Compressor Fridge on Solar

G'day Ann, Welcome to the forum ..... going back through the posts will keep you busy for some time. [smile] As far as the solar goes a good rule of thumb is to be able to replace the usable capacity of the batteries you select. To keep a battery in good condition one of the requirements is to not discharge the battery below 50 % capacity. So with the Trojans 2x 130amp you have 130amp available for use but you have to put that back every day (worst case scenario). A battery kept at full charge will double its life. A 120 w panel puts out approx 7.5 amp and I use 5-6 solar hours in the day as an average. So if we do some sums .... 2 x 7.5amp = 15 amp x 5-6 solars hrs = 75 -90 amp produced ..... which is a little short of the battery capacity but would be ok if you only use 75-90 amp a day. I'm not sure of the duty cycle of the Vitrifrigo but lets say it draws the 30w/hr continuous (or 60w/hr50 % duty cycle) thats 60amp per day just for the fridge. I would definitely be adding the third panel as it would bring you closer to the battery capacity giving better sleep at night !!! [smile] ..... and more autonomy. 3 x 7.5amp = 22.5 x 5-6 solar hrs = 112.5-135amps per day. Solar autonomy is simply the amount of excess power available to cater for bad conditions. For example ..... if you produce 100 amp per/day from your panels in good sunshine and you use only 50 amp per/day ..... the panels can be cut back 50amp by rain, cloud, shade etc and your battery still gets its charge. The more panels above your use (amount of power consumed) the more autonomy. With my BT I can handle about 6 days of rain (with current power needs) before needing supplementary charging. I have 4 x120w panels to achieve this .... nice to have a bit extra autonomy but its expensive !!! As an example Motley has a 190 fridge and an inverter and 3 x120w panels. We were talking the other night and he said " My panels are borderline (power out verses power back) I'm going to fit a 4th panel." He has 3 x 100 amp bats. To calculate it properly you can put use down on paper right down to the last light and even daily water pump power consumption etc Making 12v power (and water capacity) is the "lifeblood" of a BT .... I'd rather have one/two extra panels and flick the leather on the lounge .... [wink] .... although I did like that leather ........ Hope this helps a bit ... Anthony

Go with three batteries and three panels minimum. I started with three 105 ah batteries and two 120 watt panels which performed marginally in brilliant sunshine. A third panel has improved the situation to "acceptable" under intermittent cloud conditions. I run a similar fridge to what you list plus a 29 lt Engel and the usual lights. Any more cloud and the generator comes out on the second day. I would therefore consider my current setup the minimum. Couple this experience with that of others and you will arrive at an informed decision. Myles

I agree with Myles. I originally had 2 solar panels and 2x120Ah batteries - it was hopeless once any cloudy weather hit. Upgraded to 3 + 3 and have had no problems since, despite fact that it turns out I was running the fridge thermostat too high (see separate discussion on "Fridge Settings"). (Stating the obvious, it makes a huge difference pre-chilling all your food and drink, and running the van fridge at least 24 hours prior to departing on your trip). The thing to remember too when you do a rough estimate of battery usage is that you don't get to use all the stated capacity - the system shuts down well before that to prevent battery damage and/or too low voltage supply to appliances Phil

Gentlemen, Thanks very much for your feedback. Ann

Ann

Definately three modules. A 120-watt module puts out <90 watts. Do your sums on no more than four peak sun/hours/day input (and even that's a bit optimistic).

Thus 2 by 90 watts = 180 watts/hour times four sun hours = 720 watt/hours/day.

The fridge is likely to draw 500-600 watt/hours/day (makers' nominal figures are under extra favourable conditions).

By the time you've added the bits you'll be out of power.

Definately go for three modules.
Collyn Rivers

We started out with two 100 a/hr batteries and 240 watts of solar panels. Simply not enough battery capacity to run a in van compressor fridge in hot weather. Went to three batteries and experience soon convinced us we needed more solar panel capacity. Any shade from tall trees to light cloud caused the batteries to run down. We purchased a portable solar set of 160 watts. This maintains the car fridge battery with sufficient extra capacity to supplement the van batteries. Our total capacities are barreries 300 amp hours in the van 100 in the car, 240 watts solar on the van and 160 watts on the car. We have found the portable unit more flexible in providing charging while we are camped away from the van and when used on the van we are able to "chase" the sun. In this way the 160 watts unit probably produces as much power as the 240 static units on the van. I suggest you carry a generator, Honda EU10i or larger, and a minimum 30 amp charger for rainy days when virtually no solar power is available. There has been an excellent discussion on chargers in the forum. I run the charger through a solar cell regulator/controler to prevent overcharging. Quite a low cost option compared to smart chargers. John

Brief comment: the Vitrifrigo is an exceptionally efficient fridge. At risk of further cooment - do use really heavy cable to connect it all up. Drop me a private email if you need specific info re that.
Collyn