solar power

I'm watching 3-4 of these on eBay just now and will buy one when I find a decent seller. So will be interested if you do buy one.

I only want a panel to keep my car battery from dying when sitting unused for months during the summer. So 5W should be fine for that.
 
I've just bought one from Sunstore @ £10.08incl VAT £3.07 but next day delivery £8.33, so strictly speaking would have been cheapest to have bought the larger version as this one is only 5W, but will do for me if it does the job. Comes with 2mtrs leads and battery clips, but i may have to lengthen the leads when I fit it.
Will report back when done and tested.
There are no fitting instructions but there is a plastic box which contains a non- reversing diode.
No fuse, so will have to fit one; any idea what value that should be?


ianat182
 
ianat182 said:
I've just bought one from Sunstore @ £10.08incl VAT £3.07 but next day delivery £8.33, so strictly speaking would have been cheapest to have bought the larger version as this one is only 5W, but will do for me if it does the job. Comes with 2mtrs leads and battery clips, but i may have to lengthen the leads when I fit it.
Will report back when done and tested.
There are no fitting instructions but there is a plastic box which contains a non- reversing diode.
No fuse, so will have to fit one; any idea what value that should be?


ianat182
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It will be interesting to hear what it is like. Fuse will be quite small, 2A would probably be fine at a guess. Remember that it will just be protecting the wiring and not the panel. Max. output from panel will only be 0.3A and I imagine that the wiring is bound to be thick enough to handle 2A. Just fit the fuse close to the battery, not at the end nearest the panel.
 
A 5 watt solar panel keeps my 60Ah leisure battery topped up Ok...... More effective than the charging from the outboard, but mine is a semiflexible Spectralite panel that cost significantly more.


The fuse must be less than the max safe working current of the wiring but more than the max output of the panel. The max output is only 0.31 amps . Its unlikely that the cable will be less than 5 amp cable so a 1 amp fuse would be fine Fit the fuse as close to the battery + terminal as possible
 
Pete7 said:
Jack, it's a bit small. My parents have one of these in the caravan which works well enough keeping the battery topped up when not in use. Regulator is a simple on/off which isn't up to much, replacing it with a PWM type would be better.

http://www.ebay.co.uk/itm/13w-12v-s...3284?pt=UK_Gadgets&hash=item2579e8b314&_uhb=1
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A PWM may be a bit of an an improvement on the simple On off regulator but you need a MPPT controller to maximise the output ... probably not worth the cost though for a small panel.
 
Hello Jack I enjoyed your little blog though I can't imagine sailing in that kind of 'orrible weather. Indeed I think we are totally spoilt here for sailing.
The solar panel you are considering will help keep a battery alive. 5w might be a bit small however in UK. Especially f you are on a swing mooring. I find here in west oz for summer that an even smaller panel provides my needs but that is much different.
Generally for a boat you start with the question of where will I mount the panel. This will dictate how gig you can manage as really the bigger the better. Especially if it must be mounted horizontally so not ideal for catching the sun. (swing mooring again)
I think if you scout through ebay you should find cheaper from China although I have not looked myself.
good luck olewill
 
VicS said:
A PWM may be a bit of an an improvement on the simple On off regulator but you need a MPPT controller to maximise the output ... probably not worth the cost though for a small panel.
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I can't remember what the on and off voltages are, but I was surprised how low they were set hence the suggestion for a PWM regulator which should be cheap enough for these sized panels. An MPPT regulator would be completely wasted and if the funds were available for that they would be better spent on another solar panel.

William, makes two good points though, bigger the better and were are you going to put it warrants consideration.
 
VicS said:
A PWM may be a bit of an an improvement on the simple On off regulator but you need a MPPT controller to maximise the output ... probably not worth the cost though for a small panel.
Click to expand...



The on off regulators are very wasteful of power and many will not get the battery to 100%. its helpful to battery life to occasionaly reached this fully charged state.
A PVM modulator regulator is a vast improvement.
If you need a regulator its almost always worth getting a PWM model over the on/off type.
MPPT is only a small further improvement and I agree is not worth contemplating on these small panels.

Direct connection without a regulator is often the best option for small panels (10w or less) paricuarly in the UK.
 
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Going back to the OP.

"is it any good". You need to say what you propose to use it for.

If it is to trickle charge a 60W or 100W battery, it might keep up with the self discharge. It will not recharge a weekends use during the week. You will not need a regulator of any sort, just connect direct to the battery with a 1A fuse at the battery end for safety.
 
noelex said:
The on off regulators are very wasteful of power and many will not get the battery to 100%. its helpful to battery life to occasionaly reached this fully charged state.
A PVM modulator regulator is a vast improvement.
If you need a regulator its almost always worth getting a PWM model over the on/off type.
MPPT is only a small further improvement and I agree is not worth contemplating on these small panels.

Direct connection without a regulator is often the best option for small panels (10w or less) paricuarly in the UK.
Click to expand...

Wasteful because controlling voltages are too low or because they take too much current themselves?
 
VicS said:
Wasteful because controlling voltages are too low or because they take too much current themselves?
Click to expand...
The on off regulators will turn off the solar panel completely at set voltage say 14.2v and not turn the solar panel back on until the voltage has dropped considerably say to 13.5v.
If there is little load on the battery the surface charge takes a long time to drop. During this time you are getting no power at all from the solar panel.

A PWM regulator will maintain the absorption voltage for a couple of hours reducing the power produced by the solar panel (with PVM) as the battery becomes more charged, but not turning it off. (PVM actullay does turn the the solar panel off and on very rapidly, but the effect is like gradually turning down the solar panel)
After a couple of hours (the absorption time) the better PWM regulators will drop down to a lower (float) voltage.

The net effect is that even a very simplistic 1 voltage PWM regulator will get a more power from the solar panel unless the batteries are quite discharged. At PWM regulator with both absorption and float set points will do better again. The absorption voltage can be higher, but will be reduced to a lower safe loat voltage when the batteries are almost full charged.
 
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