But what I don't know is how an AC mini split will work with the inverter and panels. If for instance there is 500w available from the inverter and the mini split wants to run at 1100w what will happen? Will the mini split adjust to the available wattage or will it shut down or cause the inverter to shut down?
So here is my experience with the EG4 12k BTU
Hybrid mini split we installed earlier this summer:
When running direct from solar in cooling mode we set the temperature as low as possible (16C).
It was wired up to two 450W solar panels in series inputing ~80 Volts 11 AMPS. (EG4 unit can handle up to 300V @ 11.5 Amps).
When the sun first came up the unit will try to switch on (sun below horizon-dawn light). Not enough power unit kicks off (internal inverter makes the “beeeeeeep!” of not enough power howl).
Panels get full sun unit comes on and runs with as much power as the panels can provide, all day long. Overcast shade unit throttles back ( you can feel temperature of air discharging get progressively warmer). Cumulus shade conpressor disenages entirely, but unit stays on “searching” for when power becomes available again to throttle compressor back up again.
As long as the panels have some light the unit will try to run to the maximum power capacity available. If the voltage of the panels drops much below 80 volts however compressor will disengage and if solar insolation becomes progressively less available unit will self power down completely.
When running it from generator 120V plug, compressor will pull as much power as it wants to try and maintain thermostatically set temperature.
For example running with a Honda 2000 generator (1600 watts max continuous 100% duty cycle; up to 2000 watts ~30% duty cycle)
Conditions:
-Generator in eco mode (throttle automatically varies based on load demand to save fuel)
-Thermostat set to lowest possible
80F outside air temperature (OAT)
Compresssor demands say 800 watts to maintain thermostatically set temperature.
100F OAT
conpressor demands 1800 watts to maintain thermostatically set temperature.
Since this is above the 100% duty cycle of the generator, generator tries to maintain amperage demand as long as possible until duty cycle “times out” (not certain of mechanism Honda 2000 uses - either an actual internal timer or temperature probe in inverter / generator windings) and throttles back to idle. Compressor kicks off. Unit is still alive so to speak (it’s still on just “searching” for enough power to throttle up compressor again, blowing progressively warmer air out of the indoor unit. After a few minutes in “cool down” mode the compressor tries again to draw current to ramp back up (it does so slowly and progressively over about two minutes). And if power is available compressor throttles up and cool air blows again.
Split unit was only hitting the generator duty cycle limit on the hottest of days this summer. Most of the time we only ran it direct from solar panels and whatever temperature it to could us down to was what we lived with. Funny but kinda hated partly cloudy days in the middle of summer; would constantly kick the compressor off leaving us hotter than if there was a full sun day.
Other notes:
After living with the hybrid 12k unit for a summer where we used it every day I made these observations:
I’m not sure of the exact algorithm the inverter uses to detect the available current when running direct from solar panels but it seems like it doesn’t “check in” very often. For example when a cumulus cloud shades panel string the conpressor powers off (unit still “awake/ alove”), but when the sun comes back out it doesn’t immediately begin to throttle back up for awhile. It waits 2-5 minutes before it “senses” there’s enough power from the panel string before it ramps the compressor back up again.
When running on the generator and plugged into solar string the generator ramps up to provide power when a cloud passes over and the compressor seamlessly transitions between the power sources and runs continuously with no interruptions. Often on partly cloudy days that’s how we ran it. It got sweltering fast if we waited while the inverter “searched” for power after a cloud passed over and panel string was in full sun again.
One short cut to this on mostly sunny days when a few random passing clouds would kick the compressor off, was to power down the Split from the remote, and turn it immediately back on, the it will go immediately to “search”/ “check in” mode and if solar insolation is available immediately throttles up the compressor to life.
Keep in mind this is only applicable to my experience with the hybrid (solar- alternating current) version. No idea how alternating current only version does though I noticed it does offer a high SEER efficiency rating (22.5 vs 28? IIRC?)
