Thinking about installing the Renogy 20 amp DC to DC charger

[Rob Culver]

Originally Posted by Wavery

Just be sure to hook up the battery first, then the solar panel.

Did you get that solar panel?

Thanks Wayne, I read those directions to hook up the battery before the solar panel. I haven't got a solar panel yet. I just thought I'd install the new MPPT controller first and make sure that's working. So controlling one variable at a time.

When I do get a solar panel I was also considering this 300 watt one from Amazon. It looked like it might be easier to mount since it came with a frame and predrilled holes. Is there a kit you could recommend for either this 300 watt or the 370 watt panel that would make the mounting process on top of the TM go as easy as possible? I don't mind paying extra for a panel if it makes the labor involved in the mounting process easier.

https://www.amazon.com/High-Efficien...69&sr=8-3&th=1

[Wavery]

Originally Posted by Rob Culver

Thanks Wayne, I read those directions to hook up the battery before the solar panel. I haven't got a solar panel yet. I just thought I'd install the new MPPT controller first and make sure that's working. So controlling one variable at a time.

When I do get a solar panel I was also considering this 300 watt one from Amazon. It looked like it might be easier to mount since it came with a frame and predrilled holes. Is there a kit you could recommend for either this 300 watt or the 370 watt panel that would make the mounting process on top of the TM go as easy as possible? I don't mind paying extra for a panel if it makes the labor involved in the mounting process easier.

https://www.amazon.com/High-Efficien...69&sr=8-3&th=1

To install any hard frame solar panel, you will need "Z brackets". These brackets create an air flow space under the panel. This is critical to keep the panel from over-heating.

I have installed more of these panels than I can remember. I install the brackets onto the panel by drilling holes in the brackets "ears" and use self tapping screws to fasten the brackets to the panel. I suggest 3 on each side on these larger panels.

Before mounting the panel on the roof clean the roof and the under-side of the 6 Z-brackets real well with a water based degreaser like Simple Green or the orange cleaners. Don't use full strength or leave it on the roof for long as it may remove the finish. Rinse and dry the area. Estimate where the brackets will attach to the roof and wipe those spots with rubbing alcohol to remove any moisture and prep the surface.

Once the brackets are secured to the panel and the roof is clean, carefully set the panel in place on the roof and pencil mark where the brackets sit. Attach 1"x4" 3M VHB double side tape to each foot and leave the protective covering on the tape. Set the panel in place so that the feet are in the pencil marks. Remove the protective cover from the tape on the 3, far side brackets and set them in place. Lift the 3, close side brackets just far enough to remove the protective tape covers (I use tweezers) and set in place. Now, you will need a 6" long piece of 2x4 wood. Place the 1.5" side on one bracket and push down hard for 30 seconds. Repeat on all 6 brackets. That sets the adhesive. Allow 24-hours to cure and you are set. If done properly, that tape will never lift.

Now you are ready to run the wires down to the battery compartment. (see pic).

https://www.amazon.com/BougeRV-Solar...72&sr=8-9&th=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Rob Culver]

Originally Posted by Wavery

To install any hard frame solar panel, you will need "Z brackets". These brackets create an air flow space under the panel. This is critical to keep the panel from over-heating.

I have installed more of these panels than I can remember. I install the brackets onto the panel by drilling holes in the brackets "ears" and use self tapping screws to fasten the brackets to the panel. I suggest 3 on each side on these larger panels.

Before mounting the panel on the roof clean the roof and the under-side of the 6 Z-brackets real well with a water based degreaser like Simple Green or the orange cleaners. Don't use full strength or leave it on the roof for long as it may remove the finish. Rinse and dry the area. Estimate where the brackets will attach to the roof and wipe those spots with rubbing alcohol to remove any moisture and prep the surface.

Once the brackets are secured to the panel and the roof is clean, carefully set the panel in place on the roof and pencil mark where the brackets sit. Attach 1"x4" 3M VHB double side tape to each foot and leave the protective covering on the tape. Set the panel in place so that the feet are in the pencil marks. Remove the protective cover from the tape on the 3, far side brackets and set them in place. Lift the 3, close side brackets just far enough to remove the protective tape covers (I use tweezers) and set in place. Now, you will need a 6" long piece of 2x4 wood. Place the 1.5" side on one bracket and push down hard for 30 seconds. Repeat on all 6 brackets. That sets the adhesive. Allow 24-hours to cure and you are set. If done properly, that tape will never lift.

Now you are ready to run the wires down to the battery compartment. (see pic).

https://www.amazon.com/BougeRV-Solar...72&sr=8-9&th=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Very good Wayne,
Exactly the kind of detailed information I was hoping for! Luckily, I won't have to run any cables anywhere because I'm removing an existing 100 watt flat flex panel from the factory and so I'll just reuse the existing cables etc.

I read somewhere that the flex panels don't perform as well as the rigid so perhaps that could be partly due to a heat dissipation problem since they are mounted flat with no air circulation to the underside?

