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Old 08-27-2016, 08:12 PM   #1
Klipstr
2016 LTV Unity MB
 
Join Date: May 2016
Location: Rio Verde and Show Low AZ
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Default Installation of new solar panels

Howdy,

Finally the long awaited original post! Hopefully some of you will find this useful...

Photos for this install are here:

https://photos.google.com/share/AF1Q...JjdnlyUnhtY2hn


Our MB had the factory two solar panel install. Like TurboPilot I want to ensure I have enough solar up there to keep my batteries nice and topped off. I have added two panels and will put a third for a total of five. I was unsure whether I needed/wanted five but decided to go ahead and wire for the fifth and order it. Rather than staying with the Go Power panels I opted for these:

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

Glued down with this:

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

Per Turbo...

A few words about the panels. They are very nicely packaged in two cardboard and one Styrofoam layers. Light weight: can easily carry both in one arm. Sturdy. Apparently well made. I wouldn't be surprised if the same Chinese manufacturer is building the Go Power panels as the cable component on the edge of the panel is identical. One difference is the cells themselves are more of a matte rather than glossy finish. While reading the reviews one person commented that these will be slightly more efficient as they will reflect less and absorb more light. Sounds reasonable to me. Bottom line: I think this is a good panel.

I also purchased this box to be used as a junction box as I replaced the existing Y connector scheme. I originally planned to do as Turbo did and expand the Ys to add the panels but decided I preferred the junction box approach.

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

This is a decent box. Does not have stainless screws so I dobbed some Dicor on them.

If you are adding panels you will want to look at Turbo's thread to see how he replaced the wire from the charge controller to the battery in the battery bay. The wire beyond the fuse and the fuse itself in the factory installation are the wrong size for more than two panels. Here is the post:

http://www.sprinter-source.com/forum...ad.php?t=44458

I should note that Turbo's post is very good. This post has a bit more detail about the panel and cable installation than his does so is a good adjunct.

The following steps are illustrated by the photos:

1. Remove the galvanized panel covering the roof penetration for the down wire cable to the Go Power charge controller. This involves a bit of grungy work as one is required to remove the Dicor used to seal up this plate. I use a screw driver blade and my hands to pull as much of the Dicor away as required to get a driver on the screws holding the plate down. Stick your screw driver underneath the plate and gently pry it off. They used Dicor to "glue" the plate down. One could then use some paint thinner to clean up the excess. I did not have any so my install is a bit messier than I would like. I also removed the Y connectors joining the original two panels to the down wire. The Y connectors are screwed into the roof as well. I didn't know this on the first one until I pried it and the screw from the roof! Not a problem, that's what Dicor is for!

Once you have exposed the penetration hole you will see it is a 2" hole and you can see how your roof is made. Prepare to be disappointed! One thin piece of fiberglass, perhaps a 1/4" piece of MDF or plywood and then Styrofoam. Typical of fiberglass RV roofs. I did like the fact that LTV used a larger hole for the penetration. This gives you room to move the cables around.

I chose the larger box as I knew it would cover the penetration and the screw holes left over from attaching the galvanized plate.

2. Drill all the holes you will need in the junction box. In my case, I drilled a slot for the down wires and five holes in each side of the box for my MC4 cables from the panels. I did all of this on the ground. I used two Eaton bus bars that I purchased for $4.50 at Lowes for my positive and negative connections. You can get an idea from my photos where to drill these holes. The down wire enters the box at the bottom (toward the roof edge) and the MC4 wires enter the box along the side tops. This worked well for the bus bars I used.

I put a bead of Dicor on the bottom of the box and around the penetration hole and then screwed the box to the roof using four of the screws I removed from the galvanized plate. Don't put so much Dicor that you make a mess around the edges. If you do you will get your MC4 wires in it later and then get it all over yourself and the rig!

3. Mount the panels. I've included a number of photos showing various locations I considered for the panels. I originally thought I would put two toward the rear but changed my mind realizing that I will add a satellite dome at some point and that's where the prewire is for that. The fifth panel will be adjacent to the air conditioner on the driver side.

Clean the roof off using a damp cloth (it had rained before I started my install so this was easy). Unwrap the panel from the plastic wrap and flip it over and apply the SikaFlex. I ran a bead around the edge then crisscrossed the panel and dabbed the remainder of the tube just wherever.

Carefully, without getting Sika every where, including on yourself, flip the panel over and align where you want it. The Sika doesn't set up fast so you have time to scoot the panel. Obviously you want to have it close to begin with or you will have adhesive all over your roof so be careful.

Gently press down all over the panel to get the Sika to spread out along the edge and in the middle. I would think a formica roller (or the cooks rolling pin) would be a handy tool for this. Again, I didn't have one so used the old fashioned method.

