Flexible solar panel recommendations?

[Mel 0]

Hi, any recommendations for flexible solar panels?  I have had no luck with mine which apparently aren't being imported anymore due to poor quality.  I have 2x 100w currently.

[Black Panther 1,767]

I have 3x135watt from juice?. No problems at 3 years and counting. 

[2flit 52]

We have 600 watts of Flexible PV on our Bimini and radar arch combined. Then another 200 watts in panels we bring out in badly overcast winter conditions. These we strap to the boom and rotate them for altitude adjustment, occasionally swinging the boom out for azimuth. Two of the radar arch modules are also adjustable for altitude and azimuth. They do not last anywhere near as long as glass fronted modules. (I've some experience here having installed more than a 1000 modules in mostly terrestrial applications but also occasionally marine) My advice is to never get a PET front sheet and to look for an ETFE front sheet. I would also pay a premium for SunPower Maxeon® Solar Cells which some manufactures use in their flex-modules. PM me if you have other questions glad to give you my contact phone.

[syohana 37]

Juice panels are good quality and the price reflects that. Most so-called "flexible" panels are rubbish. Be aware that NO flexi panel is actually flexible. They need to be fixed to a hard, flat surface which can have a slight curve to it and must have continuous support underneath. The solar cells within the panel are not flexible, they are very brittle and any uneven pressure or vibration can crack them. for example, if you stick them down with sealant and there's a bubble in the sealant then when someone steps on the bubble, the solar cell will crack.

As 2flit said, do not install PET faced panels, the plastic surface will degrade and start to become yellow in only one season of NZ UV levels. ETFE is the only option with a moderately good lifespan. Even the very best ETFE panels have a design life of only about 5 years, compared to glass panels which almost always last in excess of 20-30 years.

Unless you have a really really really good reason why you must have "flexible" panels then it's best to deal with the weight and appearance of glass panels because they produce more power, last many times longer and cost just a fraction of what the flexible panels do. There are some nice looking frameless double faced glass panels available but standard alloy framed ones can't beaten on price.

[Mel 0]

Thanks for all the advice.  

After the first failure I asked the electricians about changing to the Juice panels and they said that the panels they supplied differed in that they were 36v and therefore charged better in low light?? The Juice panels were also a different size so cosmetic touchups were going to be required so I stuck with the same panels.  Clearly that's not an option again though!!  

I haven't checked what regulator I have yet, but could this need changing if going to 12v panels which I think is what Juice are?

The panels do go onto the solid slightly curved surface of the coachroof, I think too curved for a glass panel though.  I've attached the best pic that I have handy.

[Island Time 1,293]

Hmm, not exactly accurate. “12” volt panels often run at 20 odd volts with MPPT, and the voltage has nothing to do with low light ability. A decent controller will adjust the panel voltage to get the max power point -hence mppt. 

[syohana 37]

Juice panels are either nominally 12v or 24v depending on the size. If the maximum "open circuit" output of your panels is around 36-40v then they are actually nominally 24v panels - the same voltage as the larger Juice panels.

If you need smaller panels then two 12v panels can put in series to make the output nominally 24v (actually maximum around 36-40v open circuit).

It is true that a higher voltage set up will give better low light performance because the panels will only charge when their output voltage is higher than the battery voltage. Even an MPPT controller will only charge when the panel voltage is higher than the battery voltage. There is not an advantage to going with panels more than twice the battery voltage, except you can get away with smaller cables on higher voltages.

If you have multiple small panels then there might be more advantage to wiring them each on separate charge controllers so that shade on one panel doesn't affect the output of the other panels. That's likely to be a much bigger factor than improving low light performance by putting them in series, especially on a sailing boat where the rig always puts shade on something.

If the nominal voltage output from the panels is not the same as the nominal battery voltage then you MUST use an MPPT type charge controller which can step the panel voltage down to the battery voltage, not PWM (some very cheap controllers with MPPT printed on the front may not actually be MPPT).

Glass panels (or just one big one) would easily fit that coachroof with chocks under the corners. Not as pretty but a lot less headaches and better performance in the long run.

[Psyche 804]

Good discussion, I want to get a panel but since space is limited to an area approximately 1.2 m square on the coachroof I will need one that I can walk on when flaking the main if it is to be permanently fixed. I for boats under 12m that is probably the biggest issue; spare real estate. The alternative is a demountable rigid panel but that has its own set of issues with stowage, so its a bit of a tricky problem if you need a permanent power source. 

[syohana 37]

 

14 minutes ago, Psyche said:

Good discussion, I want to get a panel but since space is limited to an area approximately 1.2 m square on the coachroof I will need one that I can walk on when flaking the main if it is to be permanently fixed. I for boats under 12m that is probably the biggest issue; spare real estate. The alternative is a demountable rigid panel but that has its own set of issues with stowage, so its a bit of a tricky problem if you need a permanent power source. 

Consider a panel "hinged" to your top guardrail wire and outside it, either across the stern or beside the cockpit where dodgers would go. Have it vertical when sailing so it takes zero space, adjust the angle towards horizontal when moored (depending on height of the sun so don't raise it so much in winter). That will keep the coachroof free to walk on and the space taken by the panel is entirely outside the boat.

[syohana 37]

Like this: https://www.riggingdoctor.com/life-aboard/2016/2/28/solar-panel-mounting

[Psyche 804]

What is this thing "guardrail" that you speak of?🤣

No lifelines or pushpit on a Stewart!