Should I add more battery to PV

dclifford

I noticed in last few days that my system has started clipping. The system is Huawei based with 18 panels 7.56 kWp with 5kw hybrid inverter and 5kW Luna battery. System was installed early March.

When filling the battery the system has shown peaks of approx 8kW, this year. With battery full if clips at 5.5kW. I have added a pic of todays trend.

Would adding another 5kW battery make sense or not. Just wondering would it allow me to capture the extra that I am not getting now and would be available across the next few months.

Note: Elevated consumption at starg and end of the trend is PHEV charging.

graememk

(I'm going to go with no but i'll go on)

How much is another battery?

How much are you actually using, say 5kWh on the perfect days?

you may not even get the benefit of it either as the battery would be able to charge faster and still be full before mid-day!

bullit_dodger

Yeah, most people over estimate the negative side of clipping. Some back of the beer matt math - lol!

If you draw out the "missing curve" and then compute (roughly) the missing bit, you get something like.

So 6 hrs clipping, but your not being clipped by much at the start maybe 50 watts or something, and that will rise to the max limit which isn't always your installed kwp as heat plays a factor, esp on those sunny days….but assume it does go to 7.0kw. So visualize a box of 6hrs x 2kw (like above)….so that box would be 12Kwh. Since it's the area under the curve we want, then it'll probably be something like 7-8Kwh.

Then it's a question of how many sunshine days a year will you get this level of clipping and can you capture all that missing power. Like Graememk says above i'd be tending towards no. If you got 50 days of this, you'd capture another 350-400Kwh for a year. Is that worth it for a battery that costs €4-5K? By itself I'd say no, but you might have other reasons which could make the battery worthwhile. (Selling to the grid etc)