Yesterday was a funny day in Bellville. Cloudy one moment, the next clear, the next raining.
As I didn’t want to drain my batteries unnecessarily, I switched my ESS to scheduled charging (with low stop on SoC to basically just charge with excess PV but not discharge) during the high load times in my house (geysers). Then I got busy with stuff around the house.
The sun came out fully around 12:30 and I was quite excited to see how the PV was running my 3kW geyser when the panels are nice and cold.
I saw the batteries sitting on 100%, but the MPPTs chilling on 1200W (I expected 3200W at least, given the time of day and the icy wind). Demand in house was about 3300W (geyser plus the usual). This confused me as there was no shade on the panels.
I turned off scheduled charging and wham, MPPTs ramped up to 3600W (covering the loads after conversion losses).
Is this some type of safety on the DC side to prevent the batteries from being overcharged when the AC load drops off? If so, I’ll just factor in that when deciding on my scheduled charging slots.