Solar Battery Charger

Topic: Solar Battery Charger (Read 1608 times) previous topic - next topic

Solar Battery Charger

July 31, 2017, 04:10:14 pm

I have to move our coach this week and may not have access to AC power for a while. I've searched and read a number of posts about various solar charger rigs that have been tried over the years. There seems to be a preference by our forum for something in the neighborhood of 100w. What's current thought on this (excuse the pun)?

I have a Trik-L-Start installed at the isolater and it keeps the chassis batteries charged from the house batteries. Would it make sense to put something like a 100w panel on the roof (will be in the open, no shade) and connect it to the house batteries and let the Trik-L-Start continue to tend the chassis batteries?

Re: Solar Battery Charger

Reply #1 – July 31, 2017, 04:43:46 pm

I do 180 and it covers both most of the time. I would do a pair of 150s and a good MPPT controller.

12V panels can keep your controller cost down and 135-150 W panels aren't too hard to find.

Re: Solar Battery Charger

Reply #2 – July 31, 2017, 05:00:36 pm

Trik-L-Start is a good idea but I just run a double male cord from one lighter socket to the other up on the dash. While on shore power, a 2 amp trickle charger keeps both sets of batteries (engine conventional, house AGM) at 13.5 volts, just about exactly what the manufacturer recommends. A 100 watt panel with an inexpensive MPPT controller will be more than enough to keep your batteries up while you are away from shore power. That would even be enough power to keep your fridge on propane and supply the 12V to the board.

Pierce

Re: Solar Battery Charger

Reply #3 – July 31, 2017, 06:32:12 pm

I ran a 100w to a Morningstar 6a controller at the foot of the bed. $20 bucks or so on sale for chassis. John H has described his run and I did pretty much the same. It is very easy to install aft from roof into the engine compartment. Much easier than anywhere foreword for us. For what you describe you don't need MPPT unless you plan on expanding your array. We do use MPPT for the 800w going to house. Love Pierces solution male/male.

Re: Solar Battery Charger

Reply #4 – July 31, 2017, 06:43:48 pm

A $50 100 watt panel and a $20 pwm 10 amp controller will do it, If you do not want it permanent, put panel on roof and run wires down ladder into engine compartment to isolator. Remember to shut off your inverter, it will draw a good amount even with nothing on.

Re: Solar Battery Charger

Reply #5 – August 01, 2017, 10:51:21 am

Thanks everyone for the guidance. Ordered a small MPPT controller and a 150w panel.

Appreciate your help.

Re: Solar Battery Charger

Reply #6 – August 01, 2017, 11:00:49 am

Yes, we store our coach outside with no electric service and our roof solar keeps house battery charged, and our Trik L Start keeps our start battery charged. Solar charge controllers should be set for correct battery charge voltage.

Re: Solar Battery Charger

Reply #7 – August 01, 2017, 11:13:44 am

Quote from: Barry & Cindy – August 01, 2017, 11:00:49 am

Yes, we store our coach outside with no electric service and our roof solar keeps house battery charged, and our Trik L Start keeps our start battery charged. Solar charge controllers should be set for correct battery charge voltage.

I'll be sure to pay attention to the voltage during configuration.

Thanks!

Re: Solar Battery Charger

Reply #8 – August 01, 2017, 11:26:49 pm

I have bought tons of stuff from these guys for other customers. Great prices, great products, really good service:

Windy Nation

Go big on the controller, they are cheap as chips. Then you can add more later. They are 18 volt panels.

Re: Solar Battery Charger

Reply #9 – August 02, 2017, 12:29:28 am

I have still not discovered where my 3 siemens M65 solar panel wires terminate, or whether they still work (installed pre 1995). Is it true one dead cell will disable a whole panel? I assume they are trash.

Re: Solar Battery Charger

Reply #10 – August 02, 2017, 07:49:36 am

When I started putting a single panel on the roofs of my Foretravel coaches in 1986 I ran the wire down the refer vent and tied into the 12 volt system at the power junction on the back of the refer.

43 watt panels. Between the three you should have 8 amps or so.

Got tired of dead display coaches back then. No way to plug all of them in at our lots.

Re: Solar Battery Charger

Reply #11 – August 08, 2017, 04:48:12 pm

As I reported yesterday in the "what you did today" thread, I have the solar charger temp'ed in (still have to permanently mount it on the roof -- right now it's just lying there in a secure spot).

As of yesterday evening it hadn't hit float status. I went by this afternoon (a partly cloudy, partly rainy day here) and the house batteries are now at float status, and the Trik-L-Start to chassis batteries is showing fully charged. That's with the refrigerator, salesman switch and inverter off, and the air leveling system and normal, non-switched, parasitic loads on. HWH compressor was slightly warm to the touch so it's running every once in awhile.

Charging path is 150w panel-->Victron MPPT controller --> house batteries --> LSL Trik-L-Start --> chassis batteries

Ran the 10ga wires from the panel down through refrigerator vent.

I'm stoked. It's my first "toe in the water" with solar and nice to have a small success. Thank y'all for the help.

Re: Solar Battery Charger

Reply #12 – August 09, 2017, 08:48:46 am

Congrats on that toe. Not sure which Victron you chose but that is an excellent point of departure if you expand.

Re: Solar Battery Charger

Reply #13 – August 09, 2017, 10:02:12 am

Lots of info about solar on UTube. Harbor Freight has good reviews on their recent add to solar and seems to be reasonably priced.

Re: Solar Battery Charger

Reply #14 – August 10, 2017, 10:54:29 am

Quote from: Mark Duckworth – August 08, 2017, 04:48:12 pm

I have the solar charger temp'ed in (still have to permanently mount it on the roof -- right now it's just lying there in a secure spot).

