I'm not sure that it is a good idea to use 2-separate controllers on one battery bank.
The controller reads the state of charge from the battery to determine the controller's output. If you use 2-controllers on the same battery, each controller's output may cause confusion to the other controller.
I'm not sure about this and you may want to contact the manufacturer of those particular controllers. I would simply run one controller for both panels that will handle 10 or 20 amps. I have a 20A controller but you can probably get away with a 10A. You just don't want to exceed the controllers maximum rating. I would imagine that each of your panels comes with a 10A controller (I may be wrong).......
Hi Wayne, I contacted the main dealer as printed on the panel manual I posted above and he replied with the following, regarding connecting multiple controllers to the same connection at the battery (parallel). Here is his reply:
There is absolutely no problem whatsoever using controllers in Parallel. In fact, it is standard design feature in most decent quality controllers built today. No confusion between them. You can look at the Morningstar web site and you will find most of their controllers can be used in parallel also. http://www.morningstarcorp.com/en/home. It is an easy way to add solar capacity and upgrade without having to replace your old controller with a larger one. The only precaution is that the finish voltages should be set the same, but this is factory set. Unless you use controllers from two different manufacturers, it should not concern you.
Jim Mannett - CEA Solar
Hi Wayne, I contacted the main dealer as printed on the panel manual I posted above and he replied with the following, regarding connecting multiple controllers to the same connection at the battery (parallel). Here is his reply:
There is absolutely no problem whatsoever using controllers in Parallel. In fact, it is standard design feature in most decent quality controllers built today. No confusion between them. You can look at the Morningstar web site and you will find most of their controllers can be used in parallel also. http://www.morningstarcorp.com/en/home. It is an easy way to add solar capacity and upgrade without having to replace your old controller with a larger one. The only precaution is that the finish voltages should be set the same, but this is factory set. Unless you use controllers from two different manufacturers, it should not concern you.
Jim Mannett - CEA Solar
First let me preface this post by saying this is not the cheapest solar solution around BUT there are real advantages to using portable, good quality, high power solar panels. For me the portable solution was the best option. Aside from using my TM for RVing/camping I also depend on my TM for emergency housing if a disaster strikes (like earthquakes here in So Cal) or the economy tanks, my TM is my “Life Boat”, it could be my home someday. So this investment into a truly powerful portable solar solution is intended to be a serious, quality and ample producing system with more than enough power to live off the grid if needed with the help of a generator on cloudy days.
So why portable solar panels?
You can camp in the shade and move them into the sun
No holes in the RV roof, easily stowed in TM curbside dinette
Useable on any 12 volt battery
As I mentioned in my initial post that opened this thread, that after reading through the TM forum and looking around online, I decided to invest in two 80 watt portable CEA Solar Panels (see manual attached). Since then I have finished installing the system and did some real-world testing. This post is to share my results, impressions and some images of this system.
I will try to keep this summary short without mind numbing calculations and numbers. I have described my overall situation in more detail in my initial post and have attached images to this post showing key aspects of this solar power system upgrade.
For the “Do solar panels provide enough power?” question, my MAIN concern, see below:
Each panel is generating about 5 Amps in full sun of continuous power. With two panels that’s 10 Amps. If you use less than 10 Amps any surplus power is used to charge the batteries. This is very imporant, there is no wasted power, you either use it or it is stored (unless batteries are full). Also, for charging, the panel controllers use a 3-stage chargers AND the controllers are desiged to be connected in multiples, like I am doing with using two 80 watt panels. In addition, up to 4 - 80 watt panels can be used for a total of 320 watts!
Actually from what I have seen in my power use, a single panel that’s providing 5 Amps during daytime hours is probably enough for most dry campers to keep their batteries charged IF they typically conserve power. With two panels you just don't have to worry much at all unless you have cloudy days or use LOTS of power.
How much power do TM appliances use? My actual measured load (Amps) of some TM items:
Furnace 3.5 Amps
Water Pump 5 - 8 Amps
Lights (variable 0.1 Amps for LED bulb to 1.5 Amps fluorescents)
Laptop computer 4 to 9 Amps (Normal to 3D apps)
32” LCD TV 6.5 Amps
If you read through the TM Solar Panel forum you will see most people who have 160 watt solar power systems and above can easily dry camp, run the furnace as needed and use lights, and even run some high load devices occasionally and never run down their batteries. From my testing I agree with this completely. As long as you have SUN you have power. Obviously a little power management is needed to account for night time and cloudy days. Solar power is real power and it’s great to finally see a quality portable solar panel available for us RVers.
Bottom-line is I am very pleased with these CEA Solar Portable Solar Panels. They work as advertised and “FIT” the TM very well, storing perfectly in the curb side dinette seat storage area (see image). For more information on these panels see the link above and the owner’s manual attached.
