Solar Panel

ali_seton · 21 February 2009, 21:57

Hi everyone,

I have a solar panel fitted to my rib to charge the battery. on the box it says you cant have the solar panel attached to the battery when you start the engine. this is true because i had a solar panel on my boat and forgot to unplug it and started the i think it blew up but anyway it didnt work. I was just wondering... on my rib i have 2 150w marine speakers and a car cd/radio, if i was using the stereo and speakers with the solar panel attached to the battery would it do the same thing and blow it up?

thanks for your help,

alex

biffer · 22 February 2009, 08:45

you could put a resistor in the cable coming from the panel, that would only let the current go one way and not back to the solar panel, seek out goeffs on this forum, he's the man

geoffs · 22 February 2009, 11:02

Generally, most solar panels come with a reverse diode built it, what this does is prevent your battery from tryung to charge the solar panel, i.e. the charge can only pass from the solar panel to the battery and not the other way.

So, in practical terms, if your panel has one already then you should do no damage by leaving it connected all the time. Ask the people where you got the panel form if it has one.

It is possible to fit an external diode, but you will get a 0.7v drop across it, so your charging will be affected, the makers of the panles allow for this in the design.

doggypaddle · 22 February 2009, 17:17

Quote:

Originally Posted by biffer

you could put a resistor in the cable coming from the panel, that would only let the current go one way and not back to the solar panel, seek out goeffs on this forum, he's the man

You mean a DIODE

ali_seton · 22 February 2009, 17:25

http://www.maplin.co.uk/Module.aspx?ModuleNo=98358

this is the soalr panel that i have.. it says it has a built in diode but it still blew up??

doggypaddle · 22 February 2009, 18:27

TBH i wouldnt worry about it too much, just sling it in the hedge!
A 1.5 watt panel is next to useless anyway, the output will be 1.5 watt when the sun is shining at perfect 90 degrees to the panel and at a solar radience of 1kw/Msquare.
If you get 1/4 watt max on an average day for 6 hours you will be lucky, running the engine for a 10 minutes will do more.
my dad had one in his camper to charge the battery when it was sat idle, the alarm only takes a few milliamps but it couldnt even make up for that

codprawn · 22 February 2009, 20:59

I agree - solar panels are pretty crap. I have a 10W fitted and it hardly does anything. Of course in the summer it will give me a few amps a day but my bilge pump won't need it then!!!

As has been said 10 mins of engine running is worth a whole day of sun.

Smaller yachts use solar panels quite a bit but all they really do is keep the batteries from self discharge.

jwalker · 22 February 2009, 22:49

Quote:

Originally Posted by codprawn

I agree - solar panels are pretty crap. I have a 10W fitted and it hardly does anything.

Codders! Where's the logic in that?
Of course it doesn't, it's only 10watts flat out!

That doesn't mean solar panels are crap. It's kinda like having a 1amp alternator on your car and claiming alternators are crap.

codprawn · 22 February 2009, 23:44

Our local Tesco has a 40kw solar panel array. Wow 40kw - I could easily run my house on that. In the 3 years they have had it fitted they have generated about 50,000kwh. That works out at about £5,000. It cost £2 million to install - and uses hundreds of panels each one as big as a car!!!

To me that is crap.

Solar panels have their place - in remote areas where laying normal power isn't an option and current usage is very low. For example at a remote resevoir for monitoring equipment etc.

A wind generator on a boat makes more sense in the UK. Problem is they will put out too much power for a RIB.

doggypaddle · 23 February 2009, 09:06

Quote:

Originally Posted by jwalker

Codders! Where's the logic in that?
Of course it doesn't, it's only 10watts flat out!

That doesn't mean solar panels are crap. It's kinda like having a 1amp alternator on your car and claiming alternators are crap.

But If ALL car alternators were the size of a tall ship sail and 16% effecient like tescos solar panels then you would say they were crap!

The ones that heat water are far more effecient and the way to go for a house, not much god for charging a battery though.
Now a wind generator on a rib! theres a thought, it would pump out some power at 30 knots

doggypaddle · 23 February 2009, 09:10

Quote:

Originally Posted by codprawn

Our local Tesco has a 40kw solar panel array. Wow 40kw - I could easily run my house on that. In the 3 years they have had it fitted they have generated about 50,000kwh. That works out at about £5,000. It cost £2 million to install - and uses hundreds of panels each one as big as a car!!!

To me that is crap.

Solar panels have their place - in remote areas where laying normal power isn't an option and current usage is very low. For example at a remote resevoir for monitoring equipment etc.

A wind generator on a boat makes more sense in the UK. Problem is they will put out too much power for a RIB.

I know what the problem here is, the store is a standardised design Tesco used the UK over, the solar panels work in every other one except the ones in wales! its the weather thats the problem

jwalker · 23 February 2009, 10:08

Quote:

Originally Posted by doggypaddle

..Now a wind generator on a rib! theres a thought, it would pump out some power at 30 knots

Aye, but it would be your engine that was powering it.

Quote:

Originally Posted by Codders

To me that is crap.

Maybe it's my definition that's confusing. To me crap implies a poor product.

I have two solar panels, both approx 60watts, one on my boat and the other on my caravan both are connected through 3 stage charge regulators. The boat one is used primarily to keep the batteries in good condition and it does that without problem. The van is used for about 8 weeks each year and is self sufficient in power. To me, that's not crap.

You've just got to get your head around their characteristics and work within their limits...as you have to with other power producing systems.

Carl · 23 February 2009, 10:43

hey jw ive 1.5

. to stop my mercathode flatting my number 1 battery

jwalker · 23 February 2009, 10:47

Perfect in every way....

doggypaddle · 23 February 2009, 11:40

Quote:

Originally Posted by jwalker

Aye, but it would be your engine that was powering it.

Bugger thats my plans for a rib with an electric outboard and rutland generator that just needs a small gust of wind or a spin on the turbine blades to start it off, out the window

Avocet · 23 February 2009, 12:59

Quote:

Originally Posted by doggypaddle

Now a wind generator on a rib! theres a thought, it would pump out some power at 30 knots

Isn't that a similar principal to the ramjet whereby the faster the speed, the greater the thrust to increase the speed to provide further thrust etc. You might need to strengthen your transom though!

PeterM · 23 February 2009, 13:06

Quote:

Originally Posted by Avocet

Isn't that a similar principal to the ramjet whereby the faster the speed, the greater the thrust to increase the speed to provide further thrust etc. You might need to strengthen your transom though!

Have we, by roundabout route, just hit upon ( dare I say invented ! ) the perpetual motion machine & therefore solved the worlds energy problems ?

The boat moves forward driving the big fan thing which actually puts energy back into the boat ! By jingo I think we might have something here !

Or have I missed something ......

oh yea petrol .

PS - this is my attempt at humour.

codprawn · 23 February 2009, 14:48

I actually know a bloke who has a wind generator fitted to his LandRover. It's an old Series II and the alternator was knackered so he attached one to a radiator fan on the roof - it does look seriously cool - like something out of Mad Max!!!

doggypaddle · 23 February 2009, 16:56

http://www.telegraph.co.uk/news/news...ng-speeds.html

Or perhaps over unity does exist

codprawn · 23 February 2009, 19:11

I saw that a while ago - it's amazing how many investors can be conned into such crap.