One of the projects I've done this summer was to fit a fridge to the boat which I planned to try and make self sufficient via solar power and I thought my experience might help anyone planning a similar thing. I'll try and post photos soon.
Part of my reason was to have the availability of ice, cold beers and G & Ts and part was my interest in Green energy.
I fitted a Waeco coolmatic 40l fridge (bought second hand of eBay) which draws about 2.4 watts per hour on average and has a 5ltr freezer section. I'm well impressed with it.
I bought a 110amp hour AGM battery and a 100w solar panel which currently has a programmable PWM (pulse wave modulation) charge controller. The battery and fridge are standalone and situated in a Marine ply cabinet which is under the port helm seat. The panel is sikaflexed onto my cockpit hardtop. It would have been more efficient if I could angle the panel according to the suns position but it was more important to secure my investment. I was limited to panel size as I only wanted to use my small cockpit roof.
The panel is rated at 5.7amphours max but I did clock 6.4 one day! In truth a 100w panel is not enough to run the fridge 24/7 so I now put it on timed via the solar controller which controls the load also. I run the fridge from 0900 hrs to 2100 hrs and 0200 to 0400hrs. The system has coped with this during the summer. When cruising I leave the fridge on 24/7 and have gone five days with the battery being Ok. The lowest I let it go down to was 12.0v
When I first had the panel I was concerned at the lack of power but realised my front white navigation light was casing a shadow over part off the panel for a number of hours a day which meant the blocking diodes were kicking in and shutting down the relevant cells. For example on the day I moved the offending light the output changed from 1.6amps output to 2.8amps instantly.
I may change the charge controller to a MPPT (max power point tracking) which is more efficient and eeks out up to 30% more power. It is also much better on dull days as my output can be less than 1.0amp per hour on really full days. But I have spent all my money now!
I was wondering about fitting a caravan type split charge relay so that my alternator can top up the charge on my fridge battery when the other two batteries are fully charged. Could anyone advise on this please?
My advice to anyone doing this would be try and fit a 200w panel if you can and use a MPPT charger.
I vote you found this ingesting. Sorry it's a long post
Regards
Billy
Shetland Black Prince -Fizzy - Worcestershire Avon (Formerly owned a Norman 20)
Solar powered fridge
Posted - 18 Aug 2013 : 09:04:49
