wattmatters
Solar Wizard
Another day, another experiment....
I wanted to test something about my AIO inverter's capabilities. As a reminder this is a clone PIP-4048HS.
It was my (and others I know) suspicion that the inverter caps PV output based on the battery max current charge setting, no matter the AC load applied. e.g. if the max charge limit is set to 20A (nominal 48V battery) then the PV output will max out at ~1kW no matter if there is ample sun for the array to supply more and the load on the AC output is >>1kW.
So today I did a test by applying a load greater than the PV array would be able to supply - a resistive element heater. I calculated the likely maximal output of the array under perfect conditions today would have been ~1.65kW.
Sure enough despite a 1.7kW load, the PV output was capped to about 1kW.
So I used Solar Assistant on my phone to change the battery charge current limit setting, increasing it from 20A to 40A.
The inverter's solar controller did a reset, output went to zero briefly before it began to ramp back up to supply the load. No interruption occurred to the AC output and the battery was at all times supplying the balance of power. This time the PV output increased to 1.5kW.
I then repeated the exercise by changing the battery charge limit back down to 20A, then back to 40A and back to 20A again. Each time the PV output was higher with the higher charge limit despite the battery not actually charging (it was supplying the balance of demand through the whole test).
Here's the chart showing the PV output and load power during the experiment:
It's an interesting quirk of these inverters.
I'm guessing it's a limitation designed to prevent the prospect of the inverter having to dump load to the battery greater than the set charge limit in the event a large load is removed and before it has enough time to ramp PV production back down. It would be nice though if it were capable of managing this so it could ramp up PV output to meet the AC loads.
It won't be a limitation for me as I'm about to double the battery bank and when that's done I'll reset the charge limit to 50A, which is 0.13C and at the low end of the safe charging level specification for these batteries. 50A x 48V (nominal) = 2.4kW. My array is rated at 2.22kW so it will never actually supply 50A to the battery, but the higher setting will mean PV output will never be throttled because of this setting.
I wanted to test something about my AIO inverter's capabilities. As a reminder this is a clone PIP-4048HS.
It was my (and others I know) suspicion that the inverter caps PV output based on the battery max current charge setting, no matter the AC load applied. e.g. if the max charge limit is set to 20A (nominal 48V battery) then the PV output will max out at ~1kW no matter if there is ample sun for the array to supply more and the load on the AC output is >>1kW.
So today I did a test by applying a load greater than the PV array would be able to supply - a resistive element heater. I calculated the likely maximal output of the array under perfect conditions today would have been ~1.65kW.
Sure enough despite a 1.7kW load, the PV output was capped to about 1kW.
So I used Solar Assistant on my phone to change the battery charge current limit setting, increasing it from 20A to 40A.
The inverter's solar controller did a reset, output went to zero briefly before it began to ramp back up to supply the load. No interruption occurred to the AC output and the battery was at all times supplying the balance of power. This time the PV output increased to 1.5kW.
I then repeated the exercise by changing the battery charge limit back down to 20A, then back to 40A and back to 20A again. Each time the PV output was higher with the higher charge limit despite the battery not actually charging (it was supplying the balance of demand through the whole test).
Here's the chart showing the PV output and load power during the experiment:
It's an interesting quirk of these inverters.
I'm guessing it's a limitation designed to prevent the prospect of the inverter having to dump load to the battery greater than the set charge limit in the event a large load is removed and before it has enough time to ramp PV production back down. It would be nice though if it were capable of managing this so it could ramp up PV output to meet the AC loads.
It won't be a limitation for me as I'm about to double the battery bank and when that's done I'll reset the charge limit to 50A, which is 0.13C and at the low end of the safe charging level specification for these batteries. 50A x 48V (nominal) = 2.4kW. My array is rated at 2.22kW so it will never actually supply 50A to the battery, but the higher setting will mean PV output will never be throttled because of this setting.