Solar or wind power?

[tomandsophie]

Just joined and posting like a madman!

I am looking at getting either solar or wind power to top up our batteries. Which one do you think is more cost effective, etc.?

[nbtafelberg]

I have a 64 watt solar panel. Its not so great in the Winter. The thing that put me off wind was having that HUGE mast and a wind generator really don't think it looks that great.

 

I did manage to flatten all my batteries and recharge the starter from the solar panel. The downside is I'm not sure its set up right on the leisures since it seems to do hardly anything - could be I need a charge controller but I'm not sure...

Edited October 31, 2004 by clevett

[timboharticus]

A windgenerator is more cost effective in terms of £/ Watt.

 

Rutland do a small unit about 18 inches diameter that puts out about 60W.

 

Why not have a small solar panel (Maplins do a 0.5A one for about £70) to keep the batteries topped up if you are away from the boat.

[Alastair]

You *MUST* have a charge controller if you have a solar panel, otherwise they will damage your batteries.

 

I recommend cps solar. I bought a charge controller and panel + very good quality cables from them. The panel is a tri-junction, which means that it works from several wavelengths. So even on overcast days I get power.

 

As to which to buy - I went solar because there are weeks without wind where I moor. If I was somewhere windy, I'd put in a big battery bank and a wind generator.

[David Schweizer]

Has anyone ever done a proper assesment of Wind and solar power on boats. I know a lot of people who have both and they always seem to be running their engines to charge the batteries. This seems to be counter productive because with an Alternator controller incorporated into their charging system, they could produce more electricity without the need for any additional equipment.

 

I am even dubious about the topping up arguement. I was recently unable to visit my boat for over a month, but when I checked the batteries there was virtually no drop in the voltage, and half an hours charging on the engine brought them back up to full (and they are 9 years old!!)

 

The only situation I know of where solar and wind power is being used successfully is a friend who lives in a caravan on a site where there is no mains electricity. He manages to produce enough electricity to maintain lighting all the year round. But that is with a battery bank almost big enough to power a milk float, a windmill which is about 5ft in diameter and about 5 square meteres of solar panel. He uses coal and bottled gas for heating and cooking.

 

PS. It is as still as anything today, it is dull and there is no sun, how much electricity will wind and solar power devices produce today?

[Alastair]

You are fairly correct, David. I use solar for lights (led and low-wattage only), water pumps, charging phones and laptop. my good 64W panel is sufficient for that. If I had access to mains power, or cruised daily, I wouldn't bother.

 

On a day like today, my panel will produce about 4-6Ah. That's sufficient for me. On a day with visible sun (low winter sun), the panel produces about 2.5-3A per hour. On a bright day; 3.8A current.

[tomandsophie]

So it sounds like an 80w panel (or thereabouts) is gonna help us quite a bit. Hooking up a wind turbine doesn't sound too appealing, but a panel or two on the roof sounds like a good idea. We won't be moving around much, and our mooring has no electric hookup.

Thanks for all the advice people. Keep it coming...

[rustyduck]

As has been said wind power is cheaper than solar - about 1/2 to 1/3 in terms of £ per Watt.

 

Usually these systems are connected to battery banks to help smooth out the supply. It's normally expected that one day in three will be windy, and therefore the battery bank should have enough capacity to last during these calm days (5 day capacity is normal). Solar is only expected to be properly productive for about 4 hours a day - even on really bright days.

 

I'd be tempted to have both solar and wind power - after all, 24 hours of wind is the same as 6 sunny days in terms of power producing time.

 

Couple it all (through charge controllers) to a good size battery bank - discretion may be required here, 5 days battery supply requires a very large and expensive set of batteries.

 

Most of the time, solar and wind power would be wasted - going into fully topped up batteries (or not going in as it were). Consider using an immersion heater to dump some of this free power into your hot water tank.

[John Orentas]

Rusty.

 

That's a very good idea, do you know of a 12 volt imersion heater ?

 

John Squeers

[rustyduck]

I know of 12v heater elements in travelling kettles and simple ones that you can heat a cup of tea with, but I suspect that the power of these might be too low.

 

Of course you could use multiple ones in parallel for a variable load.

 

And there is always the possibility that if you have a half decent sized inverter, you could use a normal 230v immersion heater - available in various sizes from 1kW.

 

Even better if you can make the system auto sense that the batteries are full and switch over to the heater (the bigger wind turbines have this facility, as not loading them can cause problems).

 

If you want to be really fancy, there is an electric wet central heating system that you could plug it into, that could help keep you nice and toasty for free during those long windy nights in winter.

