Finally had some decent weather to allow completion of my Solar Installation today. I had no solar at all, so decided it was something I really needed to do. With space on the roof limited, I could only get a single 200W panel up there, so decided to supplement with a portable folding 100W. I have two leisure batteries and with funds limited decided on a fairly simple set up. All cables and mechanical fixings are hidden, with both the roof panel and folding panel feeding the MPPT controller. The twin batteries feed an inverter for light duty use. I was not comfortable with only bonding the roof panel, so used mechanical fixing to supplement. To enable quick and simple connection of the folding panel, I fitted a Whale unit low on the side skirt, modified to house MC4 connectors wired to the MPPT through a pair of MC4 T connectors. The twin solar input is switched/fused as well as the output to the batteries. The batteries have an isolation switch to the inverter. Im very pleased with the cosmetics and operation of the solar, all tested and functioning well. I know 300W total is not a lot, but considering I had nothing before, its a major step forward. While working up top, gave the roof a good clean too.
Finished Solar Instalation
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- Feb 22, 2011
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Neat job 
MisterB
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I like the idea of the entry point for the folding panel, very neat and practical ( though some will ask what if the sun isn't on that side ! )
I will definitely be copying your idea though !
I will definitely be copying your idea though !
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Certainly strongly held down with all those bolts ! Do the bolts only come through into a cupboard area or are any in view from the habitation area ?
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The folding panel has a twin cable about 5m long, so it can be positioned anywhere 360 degrees around van to face the sun.
Photo 4 shows the row of screw heads with nylon caps and large washers on the ceiling of the cupboard. On the other side the screws cant be seen at all, hidden inside the overhead lockers. I chose positions carefully to avoid any screws seen on living space ceiling. Screws are all stainless, and where in contact with alluminium, have nylon washers and anti-sieze compound to avoid galvanic corrosion
- Dec 31, 2010
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You do know that wiring them in parallel like you have, when the 100w one is connected it will pull the 200w down to 100w so you haven't gained anything by adding the portable panel.
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Im a mechanical engineer, so not very educated in electrics. However, before begining the instalation I did consult people who were well qualified. My folding panel was fitted with a PWM controller and I had intended to wire it direct to the batteries, independant of the roof mounted panel. I was told that it would be much better to eliminate the PWM controller and instead feed the power directly into the MPPT controller along with the roof panel. Several people in the trade gave the same advice, so if that is wrong I have been misled?
MPPT are more efficient at getting Gogo juice in your batteries, but as Ditcha says, in this case, you are negating the value of the moveable panel as you will drag your output down with a parallel connection into the same MPPT.
I would use the PWM controller and connect that to the battery for the 100w panel…
Have you got a picture of sticker on the back of the panels so that we can see the open circuit voltage and other specs for both the flat mounted and 100w panel?
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- Dec 31, 2010
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Best to have a separate controller to get the best out of unmatched panels, you could do simple tests by disconnecting one then the other to see what you are actually losing our gaining, I would have thought you would have been better keeping the PWM controller you will most probably gain more.
Please excuse my confusion, as I mentioned, I am no electrician, but is the message that if I am parked on a site with just the 200w panel on the roof in use, then I plug in the 100w panel, it will be of no use at all, or that it will contribute something, but not what I had expected?
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It will contribute something but not a lot best to do your own tests, but I would say it would contribute a lot more with the portable panel having its own controller even if it's the original PWM controller.
Tombola
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I thought in parallel was fine, and in series would be a problem.
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Different Wattage Solar Panels Wired in Series
If mixed wattage solar panels are connected in series, the total voltages are added. But the amps are reduced to the current of the lowest panel.The Advantage of Wiring in Parallel
When you connect solar panels in parallel, the amps (current) increase but the voltage doesn’t. This usually suits the greater battering charging needs of off-grid solar users.MisterB
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I am watching this discussion as I intend found something similar.
Am I correct in thinking then that if adding an additional folding panel, it's better to wire it direct to the leisure battery via it's own pwm so it basically works as two separate solar systems?
Am I correct in thinking then that if adding an additional folding panel, it's better to wire it direct to the leisure battery via it's own pwm so it basically works as two separate solar systems?
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Again, im no expert, but having just read some instructions regarding connecting the array in series or parallel, I have determined the following, using panels of different values. Panel A which is 200w, 10.8A and 19.5v. Panel B which is 100w, 5.7A and 17.5v. Using the laws of voltages and amps in series and parallel, I see that in parallel we add amps together but voltage is the lowest, so we have 16.5 amps x 17.5v = 288.75W. Now if we use series, we add voltages together and take lowest amps, so 37v x 5.7a = 210.9W. This results in parallel being the best option. Bear with me, am I wrong?
Tombola
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right, but youll soon know , connect them up and get the app or meter out.
Im a novice, but I have been told not to do this, as the two controllers are fighting each other. Ive also seen this question asked on another forum with the same answer, do not use two controllers.
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The watts add up in parallel but the voltage will be taken from the lowest panel so this will affect the greater of the 2 that's if the 2 panels already have the same voltage specs when you start so it is the best way to do it with different panels but by no means the best.
Simple test would be to see how many amps on the mppt with one connected then with the 2.
If it was me I would have separate controllers.
- Dec 31, 2010
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I have a similar setup to you 480w on the roof through a 100/30 MPPT and a 160w portable panel that runs through a separate 100/15 MPPT you can have as many controllers as you want in parallel they are simply just a charging source for your battery as long as they are configured the same.
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- Dec 31, 2010
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This explains things a bit better
www.explorist.life
Using Mismatched Solar Panel Sizes in the Same Array
This blog post will teach you how using mixed and mismatched sizes of solar panels in the same array will affect the output of the entire array.
www.explorist.life
Tombola
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Thanks guys, always good to see a healthy discussion. I realise that there are also other variables, cable lengths, quality of panels/controllers etc. as well as losses/inefficiency. At the end of the day Im pretty content with my set up, yeah things can always be improved.
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It's a nice neat setup you have done and if you need more from your setup you can easily add another controller but what you have could well satisfy your power needs
Is it all going into one battery as in your picture..? Another battery would be a good idea….
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Tombola
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says 2 leisure batteries in the post tho.Is it all going into one battery as in your picture..? Another battery would be a good idea….
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Could do with 3 then
In my original post, two matched Leisure Batteries. Plus of course the vehicle battery coupled to a Battery Master from VanBitzIs it all going into one battery as in your picture..? Another battery would be a good idea….
Tombola
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be intereseted to see your numbers when we get some full sun
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Looking at your photos again, just wondering why you have a fuse in the wiring from the panels where the fuse is situated just before the controller, what is it protecting ?
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