Solar Panels... Again!

[Driver]

I am wading through the jungle, or is it tip toeing through the minefield? of solar panels. I have read the other posts on the subject, watched u-tube until my eyes dried out and read everything I can find. I have decided about 400w would be enough for my purposes on my 50ft. Pearl motor yacht. Flexible panels would be necessary because of the weight. Some questions are:-

1) With new panels, does it matter if its one at 400w or two at 200w.

2) The are two possible mounting areas. One is over the glass skylight windows in the fibreglass canopy over the aft deck. Certainly there would be insulation using 10mm polycarbonate sheeting, of which more later. There would sometimes be minimal shading. The other position would mounting it/them over the very rigid but traditional sunbrella bimini. No shading, but there would clearly be some movement if draped directly over the bimini and attached with rare earth magnets as suggested by one company.

3) Heat. Despite assurances from the Forum, there are some warnings on the net that the panels do get very hot. Closer to home, my engineer and maintenance man tells me that he fitted a solar panel directly to a fibreglass yacht roof which became badly scorched by the heat and required insulation. This could be a disaster if it damaged the bimini sunbrella material or worse, shattered the glass in the aft deck skylights, perhaps even despite the 10mm polycarbonate insulation.

4) Price. I am happy to pay the price for quality and have found two 400w panels that seem suitable, but at entirely different prices.
One is from Shinson Technology Co.,Ltd., China, 465w at under 200Euros and another SF400w by Allpowers UK at £700. I have no idea what the qualty difference is.

As usual, all comments will be gratefully received.

 

[PaulRainbow]

I am wading through the jungle, or is it tip toeing through the minefield? of solar panels. I have read the other posts on the subject, watched u-tube until my eyes dried out and read everything I can find. I have decided about 400w would be enough for my purposes on my 50ft. Pearl motor yacht. Flexible panels would be necessary because of the weight. Some questions arr:

1) With new panels, does it matter if its one at 400w or two at 200w.

Depends on shading. if there is likely to be any shading, 2 panels would be better, otherwise, no difference.

2) The are two possible mounting areas. One is over the glass skylight windows in the fibreglass canopy over the aft deck. Certainly there would be insulation using 10mm polycarbonate sheeting, of which more later. There would sometimes be minimal shading. The other position would mounting it/them over the very rigid but traditional sunbrella bimini. No shading, but there would clearly be some movement if draped directly over the bimini and attached with rare earth magnets as suggested by one company.

I would not fit 400w of solar panels to the Sunbrella.

3) Heat. Despite assurances from the Forum, there are some warnings on the net that the panels do get very hot. Closer to home, my engineer and maintenance man tells me that he fitted a solar panel directly to a fibreglass yacht roof which became badly scorched by the heat and required insulation. This could be a disaster if it damaged the bimini sunbrella material or worse, shattered the glass in the aft deck skylights, perhaps even despite the 10mm polycarbonate insulation.

Where are you based ?

4) Price. I am happy to pay the price for quality and have found two 400w panels that seem suitable, but at entirely different prices.
One is from Shinson Technology Co.,Ltd., China, 465w at under 200Euros and another SF400w by Allpowers UK at £700. I have no idea what the qualty difference is.

As usual, all comments will be gratefully received.

Allpowers are taking the piss. What sort of dimensions are you looking at ?

 

[Baggywrinkle]

What is important is matching the panel voltage of your array over its operating temperature range to the MPPT that will charge your batteries ...

There is a calculator here: MPPT Calculator - Victron Energy

Simply pick the panel (s) you are interested in from the drop down list and if they are not listed, switch on "Advanced panel settings" and enter the values from the panels data sheet.

Then enter if they are in parallel or series using the "series" & "string" settings. Leave "series"=1 if you want all the panels in parallel. Combination of both gives a set of series connected panels (a string) and multiplies up the strings in parallel.

Then enter system voltage and boat location and it will suggest a MPPT Solar Charger and give an indication of output. If it can't suggest a MPPT then usually the voltage of the panel array is too low or too high for the MPPT to charge at system voltage - but it can be for other reasons.

Play about with it until you get a config that works for you.

I had 3 x 100W PTFE panels in series on a PVC hard foam board on my Bimini - worked fine in the Med and never got hot enough to scorch anything.

 

[Driver]

Thanks for the info, especially re the MPPT. What would be the problem with 400 watts on the Bimini, please? The yacht is based in Menton, South of France. I was thinking about 2m by1.2 metres in one or two panels. There is space for larger.

 

[Forty_Two]

I have been using 3 × 150w semi flex panels from Photonic Universe on my bimimi for the last three years with no issues. No marks of any sort on the bimimi. Wouldn't be without them. Mine are in series to minimise cable loses as shading is not an issue.

I'm in La Napoule SoF.

