I originally had this problem when I first plugged in mine with it set on ECO++, ie it starts then when drops down below 1.4kW (10 mins later when a cloud came by for a visit) it said it had finished etc.
I looked and upgraded the firmware and since then not had the problem. I am current on v5.416 on a Zappi V2
Upon plugging in now, the Zappi says waiting for surplus and when there is surplus it starts it RCD check then counts down and starts charging, when a cloud visits now it pauses and waits for surplus and then continues until the MG say's "I'm full" (whatever is set on the MG to finish charging at).
Depending on setup, for me I can't charge the MG on ECO++ until at least 11am as the house batteries take preference on solar production, once they reach 99% then the MG get's the energy. I could set the Zappi to 50% etc on the ECO++ slider so the MG will charge whilst the house batteris also get charged but this could also take energy from the grid which costs money,
You can see my Zappi charging stats
here
On a different side issue I had to query with the Solar engineer the other day as I noticed a little problem with exporting to the grid on these really good sunny days we just had. I did not notice this since install as the sun was not really great.
I noticed...
1) Lets say the panels are producing their max output which is 6.7kW
2) House batteries are getting approx 6kW to charge, house consumption is approx 600 W
3) Once house batteries are at 99% the inverter switches to export
4) Only 3.6kW would be exported and the inverter drops the panel producing to approx 4kW .
I would have expected the 6kW to be exported and thought something was wrong with the inverter or panels.
The reason is that even though my inverter can export 7kW it is restricted to 3.6kW export as this is a requirement of the National Grid in your local area and your limit is written on the G99 Connection document. You may not have a G99 as this is only required if your solar panel output is above 5kW (AFAIK as I can't remember what the installer said at the time).
So, this means that during the hopefully hot sunny summer I technically can lose 2.5kW export production per hour which is not much cost wise (export at 14p per kWh = 2.5kW x 7 hours = 17.5kW = £2.45 a day)
However it also means I have a possible 17.5kW to use
1) I could purchase another 20kW Battery to store the excess and then export during the evening
2) I could buy a couple of portable air con units and cool the house during the hot evenings
I think the air con will win, as the outlay is approx £400 for each unit whereas a 20 kWh battery will be about £5000 even though they could generate an extra £3 a day for say 180 days which would bring in £540+ a year but that will take about 6+ years to pay back and in the mean time I would still have a hot bedroom and other rooms during the summer and listen to the wife saying she can't sleep at night.
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