Solar Panel Wiring Question

[ClydesdaleKevin]

So I picked up the panels today, and they are of amazing quality!  Even more nicely made than the single Kyocera I have on the roof right now.

Question about the wiring and grounding though.

On the back of each panel is a junction box with 2 long leads coming out, one positive and one negative.  I know how to wire them in parellel so that isn't an issue.  But they have male/female plugs on the end, probably to make them plug and play with complete systems.  Do I really have to purchase the wiring harness that plugs into them, which is expensive in the lengths I would need, or can I just cut off the plug ends and use 10-3 wiring, and just splice them into it...maybe with solder and heat shrink tubing is what I was thinking. 

Also, I understand that they have to be grounded to the frame of the RV...and the suggested grounding cable from Canadian Solar is huge, very expensive for wire gauge that size, would be very hard to run down from the roof since its as thick as battery cable and I doubt I could feed it down the roof vent, and in my opinion is overkill.  They say its for lightning strike protection, which on an RV, which is grounded by its tires, I don't think I need ground cable that big.

Why can't I just run 10-3 wire from each panel to a waterproof junction/fuse box on the roof, using the third 10 gauge wire as the ground on each panel, then bring the single 10-3 cable down through the roof vent and to the charge controller, hook the positive and negative leads to the controller, and the third wire to the RV frame?

This makes sense to me.  Is 10 gauge a sufficient size for a ground?  Seems like it would be to me in an RV application, but I'm no expert, so that is why I'm asking.  Also, is 10 gauge going to be sufficient to minimize voltage drop?

I can get heavy jacketed 10-3 wire affordably by the foot, and even cheaper (way cheaper) if I get a 10 gauge extention cord like the heavy duty ones I use in my shop for my power tools, and just cut it to length and splice it in, etc. 

Finally, does it make a difference if I use stranded or solid wire?

Thanks!

Kev

[gadgetman]

Do not use solid wire, #10 is large enough for the positive leads from each panel.

Yes buy the mc4 connectors so you don't cut the panel leads, usually void the warranty. Just solder on the mc4 plugs to your own wire.

You do not have to have a separate ground to the panel frames our rvs and not grounded to ground anyway unless plugged in. Not sure I would want my panels acting like a lightening rod anyway

I would not run 3 #10 grounds, easier to run one large ground from the chassis to the roof  and its less voltage drop. #4 will do. Run it from your junction block to the frame, go down the fridge vent if you have too., Then just run #10 ground from the panels to the junction block ground buss ( I used copper 5/8 pipe flattened with holes drilled it in for a buss bar.)

[ClydesdaleKevin]

Thanks for the reply!  I went ahead and ordered 3 sets of mc4 female connectors and 3 sets of mc4 male connectors...don't want to void the warranty!  I also ordered the Morningstar Tristar MPPT 60 amp charge controller and the remote monitor panel, so that set me back 626 bucks for everything.

Then I got on eBay and ordered enough aluminum Z brackets, complete with stainless steel hardware, to mount the panels...ended up costing me 88 bucks for the lot, but was still cheaper than getting steel L brackets at Home Depot, drilling them, bending them into a Z, painting them, and then buying all the stainless hardware.

I estimate the wiring, junction box, and all the other little doodads I need to complete the install is gonna run me about another 500 bucks, but that includes 2 more Interstate golf cart batteries, for a total of 6 in the battery bank.  That also includes the fiberglass resin and fiberglass to make a solid mount over the cab for the forward panel, and the wind fairing I'm going to use in front of the panel (gonna use a bug guard made for fullsize pickup trucks...just stick it down to the fiberglass in front of the panel with the 3M tape they come with...should work great and look nice too).

Total cost for the system: 2114.00 smackaroos!  Hope this works...lol!

Kev

[ClydesdaleKevin]

Okay...another wiring question.  I went to Morningstar's website and used their string calculator to make sure the panels and the MPPT controller would work well together, and according to the calculator, 3 235 watt Canadian Solar panels are an ideal setup with the 60 amp controller.

