Question on wiring an additional 200 watts into system

[Two4leisure]

I currently have 200 watts of solar mounted on the rear of my Trailmanor 2720. I would like to add an additional 200 watts, and would like them to be portable. I am wondering could I add additional branch connectors close to where the current wires connect to the charge controler and tap in there? This way when I am hanging aroung the campsite I can deploy the additional panels in a more optimum postion to take advantage of the available sunlight. Thanks for any and all replies. I finally installed a 1500 watt inverter with remote on/off. I used 14/3 wire from the inverter to an oulet inside the trailer. Using it for a small Mr. Coffee and a low wattage toaster. Works well. Heading to Death Valley tomorrow (Thursday) just in time for the cloudy days. May have to perk that coffee now.

[tentcamper]

My portable solar panels. I used my 25' 30 amp extra # 10 extension cord and a short 10' 30 amp cord which gives me 35' reach from my controller to the panels. What I did was cut a clearance 10' 30 amp cord in half, it only cost me about $15. On the cut ends I crimped on #10 CB connectors and put # 10 CB connectors on the controller the panels. I plug the cut 30 amp cables with the factory ends into the 25' 30 amp extension cord on both ends. For short 10' or less I just plug together the two factory ends of the 10' cord and leave the 25' cord in the bumper.

Very low resistance #10 connections. get two different uses for that 25 extension cord. I always have the 25' extension cord in the camper's bumper. I never setup solar if I'm in an electric site.

I keep the modified 10' cord with my panels. If we have no plans of camping at an non-electric site the panels and that cord stay at home.

If your battery is in the rear? You could play around with a controller on the panels and using the #10 battery and ground wire on your 7 pin trailer/TV connector. You would need to make an adapter for the 7 pin connector. These wires would charge your battery. Lots of ways ways of extending your reach with a 10' 30 amp extension cord. By also using your extra 25' 30 amp cord it would give you a reach 35' in front of the camper.

[Two4leisure]

Hi Tentcamper. Thanks for taking the time to reply. So basically I have the same setup as you. The only difference being I never (or so far haven't) used hookups. I always use my panels. So I guess my question still is can I tap into my current hook up with the 2 additional panels and disconnect , say as when leaving the campsite and leave the other two panels mounted on the roof.

[tentcamper]

depending on the controller you could have both connected at the same time. Or just use a quick disconnect between the the panels and controller and plug in which panel array you want to use. If you want to have both connected at the same time I would make a quick disconnect for the portable panels.

I use the CB #10 connector. I found them on amazon

[Two4leisure]

Great. Thank you.

[rickst29]

Gets a bit complicated. I'll explain as if we're using two different kinds of panels on the roof:


If they're identical Volts AND Identical Amps, then the combination has twice the power (either way).
If they're different and wired in Series: You get the *LOWEST* AMPS, times the Voltages added together.
If they're different and wired in Parallel: You get the *LOWEST* Volts, times the Amps added together.


What you will have, when running two "groups" in parellel, is like the situation with tow different parallel panels on the roof: The *LOWEST* voltage of the two "strings", times the combined amps (of each "string" added together). If the on-ground "Portable" or Rooftoopp configurations contain different kinds of panels within each string - then calculate the output of the end string first, then combine the possibly-reduced power in parallel.

It's actually easy - but a bit unexpected. If you reply with the Rooftop panel config and your "portable" config, I'll advise the best way to connect them, along with the power which will be lost by combining the diffent panel types.

BTW, I own different panel types, 3 panels connected in Series. (All on the roof.) Possibly quite similar to one panel above and a fold-out pair on the ground.

[BrucePerens]

Because of the bypass diodes, series circuits are more complicated than you might expect. I don't believe that the behavior will be as deterministic as Rick believes. A higher amp panel might cause the bypass diode to conduct in a lower amp one if the voltage is also high enough. You might be able to reap the overall power of the whole combination, or you might lose the power of some panels.

Another alternative, and the one I recommend, is to put a small charge controller on your portable system and just parallel it to your 12 volt circuit. That way you will get the full power from both the roof-mounted system and your portable. That will also make it versatile enough to work in other applications not involving the trailer.

[Two4leisure]

Thank you both for your replies. I have 4 identical 100 watt panels. I used couplers (branch connectors?) to connect each set of 2 panels. These left me with 2 positive and 2 negative cables from the 4 panels. I then used a pair of couplers to connect those 4 cables to the charge controller. This hook up seemed to make sense to me at the time. What I noticed was when I plugged in the second set of panels my solar current produced dropped. I liked the idea of making a second separate system with another charge controller. I would like to maintain control and monitoring over the whole system with my Trimetric 2030. The 200 watts has been working well so far. I mainly added the additional 200 watts I can get a little more power on the slightly overcast days and when parked in shady areas be able to aim the panels to collect more solar energy. Thanks again for taking time to reply. Heading to Joshua Tree in 1.5 weeks. Should have no issues with sun there.

