solar panels advice please

[castaway]

Just fitted a 12volt 5w panel from Maplins (49 quid) .

Can someone tell me why when I put my multi meter across the ends of the wires whilst the panel was in the light, it showed 20 plus volts?

Also by the way can these pamels be damaged if the wires contact each other ie. a dead short across the panel, I assumed not as there was nothing to stop this happening in the packaging, and it was semi open to the light.

Thanks Nick

 

[halcyon]

Theres no load on it, connect it to a battery and it will fall to battery voltage, it will then start climbing very slowly.


Brian

 

[castaway]

Thanks I was hoping it was something like that.

Nick

 

[aztec]

iv'e got one on my boat, but it terminates in pleain wires, do i need some form of regulator. and what happens when the battery voltage is higher than the panel, like at night?

i would use it to keep my batteries topped up but hav'nt because i'm not sure how it works.

interested in stuff that needs mendin'

http://homepage.ntlworld.com/s.amos/index.html

 

[philip_stevens]

You should find - and it should have - a blocking diode in one of the wires from the panel. It may also have a small connecting block on it, where the diode may be located. This is to stop the battery discharging into the panel when there is insufficient light to generate power.

5 and maybe 10 watts panels shouldn't need a regulator, but anything over that would benefit from a regulator - or at least the battery would benefit when getting to its topped-up stage.

If the wires of you panel are completely unmarked, use a voltmeter (digital in preference, and these days cheaper) to ascertain the polarity of the wires. Then mark them.

I have a 20 watt panel on my boat that is plugged into a ciggie socket via a regulator when we are not on the boat during the week, or if we go away for a while. Normally, when on the boat, it is taken down below and stowed away.

The panel has the output enough to leaving the Navtex on all the time, while keeping the batteries topped up.

regards,
Philip

 

[Strathglass]

Just looked at the maplin web site the £49 panel has a built in diode and is quoted as giving 250mA in bright sunlight. Just connect it straight across the battery, but for safety I would sugest that you put a 1 amp in-line fuse in the positive lead as close as possible to the battery. They look quite good.
Iain

 

[VMALLOWS]

Fully agree with previous posts.
Nearly ordered one (or 2) myself. Does the mechanical/physical quality seem OK?

 

[castaway]

Yes it looks like a quality product... actually I think it has the name Exide on it

Nick

 

[jfkal]

Make sure it does not climb higher than 14.4 or else kiss your (gel) batteries good bye. Better use a solar regulator.

 

[WayneS]

I got one a couple of weeks ago and it is great. Not quite the same as the "walk on" type you can get at a chandlers but is still a v-nice piece of kit.

Wayne

 

[castaway]

If I can get my batts above 12.6volts Ill be very happy. Ive got 4x 6volt batts total ah approx 300 and they just never appear to get fully charged dispite having a "Baron" box thing which I suppose is one of these clever charging things.

Regds Nick