I'm surprised that the panels can be held down with just double sided tape and not have to screw in to the roof. But that's good news! Can you recommend a particular tape product for that with a url? I see that 3M has alot of choices and there are plenty of other brands too. Much appreciated..

[Wavery]

Originally Posted by Rob Culver

Very good Wayne,
Exactly the kind of detailed information I was hoping for! Luckily, I won't have to run any cables anywhere because I'm removing an existing 100 watt flat flex panel from the factory and so I'll just reuse the existing cables etc.

I read somewhere that the flex panels don't perform as well as the rigid so perhaps that could be partly due to a heat dissipation problem since they are mounted flat with no air circulation to the underside?

I'm surprised that the panels can be held down with just double sided tape and not have to screw in to the roof. But that's good news! Can you recommend a particular tape product for that with a url? I see that 3M has alot of choices and there are plenty of other brands too. Much appreciated..

https://www.amazon.com/Conformable-A...l%2C159&sr=1-1

[ShrimpBurrito]

I also use 3M's #94 Primer with their VHB tapes, which they recommend to help promote a tighter bond. Have no idea if it helps or not, but I'd rather do everything I can to keep those projectiles on the roof.....

https://www.amazon.com/gp/product/B0088P1LNY

Dave

[Rob Culver]

Originally Posted by ShrimpBurrito

I also use 3M's #94 Primer with their VHB tapes, which they recommend to help promote a tighter bond. Have no idea if it helps or not, but I'd rather do everything I can to keep those projectiles on the roof.....

https://www.amazon.com/gp/product/B0088P1LNY

Dave

Thanks for the tip Dave. Got the Victron MPPT 75/15 installed and now I'm just trying to get a solar panel. Almost got a new 300 watt Eco-Baeerss one off ebay for $160 but got a strange message from the seller that they were having quality issues so I should cancel my order which I then did. Now I'm going to do a little more research on reliability etc. Might be worth spending a little more to get a better brand name. I noticed on Amazon that the 300 watt panels cost considerably more than the 200 watt on a per watt basis. That makes it a tough choice as I'd much prefer the 300 watt panel if it was even the same price on a per watt basis.

[Rob Culver]

Originally Posted by Wavery

Maximum output for that panel is <11A and 34.2V. The controller that I listed will handle 15A and 75V. It should be fine for 1, 370W panel. If you ever wanted to add a second 370W panel, just wire it in parallel. That would be a max output of 69V and 11A. Within the tolerance of that 75/15 Victron controller.

Hello again Wayne,
I've got the MPPT 75/15 hooked up and I have the 370 watt panel hooked up too. But what am I missing because I can't get the panel to deliver more than 15 amps to the battery. The panel is at about 32 volts and 6.7 amps and the battery is at about 14 volts and 14.9 amps.

Using the Victron connect app I can go to a configuration menu for the battery and it allows me to lower the max amperage to below 15 amps. That works fine. But if I try to raise the battery max amperage above 15 it won't allow that.

Is there some secret to raising this amperage? Because if there's not then it would seem that the 75/15 model is really not capable of supporting a panel which is outputting more than about 220 watts like mine is.

What am I missing?

[ShrimpBurrito]

The Victron MPPT 75/15 controller is limited to a 15 amp output. If you want more current out, you need to buy one of the larger controllers.

75/15 = max 75 volts in, max 15 amps out. With a 370A panel, you'll probably want at least a 30A output.

Dave

[Rob Culver]

Originally Posted by ShrimpBurrito

The Victron MPPT 75/15 controller is limited to a 15 amp output. If you want more current out, you need to buy one of the larger controllers.

75/15 = max 75 volts in, max 15 amps out. With a 370A panel, you'll probably want at least a 30A output.

Dave

Thanks Dave. That was precisely my point earlier in the thread in which it seemed to me that the 15 amps referred to the amperage max in to the battery and not the amperage out of the panel. Now it seems that I was right all along and the 75/15 really wasn't good enough for a 370 watt panel as Wayne said.

Before that I was intent on getting the Victron MPPT 100/30 module. Do you per chance use that one? That one is larger but could still fit near the sink. It was somewhat more difficult to hook up though because it required a ground wire and so my question at the time is where I could pick up a spot close to the sink to run that ground wire to a spot which went to the chassis ground. Any idea?

[Wavery]

Originally Posted by Rob Culver

Hello again Wayne,
The panel is at about 32 volts and 6.7 amps and the battery is at about 14 volts and 14.9 amps.

What am I missing?

That is exactly what you want. The controller is lowering the voltage from 32V (which is ~max output of the panel) to 14V which increases the panel amperage output from 6.7A to the maximum ~15A.

In order for a 30A controller to go past 15A, it would need higher voltage from the panel. Installing a 30A controller will not increase the amperage to the battery any higher unless you install a second panel.

The advantage that the MPPT controller gives you is that it will start charging your battery earlier and continue charging later in the day.

I have a 30A controller on my trailer with 640W of solar panels. I'll take a pic of the output of my setup when the Sun gets a little higher today.