further divided into a main grid of 8 panels
and another remote station using the remaining 4 panels on the other Tracer controller. This looks like a
pretty flexible setup, which was one of my design goals. I personally find it easier to have just one central
large grid that everyone runs from, but recently we've been experimenting with satelite stations so I don't
know if that's going to be the way of the future or not. I'll just have to be ready to support either way.




last updated 11/30/2023 at 20:13:08