For mounting the panel, I suggest using stainless steel brackets "glued" to the roof. Ours have been up there for 2 years now, and just as secure as the day they were installed. Big plus: no screw holes in the roof, and you can tilt the panel (for optimum sun angle, or for cleaning under them) using simple prop rods.

Re: Solar Battery Charger

Reply #15 – August 10, 2017, 11:09:57 am

What Chuck says. AMSOLAR sells the mounting brackets, a little pricey but well worth it.

Re: Solar Battery Charger

Reply #16 – August 10, 2017, 12:55:10 pm

You may have a structural failure with only four glued attach points. (AKA: Flying solar panels).

Prior to using glue on only four points. I would recommend a worse-case structural analysis be performed of 100MPH winds blowing across the panels. Based on my crude internet-search-based analysis for my 79x39 inch solar panels, which are attached to my U270 roof with fifteen pieces 2 inch by 2 inch 3M VHB (Very High Bond) tape, here are the results as my feeble memory recalls:

1600 pounds of VHB tape pull-out bond strength, per 3M specifications
800 pounds of pulling force due to a 100MPH wind

During a hurricane, the solar panels could act like wings and generate a lot of upward lift.

Of course, no one has done a hurricane analysis of RV solar panel structures, but I reviewed internet analysis of sticks and bricks buildings and their roof-mounted solar panels.

Re: Solar Battery Charger

Reply #17 – August 10, 2017, 01:03:02 pm

Here is a photo of my solar panels with 15 VHB tape attach points. One issue related to my prior post is that over time, the adhesive bond force may weaken, so I recommend designing 2X the required bond strength. If you loose 50% of the bond strength in 10 years, there is still a decent margin of structural integrity to withstand a 100MPH wind.

Speaking of 100MPH wind. Picture yourself driving down the road into a 30MPH headwind. So, we may experience hurricane-force winds more frequently that originally thought.

Re: Solar Battery Charger

Reply #18 – August 10, 2017, 01:11:12 pm

Quote from: Chuck & Jeannie – August 10, 2017, 10:54:29 am

For mounting the panel, I suggest using aluminum brackets "glued" to the roof. Ours have been up there for 2 years now, and just as secure as the day they were installed. Plus, no screw holes in the roof, and you can tilt the panel (for optimum sun angle, or for cleaning under them) using simple prop rods.

What adhesive did you use?

Re: Solar Battery Charger

Reply #19 – August 10, 2017, 01:28:31 pm

Quote from: Tim – August 10, 2017, 01:03:02 pm

Here is a photo of my solar panels with 15 VHB tape attach points. One issue related to my prior post is that over time, the adhesive bond force may weaken, so I recommend designing 2X the required bond strength. If you loose 50% of the bond strength in 10 years, there is still a decent margin of structural integrity to withstand a 100MPH wind.

Speaking of 100MPH wind. Picture yourself driving down the road into a 30MPH headwind. So, we may experience hurricane-force winds more frequently that originally thought.

I like VHB a lot and we used it extensively where I worked. However the PO had FOT coat the entire area of my coach's roof with a product that both seals and provides a non-skid surface. The finish has thousands of little wart-like bumps. Because it's not a smooth surface I think I'll need an adhesive that's more liquid in consistency so the bracket is fully bonded to the irregular surface of the roof.

Re: Solar Battery Charger

Reply #20 – August 10, 2017, 04:04:34 pm

To Tim:

Your concern for the structural integrity of my solar panels is understandable, and taken in the helpful spirit that I am sure it is given. I'm a English major, so I don't know nuttin about "worse-case structural analysis". What I DO know is that my panels were installed by AM Solar in Springfield, OR. I went to them because I wanted my installation done right. They have done hundreds of panel installs, on all kinds of roof surfaces, using the "4 stuck-on brackets" method. They claim to have never had one single panel come loose, and I believe them. They have a VERY loyal online following of happy, satisfied customers.

We have driven thousands of miles since our install, and sometimes into very strong headwinds. I am sure you could propose a scenario in which the panels could be ripped off, but apparently we haven't encountered it (YET). As to how strong the glue will be in 10 years, I don't know, but AM Solar has been using this method for quite a while so I guess it's holding up OK.

In the end, you have to do what you think is right, proper, and adequate to the situation. Glued on brackets is only one way to install solar panels. Several forum members have bolted/screwed down their panels, and are happy with that method. Your method sounds fine, also!

As always, the best rule is: Do What Makes You Happy!

Re: Solar Battery Charger

Reply #21 – August 10, 2017, 04:16:03 pm

To Mark:

I don't know exactly what product AM Solar used to glue down my brackets. I have been asked that many times, and I was negligent in not getting that info when they were working on our coach. The guys at their shop are extremely friendly and helpful to "do it yourself" customers. I am sure if you called them, they would be happy to answer any questions you might have. They would also be happy to sell you some stuff, if you like their offerings!

They also have a nice website with lots of good info. Here is their discussion on the subject of panel mounts:

Mounts

Re: Solar Battery Charger

Reply #22 – August 10, 2017, 04:21:49 pm

Chuck, reading their info on the link, it looks like they put 3M tape under your brackets then sealed with the glue to keep the weather out.

Re: Solar Battery Charger

Reply #23 – August 10, 2017, 04:28:48 pm

That would also be my guess, but I hate to state as absolute fact without knowing for sure. I do have the Dicor on top of the mounts.

Re: Solar Battery Charger

Reply #24 – August 10, 2017, 04:38:13 pm

Having 540 watts put on roof at AM Solar as I type. 3M High Bond Tape, Dicor on top of brackets.

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