suggestion for a solar controller

[captsteve2002]

I have just received two 50w solar panels that I bid for on e-bay and am very happy with that purchase. My question is what controllers have people found to work well, do the job, and are dependable. I tend to lean towards a controller that shows the battery voltage, as I don't want to put in a separate guage, something like the Solar 30 controller.

I am thinking of mounting the panels on a rack over the cab of my truck, rather than on the trailer. My thinking is that I can park the truck in the sun and have the trailer in the shade if I have a tree nearby, and stay cooler.

I plan to keep the panel leads as short as possible to the batteries, and to use #8 wire.

Any other suggestions are appreicated

[Thomas G.]

I've been happy with the Morningstar brand and have found them cheaply at Solar Blvd.

[Steve Hammel]

Your 2 panels total 100 watts so all you need is a 10 amp controller, anything larger is a waste. I'd recommend going with an MPPT controller. MPPT is a bit more expensive but they are 20% to 35% more efficient, almost like having another panel.

[Thomas G.]

Originally Posted by Steve Hammel

Your 2 panels total 100 watts so all you need is a 10 amp controller, anything larger is a waste. I'd recommend going with an MPPT controller. MPPT is a bit more expensive but they are 20% to 35% more efficient, almost like having another panel.

When I was looking at this before, I came to the conclusion that for my camper, it wasn't worth the extra money for the MPPT controller, as their big efficiency gain is in cold weather.

You typically get a 20 to 45% power gain in winter and 10-15% in summer. Actual gain can vary widely depending weather, temperature, battery state of charge, and other factors.

Maximum Power Point Tracking Charge Controller

15 amp MPPT - $230 / 20 amp PWM - $76
http://www.solarblvd.com/Charge-Cont...duct_info.html

http://www.solarblvd.com/Charge-Cont...duct_info.html

[Steve Hammel]

I'd go the inexpensive Chinese route;

MPPT15 10A Solar Power Charge Regulator Converter Controller Inventer 12V 24V LS | eBay

[Thomas G.]

Originally Posted by Steve Hammel

I'd go the inexpensive Chinese route;

MPPT15 10A Solar Power Charge Regulator Converter Controller Inventer 12V 24V LS | eBay

Wasn't there a post here where someone took one of these apart and demonstrated that it wasn't really an MPPT? Maybe this?

http://www.youtube.com/watch?v=UvDr0hZKbnk

[Steve Hammel]

I don't know. I just did a quick e-bay search.

[Thomas G.]

Originally Posted by Steve Hammel

I don't know. I just did a quick e-bay search.

I'd love to see a true MPPT at that price point.

[Steve Hammel]

Originally Posted by Thomas G.

I'd love to see a true MPPT at that price point.

Some day Tom, Some day. It's getting better every day.
Hey this is "LotsGood" it has to be good LOL!

[Ron F]

I've been happy with my Morningstar controller. It's a stepped "smart" charging controller. Mine came with a battery temperature sensor and remote meter, which makes it easy to see what's going on with the charging system.

You can save some $ on your wiring if you go with the MPPT. Wire your panels in series and use 12 gauge wire from the truck to the controller. Place your controller as close as possible to the battery (but not in the battery box), and use #6 wire between the controller and battery. If you go with PWM, you'll probably need the #8 wire from the truck.

BTW, why not just make the panels portable. It seems that it would be easier to position portable panels rather than moving the truck.

Ron

[Thomas G.]

Originally Posted by Steve Hammel

Some day Tom, Some day. It's getting better every day.
Hey this is "LotsGood" it has to be good LOL!

I'm sure that as prices come down, MPPT will be the only game in town. Solar panels have already come down from over $5 a watt to $1 or less. I'm no EE, but I've got to believe that the parts inside a MPPT controller don't justify the current price.

Originally Posted by Ron F

.............
BTW, why not just make the panels portable. It seems that it would be easier to position portable panels rather than moving the truck.
Ron

I agree. With two identical panels, you could just connect them with a piano hinge and make them fold up into a case.

[captsteve2002]

I don't want the panels loose, then I have to find a place for them to ride when traveling. Mounted on a rack over the cab reduces the need to find storage for them.

As far as the type of controlller I order, Since I try not to camp in cold places I'm not to worried about getting a lot more charging from the panels. If I ever see more than 5 amps coming from the panels I will be very happy, I expect closer to 4 amps.

Thanks everone for your inputs

[Chris Jones]

Originally Posted by Steve Hammel

Some day Tom, Some day. It's getting better every day.
Hey this is "LotsGood" it has to be good LOL!

It has "thunder protection" too.

[multi-task]

I can speak from experience that an MPPT controller will likely not give you the gains you expect. At best in perfect conditions my controller simply allowed my 75W panel to run at it's Standard Test Condition rating. One could argue that's the benefit, and I would tend to agree, but if you expect any cheap panel with an STC rating of 5 amps to give you 6 it won't happen because most panels simply won't ever hit their STC rating to start with.

The only panels which might allow for this will be those with a -0%/+(any number)% tolerance and I've yet to see any of these lower priced panels have the correct numbers to make it happen (most don't even have a complete spec sheet). I'd also argue that if your panel has a tolerance of, let's say -5%/+5% you're more likely to run on the negative side than positive, it's how manufacturers can get away with posting larger numbers.

I personally love solar, and I laugh at people guzzling gasoline in their generators, but to be fair to the technology, if 'cheap' is important to you I would keep expectations down and not expect to get the gains advertised on websites because they really are talking about perfect test conditions with higher quality hardware. All that said, most solar setups will do what most of us need so long as you've spec'd your array/wire/controllers/batteries correctly.

[Steve Hammel]

Obviously, regardless of the controller, I would rarely expect a solar setup to produce its maximum rated capacity and never above its capacity. There will always be something that's not "optimum". MPPT is just 10%-35% more efficient than PWM in distributing the power received from the panel.

[rabbit]

I have a Morningstar Sunkeeper 6amp on the junction box of 80 watt panel. I hope Washington Crossing, PA doesn't mean fresh from Kowloon!

jack