Solar panel size

Hi all,

I'm currently shopping for a solar power set up for my boat like this 160w https://www.amazon.co.uk/d/Electron...=1490006385&sr=8-11&keywords=150W SOLAR PANEL. I was thinking of using a 12v 100ah deep cycle battery. I intend to use the solar power only for LED lighting on board about 12 of these 6x Interior LED Round Shape Ceiling Spot Light for 12V Camper Van Caravan LD984 | eBay https://www.ebay.ie/itm/6x-Interior-LED-Round-Shape-Ceiling-Spot-Light-for-12V-Camper-Van-Caravan-LD984/122927328643?hash=item1c9f0a2d83:g:BnYAAOSwZA1aZbQZ. I'll be spending a few months on board during the summer so I'll want power from the battery to be reliable at night. I live in Ireland so summer is not always sunny, in fact, in the west of Ireland where I live its overcast almost 70% of the time. My question is this, Is my proposed setup going to keep my battery charged enough to run my lighting at night? or will overcast weather mean that my battery will not charge efficiently enough for my requirements? Obviously I won't be using the lights all at the same time, but how much charge can I expect to get in a temperate climate like mine? Also Is my purposed set up too big? Or is a bigger panel better? Thanks in advance for anyone that can advise me on this, I'm a little confused by all the choices available.

 

Well one way to look at it would be to look at how regular solar solutions often calculate 5 hours per day of peak generation so if you only have 30% of that you can figure on generating 225W + some (150 x .30 x 5) with one panel which is close to what you will consume (240W) with those 12 lights over 8 hours. The 12V battery at 100AH (12x100) will give you 1200 Watts run time so if you get 1 nice sunny day per week you should be ahead of the game.

 

What you need is a system that will begin charging on the tiniest sniff of light, and keep going.

You need a few things ;

1. A high PV array terminal-voltage. Put simply, the controller is in a far better position to charge to charge your 12V battery system when it has 150V on its' inputs. Select panels so that everything is series is up around the max allowable for your controller. You will sacrifice some full-sunlight efficiency in this configuration, but you dont care about that.
2. A really efficient controller. MPPT. Nuff said.
3. A battery system that is not a leaky bucket. Charging a leaky-bucket battery with a drop of blood wrung out of a stone is as bad as it sounds. Use a super-efficient battery system, and that means not a liquid filled lead acid battery. AGM or newer technology plz.

I've seen systems like this put a couple amps into batteries in the rain with total cloud cover. Current from the panels was a few hundred milliamps, as expected, and battery charge current was humming along at five to ten times that!

 

Thanks for the info guys I was in touch with a solar panel supplier, I told them what I needed and they have me a package that is great