[nbtafelberg]

Right then...

 

I have just got a Sollatek Solar Controller it is BRILLIANT my solar panel is right now trickle charging the batteries even with this grey weather.

 

I have a 64watt panel and a Sollatek Charger with a set of 3 leisures.

 

I can supply the sollatek Charge controller if anyone is interested.

[Alastair]

I have a similar panel, but with the digital controller. Bought from

www.solar-wind.co.uk

[GeorgeL]

One problem with solar panels is that they are never in the right position, by which I mean that the face of the panel needs to be perpendicular to the sun.

 

Most solar panels operate at about a third of their potential efficiency because of this, whereas wind turbines always turn to face the wind.

 

Somebody needs to design a cheap sun-seeking frame for solar panels that will rotate the panel and change the elevation in order to ensure max efficiency. With decent bearings, and a balanced design, it shouldn't need much energy to operate.

 

Meanwhile, if you're sunbathing while panelling, turn the thing yourself.

[gwinsk]

One problem with solar panels is that they are never in the right position, by which I mean that the face of the panel needs to be perpendicular to the sun.

 

Most solar panels operate at about a third of their potential efficiency because of this, whereas wind turbines always turn to face the wind.

 

Somebody needs to design a cheap sun-seeking frame for solar panels that will rotate the panel and change the elevation in order to ensure max efficiency.  With decent bearings, and a balanced design, it shouldn't need much energy to operate.

 

Meanwhile, if you're sunbathing while panelling, turn the thing yourself.

<{POST_SNAPBACK}>

 

I've only just dropped across this thread, so hope I'm not too late!

Living across the Irish Sea from the boat, months go by between visits. The worry then is that batteries will be low on arrival. Solar panels seem an ideal solution, since there's plenty of time to push in a decent charge.

Reading the thread has answered one of my questions; I'll obviously need a controller. If I'm leaving the batteries isolated, will I need one panel for Starter and another for the three Leisure batteries?

 

Gerry

[rustyduck]

Hi qwinsk,

 

It's never too late for a bit of the old solar.

 

You would be best to have a charge controller for each battery bank, although you could connect these to a single panel, or multiple panels joined up as one.

 

P.S. Using the FastReply or AddReply buttons instead of Quote or Reply will stop the inclusion of the previous text.

[Amicus]

Rusty.

 

That's a very good idea, do you know of a 12 volt imersion heater ?

 

John Squeers

What would happen if you dumped this spare (12V) energy across a 230V immersion heater?

[DHutch]

What would happen if you dumped this spare (12V) energy across a 230V immersion heater?

You got a point there.

- Its not junna make much diffrence, but it would get rid of the spare in a constuctive way i guess.

 

[edit]

Infact, i know a guy (friend of my dads) who did basicaly the same thing with a towel rail in his house.

- He had about half a kilowatt of pannels on roof, which he could moniter induvidualy in blocks of 10cells via his pc.

- Just for fun, becuase he was interested in solorpannels and other techy stuff.

 

On thing he did say that there very sensotive to shadow and uneven lighting, which can very quickly kill of a whole block of cells.

[/edit]

Edited November 24, 2005 by dhutch

[Guest]

What would happen if you dumped this spare (12V) energy across a 230V immersion heater?

 

Cant be bothered working it out right now, but have done this in the past and it is the equivalent of a heater of just a few watts. It certainly will dump "unwanted" electricity (it is a common trick with large wind generators in the States), but I believe it would be of little benefit to the heating.

[ChrisPy]

Cant be bothered working it out right now, but have done this in the past and it is the equivalent of a heater of just a few watts. It certainly will dump "unwanted" electricity (it is a common trick with large wind generators in the States), but I believe it would be of little benefit to the heating.

say you've got a 1000W heater. That means it draws a current of about 4A on mains voltage, its fixed property is its resistance which is R = V/I = 60 Ohms.

Apply 12V. Then I = V/60 = 0.2amps. Power = 2.4watts. Negligible.

[John Orentas]

Cant be bothered working it out right now, but have done this in the past and it is the equivalent of a heater of just a few watts. It certainly will dump "unwanted" electricity (it is a common trick with large wind generators in the States), but I believe it would be of little benefit to the heating.

 

 

Don't write it off so easily, it may just be a few watts but if it is there hour after hour day after day it may be worth having. Using a 230v heater though does not sound right (not sure why) someone mentioned those small 12v heaters you can get for making a coffee in your car, they seem a good size.