How to choose a solar panel ?

affinite

affinite

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Has anyone any tips on selecting a solar panel for a sailing yacht ?
2 of my 3 existing panels have failed and Id like to start again with a large single large replacement
I have a stern gantry which is large enough to support a 2m x 1m panel so Im aiming for 400W
Im aware of the pros and cons of monocrystalline vs polycrystalline but beyond that I don't really understand why some panels are more expensive than others.
Any recommendations or advice welcome
PS - must be available to buy in Greece :)
 
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Look at Photonic Universe - lots of info and helpful when you talk to them. They will possibly ship to Greece. Just looked, they do a 360w panel for £299.99 which they say is suitable for marine use. 195 x 99 x 4cm.
 
I got mine through Photonic Universe, good advise and customer service.

The expensive ones are from Europe (Germany I think) where as the ones that are <50% of the price are far eastern.
 
Be careful of Photonic universe.
I bought flexible ones and they delaminated after 12 months.
I called them to see if there was any help and blank response.
Didn't want to know unless spend on new ones.
Bought some solid ones and mppt controller(a must)from greengoods4u.com much cheaper and seem better quality.
absolutely brilliant.
 
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affinite said:
Has anyone any tips on selecting a panel for a sailing yacht ?
2 of my 3 existing panels have failed and Id like to start again with a large single large replacement
I have a stern gantry which is large enough to support a 2m x 1m panel so Im aiming for 400W
Im aware of the pros and cons of monocrystalline vs polycrystalline but beyond that I don't really understand why some panels are more expensive than others.
Any recommendations or advice welcome
PS - must be available to buy in Greece :)
Click to expand...

I would suggest a pair of 200w panels wired in series will give better results on a gantry with little to no shading.
 
affinite said:
Paul
Can you explain why 2 x 200w will give better results than a single 400w?
Click to expand...

Apologies for being brief, have to be somewhere in 15 mins.

A few reasons for series being better, low levels of sunlight being a big one. At lower levels parallel panels can easily fall below the voltage levels of the battery, = no charging. Wiring in series doubles the voltage, so the same lower levels they will still be above battery voltage and keep charging. Some controllers also benefit from series connection, for instance, Victron controllers will not start until the panel voltage exceeds the battery voltage by 5v, this is obviously reached sooner in the morning with series wired panels.


Crude example, say the panels are at 12v, in parallel that's not going to charge a 12v battery. Wired in series, that 12v becomes 24v and your batteries are charging. Series connection doubles the volts but halves the amps at the panel output (controller input), the controller then "modifies" the voltage to suit the battery charging, so it might change that 24v to 13 0r 14 volts or so and as the volts drop, the amps go back up.
 
Victron was what Moor & Dock offered. They weren’t hugely expensive so I didn’t shop around. I bought a Victron controller in uk (much cheaper) & installed everything myself.
 
My experience is that "semi flexible" panels are to be avoided, they just don't last (delamination) and are regarded I think by many this way. I've had no problems at all with any of the rigid mono panels that I've bought and usually go for the least expensive that I can find. On some the finish on the aluminium frame has been a bit lacking but that's easily resolved - filing too sharp corners off a bit, e.g. A bit of extra sealant around wires going into little black boxes sometimes doesn't go amiss either. The output and longevity has never been an issue...
 
Once you go over about 250w the prices (per watt) drop considerably because you are into "house" size panels. Also you will be looking at 60 or 72 cell panels, which as Paul says have higher voltages so thinner wires to the MPPT. I fitted a 300w an ordinary panel with 60 cells which was £100 plus P+P. Performed really well during the summer. If you can get 400w or higher even better. Don't remember anyone ever saying I have too much solar. One thing to be aware of is the bigger panels often have a double aluminium edge for strength which foxed me for a while trying to mount bars across the panel but we got there in the end.

I agree with others, tried the semi flexible ones and they just didn't last.

Pete
 
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I've bought two different panels, both the cheapest per watt I could find from eBay, rigid.
One is now five years old and still going strong, proved very robust, even fell overboard one night and dangled by its cable in the sea for the night- it still works.

IMHO Photonic universe sell the exact same stuff you can get on eBay but at a markup. Maybe they are worth it in terms of after-sales.

When we come to upgrade to a larger array, I'll probably buy from GWL who are based in the Czech Republic... I'd expect them to deliver to Greece, and their prices are very good. I may pay a little extra for half cut panels which are a bit more shade tolerant.
 
"..2 of my 3 existing panels have failed and Id like to start again with a large single large replacement.."

So, one still works so you still have 33% capacity - if you only have one large panel, and it fails, you will have zero.

Don't throw the old ones away; unless there's delamination of flexible panels, or you're particularly unlucky, there's not much to go wrong with solar panels that a soldering iron and silicon sealant won't resolve.
 
I would suggest that OP look for suppliers in Greece of domestic PV systems to supply 2 panels. These will be 40v (no load) ie equivalent to 2 "12v" 20v no load panels in series. There are so many used around the world that cost is reasonable. I have 8 on my roof and our club has 200 on the roof. Some 40% of all houses around Perth have solar PV systems 1500 to 6000 watts. So panels either German or Chinese are cheap and seem very reliable on a house roof. Can't see why not good for a boat but they are rigid type in ali frame. Companies and prices are usually set up for whole of system ie 6Kw with inverter and installation but hopefully you can get just 2 panels. ol'will
 
I'm building a ketch and want to install solar panels but I'm worried about shading making the system marginal

Apparently these days you can buy panels with bypass diodes to stop current flowing to the shaded cells. They are more expensive but I think they would make the system viable (particularly on a ketch)

 
V1701 said:
My experience is that "semi flexible" panels are to be avoided, they just don't last (delamination) and are regarded I think by many this way. I've had no problems at all with any of the rigid mono panels that I've bought and usually go for the least expensive that I can find. On some the finish on the aluminium frame has been a bit lacking but that's easily resolved - filing too sharp corners off a bit, e.g. A bit of extra sealant around wires going into little black boxes sometimes doesn't go amiss either. The output and longevity has never been an issue...
Click to expand...
If money is an issue then I agree that semi-flexes aren’t a good option. We did go that way though for Bimini panels as that was easier and simpler for us than reinforcing the frame, and we wanted to be able to take down the windage if storms were blowing through. But the cost of really good semi-flexes (Sunware TX) was eye watering. The reputation of them for longevity, according to our fitter, was very good and they were his go to solution for Biminis. He pointed us at a neighbouring boat where the owner confirmed that he had had the panels for 8 years with no problems.
 
coopec said:
I'm building a ketch and want to install solar panels but I'm worried about shading making the system marginal

Apparently these days you can buy panels with bypass diodes to stop current flowing to the shaded cells. They are more expensive but I think they would make the system viable (particularly on a ketch)

Click to expand...

Has anyone got a comment on bypass and blocking diodes?
Am I on the right track:confused: (or wasting my money?)
 
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