Just a quick word on the solar inverter efficiency number you saw in the last blog groov screenshot.
The code behind the number is pretty simple.
gti_efficiency = (gti_output_power / panel_1_watts) * 100;
gti_wasted_power = panel_1_watts - gti_output_power;
This gives me both a percentage and a wattage.
The wattage is of interest because the heat sink on the unit gets really hot
(As you can see in the screenshot – the air temp was 31 and the heatsink was 60.)
The slight twist to the code caught me off guard (I’m getting old and rusty!). At night, the ouput of both the inverter and solar panel is zero. For some reason the computer was not happy about dividing by zero.
My solution, wrap the above code in more code;
if (panel_1_volts > 15) then
gti_efficiency = (gti_output_power / panel_1_watts) * 100;
gti_wasted_power = panel_1_watts - gti_output_power;
endif
So, yeah, if it’s dark (or really really really overcast) don’t bother doing the code.
For now, that seems to work.
It’s oddly overcast today, a welcome respite from the heat we have been having, but not the best for solar system testing. At the moment we are only getting around 50 watts from the inverter….. and 87.1% efficiency.
