Solar Panels: as good as advertised?

[dancrane]

Plenty of different panels available; cheap trickle chargers, pricey, robust low-output versions, mega-pricey foldaway walk-on 150w versions...the only thing they all seem to have in common, is quite a lot of cost, for not a lot of output.

I like the idea, because they can quietly tend to the batteries when I'm elsewhere and make a difference when I am there, but before I buy, I want to profit from reportage of what's hot and what's really not.

I heard of a far-east oil tanker that had 60Kw of panels aboard. I guess considering those vessels' tiny crews, 90HP of electricity generation made a serious difference to their needs. Just a pity it couldn't help their main propulsion.

Any stories of shockingly inadequate/inspiringly competent solar panels?

 

[planteater]

I wonder why a short crewed tanker would want 60Kw of panels? Most domestic installations are in the 2-3Kw range and reckoned to provide 30-50% of the average household needs even in these gloomy latitudes.

There was a recent thread on here with links to some very reasonably priced panels.

 

[longjohnsilver]

Had one of these
http://midsummerenergy.co.uk/buy/framed_solar_panels/XM100-polycrystalline-solar-panel.html

on my boat for the past year, keeps my 1000AH battery bank nicely topped up. Very pleased.

 

[Fr J Hackett]

I just installed a 50W Midsummerenergy (BP) panel and SS6 regulator putting out 2.5A as expected. Main problem is finding space to install them I would have bought the
100W if there had been room on the gantry.

 

[V1701]

I bought this 40 watt panel from Sunrise Energy off ebay. Was £105 when I bought, now down to £95. I got slightly better than the claimed max output amps (2.4ish) and very pleased with it. Better value per amp than the Rutland 913. That panel went with the boat that recently sold and I will be getting another...

 

[dancrane]

The Viscous Circle

Thanks for those leads.

It seems, looking at prices, that with solar panels, at almost any level, paying double, buys treble. Granted, most of our budgets are restricted enough that we can't benefit from the efficiencies of scale, but has anybody taken solar-charging to a higher level, where 8 or 9 hours of steady sun will heat 100l of water to shower temperature, as well as setting the batteries bubbling?

I guess (and it really is, only a guess) that anyone able to afford sufficient solar panels to supply their ongoing electrical requirement, is easily well-off enough not to care about the cost of running a diesel generator for however long a full charge takes. Which marginalises use of solar cells...which keeps prices for solar cells high...I think I'll call this the viscous circle...it's so damned difficult to rise out from use of oil.

 

[Twister_Ken]

Thanks for those leads.

I guess (and it really is, only a guess) that anyone able to afford sufficient solar panels to supply their ongoing electrical requirement, is easily well-off enough not to care about the cost of running a diesel generator for however long a full charge takes. Which marginalises use of solar cells...which keeps prices for solar cells high...I think I'll call this the viscous circle...it's so damned difficult to rise out from use of oil.

In real life, the percentage of the photovoltaic market taken by yotties is minuscule, so it's not rich yotties reluctance that's keeping prices high.

In fact, prices are falling because photovoltaics are being used in many applications, domestic and industrial. We just represent a few incremental sales.

 

[planteater]

.......but has anybody taken solar-charging to a higher level, where 8 or 9 hours of steady sun will heat 100l of water to shower temperature, as well as setting the batteries bubbling?
.

We have domestic solar water heating - a 1 square meter collector (small for a house but big for a boat) will heat 200l of water to near boiling point in summer and take the chill off it in winter.

To heat water with photovoltaics probably isn't practical in the UK. It might not be practical on a sailboat anywhere.

 

[dancrane]

Solar Panelist

Thanks, Planteater, that's actually very encouraging.

Otherwise...I'm persuaded by Ken, that the non-industrial majority of us don't much count, at least yet. But what are any of us doing, NOT enjoying the photovoltaic advantage? We may be a market that's barely touched upon, but anyone who enjoys the free advantage of wind in their sails, likewise ought to recognise the usefulness of sun on their panels...

...especially as it's certain to get cheaper, provided we all use it.

 

[Searush]

FWIW, I have a 10squid panel off e-bay, only about 5-6W I think, but it trickle charges one battery when I am not at the boat so it is in excellent condition for starting the engines when I am there. I nlike it so much I am planning to buy another to keep the domestic battery in good condition too. The output is low enough that no regulator is required.

 

[dancrane]

Thanks Searush; now I do the maths: £10=5w or 6w...so, what'll it cost, to substitute a Volvo, cranking out about 32hp...excuse me...

...seriously, whatever I'm floating on this midsummer, will have its power supplemented or very profoundly charged, by whatever segment of the sun I can point a panel at. I'm easily idealistic (AKA daft) enough, to adopt 50 solar panels then run the volts through Lynch motors for thrust. Thanks for the thought about small ones not needing a regulator.

