TimB 7 Posted September 11, 2017 Share Posted September 11, 2017 Wheels, I thought series connection would be a problem (for a boat based set up) as if one panel is shaded it drops the output significantly, but it not so significant if they are in parallel and one panel is shaded. I have 2 x 150W panels in parallel on my caravan roof and the max current I have seen is about 10 amps, it blew a 10amp fuse so might have been higher once, now have 15amp fuse, didn't want to go any higher and it has been fine. I have a MPPT reg. Keeps the fridge cold nicely even on cloudy days. Cheers Quote Link to post Share on other sites
Island Time 1,239 Posted September 11, 2017 Share Posted September 11, 2017 Agreed Tim, Serial is good on a land based system, facing the sun, clean and completely shade free. Parallel is better if there is multiple panels and any shading. AT ALL. Quote Link to post Share on other sites
wheels 543 Posted September 11, 2017 Share Posted September 11, 2017 Not quite. It greatly depends on the Panel.Flexible panels (Amorphous) don't suffer so much from shading.Solid Crystaline panels do to a point. For small panels yes.Large panels not so much. It's all in the number of solar modules inside the panel. With enough modules, they can afford to have them connected in "strings" of parallel modules. A shadow falling on a module in a string will drop the output away of that string, but the current still flows through the other strings. Unless the Shadow is really large of course. So for large panels, it is pretty much a given that they internal modules will be connected in such arrays.Real flash panels incorporate bypass diodes. This is not the diode that stops the current flowing back into the panel when the Sun drops. These are diodes inside the modules themselves. They bypass the current around an individual module that may not be producing current due to a fault or shadow.But it would pay to check if the panels by measuring the output when you cast a shadow on the panel. If it significantly drops in output with a small shadow, then you need to connect your array in parallel. If it does not drop by much, then you can get away with Series.Oh and an MPPT reg also helps with shaded panels as well, because it constantly optimizes the load to obtain the best current output. Quote Link to post Share on other sites
wheels 543 Posted September 11, 2017 Share Posted September 11, 2017 Here's some good info regarding rating of panels to understand what is current good on the market.http://www.toptenreviews.com/home/smart-home/best-solar-panels/But remember that technology changes really fast in this stuff, although sometimes it could be said not fast enough. and in saying that, this is what 2017 was or is supposed to offerhttp://news.energysage.com/new-solar-panels-whats-coming-market-2017/ Quote Link to post Share on other sites
Island Time 1,239 Posted September 11, 2017 Share Posted September 11, 2017 That's all technically correct Wheels. However in the testing I have done in real life boat installs, where panel angle and shading is sub-optimal almost all the time, I have yet to see an install in serial that produces more watt hours per month than the same install in parallel. I have done this experiment on 4 vessels with proper monitoring systems now... Yes, it could be the panels. Most people wont pay for the premium product, and todays premium is tomorrows common place. Flexi panels are better in partial shade in my experience. But not as efficient in good conditions... Quote Link to post Share on other sites
Black Panther 1,591 Posted September 11, 2017 Share Posted September 11, 2017 Keep them pointed away from the sun or they will fade. 2 Quote Link to post Share on other sites
Island Time 1,239 Posted September 11, 2017 Share Posted September 11, 2017 Quick explanation of the series verse parallel could be handy. I have 2 x 100W panels I can easily orientate to very good sun angles. Am I better to have them one way more than the other? That depends KM, If they are always in direct sunlight, no shadows etc, then serial and MPPT will be best. But boats move, have rigging etc that can cause shading . If the panels are mounted in serial, and you get one with lots of shading, the whole array will drop its output considerably. If its in parallel, then only the shaded panel will drop.... Your call... Quote Link to post Share on other sites
wheels 543 Posted September 12, 2017 Share Posted September 12, 2017 That's all technically correct Wheels. However in the testing I have done in real life boat installs, where panel angle and shading is sub-optimal almost all the time, I have yet to see an install in serial that produces more watt hours per month than the same install in parallel. I have done this experiment on 4 vessels with proper monitoring systems now... OK, I will buy into that. You can't beat solid data from monitoring. It had always been a difficult one to answer when I had been asked and played around with the panels on my boat to test my theories. But I have the luxury of having three large panels across the aft davits. Quote Link to post Share on other sites
Zs2mat 0 Posted September 19, 2017 Share Posted September 19, 2017 Just a thought. Have you checked the cables and connections in your solar system? That can deteriorate with age and exposure to weather and may not be capable of carrying the load. Quote Link to post Share on other sites
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