partial charges, SoC drift, and further thoughts on shade

harvest patterns vs shade

Normally my peak harvest from the van-mounted array would come at local solar noon. At this place/date solar noon is 1302 (1:02p).

But since I am (intentionally) in shade at “noon” and thereafter my actual peak is during a brief window when the whole array can see the sun:

  • 0951 - 555w
  • 1302 - 51w (!)


This is where overpaneling the bank pays off; MoAr PaNnul in challenging conditions means more harvest. Overpaneling is mainly a space problem rather than a cost problem, since higher voltage panels are dirt cheap on the used market.

measuring State of Charge

Once again I’m seeing the coulomb-counting monitors becoming unreliable under odd charging conditions. I think it is due to:

  1. low charge currents, dipping below the minimums the shunts need to count accurately
  2. failure to reliably hit Vabs where the shunts reset to 100% SoC. Normally the reset would counteract drift.

Update: later today it broke the streak and finished absorption. The shunts agree again.