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johnhb asked

ESS - strange behaviour at low power

I have installed a 3 kVA Multiplus, SmartSolar Charge controller, CCGX and Li-Ion battery, configured for ESS and Mode = Optimised(with BatteryLife). It is all working pretty well. My understanding is that when ESS mode = Optimise the system will use AC mains as last resort. However, in the morning when the panels are generating say 400W and the battery is starting to recover, a load of say 300W is fed directly from the AC mains and the PV yield of 400W all goes to charging the battery. This contradicts the above policy. This is not a big deal because as the yield increases, the PV panels drive the load as well as charge the battery and the AC consumption drops back to the +/- 60W we normally see. Does anyone have an idea of what is going on here ?

ESS
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sinbad answered ·

With the batterylife system, you'll find that the system changes the minimum SoC dynamically. At night, when your batteries drop to the SoC limit, the system raises that limit by 5%. (It drops it by 5% when they hit 85%, and another 5% when they go over I think 90 (can't remember exactly).

In the morning, when the PV starts generating, the system will stay on AC power until the SoC reaches (SoC limit + 5%) - ie, if your SoC limit is 60, then when the batteries hit 65, the system will switch to using the AC target (60W in your case)

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