Upgrades, People, Upgrades

[Autosnap]

Originally Posted by Wavery

Here's a few suggestions. That Class T fuse should go between the battery switch and the battery. It is your last ditch protection to cover you for any catastrophic short, including the internal connectors of the shut-off switch.

Yeah, I misunderstood you on that one. I think you had said it that way first, then I saw something else that gave me pause. No big woop, it's just lines right now.

Originally Posted by Wavery

I made a few other suggestions. You can put a switch between the solar controller and pos busbar if you want but I can't imagine what it would be used for. The fuse is important.

If it doesn't hurt anything, I'd like to isolate the whole system if I have to, I know I need to switch off the PV first.

Originally Posted by Wavery

BTW..... I have been meaning to ask you, why such a large system? Do you plan to run the A/C off of this.

I already have a lot of this stuff from other applications or Friends giving me surplus things or items they thought they would use and never did. The only thing I've had to purchase so far is the converter, and the inverter... odd that huh? Oh, and the shunt. I still need all the connectors, switches, breakers, and the ATS and any misc. posts or whathaveyou.

I know the A/C is a pipe-dream on a TM until they make some strides, but I'm gonna hit it with what I have, for now.

[Autosnap]

Again...

[Autosnap]

What size wire should I use for the ac side?

[Wavery]

Originally Posted by Autosnap

What size wire should I use for the ac side?

Nothing really changes on the A/C side except the inverter to the AC busbars (and ATS). 10G wire is adequate. The camper is all wired for 30A in and 20A out.

The biggest problem that you will have with this whole set-up is going to be the weight on that front roof. I put 2, 100W panels (28#) on my front roof. I cranked the torsion bar adjustment all the way down and it was still harder to open. I can only imagine what it would be like with 75+ pounds on that roof. I think it might take 2 people to open and (carefully) close that roof.

I removed the TV antenna on my current TM, so that I could mount 2, 320W solar panels but I don't have to worry about lifting the roof on the Elkmont.

[rickst29]

Originally Posted by Autosnap

Again...

This diagram looks good with the limitations imposed by vents, AC, and the antenna mast. Thanks for showing those. Shading, from the relatively tall Air Conditioner Shroud, will vary with camper "parking" orientation versus sun angle on nearby panels.

Considering only issues of shade, the middle front panel should probably be as far forwards from the AC shroud as it can go, while not being hit or damaged by the antenna mast. But that placement puts more weight on the front pair of struts, and TM puts the weakest torsion bars there. You probably won't have enough bolt adjustment "room" to handle 75 lbs of glass panels near the front.

The OEM pairs of "front shell" torsion bars at the REAR of the shell are put in bigger (more diameter and more lifting power), to handle the extra weight of the AC unit. Each 1/8 turn of the adjustment screws has more effect, so you might achieve better balance moving all 3 panels towards the rear.

The torsion bars can be replaced with upgraqed (stronge) ones, but shipping costs air fairly higfh on those. The job is not trivial either, you will need to construct a frame of 2x4 lumber to support the shell while messing with the lift arms and their torsion bars. The ends of "upgraded" torsion bars (from the factory will also (probably) need to be ground down fit into the lift arm ends, the diameter is too big until you grind them down.

I never did that job, Shane is an expert on doing that, and some others have done that as well. I did something complicated with car/truck "gas struts" to assist my my inadequate torsion bars. That avoided gettng a fine from my HOA "for building an RV repair frame structure in my driveway", but I spent even more money and time designing and building my funny-looking "lift assist" strut clamps.

- - -

Within each 'serial' pair, the LOWER CURRENT of the two panels in that pair will determine the total current. The VOLTAGE adds together within each pair, but when the two sets are connected in parallel (at the MPPT, the Solar of those two 'summed' values wins. The CURRENT from the two sets adds together t the parallel connection.

[Bill]

Originally Posted by AUTOSNAP

I've done some preliminary layouts and it seems to work. ... My major concern is it adding 75 lbs to the roof of the front shell. I certainly don't want to break something VERY important.

Beyond torsion bar adjustment/replacement, there is another thing to keep in the back of your mind. TM roofs, especially the front roof, have a limited ability to bear extra weight. In the Owner's Manual, TM limits snow load on the roof to a foot of light fluffy snow, about 160-200 pounds, carried as an evenly-distributed, quiet load. Failure to heed this limit can result in loss of the arch in the roof, generally considered a non-repairable problem. So 75 pounds of solar stuff won't hurt your roof, but it eats up almost half of the allowance. In the years after you install and enjoy your solar equipment, you must not forget this limitation if you find yourself in an unexpected snow storm.

