solar panels

[Guest]

Is it possible to use solar panels with ordinary lead acid car batteries ? Has anyone done this and did it work well.

 

[Peter_the_Grate]

Yes.
I'm considering fitting one permanently. Until now I've used one during the winter lay-up, to keep the battery topped up, and it works well. The one that I used cost £30 at Maplin and provides between a half and three-quarters of a watt in sunsunshine. It doesn't sound much but it is enough and removes any worries about overcharging whilst unnattended for weeks at a time.

 

[snowleopard]

Small ones can be hooked directly to the battery, bigger ones must have a regulator to prevent overcharging. I have 2 big ones and they develop 25v in bright sunlight which is enough to make a fully-charged battery start gassing.

 

[Guest]

I'm thinking of fitting a solar panel rated at 30 watts. Any idea of the actual output I can expect in (a) sun (b) cloudy conditions?

 

[Guest]

Peter, thanks for the reply, first of all could you tell me Maplins address, and second, do you use a regulator (apparently this prevents overcharging) Thank you , David.

 

[philip_stevens]

If you only have a 5 watt trickle charging solar panel you need not bother with a regulator. If you go for a 15 watt unit, you should install a regulator - as I have with mine.

Over the winter, you will find that a 10 or 15 watt unit will keep your batteries topped up, but not overcharging them.

regards,
Philip

 

[Guest]

solar panels - expected outputs

here are a couple of examples of what you can expect out of a solar panel depending on where you are located. These figures are fro Solarex's data sheets.

30Watt panel SW England summer time 7.5Ah per day, winter time expect 2.1Ah per day

30 watt panel Scottish Highlands summer time 6.0Ah p/d, winter 1.2Ah p/d

Smaller solar chargers such as the ones by Exide are self regulating.

kev
www.yachtbits.co.uk
exide & solarex distributors

 

[Guest]

Philip, have you measured the actual output for a 15 watt panel. How is it effected by full sun, cloud, angle to sun etc. I'm trying to decide what size to fit. I can find no sensible information from any of the manufacturers.

 

[Guest]

output data

see posting above, "solar panels - expected outputs"

 

[philip_stevens]

Nic,
I have my panel at home now, so will get some readings in the next few days. I will give you voltages before the regulator to give you some idea of output from a good panel.

The correct angle to fit it, is the same as your latitude, from vertical. i.e. at my latitude, 50 13.00S, the angle to set it to is 50 degrees from vertical.

I will reply to this posting in a few days.

In the meantime, see Kev's Sunday posting.

regards,
Philip

 

[colinroybarrett]

Fitting a Solar Panel:-

Here is an article by Vyv Cox, on installing a soler panel with the results from his first year’s use:-

http://www.crblimited.btinternet.co.uk/kahawi/solar.html

Cheers, CRB

 

[Guest]

Thanks for the replies so far , much appreciated , but was all this done on ordinary 'car' type batteries ?

 

[Peter_the_Grate]

David,
Sorry for the delay, I've been away on a course. The address for Maplin is www.maplin.co.uk. I don't use a regulator because the output from the panel that I use is really quite small. As I said, I only use it to keep the battery topped-up through the winter when the boat is laid up.

Peter.

 

[Guest]

Charging of lead-acid batterys is the comon use, as the panels unless large powerful expensive do not deliver enough to do much else ....

 

[snowleopard]

Not a lot!!

You would get 2.5A into a flat battery in full sun. If the battery is 90% full, expect around 15% of the rated value. Halve those figures for cloudy conditions.