Sun V Wind

[Flapjack]

The boats going back into the water in June and for the first time under my ownership, onto a swinging mooring. I have to choose between solar and wind to keep my batteries charged. I'm thinking solar as the stern is quite crowded as it is with the boarding ladder one side and the outboard mount on the other. Any info or tips happily received.

 

[narooma]

My choice for this lattitude would be wind.

 

[jerryat]

I'd go for solar. With a 410amp service bank and a 85amp starter battery, our little 30 watt Solarex keeps them all in top condition when in this country. We do have a Rutland 913 and a 55watt solar panel, but only fit and use them when full time cruising.

The windgen was providing too much power in the UK (on a mooring) besides the associated bearing wear etc and the baby Solarex is the ideal alternative.

 

[Allan]

I know there are lots of factors that will help make the decision but I would love to see a watts/pound comparison. For instance, if you buy a standard Rutland for £X what is the realistic output (over, say one year)? From that you could get a true comparison with the same value of solar panels. The impression I have is that wind would win in the UK and Solar in the Med.
Allan

 

[vyv_cox]

I suggest that nobody can answer at this stage, because nobody knows what you expect your batteries to do. For example do you run a refrigerator, freezer, 1000 Watt stereo system, TV, or do you only want to keep your batteries in the state of charge that you left them on Sunday night?

From my experience, 38 Watts will not run a refrigerator plus instruments in the UK, even at midsummer. 70 Watts will just run them in the Med in June and July, but not in September.

In general, as someone else has already said, wind power tends to be more useful in UK, and the sets give more power unless comparing with very large solar panels. Solar tends to work better in the Med and is less intrusive.

Just a comment on your crowded stern. Look at virtually any liveaboard boat and you will see huge amounts of kit on the stern. A boarding ladder and outboard is almost the minimum that anyone has. I would be very surprised if you could not find space for a wind generator.

 

[roly_voya]

Also depends of what else you want to do. If you just want to keep the batteries up with everything switched off sounds ideal. If you also want power when underway might be worth looking at combined wind/water set like the aquagens that give 5/6a when towed and hang in rigging when on the mooring.

 

[Billjratt]

All seems too small to me. We had 150 watts of solar and an aquagen (in aero mode most of the time) in the Med, and needed to run the engine for charging sometimes. It really depends on what you're using/losing. If you're going to get a wind generator, get a real one that can deliver lots of amps, otherwise all you get is lots of noise and the batteries are still flat. As for solar panels, they really do need to be facing the Sun to give their full wattage, that means moving them to follow the arc, and (in the first place)getting a decent mooring so it's possible. If you have a mains charger on board, it is likely to be 30 amps or so - now figure out how you're going to get that from the sun and wind. (30 amps will be about 400watts and then add for all the losses and contrary weather). On the current boat, we now have a wee petrol generator that whacks the 30amp mains charger into action and I can drill holes at the same time. We paid £100 for the aquagen second hand and nearly £600 for the cells in Ibiza, you can get a genny for £60......

 

[rwoofer]

Assuming you meant to top the batteries up, I have just invested in two 18 watt solar panels to top-up my 220ah batteries and they seem to be perfect for the job. One is on the companion way hatch cover and the other between the mast and the babystay. Totally inobtrusive and for the last 6 weeks the batteries have been fully charged every time I go to the boat.

 

[William_H]

I reckon that you won't find an answer to your question. Only your own experience will answer the question.
A swing mooring is bad for solar in that you can only mount the panel flat. In UK that is not so good for best sun collection. To try to point it south for a particular tide or wind might be better but still a variable.

I use a 5watt solar for my battery but then at 32 degrees south latitude angle is not so important.
So you will need at least 20 watts mounted flat to keep batteries charged with no load. May be need even more. (you can add panels in paralell.

Wind would be much more reliable charging but more expensive and noisy difficult to mount.

So I guess you should try solar first and good luck. However if you have an inboard engine with decent generator and you run the engine say every 2 weeks you should not need auxiliary charging.
Yes it is nice but we survived for many years without solar or wind battery top up.

olewill