Repeat for the other panels.

4. Measure the approximate distance from the panel wires to the junction box so you can make the cables. Make them a little longer that you think you need or you may need a cable stretcher later. In my case it turned out they were all about 40" so I just made six this length. Making the cables gave the Sika some time to setup so I didn't need to be concerned about the panels moving around when I connected them. I marked the positive cables with a piece of red electrical tape. That will be the wires with the female connectors. The male connectors on the panels are marked positive. These will be connected to your marked females.

Connect your MC4 wires to the panels and route and tie down the wires to the junction box. I used wire ties and sticky tape pads for this.

http://www.lowes.com/pd/Utilitech-10...-Ties/50005766

I don't expect these will hold up well in the long run. I used 1/2" black plastic exterior cable loops screwed into the roof and then Dicor'ed on my previous installs.

5. Before I started this step I disconnected the Go Power charge controller from the battery. In my case I simply pulled the fuse. I did not want to confuse the controller during my connecting phase. Disconnecting from the battery effectively shuts the CC off.

Once you have all the wires running to your junction box you can determine the best entry point for each one. I first connected the two existing panels. You can see the crossed wires around the box connecting those. I did my install in two goes as I had rain when I wanted to glue my panels down so the photos don't quite represent my words...

Strip the wires about the width of the bus bar. Connect your positive panel wires to the bus bar connected to the red/positive down wire. I tighten the down wire in the bar but try to leave the MC4 wires loose until I get them all in there. That can make it a bit easier on you. Once they are all in tighten them up. Neatness counts here and you don't want to have strands of wire outside the bus bar hole. Twist them a bit with your fingers after stripping to help with this. The wire strands will flatten as you tighten. That's normal.

Once you have all the wires connected to the bus bars, put a piece of wire mold around each as I've shown to keep the bus bars from touching one another. You can be creative with what you separate your bars with. I had this on hand and it worked very well and looks neat.

6. Install the cover on the junction box and Dicor your work. I ran a bead around the junction box and over the screws attaching it and then all around the MC4 wires penetrating the box. Dicor is messy. Be careful not to get it on the panels! It will wipe off but not fun. In my case since a night of rain divided my work effort I had to glue the box down first when I would have preferred to use the Dicor just once.

7. Reconnect your charge controller to the battery. It should boot and you should see a bunch more amps!

Turbo has provided a bunch of data about what you can expect from additional panels. I haven't had a bright sunny day since to see how I'm doing so can report nothing!

I am concerned about the cable length between the charge controller and the batteries. I need to carefully watch the maximum voltage delivered to the batteries at the end of the charging cycle to satisfy myself that the Go Power can do the job where it is. I, without nothing but my gut, believe it can't deliver a high enough voltage to fully charge my batteries. But I am going to monitor it carefully and hopefully will prove myself wrong.

If I am right, though, my plan is to install a different charge controller closer to the batteries and jump the Go Power using that wire run to my new CC. This helps as the voltage drop between the charge controller and the battery is more important than the drop between the panels and charge controller. More details if necessary...

Hope this helps you guys and gals!
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2016 Unity MB

Last edited by Klipstr; 08-28-2016 at 12:31 AM.
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The Following 7 Users Say Thank You to Klipstr For This Useful Post:
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Old 08-27-2016, 09:32 PM   #2
turbopilot
 
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Default Re: Installation of new solar panels

Great post. I see what mean about the problem with the air conditioner unit further aft. Really limits where you can place a satellite dish, if you want that option. Need to have the satellite dish as far as possible from the air conditioning unit to avoid blanking the dish when operating up north with low satellite elevations.

So far my installation continues to operate trouble free keeping both the house batteries and cab battery charged when the rig is in storage.

There will be exceptions, but with 500 watts of solar on the roof, so far this summer, I have always had the house batteries at 100% SOC by sunset no matter how many amps I use during the day or how cloudy it is without running the generator. For summer operation the standard house batteries always carry me through the night if charged to 100% at sunset without getting anywhere near 50% SOC.
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Old 08-28-2016, 05:55 AM   #3
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Default Re: Installation of new solar panels

Great information, Klipstr! Thanks for all the details. Will make my future install go much more smoothly, I'm sure.
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Old 08-29-2016, 10:07 PM   #4
Klipstr
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Default Re: Installation of new solar panels

A little update on the install...

I'm seeing about 21A as indicated by the Go Power (about 19A on the BMK) at the peak of the day so pretty pleased with four panels. Going to add the fifth just because. That will probably get me to 26-27A at peak daylight. More than enough to return my batteries from 75% SOC to full during the day.

