Solar Panel - how many watts?

[Louis_5040937]

I'm investigating getting a solar panel to keep the 110A battery topped up when we're not on hook-up. The main things that we'll (2 adults, 2 young kids) be running is a 4amp 12v LCD TV and a sky Digibox for say 4 hours a day over 3 days. We'll also obviously be using lights, water pump etc). The question for the forum (and please resist the temptation to tell me that I should not be watching TV !) is how big a solar panel in terms of watts would I need ? I'm new to the hobby and haven't actually got the caravan yet so I have no experience of how long I can expect the battery to last. Thanks in advance

 

[ProfJohnL]

Hello Louis, Without knowing exactly how many lights and what type it is difficult to put an exact figure on the amount of 12V current you will be using. Based on your figures of 4 hours of telly & Digibox, my guess is that you will be using approx 7 amps for about 4 hours (28Ahr) plus a couple of amps for a further 2 hours giving a total usage of about 32Ah.

The fully charged 110Ah battery theoretically should give you about 4 days usage, without recharging. However based on an estimated use of 32Ah, a solar panel will give average current for about 8 hours a day, so requiring a output of 4A. this equates to a 48 Watts panel, I suggest that you need to look for 50 to 60 Watt panel. With that you should see out your holiday quite well.

 

[PeterT]

Louis, We have a 110 ah battery, colour tv, lights, pumps etc and we find a 55w panel keeps us going from Easter to October, in the winter we take the genny as well in case. I actually lift my panel onto the roof to save moving it up to face the sun.

 

[ProfJohnL]

Louis, We have a 110 ah battery, colour tv, lights, pumps etc and we find a 55w panel keeps us going from Easter to October, in the winter we take the genny as well in case. I actually lift my panel onto the roof to save moving it up to face the sun.

Hi Peter, Your response seems to indicate that my thumbnail calculation was about right. Louis should find the information useful

 

[Louis_5040937]

Gents - Thanks for taking the time to reply - your comments are very helpful. Louis