Flexible Solar panel -> Back panel

[VeloSolaire]

I am looking for portable flexible solar panel. They are advertise as Boat or RV solution.

Searching on amazon, I found that most of them use SunPower Cell. The difference is with the back panel
I found some in aluminium, fiberglass or plastic.

Is there some particular thing I need to know about those different back panel to do my selection.
Weight is important to me (I am building a solar Bike) but maybe there are important physical fact.

Thank you

they all look similar to this

FlexiblePanel.jpg

[Dasadab]

I am looking at these. New product apparently and they advertise it has a very durable coating. It's also very light at 4 lbs.

https://www.amazon.com/ALLPOWERS-Fle...tt+solar+panel

[Sunking]

Yeah you need to know they will need replaced in a few years along with the batteries.

[Dasadab]

Yeah you need to know they will need replaced in a few years along with the batteries.

Basis for statements? Are you saying that all flexible panels are no good? I could not find any reference on the RV or sailboat forums to failures. Regarding battery failure? The panels will fail and the batteries will fail from being undercharged?

[SunEagle]

Most flexible panels trade structure integrity to get them to be low weight.

Unfortunately they can be damaged easier due to not having any solid frame around them as well as have their "plastic" encasement fail from UV which can make it brittle.

[Dasadab]

ETFE is a new, very durable coating. ETFE is what caused me to explore whether these panels are a game changer.

http://www.polyfluor.nl/en/archive/etfe-foil/

http://www.architen.com/articles/etf...w-fabric-roof/

[Sunking]

Basis for statements? Are you saying that all flexible panels are no good? I could not find any reference on the RV or sailboat forums to failures. Regarding battery failure? The panels will fail and the batteries will fail from being undercharged?

Simple they are Thin Film and only have a 5 year life span. Last about as long as batteries. UV light destroys the printed circuit substrate. .

[VeloSolaire]

[QUOTE=Dasadab;n353924]ETFE is a new, very durable coating. ETFE is what caused me to explore whether these panels are a game changer.
/QUOTE]
Thank you for the link. I was wondering if this layer could lower the efficiency of the panel, or if by blocking UV it could help ?

[SunEagle]

[QUOTE=VeloSolaire;n353993]

ETFE is a new, very durable coating. ETFE is what caused me to explore whether these panels are a game changer.
/QUOTE]
Thank you for the link. I was wondering if this layer could lower the efficiency of the panel, or if by blocking UV it could help ?

The problem with most pv cells is which frequency of light they can easily convert to electricity. Most tend to work better on the shorter freq wavelengths which is more toward the UV side. So blocking the shorter wavelengths could reduce the efficiency.

If the scientists can figure out how to get the longer wavelengths to produce it would increase the cell efficiency.

[J.P.M.]

[QUOTE=SunEagle;n354047]

The problem with most pv cells is which frequency of light they can easily convert to electricity. Most tend to work better on the shorter freq wavelengths which is more toward the UV side. So blocking the shorter wavelengths could reduce the efficiency.

If the scientists can figure out how to get the longer wavelengths to produce it would increase the cell efficiency.

One other scheme or adjunct to finding new device materials is to produce panel covers that have wavelength selective glazing or covers.

If, for example, a glazing can be produced that reflected all irradiance that had a wavelength > 1.15 micrometers or so (for silicon devices, solar radiation at higher wavelengths does not produce hole-electron pairs, but only produces waste heat which only increases cell temperature), that might result resulting in about 25 % less waste heat input to the cell and perhaps increasing efficiency.

But, the glazing would also need to be an effective emitter of all radiant energy with a wavelength of > ~ 2-3 micrometer or so to avoid reductions in thermal infrared radiation that's emitted from the surface. Such reductions at higher (longer) wavelengths would only inhibit and reduce thermal radiation heat transfer to the sky and the surroundings and counterproductively increase the cell temp. The thermal radiation amounting to something like ~ 1/3 to 40+% of the total heat transfer from the top surface that most rooftop PV operates at.

All this selectivity must also take into account that the character of the incident irradiance wavelength distribution, at least and insofar as the glazing surface is concerned is also somewhat as f(incidence angle) in convoluted sorts of a ways.

A bit complicated but reasonably well understood state of affairs from the science standpoint. Execution is a matter of technology, material science and production.