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Old 17-04-2014, 16:25   #1
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Help On Understanding solar panels

Could someone help me understand why this 40 watt set-up on eBay is not a good deal???

40W 12V Mono Flexible Solar Panel 10A Regulator 5M Cable Complete Kit | eBay

Thanks
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Old 17-04-2014, 19:45   #2
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Re: Help On Understanding solar panels

It is an ok deal, but not fantastic. 40W solar panels can be found on eBay for about $75. A name brand Morningstar PWM controller can be found for about $25. 5 M of wire is about $5.

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Old 17-04-2014, 19:50   #3
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Re: Help On Understanding solar panels

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Originally Posted by Snore View Post
Could someone help me understand why this 40 watt set-up on eBay is not a good deal???

40W 12V Mono Flexible Solar Panel 10A Regulator 5M Cable Complete Kit | eBay

Thanks
Here is what's wrong with it.

1. It's junk.
2. It's too small. I have cell phone chargers that pull more power than that panel produces.
3. It's too expensive.
4. Because of 1 and 2 above, it's not worth even bothering to install it.

There is a certain minimum size below which it's not even worth the bother of running the cabling and drilling holes, etc.

Most panels these days are in the 250 - 300+ watt range, and people are installing 2 or 3 of them. There are plenty of threads around here where people are discussing good quality panels and controllers. Outback, Midnight Solar, and many others make good quality MPPT controllers. The brand of panel is usually not as important on a shore installation, but on a boat you want good quality panels that can hold up and are high efficiency to maximize the limited space onboard.

There are plenty of threads discussing the different brands of solar panels and controllers. That one on Ebay is similar to a small solar setup I rigged up to keep my truck batteries charged while it sits. I pop it up on the dash while it's parked, cost me $40 to throw it together.
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Old 17-04-2014, 20:17   #4
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Re: Help On Understanding solar panels

DJ thanks. I will do some more shopping.


FWIW, +/- 40 watts meets my need for 3-7 day cruises. Investing in 500 watts would be a poor allocation of my resources. Also these are semi-flexible, so I can put them on top of the dodger and will not need to make another investment in a mounting system.

Thanks for the inputs.
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Old 17-04-2014, 20:49   #5
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Re: Help On Understanding solar panels

Quote:
Originally Posted by Snore View Post
FWIW, +/- 40 watts meets my need for 3-7 day cruises. Investing in 500 watts would be a poor allocation of my resources. Also these are semi-flexible, so I can put them on top of the dodger and will not need to make another investment in a mounting system.
Not so complicated:

Installing A Small Marine Solar System Photo Gallery by Compass Marine at pbase.com
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Old 17-04-2014, 21:13   #6
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Re: Help On Understanding solar panels

Well, if you're positive you want 40w flexible solar panels, you can get them from Eco-worthy.com for $72. If you still want to go with a 10A PWM controller, they sell one for $18.99 with free shipping. They sell a very nice 20A MPPT controller that will get max. power from your panels, for $102, a real bargain.

I wasn't exaggerating when I said my cell phone charger draws more power than a 40w panel. At those prices, you could get 2 40w panels for $144 and the $19 controller for a total of 80w for $163 plus cabling, or get the MPPT controller with higher output and a digital display that tells you solar voltage and current, MPPT output voltage and current for $83 more. I've installed 3 of them so far, very nice units.
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