ajw22
Member
- Joined
- Nov 16, 2018
- Messages
- 733
Just a report to help others avoid potential troubles in the future.
TL;DR: Install breakers with high enough Amprating to account for higher current during hot weather.
I have 3 solar chargers, each connected to their own oversized PV array, so that I can get enough power on days with less than ideal weather.
Each array is 3180Wmp, Vmp 91.8V, and Imp 34.63A. The solar charger limits itself to at most 2285W, so the draw from the solar panels should never ever exceed 2285W/91.8V = 24.9A, right? And in practice during spring, it was closer to 20A.
So I used 32A breakers for chargers #1 and #2, and a leftover 25A breaker for charger #3. A bit tight, but they don't trip until at least +15% or so anyway...
It worked well for 5 months, buttoday #3 breaker tripped. The weatherwas super hot, so according to the "temperature coefficient" stated in the datasheet and assuming panel temp of 55C, the panels now had a Vmp of just 81.3V (11.5% lower!!). The solar charger compensated by pulling more than 28A. The 40+C heat in the electrical room probably helped set off the thermal trip of the breaker, too.
Solution: replaced the 25A breaker with a 32A.
TL;DR: Install breakers with high enough Amprating to account for higher current during hot weather.
I have 3 solar chargers, each connected to their own oversized PV array, so that I can get enough power on days with less than ideal weather.
Each array is 3180Wmp, Vmp 91.8V, and Imp 34.63A. The solar charger limits itself to at most 2285W, so the draw from the solar panels should never ever exceed 2285W/91.8V = 24.9A, right? And in practice during spring, it was closer to 20A.
So I used 32A breakers for chargers #1 and #2, and a leftover 25A breaker for charger #3. A bit tight, but they don't trip until at least +15% or so anyway...
It worked well for 5 months, buttoday #3 breaker tripped. The weatherwas super hot, so according to the "temperature coefficient" stated in the datasheet and assuming panel temp of 55C, the panels now had a Vmp of just 81.3V (11.5% lower!!). The solar charger compensated by pulling more than 28A. The 40+C heat in the electrical room probably helped set off the thermal trip of the breaker, too.
Solution: replaced the 25A breaker with a 32A.