Solar power usage for a 500ltr fridge over 24hours

yes you can run two cables to allow cable to draw approx 1/2 thru each

I'm missing something here...a 500ltr fridge ? Must be a big boat ?

Alan,
Sounds like you are running 2 seperate systems[each 4x80watts+20A regulator] in parallel to 1 battery bank?

Are the regulators that closely matched in output voltage to allow this mode?

Alan.

First off an "AMPS" measurement is an instantaneous reading. Amp hours are the measure we need to use here ie 10 amps for an hour is 10 amp hours. So you are getting 80 to 100 amp hours per day out of your solar cells.

To run a 2000 watt kettle of 12 volts via an inverter could use up to 200 amps (or if it takes 10 minutes to boil 200/6 = 33 amp hours.

If your fridge draws 440 watts then you are looking at a current draw off 12 volts of around 40 amps. So if it runs continuously for an hour, thats 40 amp hours gone.

So if you are putting 80 to 100 amp hours in, thats about 2 hours of fridge running continuously (I know, I know they dont run continuously) or 3 hours of kettle boiling.

I find a rough rule of thumb for determining current draw through an inverter is to divide the 240 volt watts by 10 ( ie divided by 12 with an allowance for losses in the inverter).

Hope this helps

OOOps

Thats 30 minutes of kettle not 3 hours.

Yes you can split amps, but its often difficult to split it evenly. A difference in specification on the load (the regulator) could see an uneven split. Not sure what the impact would be if both regulators were connected to the same battery bank, you would need expert opinion on that.

You have not indicated the size of your battery bank. That has a big impact too in charging rate, discharge rate, and spare capacity.

avro

If solar regulators are Morningstar you can hook up as many as you like together
To hook regulators in tandem requires them to be precision regulators. Morningstar is your only reasonably priced precision regulator
Morningstar website
In low current regulators up to 30 amp this is the top line brand used by reputable installers
Other brands are desperately trying to play catchup games to Morningstar

Ok,
Thanks everyone for your replies.

Someone mentioned about the battery capacity, it was mentioned, but here it is any way - 12 Trojan T105's 6volt each - so working as 6 12volt batterys - each 12volt battery is rated at 225aph - i think that's right.

I measured the 12vlt Amps with a DC Cable multimeter on the POS lead going FROM the Batterys INTO the 3000W Inverter, which showed abut 150Amps12v dc when i used the 2000W 240v 8amp kettle.
The Inverter showed 1600W when the fridge went into compression mode (I left the thing off for 1 hour - Don't tell the wife :) to see what it would draw.

So still wondering how to work out, assuming the batteries are fully charged at say 13.00vlts and say the fridgewent into compression mode 3 times a day for 20minutes each, then ticking over at say 500W for 6 hours - if the batteries could handle it ?? Owch my head hurts :(

I have another 4 12v T105's put to one side. Tried to cable everyting up, but the solar panels i have, just didn't seem capable to keep them all going properly - so so far the sweet spot seems to 6 12v T105's - which is why i want to get 8 more panels and then hook the fridge up. Hopefully having most of the house on Solar.

As for the Regulator, i am using a standard 20Amp at the moment.

But i was hoping to get 8 * 80watt (40amps), panels on the roof of the house, and use 2 of these regulators - if i could get away with halfing the cable into each reg.

I have a spare (thank god!), cable runing into to the house (The rest of the 12v and 240v supply is well and truely buried, concreteted and condueted in), so i was hoping to use that cable, which is capable of handling 12volts 50amps.

So i don't mind if one of the regulators decides that the batteries are topped up, and the other keeps going for bit longer - of course that would apply to 'floating' the batteries as well. But they are made by the same company and are the same model. the type on e-bay selling for about $50.

I did a previous post asking about better quality regulators and was shocked at some of the prices and the quality issues with them. I spoke to the actual manufactor (long time ago), of my 20amp reg and i have no doubt of his integrity and quality of the product. Also having one super duper reg - and it fails - then you have nothing.

So, the question was (which i think was answered), yes i can 'split' the cable and feed each half into a 20amp reg.

Once again, many thanks. So just need some help in working out the fridge issue.

Cheers.

09.00 to 13.00 is only 4 hours not 6 hours. I assume you meant 09.00 to 15.00

Allan, you have posted -> So, my 50ltr fridge (which has 1Amp on the power sticker)

What brand and model fridge is it that has this 1Amp sticker on it ??

Hello again all,

With the time, oops! I did mean 9:00am to 3:00pm.

Mainey, my fridge is a 500ltr not 50ltr i think you mean.

But the model is a Fujitsu Er 502F - W: Input current 0.7A - and The Defreosting Current = 1.0A

So i assume the 'compression' phase is the Defrosting Current, or have i got that wrong?
Cheers,
Alan.