Guru
Joined: 13/10/2014
Location: AustraliaPosts: 2101
| Posted: 05:01am 11 Apr 2025 |
I've finished rebuilding the Solar Charger Wall and it was worth the effort.
There are Seven * 60A solar chargers and a 1.5kW AC battery charger, the same physical size as the solar chargers, just slightly wider, likely never needed but got one for 75$ so what the heck.
The load sharing and switching between shaded panels is even better than before the rebuild. Each Charger runs a Max of 40A output for the amount of solar connected to each charger, this gives plenty of headroom in a 60A charger, so 280A @ 54V.
I then decided to try and measure the overall Inverter efficiency over Long term running under all load conditions encountered in the off grid system.
I rewrote my old kWh Code in my Solar Monitor, it's running on an ARM H7@480mHz with a 9" touch panel.
I have three commercial AC kWh meters, one in the Wall Fuse Box in the AC output path from the Auto Transfer switch, one on each Toriod output (1/2 AC power) with a combined AC kWh meter mounted on the Inverter.
So unless these are all crap and nothing can be believed, they should be able to give me some meaningful comparison long term results.
The idea is to measure accumulated DC kWh input into the Inverter and compare it to accumulated AC kWh out of the inverter over an extended time frame.
This should account for low power overnight running and high power daily running under all types of reactive and restive loads and combination of loads.
I note that bad loads (like Diode in one side of the mains feed) show a higher DC input compared to AC output load, over time these short transient loads should fade into the accumulated kWh background (I hope).
I programmed the Solar Monitor to allow me to enter a power loss in watts for the Inverter, from then on the Solar Monitor calculates the AC output in kWh from DC input kWh, accounting for Idle power + Conversion power loss and displays it in real time for total running time kWh, the display just ticks over every minute and all I do is look at the AC kWh meters and see if they match the DC calculated input kWh, changing the power loss value until they match and track within 0.03kWh will indicate the conversion loss as a % of total running kWh by this method, how useful and meaningful it turns out to be remains to be seen.
Right now it's tracking the two AC kWh meters to within 0.01 kWh after 30 hours.
The Test loss value entered is 50 Watts Idle + 70 watts conversion loss, a total of 120 Watts in kWh over each accumulated kWh.
The total conversion loss including Idle power is 14% after 30 hours running time, not really long enough but it's in the ballpark which is encouraging, it's getting less as the heaver daytime loads start mounting up in kWh, most of the 30 hours run time has been below 1kW which reduces efficiency due to % of idle power to output power.
This should account for all loss through the entire path from battery to AC out, if nothing else, once set up, it might be a good indicator of changes in Inverter running efficiency.
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Edited 2025-04-11 20:17 by KeepIS