[rickst29]

With 4 identical panels, you should be in GREAT shape for running a 2x2 configuration. (Series pairs, connected together in Parallel at ONE Solar Controller). I would use a single BIG controller, rather than two small ones, for the following reason:

"Parallel Controllers" will have one controller falling into "premature" FLOAT mode - because, when it "sniffs" the current battery Voltage to choose an operating mode, it will be extremely likely to see a Voltage above the Float Threshold: This is because the other Controller is actively running, and pushing the "Battery Voltage" a lot higher than the Voltage of the naked batteries. Conversely, even if the first controller then sees the second controller creating only "float" Voltage- they might both fall into float mode too soon.

Some manufacturers (such as Morningstar) feel that the unused power "lost opportunity" from the too-early Float Mode "errors" don't amount to much. They do not offer any kind of master-controller/slave controller software and interconnect products. But other manufacturers (Victron, my own now-defunct Rogue Company, and several others) DO have wiring and software (and even separate devices) to create such "relationships", running multiple controllers with a single master-device momentarily shutting the others off to obtain a valid "Battery Voltage" measurement.
- - - - -
Anway: My way would create the appearance of two panels at the Controller - each with the same "current" as the current individual panels, but each running at 2x the individual panel Voltage. V(mp) for each "normal" 12V panels will be 17-19V, but V(disconnected) might run roughly 21-23 Volts. This gets doubled (each set is wired in Series). Then at the Controller, the Current at V(mp) gets doubled by connecting two ssets in parallel. (from 5.6-5.9A, up to 10.2-11.8A) If your controller isn't rated > 50V for panel input, it might be protecting itself from "excess Input Voltage". Your other likely source of trouble is internal to one of the Panels: "Stressed" by parallel connections, the second panel within each pair must handle up to 46V differential at it's output (versus common Ground), and might be leaking power (backwards, into strings which should be isolated via diodes.) (That would constitute a "bad panel" - one which can' even be mounted in parallel with a single identical, additional panel.) I still don't know what particular kind of Controller you're using, and what specific panels you have - but they might need to go all-parallel. For the Controller, that would be 19-23A at 17-19V. If the Controller will throttle at 20A and can't handle nearly 50V, then you need a better controller. If you don't need a better controller, then one of the panels probably contains a failed diode.

[Two4leisure]

I have 4 Giaride 100 watt flexible panels. Each pair are wired in parallel 12 volts approximately 10 to 11 amps. I am using a Bogart Engineering SC-2030 charge controller.
For 12 or 24 volts systems
Up to 30 amps maximum current
Open circuit voltage limit from panels must not exceed 55 volts
I have it wired like the diagram as shown in the Renogy 400 watt starter kit wiring diagram. A picture is worth a thousand words. I would like to think it is not a panel problem. I will try connecting both sets of panels to the charge controller again and see if I get the readings that I should. I will also see if there are any settings that need to be changed within the controller. But I don't think that is the case. Thanks for your reply.

[rickst29]

Yiour panel specifications are:
Working current [Imp]: 5.56A
* Short circuit current [Isc]: 5.8A
* Open circuit voltage [Voc]: 20V
* Maximum system voltage: 1000V.

This implies V(mp) of about 18v ( 100 Watts / 5.56 Amps = 17.986 Volts)


Your PWM controller quotes "30A" maximum. If all the panels are good, and the output current goes DOWN, then it's not accepting even 23.2A on the input side. (With wiring losses, your I(sc) is going to be less than that figure, and the controller still goes into self-protect.) You have basically proven each parallel "pair" to be good by itself, but when you build up to 4*1 (all parallel) the controller goes to heck, switching into a current-limited "protection mode" of operation and putting out less than the output of just two panels on the input side - far earlier than specifications say it should. Grrrr. :new_cussi

From your posts and these conclusions, the problem seems to be a broken controller (or perhaps a "working as designed" one sold with fraudulent specifications).
- - - new edit, 5/15/2019 - - -
I'd upgrade the controller, into a "really great" MPPT. This one: https://www.ebay.com/itm/EPEVER-Trancer-BN-10A-20A-30A-40A-MPPT-Solar-Charge-Controller-or-MT-50-150V/352276005682. "3215BN with MT-50 monitor". It supports 150V input panel Voltage, and you could wire your panels all-in-series. VOC would be 80V, far under the "Tracer" 150-Volt limit. Current would be limited by the "weakest" panel, at about 5.56A under current conditions - you'd have far less wiring loss, on the path from the Controller through the Panels and back again.

If you buy that particular Ebay offer, you need the temp monitor. I've got an extra which I can send to you, N/C.