 

[William_H]

Solar panels

I have used solar as the only power source on my boat for 25years. Through 5 panels if I remember rightly.
I don't use outboard and boat lives on a swing mooring. However for my purposes a few watts seems adequate. (no shortage of sun). (Coming up officially 9 weeks straight without rain or even a cloud in the sky though really more like 5 months.)
Anyway my conclusion is that solar is good for a boat if you have nothing else. Certainly beats taking battery home for charge. Far better however is a shore charger used occasionally or engine driven alternator used regularly. That is the thing. if you use your boat engine eg every fortnight for 20mins then that should be adequate. If however the boat stands not used for longer periods then solar can keep batteries sweet.
The problem with solar is not just the cost of the panel but cost and inconvenience of mounting larger panels. If you want refrigeration then you really need a lot of power. I still think engine driven alternator charging is best. Just an opinion olewill

 

[dancrane]

Thanks for the input. I'm insanely optimistic about what 6m2 of panels could do, to maintain 1000ah or so of deep-cycle cells. I've even thought in terms of re-ballasting a pretty big motorsailer, with batteries instead of pig-iron.

I guess there may be problems I haven't considered, but when enough like-minded people do think seriously about it, much more likely we'll find a way to make it practical on cruising yachts in ways not yet attempted.

 

[macd]

I guess (and it really is, only a guess) that anyone able to afford sufficient solar panels to supply their ongoing electrical requirement, is easily well-off enough not to care about the cost of running a diesel generator for however long a full charge takes. Which marginalises use of solar cells...which keeps prices for solar cells high...I think I'll call this the viscous circle...it's so damned difficult to rise out from use of oil.

Yippee, I must be rich! Or maybe just in a sunnier place. Solar panels are the most called-upon charging solution for liveaboards this far south -- along with much less power-hungry demands than heating a hundredweight of water (for which directed solar heating makes far more sense, or would if it were practicable on a boat). Panels meet my needs, even at this time of year, but partly through careful energy budgetting (not to mention a solar camping shower).

One of the yacthing mags (PBO?) did a fairly extensive test of all the major panels maybe five years ago. Since then new makers seem to have arrived on the scene, but the general thrust was that rigid panels gave more bangs for your buck, followed by semi-flexible, with flexible last. The latter, though, are less prone to high output losses from halyard shadows.

The article also suggested that prices would NOT drop appreciably with increased scale, since one of the basic crystal constituents was somewhat finite. Perhaps some of the cheapo panels mentioned suggest this is not the case, although maybe that's more to do with high-volume/low margin sales. On the other hand, some well-regarded brands of panels are no cheaper now than they were three or four years ago. Personally I'd be wary of budget panels unless I'd given them a close inspection. The marine environment is pretty hard on them although quality brands seem to stand up to it well.

I don't give much credit to your viscous circle: as others have said we're minority users of an increasingly common product, with correspondlingly little effect on prices. Rather, the lesson is the same as for many other bits of kit: "marine" suppliers usually charge more. That's just a fact of life, not a thick disc .

 

[longjohnsilver]

We have domestic solar water heating - a 1 square meter collector (small for a house but big for a boat) will heat 200l of water to near boiling point in summer and take the chill off it in winter.

.

That's an interesting thought, do you have any details on what you have and how it was fitted?

 

[dancrane]

MacD, that's the best reasoning I've heard in a while. And a simple solution: it's latitude adjustment time. Much more sense relying on solar, somewhere where the sun itself is reliable!

Fascinating that a halyard's shadow would interrupt output from some types. I'll look up the PBO review, cheers. I expect you're right that marine suppliers make quite a few quid extra, supplying widely available products to consumers believed to be affluent.

 

[vyv_cox]

My 125 watts of solar panel run my refrigerator and other electrical requirements full time, May to October, in Greece, via 330 Ah of battery. I don't bother tilting the panels as leaving them horizontal gives enough. The worst situation occurs when we are in port for several days and one panel is in shadow for several hours. At anchor any shadows are mostly moving around and the overall effect on battery power is improved.

 

[dancrane]

Interesting. Has anyone thought up a way to have panels mounted on some kind of rotary support that could surround the mast, hoisted high out of any shadow, and be twisted to follow the most direct sunlight? For use in port, not when sailing.

 

[ukmctc]

I sell my excess power to the national grid....lol, I have 245 watts (3 panels) of solar energy and 2 rutland 913's, they charge 4 domestic 110's, 1 fridge 110, and 1 heavy duty 1000crank engine battery.

The panels and genny's are mounted on the back, high up on steel. They have been getting the sun and wind all winter and my batteries have not dropped below 13.6v in the last year, so it works for me.

 

[dancrane]

That's want I like to hear, very encouraging.