I just got my coach back from Gone Fishin' RV in Glendale, Ca, where the solar panels, controller, and battery monitor were installed. I thought I'd share some photos with the forum.
So far, I have two of the 136 watt panels, installed. If room permits I would like to add one more panel in series as the controller can handle three times the open circuit voltage of a single panel and just under three times the battery charge current a single panel could supply under ideal conditions.
The Tracer MPPT charge controller is mounted just below the inverter/charger in the equipment bay.
The Tracer remote readout panel and Tri-Metric battery monitor are mounted in the cabinet above the microwave, formerly housing only an AC receptacle and the microwave power plug/cord.
It appears to work well, but time will tell how well. So far it is only supplying float charge to the batteries.
Wow! ^.^d You beat me to it Tom... I have room for two of the 136w panels Max, three of the 68w panels, and four of the 90w panels by a different manufacture (Global solar). However, I'm still doing other projects and haven't progressed on that one except to lay them all out and make sure they'll fit. I had them all up on the roof lightly taped down when a big wind came up necessitating an emergency takedown! From now on, I'll just be doing one at a time... ::)
Don
Don, I'm not racing you, just showing you one way it can be done.
I would like to add more panels, but another 136w or 144w is too big and the 68w panels cost twice as much per watt, I need to take more measurements and see what can be done. In addition, I can now see how they do with just the two panels.Keep in mind you can connect any number and type of panels in series until the open circuit panel voltage reaches the controller's max. These panels are around 43 volts each, so three would still be under the controller's 150v max. Connecting panels in parallel is more persnickety, as the voltages need to match. This makes mixing and matching all the more tricky if you use parallel connections.
I have two "solid" 240-w (24vdc) panels and two of the 68-w Unisolar panels. I was kind of planning to install the Unisolars along the curved edge of the RV but also thinking about flat and use them as the "walkway" down along the solid panels.
Hopefully I'll end up with three 240-w solid panels and the two Unisolar by the time I'm through.
Did the built-in glue on the Unisolar panels seem to stick ok? Did you remove the chalky oxidation on the gel coat? And what did you use to do that (if you did). It is just now getting warm enough for me to start that project. I have to get a weekend with no other chores planned (or unplanned).
Craig
I told the installer to lightly sand the gelcoat and clean with paint thinner. I think it stuck well, but will find out when I set out at freeway speeds next week.
Good... I'll wait... :P
Craig
I would be concerned about heat damage to roof and solar panels. All panels I have seen are a very dark color. My coach is currently at Xtreme P&G where Rance just suggested removing the non-slip panel near the step. It is turning dark and heat will damage the fiberglass from the sun shining on a dark object. He also said to keep the mildew cleaned off because of the additional heating of the dark spots.
What is the opinion of you who know way more than I about solar power?
I'm hoping it's no worse than dark paint. For what it's worth, some of the Sun's energy is converted to electricity instead of heat.
Lots of heat generated by panels and that is why they suggest keeping them a few inches off roof. The summer sun is a real killer on heat. Mine tilt so not a problem.
JohnH
Tom, I haven't tested them under load yet, but when I had them laying on my roof in the midday sun I used my IR gun and found that they were about the same temperature as the light blue (the darkest part of it) graphics on our coach. I also used a thermometer attachment for my fluke meter under the panels and it was about the same or cooler than the top. Time will tell, but I came across this tidbit (which may not be relevant, but maybe so) http://maeresearch.ucsd.edu/kleissl/pubs/DominguezetalSE2011.pdf (http://maeresearch.ucsd.edu/kleissl/pubs/DominguezetalSE2011.pdf)
Anyway, the point is that these panels are not the same as the commonly available rigid panels used by most. They were made to be part of the roof and it isn't likely that it would be practical to cover your roof with these if the heat gain would cost you nearly as much in A/C energy use as the panels produce. Or so I hope :D
Don
Not an ideal load test, but around midday today, I turned off the Xantrex charger and turned on most of the lights. The 2x136W panels peaked at 19A and 14.1 volts to the batteries. Don't know if the four stage charge controller was the limiting factor or the sun. Either way, that's 268 Watts from panels nominally rated at 272 Watts. I'm not complaining.
Unfortunately, the installer didn't exactly follow my directions, and there is no room for a third panel. I'm looking into other similar panels, and one or two of the Global Solar Powerflex 90W 12V panels would fit. They could be connected in series with the existing panels without exceeding the controller max PV voltage, and should give me the full 30A the controller is capable of sending to the batteries.
Tom,
That sounds pretty good! When you were load testing the panels did you by any chance use and IR Thermometer to check the temperature on the surface of the panels? If so, please share what you found...
Don
Not this time. I'll see if I can in the next day of two.
I suspect they don't run any hotter under load than unloaded. I think any heat gain is simply from the sun beating down on a dark surface. What gets hot would be the load itself, taking that energy away from the panel.
Same conditions at yesterday, clear sunny sky, 90 degrees air temperature. My neighbors black car is 158 degrees, the solar panels a cool 131 degrees.
By the way, I ordered a pair of 90 watt Global Solar Powerflex2 panels from a dealer on eBay. Like the Uni-Solar panels, they are flexible and self-stick to the roof, and also like the Uni-Solar panels, they claim to generate good power at lower angles of the Sun. They can be added to the series circuit with the existing panels and easily fit in the space available. This all bring my total solar power capacity to 452 Watts, which translates to 31.4 Amps at 14.4 Volts. This is just above what the 30A charge controller can put out, so I have a small margin for when the sun is lower in the sky. Since I don't have plans to go totally generator free, this should meet my needs.
Subtract 4A from that peak amperage. My charge controller was fibbing for the first week. That makes for 211 Watts from 272 Watts of panel rating.
I'd finish up this project with 3" or 4" EternaBond (ADCO) mastic tape
(I like the white 4" X 50" roll) with my fiberglass roof. You can get it from ebay.. & get the EternaBond 2" w/half round (2 lbs.) roller to insure it is stuck it down properly.
Get it right the first time because it does not like to come up. pc
I looked at the roof today (from a ladder), and the Uni-Solar panels look like they plan on staying stuck down for the long haul. No sign of lifting anywhere. This is after about 1400 miles of highway driving in a variety of winds.