I'm not speaking from personal experience here. But the forum has seen a number of cases where the rear edge of the front roof has lost its arch. You really don't want that to happen.

Bill

[Autosnap]

Good points guys, I'm thinking very seriously about punting on this one and dropping to 3 panels. I have very little apatite for so much modification on such a new camper, and Bill's points are pushing me even further toward this decision.

I simply need function and a bit of oomph, my intentions are to wire them in series, as I think that's the best way to keep the Voltage up. Let me know your thoughts please?

An option would be to make a ground unit out of the 4th panel, but transportation in the TV would take up a large amount of room. Also, damaging the panel in transport is a concern.

I would need some type of detachable connection at the bottom of the TM before it goes into the battery compartment to put them all in series. Are there any problems doing this as anyone is aware, or would it put a strain on the MPPT to have to adjust to the higher Voltage? The MPPT spec says 150 at 25degC down to 145 at -25degC. looking at the Voc per panel being 27V per panel, and approx 121V total in series at 0C [multiplying (27x4)x1.12] Is this getting too close to the max VDC?

One concern becomes heat generated taking 121V or even 108V down to the 14.4V. Judging by the curve, it also becomes less efficient the higher the Voltage from the PVs. So I'm thinking just wave off the ground unit unless I have an extra MPPT laying around, but that gets more complicated... so I'm thinking I'll drop the 4th panel.

[Wavery]

Originally Posted by Autosnap

I would need some type of detachable connection at the bottom of the TM before it goes into the battery compartment to put them all in series. Are there any problems doing this as anyone is aware, or would it put a strain on the MPPT to have to adjust to the higher Voltage? The MPPT spec says 150 at 25degC down to 145 at -25degC. looking at the Voc per panel being 27V per panel, and approx 121V total in series at 0C [multiplying (27x4)x1.12] Is this getting too close to the max VDC?

One concern becomes heat generated taking 121V or even 108V down to the 14.4V. Judging by the curve, it also becomes less efficient the higher the Voltage from the PVs. So I'm thinking just wave off the ground unit unless I have an extra MPPT laying around, but that gets more complicated... so I'm thinking I'll drop the 4th panel.

4, panels wired 2S2P is doable (with 1 portable. You would end up with ~42V and ~20A (assuming panel rating of 10A).

3 panels would have to be wire parallel and would be ~21V and ~30A. The decreased voltage with parallel is safer but the increased amperage will take larger wire to keep the resistance (and heat) down. You would probably want to still use the same wire as in your diagram.

I think you might be happy with a 600W system and it would be a little easier on you and your trailer (weight wise). I have 640W and we never conserve. We run anything that we want except A/C.

If you decide to throw on a portable in the future, it's just a matter of switching some "Y" branch connectors. Your MPPT controller doesn't care either way. I would recommend turning off the breakers from your solar panels anytime that you do any servicing. After you're done, the MPPT controller will just accept anything that it is given (within factory specs).

[Autosnap]

Does anyone know why the purchased "Solar" wire is much larger diameter, has finer and more stands (like 10 to 20x more), are tinned copper, and have twice the thickness of insulator than my full copper awg cable?

I know it's softer and easier to pull, but it doesn't feel safe. Should I be concerned that my insulator isn't as thick or should I just take all the bought solar wire back and use the copper I have from my friend and just make up my own cables? They are stiffer, but I'm not concerned about that.

[Wavery]

Originally Posted by Autosnap

Does anyone know why the purchased "Solar" wire is much larger diameter, has finer and more stands (like 10 to 20x more), are tinned copper, and have twice the thickness of insulator than my full copper awg cable?

I know it's softer and easier to pull, but it doesn't feel safe. Should I be concerned that my insulator isn't as thick or should I just take all the bought solar wire back and use the copper I have from my friend and just make up my own cables? They are stiffer, but I'm not concerned about that.

Do yourself a favor and just use the proper solar wires. The thicker wire strands are more prone to cracking and corrosion (more air space), the tinned wire is less prone to cracking and corrosion, the insulation is thicker for UV protection and any electro-magnetic leakage. That's especially important with a metal roof.

The proper solar wires come with the MC4 connectors (important for solar panel connection) already properly installed and moisture proof.

Don't get me wrong, the wire that you are referring to will work. They are just less durable and efficient (especially over time). You will need some special tools for installing the MC4 connectors unless you plan to cut the connectors off of the solar panels and use crimp connectors and heat shrink. If you do that, be sure to leave some slack in the wire. If you ever have to remove a panel, you'll have to cut the wire and shorten it for replacement.