 

[Bigplumbs]

You can overcomplicate this very easily. Just get 3 150 watt panels wire them in series and use a Victron MPPT Controller and some isolators and job done

People love to over complicate that which is so easy

 

[PaulRainbow]

Thanks for the info, especially re the MPPT. What would be the problem with 400 watts on the Bimini, please? The yacht is based in Menton, South of France. I was thinking about 2m by1.2 metres in one or two panels. There is space for larger.

"Flexible" panels are only semi-flexible and that a one time bend, not regularly bending back and forth. So, they need to be fixed to a solid surface. If you intend to fit something like PVC board (nothing wrong with that) why not fit rigid panels ? A little more weight, but what's a few kilos on a 50ft mobo ? You can buy rigid panels for peanuts at the moment, a single panel would give you about 450w

 

[Driver]

"Flexible" panels are only semi-flexible and that a one time bend, not regularly bending back and forth. So, they need to be fixed to a solid surface. If you intend to fit something like PVC board (nothing wrong with that) why not fit rigid panels ? A little more weight, but what's a few kilos on a 50ft mobo ? You can buy rigid panels for peanuts at the moment, a single panel would give you about 450w

The position is weight critical, so it needs to be flexible or semi flexible, but they are very expensive to send from the UK. Does anybody know of a good supplier in France?

 

[PaulRainbow]

You can overcomplicate this very easily. Just get 3 150 watt panels wire them in series and use a Victron MPPT Controller and some isolators and job done

People love to over complicate that which is so easy

And some people love to over simplify that which needs some thought.

For instance, what if one or more panels are subject to some shading ?

Why did you not include fuses in the above ?

Did you use suitable wire ?

Are those panels semi-flexible or rigid ?

If semi-flexible, once fixed can they still flex at all ?

 

[PaulRainbow]

The position is weight critical, so it needs to be flexible or semi flexible, but they are very expensive to send from the UK. Does anybody know of a good supplier in France?

Semi-flexible panels should be mounted to a rigid substrate, if they are allowed to flex once fitted they will have a very short life. So you need to calculate the weight of whatever you intend to use to fix them to and add that to the weight of the panels.

 

[Bigplumbs]

The position is weight critical, so it needs to be flexible or semi flexible, but they are very expensive to send from the UK. Does anybody know of a good supplier in France?

Amazon

 

[Zing]

I am wading through the jungle, or is it tip toeing through the minefield? of solar panels. I have read the other posts on the subject, watched u-tube until my eyes dried out and read everything I can find. I have decided about 400w would be enough for my purposes on my 50ft. Pearl motor yacht. Flexible panels would be necessary because of the weight. Some questions are:-

1) With new panels, does it matter if its one at 400w or two at 200w.

2) The are two possible mounting areas. One is over the glass skylight windows in the fibreglass canopy over the aft deck. Certainly there would be insulation using 10mm polycarbonate sheeting, of which more later. There would sometimes be minimal shading. The other position would mounting it/them over the very rigid but traditional sunbrella bimini. No shading, but there would clearly be some movement if draped directly over the bimini and attached with rare earth magnets as suggested by one company.

3) Heat. Despite assurances from the Forum, there are some warnings on the net that the panels do get very hot. Closer to home, my engineer and maintenance man tells me that he fitted a solar panel directly to a fibreglass yacht roof which became badly scorched by the heat and required insulation. This could be a disaster if it damaged the bimini sunbrella material or worse, shattered the glass in the aft deck skylights, perhaps even despite the 10mm polycarbonate insulation.

4) Price. I am happy to pay the price for quality and have found two 400w panels that seem suitable, but at entirely different prices.
One is from Shinson Technology Co.,Ltd., China, 465w at under 200Euros and another SF400w by Allpowers UK at £700. I have no idea what the qualty difference is.

As usual, all comments will be gratefully received.

I have nearly 2kW of power installed. Flex solar panels.

Replace the bimini with PVC foam panel sheets and mount the panels on top. This only works if you can support the foam. Maybe stiffen with carbon fibre if needed. Flexible panels shouldn’t be flexed as in they can’t cope with vibration or wagging in the breeze. Bend over a curve a bit if you must, but treat them gently or they will crack internally and be useless.

Some panels are hugely better than others and can suffer partial shading with little loss. Others suffer total loss from shading. Buy a small one to test.

Get ETFE coated panels. They last much longer than the alternatives. You can buy from many places. Amazon, AliExpress and others like Renogy etc.

Fit an air gap under them to reduce heat, but this is not a big worry, so don’t labour it.

Costs are in the region of 50p to £1.00 per Watt installed power. Whatever you pay, it’s dirt cheap. Not a big issue at this price level. You can pay 10x more, but don’t get more quality necessarily. Shark infested waters…