Solar output/charge

[Rum_Pirate]

I have a "United Solar" panel, Flexible Model # 437392 on my boat.

The panel (according to the West Marine catalogue advertising blurb) has :
- internal bypass diodes
- Max Watts 5.00
- Max Amps 0.30
- Approx Ah/Day 1.9
- It is not self-regulating.

The blurb also says that voltage regulation is not necessary unless peak amperage exceeds 1.5% of the batteries Ah capasity.

A friend put a voltmeter on the output cable wires. Panel was not attached to the battery. It produces 19 volts.

As an absolute non-electrician, I need and would appreciate helpful advice on the following :
1. How do I determine the Ah capasity of the battery and thereby the 1.5% to determine if I need a voltage regulator?

2. More importantly will I "destroy" the 12 v battery, if it has say "525 cranking amps" and I use the panel without a voltage regulator?

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[Evadne]

I would always try and regulate things going into a battery but you should be able to plug this device straight in, 5W is under 420mA and the typical engine start type battery you describe is going to be at least 40Ah, 1.5% of that is 600mA. The danger of regulating low-power chargers like this is that you'll end up getting nothing out at all. The 300mA quoted shows just how easy it is to lose current.


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[bruce]

it has to put out higher voltage to allow it to charge. while it put out that much, and it will run your vhf on receive, the moment you key the mike, the radio will go dead, till you let up on mike. just check your battery water weekly to add, if needed. this is a hook up and forget it panel. you might even have to charge on shore if you used a lot of lights and other electric stuff, or lots of motor starting.

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[steve_cronin]

As then others have hinted, this is a very low output panel and it is intended only to replace natural discharge.

Our boat, in the Med. has two 55watt panels mounted on a gantry. These certainly are regulated but this regulation is at a cost. If I bypass the regulator I can get the battery voltage up by 0.2 volts within a few minutes.

Another, more important in your case requirement, is some sort of blocking diode in line (this too will reduce output to the battery) to prevent discharge back through the panel at night unless you are there to disconnect at dusk and re-connect at dawn. Some panels do however have one already built in. Remember that solar panel charging relies upon the longest possible period of connection to the battery and the brightest possible light conditions.

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[pvb]

Blocking diode...

Yes, this is a good point. All the UniSolar flexible panels (like the one Rum Pirate has) are supplied as standard with a blocking diode, built in to the connection box. Not all solar panels have blocking diodes, though, so other people considering buying panels should bear this in mind.

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[Twister_Ken]

Crikey

So at night, a solar panel tries to recharge the sun?

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[bruce]

Re: Crikey

without the diode in line there is a reversal of power, the diode is cheap, 2/$1.00 at most, yours has one. the diode only allows voltage to pass in one direction.

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[Rum_Pirate]

Re: Crikey

West Marine

http://www.westmarine.com/webapp/wc...0001&catalogId=10001&productId=33560&y=5&x=19

has the Solar Panel Blocking Diodes for sale (in pairs) at US$12.99

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[Twister_Ken]

Re: Crikey

I guess you have to be careful not to put them in the wrong way round.

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[bruce]

Re: Crikey

your local radio repair should be able to beat that price by $10. put it in line and hook the wires to your vhf on receive, and a sunny day, and if in proper position, the radio will turn on, if reversed, it won't, or hook a volt meter and look for output. you can splice one into the pos wire from the solar and tape over it.

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[pvb]

Your panel already has one...

UniSolar flexibles come with a diode as standard. Should be built in to the connection box.

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[vyv_cox]

My nominally 2 Amp panel is a 38 Watt unit, so will also produce 19 volts. However, note that this is at a relatively low temperature. As the panel heats up in the sun this voltage will reduce to something less, but still well in excess of the 14 or so that might be produced by your alternator. This is quite normal for a panel. Your maximum current will not be achieved in UK, or even quite a lot further south. Maximum I have seen in SW France in a clear, cloudless sky, was 1.5 Amps.

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[Twister_Ken]

Hi Vyv

Where've you been?

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