However, the controller can handle the panels wired in a parellel circuit...OR a series circuit.  Wired together in series, the voltage is a lot higher, but according to the calculator, the MPPT 60 can handle it. 

My plan was to wire them in parellel.  Is there an advantage or disadvantage to wiring them in series?  Will higher volts result in more charge capacity, or are there other factors I'm not thinking of, like one panel goes out they all go out...lol?

Kev

[gadgetman]

wire them in parallel. Reason being is in series if you shade a section of a panel you loose all that is in series. Parallel you loose part of 1 panel. Parallel is more shade tolerant. But it is critical to have each panel fused before they are in parallel when there is more than 2 panels. 1 panel can not short out another panel if there is a problem but 2 panels can if the 3rd has a issue. FUSE each panel BEFORE the parallel connection !

[ClydesdaleKevin]

Thanks Gadgetman!  I'll install a breaker on each line before connecting them in parellel.

Kev

[gadgetman]

use a fuse dont need a breaker just a inline fuse

[gadgetman]

One other thought on main breakers. You could just use a large maxi fuse. They are like a atm fuse but huge. Easy to find and less chance of a voltage drop. Almost any radio store will have a fixture for them. They just have huge spade terminals on them. I use a 60 amp one for my converter. Granted this will mean you would need a main cut switch. I use these switches on my solar.


http://www.ebay.com/itm/Battery-Disconnect-Kill-Cut-Off-Cutoff-Switch-Car-Boat-Truck-Brass-Terminals-/270913798783?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f13b8827f&vxp=mtr

[ClydesdaleKevin]

Thanks again!  I'm going to see if there are any car stereo specialty shops nearby that have the breakers and fuse holder and whatnot in stock.  Otherwise eBay, which sucks, since I have the time today to finish the project, but can't without the fuse holders and circuit breakers.

Kev

[ClydesdaleKevin]

So the panels are wired in!  Well, as far as the fuse block.  I ended up going to West Marine, and they had all the goodies needed and more!  I ended up going with a 6 gang glass fuse holder made by Blue Sea, surface mountable with a clear cover, and very heavy busses to limit voltage drop.  It sure simplified the wiring I tell ya!

I brought down the all 3 heavy 10 gauge cables through the mushroom cap vent...tight fit...and routed them to the power cabinet, and terminated the positive and negative leads at the fuse box.  The 3 10 gauge grounds from each panel I connected to a 4 gauge cable right to the massive thumb thick cable a previous owner installed that goes from the inverter right to the chassis frame.  Since the positive cable from the inverter is the same insanely thick cable, it will also simplify the wiring, since I can tie the charge controller right to it with 4 gauge cable and not have to worry about voltage drop at all.

Up on the roof I ran the cables as neat and short as I could, and soldered the pins for the Mc4 connectors on the positive and negative leads, then filled the tightening cap with silicone before tightening it to totally waterproof the connection where the wire comes in...where they connect is already waterproof with O rings.

On the front panel I used 2 cable clamps to attach the Mc4 connection to the side of the air conditioner shroud...just laying them on the roof wasn't a good idea since that would have placed the connection under water at certain times of the year...we have a slight dip in the roof right there and water does pool there sometimes, so I thought it a much better idea to keep the cables out of harms way and a little higher.  A couple of zip ties to the back of the shroud vents, and the cable is secure.

The rest of the cabling was attached right to the roof with cable clamps and stainless steel screws, through a piece of eternabond tape, then silicone over the screw heads. 

The ground on each cable was attached to the ground crimp clamp already attached to the panels at each panel from each cable. 

So everything on the roof is nice and neat and waterproof.  Sweet!

