Right or Wrong

It depends... Probably the greatest "hit" is possibly your food... Monitor the temperatures in the AM and see if they have risen enough to be "unsafe" or at least, shorten the storage life of your food.

Back in 2006, I found a US Gov study (circa 1945) on the best freezer temperature for long term food storage... At that time, they decided that 0F or cooler was best... And even 5F showed food losing a bit of its quality. So, if you are looking for long term storage of frozen food, you don't want the temperature to rise much above 0F.

On another issue--I have always associated "temperature cycling" with the acceleration of "freezer burn". The food warms up a bit (still well below freezing), freezer compressor turns on an dramatically lowers the air temperature the the freezer--Causing "sublimation" (water ice turning to water gas) of ice from the food to the inside surface of the freezer bag/container... If the overnight temperature transition is not very much--I guess that freezer burn would be less of an issue.

There is probably not much energy saved in turning off the compressors overnight... Although, if you only run the compressors when the "sun is up"--The batteries are certainly cycling less.

There is also the question of how your frost freeze fridge/freezer (?) respond to "power outages". The simple/cheap units I typically buy have a mechanical timer that probably advances the defrost timer while the compressor is running--Turn off the AC power, no running compressor, power starts up and defrost cycle will start when compressor cycle timer kicks off (ignoring the question of cutting power during defrost cycle--Evaporator heating element needs to heat hot/long enough to defrost light icing--Does lack of compressor cycle after defrost "heat" the fridge/freezer enough to cause food storage issues?).

The more expensive fridge/freezers may use an electronic defrost timer--And somebody here reported that their fridge (?) started a defrost cycle as soon as the power was restored. Probably a bit of a waste of power (more defrost cycles than necessary?).

And there is the question of inverter "tare losses" (idle current just from the inverter being "on")... For larger inverters, it is probably in the 10-40 Watt range (some are higher) if you leave them running over night.

So how much power is that costing you? Say fridge and freezers use about 1,500 Watt*Hours per day (average SWAG for relatively efficient units). Say you turn them off for 10 hours a night:

• 20 Watt inverter Tare (SWAG) * 10 hours = 200 WH per day
• 1,500 WH per cooler * 2 coolers = 3,000 WH per day
• 200 WH savings / 3,000 WH per day = 0.07 = 7% energy savings (again, just a guesstimate)

Of course, you are cycling the battery bank much less overnight. Need more information on battery bank AH capacity, voltage, and type (you are using LeFePO4 batteries?).

Overall, you are probably not saving much energy (inverter off ~200 WH per day)--And assuming you solar array probably harvests around 4,000 to 6,000+ WH per day (rest of house loads, location, over sized array for winter/less genst usage, etc.)--200 WH is pretty much roundoff error in your system usage.

Anyway, my first set of reasonings and guesses.

-Bill