Should probably add, fridge was set to a temp of 3 degrees, in it's fridge cover. Placed under a gazeebo, so in the shade all day. Ambient temps were approx 18deg during the day, dropping to 5 at night.
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As well as cloud cover affecting your panels efficiency temperature also affects how much power you'll get out of them so on the really hot days with clear sunlight your fridges will cycle more but the panels will produce less .
I had 600 watt of solar on the caravan roof which easily coped with the the two house batteries but plugging in the 4by to charge the aux battery as well was starting to stretch the capacity .
I agree with Cuppa and GQtdauto, too many variables to give a one sentence answer. I run 2 off 60w Canon Shade tolerant panels into a 200a/h deep cycle, with current monitoring. The max rated output is 3.88a/panel. I get anywhere from 0.1 to 4.1amps per panel depending on the time of day, the ambient temperature, cloud cover. I try to keep the depth of discharge as minimal as possible to prolong battery life, so when I get to say 12.5V, I start the car and give the battery a booster shot from the alternator. I run my fridge at 1 degC plus minus 0.2degC using a calibrated external controller. I have an old 60L Engel fidge with the old compressor that draws 6amps - the newer compressor draws 4 amps using a smart controller. I also run a thermostatically controlled circulation fan that draws 0.1a and comes on at 35degC and off at 28 degC - this circulates the cabin air to improve the heat transfer process of the fridge. I love these panels as they are glass free and laid on SS sheet - basically indestructable, but Canon have stopped making them now. If going for a panel, look at a shade tolerant panel, probably monocrystalline for the highest efficiency. Mine are fix mounted on the roof rack with a 10" airgap to the roof, so they don't suffer too much from reflected heat, the portable panels are a good option as it allows you to optimse the charge with repositioning/aligment during the day, but for me thats too much effort. Hope this helps. Also, your fridge consumption will increase with ambient temperature, so bear this in mind when doing your calculations, plus you only get abot 5 hrs a day at max radiation, and this is approx 60% of the value the panels are rated at, another allowance required.
That book that Cuppa refers to I believe the guy recommends something upwards of 250 watt of solar per battery from memory , his reasoning is that on even the bad days you will still get enough to get you through .
Clunks example makes some sense now he's explained the conditions , Wonnangatta last year was mid to high 30s during the day and close to zero at night , I actually turned the fridges off before going to bed and noticed when I turned them back on in the morning they were colder than when I turned the things off .
My fridges are both fixed in position though so airflow is always a hassle .
FWIW a recent 40+ degree long weekend with minimal to none daily cloud up on the border found my 120W Waeco portable panel struggling to pump over say 4.5amps at absolute best. (All panels were struggling there I believe)
Regularly pooring warmish river water over the panels helped it briefly back to between 6&7Amps according to the clamp meter. Quite tedious work but was trying to keep the icy poles frozen for the kids in one and beers and tucker at 1 degree in the other without too much DOD over 252Amps storage.
My old DX setup had 240W on the roof and used to make slow ice in the old TrailBlaza beast. Can’t remember ambient temps there then though but still well in the 30’s for sure!
Excessive ambient heat appears to affect as much as cloud cover in my elecy nuffy learnings so will be expanding panel size again one day too!
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Not really... soooo in trying to reduce it to one sentence.
Sawafuji Compressors are very efficient, Danfoss type are not so when all else is equal (cabinet materials, useage, solar energy, etc) getting similar cooling performance out of the Sawafuji system means less power, sometimes a lot less.
Please excuse my ignorance here ET mate, which compressors are in which fridges?
We’ve collected many fridge brands over the years from old RB’s faithful ‘TrailBlaza’ to oldish ‘Waeco’ 50’s/60’s/80FF and Engel recent 21L retros. Still do love the ‘TrailBlaza’ the best but man it’s outer size (insulation) is huge, only ute fitting!
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Brief history lesson opportunity beckons...
Waaay waaay back in the 50's a mob of Germans were making portable fridges and the compressor of choice was also German, specifically Danfoss.
Another German, specifically Mr Delt was making this nifty outlandish Compressor that all the other Germans laughed at (more about him later)
Then a Japanese dude, specifically Mr Sawafuji came and saw one of the German dudes, specifically Mr Engel and said "maaate, they are really awesome fridges you make but I have a radical new compressor that will make 'em even better".
Mr Engel said "OK lets give it a shot" and dumped Danfoss for Sawafuji and all the other Germans threw sauerkruat at them.
But Mr Sawafuji was right and Mr Engels' fridges with his Compressor were indeed much more reliable and used less power which was vitally important back before Solar Panels etc when the fridge had to run on Battery alone.
What many didn't know was the Mr Sawafujis Compressor was actually the design he had bought from M Delt and was German all along.
Mr Engel got tired of getting showered in Sauerkraut every time he went to the Brewhaus and told Mr sawafuji he wanted to sell Sawafuji Compressors to his mates.
This pissed Mr Sawafuji off so he bought out Mr Engel but didn't want to upset the apple cart too much so didn't change the name and kept the fridge manufacturing in Germany.
The other Germans pleaded with Mr Sawafuji to sell them his compressors as well but he told them to stick it up their lederhosen and went on to make an even larger fortune in the great sauerkraut famine of '68
Soooo, the first few iterations of Engels had Danfoss but from then on Engel (and only Engel) have been 100% Sawafuji.
Everyone else uses Danfoss or Danfoss clones
Sawafuji (Delt) compressor design and operation is totally different to the Danfoss style rotary jobbies and the design is locked up rock solid in world wide patents and Sawafuji refuses to licence them out or onsell to this day