One item of note, they weigh 35-lbs per panel. That adds some weight to your TM but it’s very important so they don’t blow over in the wind, it also reflects the heavy duty nature of the construction of these panels.
Overall very pleased with this upgrade for my 2619
For what it's worth........I used to have my panels set up as "portable" with my 2720. When we broke camp, I just laid the solar panels on the forward bunk (making sure that they were between the lights). They road there just fine and a lot less hassle.
BTW, we camped for 4 days last weekend and it was cloudy about 80% of the time. My batteries were still @12.5V (before Sunrise, the day of departure) when we left. It was ~40* at night and the furnace ran a lot. They were at 13.8V with the panels in partial Sun.
looks great a little more power then we use. No tv but do have a laptop and netbook. With our power needs and only a 400 watt inverter I'm about have what your set is. Quite agree on the TM making temp housing, used the pop-up during 04-05 hurricane season cause it was cooler then the house without AC
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Axis 24.1 E 450 chassis, 6 spd tranny. GVWR 14500# GVCWR 22000 # GW(scales) 12400 #
[SIGPIC][/SIGPIC]
mods: 2- 100 watt solar panels, on roof, 300 watts portable
“They who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.” Benjamin Franklin
... An MPPT controller is somewhat like a transformer in that it takes total power into (V*A)the controller and coverts it to the charging voltage (approx 14V) at the same total power ( V*A) out which results in a higher output current than the input current...
Thanks for the explanation. Just to make sure I understand:
So basically an MPPT controller does the same job as a PWM controller but ADDS a transformer function to convert 17v into "battery friendly" 14v maintaining the same Current flow allowing it to USE this 3v PWM controllers normally cannot pass to the battery.
On an 80w panel at 17v = (4.7 Amps), this step down to 80w at 14v = (5.7 Amps) should add 1.0 Amp to the battery more than a PWM controller would. Is this accurate? How efficient are these MPPT controllers?
It seems in a large solar panel array this 3v gain per panel makes sense, but for smaller systems, until prices come down, it may not.
Thanks for the explanation. Just to make sure I understand:
So basically an MPPT controller does the same job as a PWM controller but ADDS a transformer function to convert 17v into "battery friendly" 14v maintaining the same Current flow allowing it to USE this 3v PWM controllers normally cannot pass to the battery.
On an 80w panel at 17v = (4.7 Amps), this step down to 80w at 14v = (5.7 Amps) should add 1.0 Amp to the battery more than a PWM controller would. Is this accurate? How efficient are these MPPT controllers?
It seems in a large solar panel array this 3v gain per panel makes sense, but for smaller systems, until prices come down, it may not.
Muddog and I have the exact same solar panels only he has 8G wire and I have 10G, he has the MPPT controller and I have the PWM controller. We were camped together at Pt Mugu this summer and we did a test. (both arrays were flat on the roof of our TMs in full sun). I put my ammeter on both controller outputs. I was getting 8.6A and he was getting 9.5A.
We ran the test several times during the day and the MPPT controller was putting out consistantly ~10% more amps than my PWM controller.
IMO, the difference in $ might be better spent on higher wattage panels than the MPPT controller. On a large system, the MPPT controller would definitely be the way to go.
I just wanted to say THANKS to everyone who posted to this thread. I hope the posts continue regarding all things related to Portable Solar Panels. All comments are greatly appreciated and have been extremely helpful and assisted in my successful completion of this project.
I think anyone who thinks they could benefit from solar power on their TM should definitely explore the options available to them because solar power works extremely well, it's NOT a fad or luxury. A small solar panel system adds a great new capability to the TM, self-generated REAL power for FREE.
It seems solar power has become mainstream and is more affordable and more efficient than it used to be IMHO.
All the real-world examples you will read throughout the solar power forum really tell the story of the benefits of investing in solar power for your RV.
Just today I had my panels hooked up, just monitoring them and getting used my power use versus panel power charging. At the same time I was installing a higher power 12v DC power outlet next to my inverter, using that same power source for 30 amp DC service.
I was using my inverter for AC power, I found it's much more efficient than expected. I was listening to online radio using my laptop, I had the Fantastic Fan on and needed to do some soldering. I didn't even consider plugging the RV into AC power because there was plenty of power being generated by the solar panels. I just didn't worry about running down my batteries.
Solar power provides a whole new way of thinking and opens up a new world of dry camping scenarios that use to be much less doable or desirable. That's a pretty nice feeling
Bob - Don't forget to check out whether you are eligible for a tax credit on those panels. I forget the IRS schedule, but I when I checked into it briefly a few years ago, panels on RVs was generally considered a qualifying expense for the credit.
Dave
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2000 2720SL & 2007 3124KB
2005 Toyota Sequoia Twin Battle Born 12v 100Ah LiFePO4 (BBGC2) batteries, 300W solar on rear shell, Link 10, Lift kit, Maxxis 8008 225 75/R15 E tires
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