I also watched the voltage and current provided by the charge controller (CC) at the end of the charge cycle. Ideally what happens is as the battery gets closer to full the voltage will increase up to the max charging volts as recommended by the battery manufacturer. In the case of Interstate that should be 14.7 volts. This is the absorption phase. If you are watching the battery voltage at the battery terminals you will see it gradually increase as the amps gradually decrease. In my case, the highest voltage I saw delivered by the Go Power was 14.31V. The Go Power itself actually showed the voltage to be 14.3 as well which surprised me a bit as earlier in the charging cycle, say around 13.7V as indicated by the Go Power, the actual voltage at the batteries was 13.4V. Now that difference is to be expected: the wire length contributes to voltage drop (loss). As less amps are moved through the wire the loss is less (these losses are really called I squared R losses: I being current and R being resistance. So the loss goes up as a square of the current so higher current = higher losses). So the reading converged.

So what? OK, if one is going to ideally charge Interstate batteries then the charger should have as its setting the ability to provide the maximum voltage expected by the battery. That won't happen here. Theoretically, then, the batteries are never going to be fully charged. However, we are saved a bit. Once the absorption phase is over we move to float where the CC continues to provide a trickle current (couple of amps) at 13.5V. As long as this happens for long enough the batteries will ultimately get completely charged. In my case there were still plenty of daylight hours to squeeze the last little bit of current into them.

My reason for concern is twofold: the charge controller itself was not finishing the absorption stage at a high enough voltage per the manucturer spec and the wire loss between the charge controller and the battery may prevent that higher voltage from getting there in the first place. Chronically undercharging lead acid (or AGM) batteries contributes to shorter life spans for said batteries. Ideally the charge controller would sense the voltage at the max value and keep it there for some time or until current dropped to some level (the charge controller should be programmable) and there would be no voltage drop between the charge controller and the batteries. One could conceivably overcome the latter by setting the max voltage sufficiently high to overcome the loss. Another way to do that is to put the charge controller next to the battery (like in the inverter compartment on our rigs). That will minimize the voltage drop and improve performance. This isn't done in our case as Go Power wants us to look at the nice display they have and one isn't likely to do that if said display is in the inverter bay...

OK, you are all screaming Uncle. But by gosh by golly you are all going to be solar battery charging experts when I am through with you!

I'll post the max amps I see with the fifth panel just for tickles and grins.

Thanks and good battery charging...

K
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Old 08-30-2016, 03:57 AM   #5
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Default Re: Installation of new solar panels

Thanks for the update and insights.

I'm a software guy. All I know is that I have a lot of hardware arriving this Wednesday including 3 of the panels you referenced, Blue Sea 30A circuit breaker & manual ACR Turbo mentioned, a Stebel Nautilus air horn and misc. hardware, connectors and adhesives. Since May, my wife and I have been full-timers in our '16 Unity TB. With 8,000 miles, 20 states, and 80 nights under our belt since then, these additions should have a comforting, positive impact. Thanks again.
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Old 08-30-2016, 04:28 AM   #6
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Default Re: Installation of new solar panels

Quote:
Originally Posted by geeque View Post
...manual ACR Turbo mentioned,
You're are going to like the BlueSea ACR. Really makes a big difference protecting both DC electrical systems. Should be standard equipment on the Unity.
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Old 08-30-2016, 02:35 PM   #7
jackfish
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Default Re: Installation of new solar panels

Kelly, does the Go Power have temperature compensation?
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Old 08-30-2016, 03:39 PM   #8
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Default Re: Installation of new solar panels

@jackfish, the manual for the GoPower PWM charge controller states that it is "temperature compensated", but does the schematic does not show any wiring for a remote temperature sensor.
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Old 08-30-2016, 11:28 PM   #9
Klipstr
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Default Re: Installation of new solar panels

No, it is not. Perhaps it senses its own temperature and works from there. That is one of the problems: as temperature goes down the voltage the battery can take will go up. In my previous rig I sometimes saw high 14.x V late in the day when it was cold out. That really the made the LEDs glow and the fans spin!

This is is the charge controller and meter that they should be using:

http://www.bogartengineering.com/pro...solar-charger/

http://www.bogartengineering.com/products/trimetrics/
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Old 08-30-2016, 11:37 PM   #10
jackfish
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Default Re: Installation of new solar panels

If the Go Power controller is next to the batteries then it might work OK. For competent systems, temperature compensation sensed at the batteries is essential.

Kelly, when will you be pulling the Go Power controller for the Bogart?

Currently at Trinidad Lake State Park, CO
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Last edited by jackfish; 08-31-2016 at 01:06 AM.
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