DarrynRow Posted April 28, 2022 Posted April 28, 2022 Hey guys So I have a mecer 3kw hybrid inverter that has 600w of solar input capacity. My question is… What would happen if I installed 900w of panel so that I can maximize the 600w input on cloudy days/mornings and evenings. What would the inverter do with the over supply. Would I need to throttle the input before the inverter or does it have the capacity to dump that extra power? thanks in advance Darryn Quote
Coulomb Posted April 29, 2022 Posted April 29, 2022 (edited) On 2022/04/28 at 8:56 PM, DarrynRow said: What would happen if I installed 900w of panel so that I can maximize the 600w input on cloudy days/mornings and evenings. It will mostly work as you want. But you run the risk of over-charging the battery with the well-known overshoots that Axperts are known for. It's generally accepted that about 20-25% "overclocking" will work safely. 50% is really pushing it. But finding a well-matched ~150 W panel will be a challenge. On 2022/04/28 at 8:56 PM, DarrynRow said: What would the inverter do with the over supply. Most of the time, it just won't "ask for" more than it can handle. The trouble is that when the sun comes out from behind a cloud, suddenly the PWM value that worked well a second ago now cause far too much power into the battery, until the control system reacts and changes the PWM ratio. Meantime, the SCC electronics is overheating, and the battery may be suffering from over-voltage. If you have a BMS on the battery, it may disconnect the battery to protect the cells, but that could destabilise the inverter. You could try connecting the extra panel only on cloudy days, but you'll eventually get caught by surprise. Perhaps not a pleasant one, unfortunately. Your best bet is probably to add an external MPPT direct to the battery. It could be rated at much more than 600 W, and it might be convenient to retain whatever you have connected to the PV inputs now. It can be tricky to get the two to play nicely together however. I used to run such a setup before I went to two inverters in parallel. Depending on your existing inverter model, that could also be an option, though the baby sized models tend to have very small processors that can't parallel. Edited April 29, 2022 by Coulomb Quote
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