Solar Panels

Goona,

Before you can decide on a panel size you need to know your daily amperage draw. This is the amount you will need to replace in the 8 hours or so of sunlight you get during the day.

Add up your individual light draw and multiply by the hours they are on eg 2 x 10 watt lights will draw 20 watts in an hour and that is 1.6 amps approx. on for say 3 hours and you have a total evening draw of 4.9 (say 5 amps). This is the amount you will need to replace the next day. A 20 watt panel puts out just under an Amp and would be enough to recover a 5 amp per night draw. How does 20 watt convert to only 1 amp. For a start Solar panels put out not 12 volts but 16.8 volts giving a theoretical output of 1.2 amps (20 divided by 16.8) and by the time system losses are taken into account the panel is rated ot only .95 amp.

Now as for the fridge. You need to know the draw. i understand that some of the newer 12 Volt fridges are quite advanced in their power management. Consult your handbook or talk to an Engel dealer.

This draw will be a lot higher than the lights and of course has to be added to the lights.

If you have an older Engel you may find that you will need a whole heap of solar panel output to replace the current drain.

I use, and have for last 30 years, 3 way gas fridges (12, 240 volt and Gas). The first unit lasted 25 years before it spat the dummy. My new one, also a Finch, works just as well as the old one did. As a plus, it cost half the price of an Engel. But no freezer. Don't need one. Have to watch it does'nt freeze things in any case especially working on Gas. My wife won't carry eggs or lettuce in the fridge. Frozen fresh eggs sort of never recover. As for frozen lettuce, forget it.

That way I get by with just a 20 watt solar panel costing $260 and not needing a regulator. And up till April was using only a 27 amp hour sealed lead acid battery arrangement. That gear reached the end of its life cycle in April and I replace it with a 70 amp hour SLA deep cycle unit.

Have never run out of power with the 20 watt panel and the Gas fridge.

By way of comparison an 80 watt solar panel costs $720, measures approx 1200 x 540 and will require a regulator costing between $90 and $230 depending on how many bells and whistles you want on it.

A new gas fridge starts to look decidely cheap.!!

Whatever you do, do the current draw sums carefully or you could find yourself unable to recharge and with a flat battery real quick.

Also make sure your battery is fully charged before you leav home.

I was camped beside a new off raod camper trailer in late April and his unit came with 100 watt solar panel on the roof. However he leftt home without fully charging the deep cycle battery and was without power within 24 hours with a flat battery

Cheers.

Magnus

Goona - the maths from Magnus is all good advice - you should be calculating what the real needs are, but another few factors to ponder might be:
BP solar make a range of panels - ring them in Sydney for your local agent. The articulated (hinged) panels cost a lot more than the fixed jobs, $ per watt. A regulator only costs about $45 which avoids cooking batteries if the sun is blasting down.
IMO, its impractical to plan only for solar supply - it may be overcast at times, and anyway, you are likely to run the battery down even if you have al ot of sun.
People I know that use solar see it as an aid - they have a genny, or run the car, or top on on daily drives, while camped.
Quality gennies are great, but who wants to camp by one ? Its 3 way for me, but this might be revised when I head into the far north.

Note re Whitworth's Magnus....thanks....I'm getting a camper soon and will need something to top up the deep cycle within, when static for awhile.....a panel may well be the go.

Oops

That enough is a stray word!!

Magnus

G'day Goona, Over the past 20years I've used Solarex solar panels, used 20w and 60w never had any problem. I used a regulator with the 60 w. For 18 months I lived up in the High Country and that was my only source of power, ran 12v drills, fluros and a 12v television. Even in winter I had enough power with only one deep cycle battery 70 amp and a few old car batteries, just one panel.
Now days I used the same 60w panel on the Jayco outback, I don't mount it on the roof I have 2 12volt connections, one on either side of the camper(snap in connectors) so I can move it when the shade is a problem. Battery mounted inside the van, charged while I travel, isolating switch when needed.
The reason i chose Solarex is their robust construction, C-section Aluminium frame
toughened glass(not my choice really, as a glazier I'd use 5mm Laminated--but that's just me)
Good luck
MightyQ