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Old 04-07-2015, 23:12   #1
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Using reflector panels to boost solar output.

Has anyone tried, or know anything about, using reflector panels beside solar panels to catch the "near-miss" rays from the sun and bounce them into the solar panels? I am thinking in particular of cloudy, or partly-cloudy days when you want to keep the current moving at the best clip.

I understand that solar panels can be damaged if they are subjected to too much of the suns energy, but maybe carefully monitored use of reflectors attached at about 45 degree to the solar panel could help in the game of charging when in less than optimum conditions. When not needed, fold them away or remove them. Maybe as a side benefit, the folded reflector panels could be used to protect the solar panels when not in use.

A caution to those thinking of buying big panels - I am trying to install two big 135 watt panels (5 ft by just over 2 ft wide) on my tri and it is difficult to find a good location that will provide power while not getting in the way. I wish I had bought smaller panels but it is too late to swap them for smaller ones now.

Looking forward to the pearls of wisdom from the sages on this forum...

RR.
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Old 05-07-2015, 07:57   #2
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Re: Using reflector panels to boost solar output.

I don't know anything about the efficiency of using reflector panels, but my first thought is -- if you think your solar panels are in the way now, what do you think it's going to be like when you add reflector panels?j
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Old 05-07-2015, 08:15   #3
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Re: Using reflector panels to boost solar output.

Sunpower commercially makes their C7 product (http://us.sunpower.com/sites/sunpowe...-datasheet.pdf) which uses reflectors to concentrate sun by a factor of 7 (hence C7) onto standard silicon cells. Developed when silicon was expensive, it is hard to make it economically viable with current silicon prices. And it doesn't save any space, capturing 1000W of solar rays still takes a square meter. Just a different material.

And massive heat sinks, with fans, on the silicon raise prices and complexity. So, yes, it can be done, but why?

[edit] one other factor in an ad-hoc approach, you have to make sure your reflected light is equal across all cells in a series string. Cells put out more current when the sun gets brighter. And the lowest current cell in a series string will control the current output of an entire string. Since the lowest commercial string length is generally 32 or 36 cells, you'll have to make sure your reflected light is spread evenly over at least that many cells. [/edit]
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Old 05-07-2015, 10:52   #4
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Re: Using reflector panels to boost solar output.

Thanks for the feedback, O Gurus!

I should have made the two parts of my post so that they are not necessarily related, but I can see why you could shake your head!

The solar panels are to be used on my travel trailer as well as the boat, and I do not have much of a problem finding space for the panels of both kinds on the trailer. The aluminum frame that I am making to hold them will have the ability to be raised and rotated on a top, inner post to the direction of the sun, and also incline to make it even better.

The outer, base aluminum post will be on the back of the trailer, supported by the inside face of the bumper at the bottom and a bracket at the top to just hold it vertical. The upper bracket will have to have it's fastening spread over a bigger area than normal being as RV walls are not exactly heavy duty. For the rigours of travelling, the frame folds so that the solar panels are facing each other, then flat to the roof, or flat with the rear wall, and then secured.

Trying to do a similar thing on the boat is a bigger challenge!

So the weakest link in the solar panels will restrict the total output, so all cells have to be similarly boosted. Thanks for that info.

Thanks again,

R.
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Old 05-07-2015, 19:16   #5
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Re: Using reflector panels to boost solar output.

I have noticed this effect on my boat. I am thinking about putting one of those windshield protectors next to my panels and see if there's an effect. Pnw doesn't get as much sun as the rest of you guys.
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Old 06-07-2015, 07:47   #6
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Re: Using reflector panels to boost solar output.

The real issue I see is will it get old constantly adjusting the panels and reflectors and eventually, you don't.

The biggest advantage of solar is you set it and forget it. Pretty much every other method of power generation requires some level of monitoring and interaction. Other than a quick hit with the hose when I wash the boat, ours just do their job.

With the width of a tri and the roof space of an RV, probably simpler and possibly even cheaper given todays prices to just put in two seperate system that are permanently mounted.
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Old 06-07-2015, 09:58   #7
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Re: Using reflector panels to boost solar output.

As Beth says, we do not have the amounts of sunshine in the Pacific Northwest that other locations have.

I read you Valhalla - sometimes the extra effort is just not worth the hassle. Yes, the trailer roof is easier to use - however, it is much harder to find a spot even on my 38 ft by 25 ft tri acreage that will not be in the way. I have no dodger at this time, but I am sure that I will mount solar panels on that when it is built.

Like a lot of things in life, compromise is needed on numerous fronts. Along with the lack of sunshine for much of the year, there is the inclination of the sun up here near the 49th parallel, so that has a serious impact in reducing the rays hitting the area presented by the panels.

The trailer remains stable in direction when parked, of course, and the boat is likewise if tied at a dock. Sometimes we can get shore power, sometimes not. If at anchor there will be movement and one can only hope for a somewhat general setting of the panels, but even that general setting, maybe adjusted only a couple of times a day, should have a major impact. One way of maintaining direction is using a stern anchor, which will help, but is not perfect either. And it all depends on the weather and sea conditions and a dozen other factors. It is hard to keep it simple but get maximum effectiveness for power generation.

The more years that pass, I think how lucky we are to be able to experiment with this sort of thing. How lucky we are in general....

Fair winds to all,

RR.
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