What size solar panel do I need for my fish house?

[Christopher Quast]

I will be running 3 camper lights and also my stereo. I am looking for something to keep them up to par while I am gone which is usually a day or two.

I have no clue what to look for or how to tell and the reason I put NEED in my post is because of my fund shortage. Thanks

[Tom7227]

Go to the Northern Tool Website and look around. They have a pretty decent selection and the site has some info on the strength of the units. There's one on there for $80 that would most likely take care of your needs. You probably don't use that much juice in one sitting.

[superbee]

How long would you have everything running in a sitting and how many days in a row would it be getting used? If you are not there everyday/all day, it will also have a better chance to recover. You should be able to get by with a small panel and you could just add another battery to the system.

[Whoaru99]

To get a really good answer you need to estimate the load and how long you run it to determine the amp-hour used. Then, you need to look at the solar panel rating to understand its output.

For example,

Let's say the sum of your loads is 5 amps and you are using this 5 amps load for 6 hours. You have now used about 30 amp-hours of power (5 amps x 6 hours).

If you want to return the battery to the pre-use state of charge, then you have to put back in what you used. In this case, 30 amp-hours (more maybe a bit more due to losses).

So, now you have a solar panel that is say 50W of output (a 50W panel is a pretty big and expensive one, most cheaper ones are 10-15W, I think). 50W /12V = ~4 amps.

Now you have about 4 amps of charging potential and need to restore 30 amp-hours to the battery. 30 amp-hours / 4 amps of charging current = ~7.5 hours of charging time. If your solar panel was only a 10W model (more common at low price point), your charging time would be 5 times longer.

Note the solar panel output is at perfect placement in full, direct sunlight. Anything other than that will reduce output and cause longer charge time.

Of course, you'll have to substitute your own numbers into the calculations.

[sparcebag]

Right on whoaru. Large cost with little satisfaction! You'd also have to add a regulator so you dont overcharge batts.Reg.& cutoff. I figured it once for my boat and If I remember right it was about $500 just for a daily recovery with the sun out and max absorbtion from the pannel

[Tom7227]

Sparc,

I put about $150 into a 15 amp panel from Northern last summer and it worked like a champ. I don't use the boat every day but I had a battery that was close to DOA and it got things done for me. I would bet this rig would do the trick for this poster unless he lives in the shack.

Tom

[Whoaru99]

15 amp panel

Probably 15 watts. Big difference.

And, there are a lot more hours of daylight in the summer than in the winter (well...depending where you live).

I don't think anyone is saying a small panel won't help, it'll be like a trickle charger. But, depending on how much power one uses, the size of the solar panel, and how much recovery time there is, the batteries may or may not ever come up to full charge.

Batteries that are fully recharged after use last the longest.

Besides, I'd be afraid that someone would steal a decent solar panel left out 24/7 as it would need to be for most effective unattended use.