Solar Panel Question?

[Dougal]

I've taken off the Rutland 913 wind charger, and decided to go with solar panels instead. Much as I'd LIKE to ask for recommendations, I'm also aware that it's emotive. Everyone will probably have their own favourite. I am interested in learning what I need though, in order to make an informed choice. So if anyone knows of any 'solar panels for dummies' websites, I'd be grateful;-)

Almost everything I've read so far, seems to have to angle to selling you something.

 

[VicS]

I've taken off the Rutland 913 wind charger, and decided to go with solar panels instead. Much as I'd LIKE to ask for recommendations, I'm also aware that it's emotive. Everyone will probably have their own favourite. I am interested in learning what I need though, in order to make an informed choice. So if anyone knows of any 'solar panels for dummies' websites, I'd be grateful;-)

Almost everything I've read so far, seems to have to angle to selling you something.

'solar panels for dummies' I think it's better known as 'YBW Reader to Reader'

 

[RichardS]

'solar panels for dummies' I think it's better known as 'YBW Reader to Reader'

Ouch! :encouragement:

 

[Tranona]

I've taken off the Rutland 913 wind charger, and decided to go with solar panels instead. Much as I'd LIKE to ask for recommendations, I'm also aware that it's emotive. Everyone will probably have their own favourite. I am interested in learning what I need though, in order to make an informed choice. So if anyone knows of any 'solar panels for dummies' websites, I'd be grateful;-)

Almost everything I've read so far, seems to have to angle to selling you something.

Why not say what advice you are looking for? What are you expecting out of your panels in terms of output and how are you intending mounting them? This determines the size and the type of panels that might be suitable.

 

[TQA]

How and where you mount them is critical.

You want to avoid them being shaded and you want to be able to tilt them to follow the sun.

A rear arch is the most often used successful installation that I see in the cruising community. It is what I have.

High voltage panels say 28volts for a 12 volt system plus a good MPPT controller works well and can cope with some shading which is almost inevitable at some time of the day on a sailboat.

 

[Dougal]

That's pretty much the point.... I don't know WHAT to expect from them. I've been used to the wind generator, but have no idea how the panels compare. One reason being for example; do manufacturers measure the output in different ways? The reason i ask that, is I can see 30watt panels for the same price as 100watt panels!!!! (Force4 catalogue). That's why I'm somewhat confused (nothing new).
Not at the boat, but I think my cranking battery is about 85Ah and the the domestic bank (2) totals about 160Ah
I expect to get two panels.... one just for just 'trickle charging' that will be left on over winter months (boat in the water), and another heftier panel for cruising during the summer. Won't be leaving the expensive one out as we had stuff stolen last winter, including my BRAND NEW Delta anchor:-(((

I don't have much desk space, so will PROBABLY make a mounting bracket across the davits.

 

[Tranona]

For trickle charging you only need a small sub 10w panel. For more you need the largest panel you can reasonably fit. The actual output compared to the nominal output will depend on how much sun you get and whether the panel is fully exposed - any shade such as a boom over a deck mounted panel will reduce the output significantly. Hence the popularity of panels mounted no poles or gantries on the stern. Once you get over 10w or so you will need a regulator to avoid overcharging.

Clearly prices vary according to output and then different methods of construction and quality, with generally flexible ones being the most expensive for a given output. The Force 4 page you are looking at has a fair range of the possibilities.

 

[Dougal]

For trickle charging you only need a small sub 10w panel. For more you need the largest panel you can reasonably fit. The actual output compared to the nominal output will depend on how much sun you get and whether the panel is fully exposed - any shade such as a boom over a deck mounted panel will reduce the output significantly. Hence the popularity of panels mounted no poles or gantries on the stern. Once you get over 10w or so you will need a regulator to avoid overcharging.

Clearly prices vary according to output and then different methods of construction and quality, with generally flexible ones being the most expensive for a given output. The Force 4 page you are looking at has a fair range of the possibilities.

Thanks for that. Still not 100% clear on pricing though, as those with similar prices are a mile apart on output. I'm guessing I'm just missing something very obvious.

 

[vyv_cox]

Have a look at Midsummer Solar http://www.midsummerenergy.co.uk/buy_solar_panels.html. They keep a good range of panels of all types, Kyocera in particular seem to be very good quality for framed ones, ours are about seven years old, still as good as new. You can compare the various types with prices, which will give you an idea why one costs a lot more than another.

As a guideline we have 125 watts on a stern arch that runs everything including the fridge in the summer months in Greece. If you were based further north and/or wanted the panels to provide power earlier and later in the year you would need to increase to maybe 200 watts. These are minimum figures, some cruisers have as much as 1000 watts. In winter we disconnect these panels and use a 38 watt one on the deck to charge our 3 x 110 Ah domestic batteries plus a Red Flash starter battery, in both cases via a twin-bank regulator. See it here http://www.sunworks.co.uk/

 

[fireball]

We had 2 domestic batteries totalling 260Ah and a starter battery. Coupled with this we had a 30w semi-flexible solar panel (more expensive) - this was screwed to the coach roof just in front of the sprayhood - this fed the banks via a regulator with two outputs.

Our power requirements weren't huge - we didn't bother with radar, but did have plotters - lights were mix of LED and halogen. The main drain was the fridge (compressor).
30w panel would nowhere near keep us running - but it added a bit - more importantly for us, it kept the batteries topped up whilst we weren't using the boat (on a swinging mooring)

 

[Whitty]

Try Sunstore good products and service.

