Assuming you have enough load to require more than 4kW, 4kW this time of year with a theoretical max of 6.8kW doesn’t sound that crazy. It will depend on the angle of your roof and the angle of the sun, but for example I’m only producing about 55-60% of my max at the moment.
Thanks. I also thought of the weaker sunshine/irradiance during winter. and I hope this is the issue.
During April I reached a peak solar yield of of 6296W (from a max of 6600Wp) so the 2 Mppts can definitely reach max. But this yield was to charge my 2 x 5.6kwh li-ion batteries.
But I have not seen when charging the geyser from the excess solar via the Victron ET112 meter that the solar yield goes past 4000w. Past around 11 am, when the batteries are 100% SOC the geyser gets charged at +/-3000w. I notice that the inverter will only allow a solar yield for another 1000w passing through the inverter Anything requirement above +/-3800W starts to reduce the 3000w being fed to the geyser and to the load. Hence I’m not sure if there is a setting or is this a limitation of the Inverter against a max of 4000…which is also the max on off-grid charge on a 5kva inverter.
I also noticed that OP had an 8kva inverter. That inverter has a max off-grid allowance charge of 6500w, hence the ability to yield additional solar charge more than a 5kva inverter which is limited to 4000w. At a peak day on 12 Apr, I had a solar yield of 29kwh and the hourly yield did not go past 4000w.
Hence I’m looking for validation or confirmation from a victron expert to see if this is a setting issue or an equipment limitation issue.
Well it seems to me that your batteries are full and therefore your PV yield would only be what is needed to service the immediate loads. Nothing wrong there.
If you take a look at the datasheet you will see the inverter has a continuous output it can provide as different temperatures. This is AC that it inverts from DC (battery and/or PV) and what is used by your house and being fed back. In the case of the 5kVA that is 4000W at 25°C, 3700W at 40°C etc. and seems to be exactly what you’re seeing. The MPPT/s are basically being limited to create what the inverter can output at the time with full batteries.
Where you saw 6000W+ from the PV panels is when the battery needs charging. For that there is no inverting required as the DC energy from the solar panels goes directly to the panels and not through the inverter, so the MPPT can go up to what the battery limits you to plus whatever you are consuming / feeding back up to ~4000W (extra).
So if your battery is not fully charged and still accepting large amounts of current and you have high consumption like the geyser then you should see the panels outputting high numbers.
Probably derating also comes into play. Hotter the inverter gets, the less it will invert.
Derating for all other inverters is based on ambient temperature, not inverter temperature…
How can this be?
My reasoning tells me that ambient would necessarily cause the inverter to heat up more than usual and then it will derate.
Because the cooling fans are there to cool the inverter?
Or did you mean all other inverters work on ambient except for the Victron range?
The standard definition is usually derating from ambient. I’m not sure how Victron is specified.
Well, the sensor is inside the box, so ambient is a little academic anyway. I also believe it sits on a heat sink, so it probably derates based on hardware temperature.
from here
1 Like
[/quote]
In the case of the 5kVA that is 4000W at 25°C, 3700W at 40°C etc. and seems to be exactly what you’re seeing. The MPPT/s are basically being limited to create what the inverter can output at the time with full batteries.
Thank you @fredhen. Confirmed - The validation does make sense to me now. The inverter is being limited in the Inverting mode to the 4000W limitation. Temperature also seems to play an active role in the Victrion equipment. It seems that my best bet is for me to include another 5KVA inverter to increase that limitation from 4000 W to 8000w.