So back to the inside, and as said I used a heavy duty fuse block from Blue Sea.  I kept track of which wire went to which panel, so on the clear cover of the fuse box I wrote 1, 2, and 3 with a Sharpee.  The beauty of using the fuse block in reverse to terminate the cables is that each positive cable comes in and ties into a 15 amp fuse FIRST, before going through the fuses and joining together in parellel on the other side.  The negative cables join directly together on the negative bus of the fuse block.  What that means is that there is now a heavy post on each side of the fuse block, the positive for running a heavy 4 gauge cable to the 80 amp breaker, then to the controller, and the negative for running a heavy 4 gauge cable right to the controller.

That was as far as I got last night, since I had other duties to perform, like staining the last run of catapults, and driving up the hill to fetch dinner and whatnot.

So before stopping work and staining the catapults and whatnot, it was 4:30 pm, the sun low in the sky, slightly overcast, and we are camped shaded by trees.  I had the panels wired in and the fuses in place, so out of curiosity I put my Fluke volt meter across the bus terminals...amazingly the panels were putting out 32 volts cumulatively!

So I finished my duties and got back to camp with the sun even lower in the sky, not much daylight left, and again out of curiosity I wanted to check the panel output, this time at each individual panel.  I pulled all 3 fuses, easy to do with the Blue Sea fuse block since there is a little plastic rocker at each fuse that pops the fuse right out, and checked the voltage at all 3 cables.  All 3 panels were still producing, right around 29.2 volts at each panel...sweet!

So thats it...just have to neaten up a few things and wire in the controller and meter this M/T and the air foil, but almost done!

Kev

[tiliman]

have a other qustion, 285watt, 48 volt wired to a morning star ps30m charge controller. all is fine for off grid and shore power. the man that installed wiring put in a switch to disconect old style converter/charger.said cant run onboard charger and solar charge controller at the same time.  all works great and will keep house batteries full charge. the problem is when i run the old 78 onan 5kw generator it seems to just keep charging batterise untill there is and over charge and that shut down solar charge controller with high voltage error. batteries show 16.6 or 16.7 charge when i noticed how high they were charged, i shut down generator and reset solar charger. should the on board converter charger be on all the time? even when running generator and solar charge controller. this only creates the problem when running the generator but does not have a problem on shore power.

[DaveVA78Chieftain]

Not sure what model generator you have however, most RV generators have a separate 3-10 amp battery charging function built in that is intended to restore the DC energy used to start the generator.  It is completely separate from your normal converter.  Sounds like something is awry with that circuit in the generator itself.  Need to know the MFG, Model, and spec number of your generator to answer anything else.

Dave

[tiliman]

Hi Dave, genset is 5.0cck-3cr/12016r-
little confusing as it does not over load solar charger on shore power with switch off  or on  that is suposed to disconect batery charger in old progressive dyamics converter. so with switch off and runing generator in the boondocks to run ac unit, it over chargers batteries and sends high voltage error to solar charge controller

[DaveVA78Chieftain]

Again, I said, IT IS NOT your normal (Progressive Dynamic) converter that is causing the charging problem (you said it's turned OFF).  It is the charging circuit built into the 5.0CCK Spec R generator causing your problem.  Please turn to page 3-5 (PDF page 27) of http://www.cumminsonan.com/www/pdf/manuals/900-0196.pdf for a description of the charging circuit in the generator.

http://www.flightsystems.com/p-ONAN-300-C859-0859.html

Dave

[tiliman]

thanks Dave, i down loaded and gave info to man that wired solar for me and he is checking it all out. but what you said, now make sense to me. i had no idea that the genset had its own charging system, but i do now.
thanks again
John

[ClydesdaleKevin]

Glad you are figuring it all out.  Lots of systems working together with no "brain" to control it all but you yourself when it comes to cobbelling all these systems together.  I've even taken to leaving my breakers to the solar power system off when connected to shore power since the Boondocker converter and the Morningstar charge controller don't communicate with each other AT ALL...with both on on a sunny day my battery voltage was reading over 15 volts as a low average.

Kev

[tiliman]

and to make it even more chaotic,Kev, the operator cant figure out what the operations cant figure out lol!! but i think you are right to just disconnect the solar all together while on shore power. better safe than sorry? bunch of boiled out batteries.
John