 

[lpdsn]

I've taken off the Rutland 913 wind charger, and decided to go with solar panels instead.

That's one way of ensuring lots of wind and rain this season.

 

[Dougal]

I will miss the wind generator, as when anchored overnight in our sailing grounds (southern Brittany), the wind almost always pipes up at night to replenish our supply. I just find it too much of a nuisance on a 32 footer. No radar and no electrically powered fridge, but mostly incandescent lamps. Definitely thinking of a rigid panel across the davits.

 

[JumbleDuck]

That's pretty much the point.... I don't know WHAT to expect from them. I've been used to the wind generator, but have no idea how the panels compare. One reason being for example; do manufacturers measure the output in different ways? The reason i ask that, is I can see 30watt panels for the same price as 100watt panels!!!! (Force4 catalogue). That's why I'm somewhat confused (nothing new).

Rigid panels have (normally) aluminium frames and glass in front. Good efficiency, robust, heaviest, can be hard or ugly to mount. Cheap, because thety areused for most land-based applications and the economies of scale kick in. Expect to pay about £1 per watt

Boats often have semi-flexible panels, which are thin and use a plastic substrate, so you can get a bit of bend into them. Great for mounting on hatches and coachroofs, but too flexible to be used on their own. There are two distinct subsets: the cheap and cheerful (typically £2 per watt) and the much more robust, with a non slip surface (anything from £4 - £10 per watt).

There are also flexible ones, which can be rolled away after use and super-flexible one suitable for us on sails have been on the point of availability for fifteen years now. See also: nuclear fusion.

I bought two 50W semiflexible panels: one for £100 and the other with rather posher back contact cells (less obstruction) for £160. They work fine.

Shading is much overstated as a problem. Unless you have a shadow which is more than a cell wide (ie about 10cm) and runs across the full width of the panel, there isn't much effect.

 

[Dougal]

Rigid panels have (normally) aluminium frames and glass in front. Good efficiency, robust, heaviest, can be hard or ugly to mount. Cheap, because thety areused for most land-based applications and the economies of scale kick in. Expect to pay about £1 per watt

Boats often have semi-flexible panels, which are thin and use a plastic substrate, so you can get a bit of bend into them. Great for mounting on hatches and coachroofs, but too flexible to be used on their own. There are two distinct subsets: the cheap and cheerful (typically £2 per watt) and the much more robust, with a non slip surface (anything from £4 - £10 per watt).

There are also flexible ones, which can be rolled away after use and super-flexible one suitable for us on sails have been on the point of availability for fifteen years now. See also: nuclear fusion.

I bought two 50W semiflexible panels: one for £100 and the other with rather posher back contact cells (less obstruction) for £160. They work fine.

Shading is much overstated as a problem. Unless you have a shadow which is more than a cell wide (ie about 10cm) and runs across the full width of the panel, there isn't much effect.

That's a great and informative post. Many thanks!!!

 

[lpdsn]

No radar and no electrically powered fridge, but mostly incandescent lamps. Definitely thinking of a rigid panel across the davits.

Fred drift but...

You can certainly cut the current draw from domestic lighting by fitting LEDs. There are still a few UK websites trying to sell LEDs as though they're a luxury item, but they are readily available on the web at pretty low prices. LED technology, especially white LEDs, has moved on substantially in the last few years. The expensive LEDs I fitted in 2009 look pretty poor compared to the cheap ones I fitted last year and the year before.

 

[Tim Good]

In winter we disconnect these panels and use a 38 watt one on the deck

Why do you bother to do that if you have a decent regulator?

 

[LadyInBed]

Google - ybw solar panels
there will be enough reading to last you into summer!

 

[C08]

I had two Rutland 913 WG managed by a HRDX Controller. I sold one WG and fitted two 80W panels on my wheelhouse roof-fixed & flat. Generally speaking I get at least 2x the output from one panel as I did from the Rutland. Winter days usually .5-1 amp summer days 2-5amps. I think the effect of partial shading is overstated from many people, from my experience with my panels. I can be seeing 4 amps from a particular panel and then shade half of it and I would then see a proportional decrease in current say 2 amps not the dramatic reduction some seem to think. I am pleased I kept one Rutland (modest output but well engineered and so quiet) for those wet windy days which we still get in Uk summers.

 

[JumbleDuck]

I had two Rutland 913 WG managed by a HRDX Controller. I sold one WG and fitted two 80W panels on my wheelhouse roof-fixed & flat. Generally speaking I get at least 2x the output from one panel as I did from the Rutland. Winter days usually .5-1 amp summer days 2-5amps. I think the effect of partial shading is overstated from many people, from my experience with my panels. I can be seeing 4 amps from a particular panel and then shade half of it and I would then see a proportional decrease in current say 2 amps not the dramatic reduction some seem to think.

Absolutely. I have posted about this before. Panels are made up of strings of cells wired in series (to get the volts) with the strings combined in parallel (to get the amps). Normally that means series connections down the long axis of the panel. Shade some or all of the cells in a string and you'll lose a proportionate number of amps - from 4A to 2A in your case. To cut the whole thing off you have to put a dark shadow across the whole of at least one cell in every string, which in practice means across the panel and simply doesn't happen much. It has to be a dark shadow too - think total rather than partial eclipse. A light shadow just trims the output a bit.

Source: lots of tests I did on my two panels before installing, and observations since.