Marinising Solar PV Modules

When specifying a marine solar pv system there are a number of considerations which can make quite a difference to the lifespan of the system.

Solar PV Warranties

The issue with warranties is that there are very few brands of pv modules that are warranted for marine use, and those that are either have a very short warranty, or are disproportionately expensive.

Most mainstream solar pv module manufacturers exclude marine or mobile use from their warranties. However, in over 20 years of supplying solar panels for marine use, we are happy to say that there is no real reason not to use standard solar panels - assuming they are of good build quality.

Almost all decent quality modern solar panels use anodised aluminium frames, and many are tested in a salt mist environment. The better ones have an IP68 rated junction box fitted to the back of the panels for the cables to connect to the pv module. Some of the top manufacturers such as LG and Panasonic fully pot their junction boxes, ensuring that nothing can get inside to corrode the cell contacts andamp; diodes.

Flexible Solar PV Modules ?

When cheap flexible solar pv modules first became popular a few years ago, we had our reservations. We had seen the beating that our early Uni-solar flexible panels had taken over the years and were fairly sceptical about their lifespan. Unfortunately, our suspicions have been confirmed - only top quality flexible solar panels will last a decent length of time in a harsh environment.

One of the big issues is that many people bond the flexible solar panels directly to the cabin roof, often with a high strength industrial adhesive. This has two knock-on effects : 1) it stops air from flowing underneath the module to cool it, thus increasing the chance of a thermal failure on poorer quality designs and 2) it makes it really difficult to get the panels off easily in the case of any issues.

Compared to the thinner, highly flexible modules, the more rigid semi-flexible panel construction is less likely to develop microscopic cell stress fractures. At the same time, some of the surface coatings on the cheaper panels don't have as good UV protection as the better quality modules.

If you are looking for a flexible panel for your boat, the ActiveSol Ultra range carry an industry-leading 5 year warranty and in comparison to their nearest competitors, their range of marine flexible solar pv panels represent excellent value.

Solar PV Connectors

The majority of solar pv modules these days are supplied with industry standard "MC4" solar connectors. Depending on their quality, they are often only rated at IP66. We've also found that some MC4 "compatible" connectors aren't as good as the original connectors from Staubli - and when you combine the two, the seal and connection isn't as good as if the two connectors are of the same brand.

One solution to this is to eliminate the connectors from the potentially harsh environment outside of the boat. You could remove the supplied solar cables  (with MC4 connectors) and replace them with longer solar cables which run though a suitable cable gland and terminate inside the boat (either at an isolator / mcb, or at the solar controller).

However, as mentioned above, some top quality solar panels have fully potted junction boxes that prevent this from being an option. One solution in this case is to cut off the connectors and extend the supplied cables with a very careful splice, using suitable splice connectors and 2 layers of adhesive-lined heatshrink. 

Solar PV Mounting / Brackets

Secure mounting is obviously essential on any sea-going vessel, and is perhaps one of the biggest challenges on smaller boats where the number of suitable locations to mount the solar pv panel/s are very limited.

In our experience, many boat owners end up having a custom mounting bracket fabricated to attach to their safety rails or radar arch. If there is more space available, standard plastic or aluminium mounting brackets can sometimes be used. The mounting solution is very often individual to the boat. The cost of good quality flexible panels is mitigated if they avoid a complex custom-fabricated mounting arrangement. 

In Summary ...

If you are considering solar pv panels for your boat - the one thing to look out for is quality. We offer to fully pot junction boxes for clients as well as extend the solar pv cables, thus making the majority of the solar panels we supply suitable for use in a harsh off-shore marine environment. Inland boats have less of a corrosion issue as there is less salt in the air.

Contact us to discuss your requirements. Alternatively, feel free to comment on this article and we'll do our best to reply.

See also : "Make Your Off-grid Solar PV Installation 4X More Reliable"