2016 Solar Prepped Coach - Solar Installation

[C.Martin]

I've been asked to share the details of my solar installation.

I am happy to share the details...and pass along a few pearls of wisdom. But be forewarned...I am not an expert. I am mechanically inclined...but I am not formally trained...so please investigate and make your own informed decisions.

Step 1... How much solar will I need?

There are a few things that come into play in this decision. I think the most important is to realize that an off grid system is centered on Batteries. So, a rule of thumb I heard was...have as many watts of panels as you have Amp Hours of storage. That, obviously, is an oversimplification. Solar is more or less a way to charge your batteries from sunlight. Having an all-electric coach...I came to this party with three things. I have eight 6v Interstate Batteries with 928 AH of storage...a Magna Sine MS2812 Inverter/Charger...and the Solar Prep by Newmar with #6AWG wire. If your coach was built before 2016...the prep may have been wired differently.

If you are working with a similar setup...my install may be helpful in your process. If you are unhappy with your batteries or inverter setup...you really need to address that as a first step.

Now...I first searched Interstate to find out what charge recommendations they have for my batteries. It is important to know 1) Bulk/Absorb/Float/Equalization Voltages, 2) Maximum AMP rate during charging, 3) Temperature compensation Voltage/Temperature change...

My batteries are limited to C/10 amp charge rate. If you have AGMs or Lithium...you won't be limited in all practicality. So my 928 aH bank means 92.8 amp charge rate. Having more solar than this would be wasted in my case. It would take about 1440w to hit the 100amp mark on my system...perfect day, with panels putting out full spec wattage. So, I calculated my charge controller and wiring for this amount...just in case. But I only started with 1080 w...being 6 - 180w Grape Solar panels.

The next thing I did was try to validate my planning. This is done by installing a Battery Monitor kit. Since my coach came equiped with Magnum products...I went with the ME-BMK. Got it off of Amazon. My next post will include a few pictures.

[C.Martin]

This is a couple of shots of the Solar Prep.

The bay directly behind the battery compartment had a red and black #6 wire and a network cable ziptied and fastened to the bulkhead.

The other end of these wires are located under /near a metal plate on the roof. There isn't a hole there...just a metal plate held down with four screws and sealed with dicor.

The network cable...well I didn't use it. I've heard you can find it in the control cabinet over the passenger seat...but I didn't look for it.

Reading thru the forum...previous years solar prep wiring wasn't done in this manner.

I posted these pictures to help you find your wiring. If you do not find it there...before you go any further...find out what you're working with. You may elect to run all new wiring.

[C.Martin]

This is the ME-BMK.

I installed the shunt by bolting it to a piece of Delrin which I in turn bolted to the frame rail using an existing hole.

I fastened the module to the fwd bulkhead between the frame rails...in the pass thru compartment.

In addition to the ME-BMK kit you will need a short grounding wire...I used 3/0 for that...it goes between the bolt on the frame rail and the shunt.

You'll need a 4/0 section of wire...to go between the battery bank...and the shunt.

You'll need some 18ga wire, ring terminals and inline fuse to power the BMK module from the battery bank.

IMPORTANT. Follow the instructions carefully. There is a caution in the Inverter Manual...it says to disconnect the red positive from the inverter BEFORE disconnecting the black negative. Failure to do so may damage your network accessories. The caution isn't in the BMK manual...but the installation instructions have it listed in the steps. Easy to accidentally skip over.

Also...the BMK kit comes in a different kit called the ME-BMK-NS. It's cheaper...and tempting. But the NS stands for No Shunt. You will definitely need the shunt.

[C.Martin]

If you really search...you can find the inline fuse and wires that power the ME-BMK.

[C.Martin]

Now with the BMK installed...you can measure amps going in and out of the battery bank.

Now...disconnect from all AC power...no shore power and no generator power. Zero out the BMK meter page that has resettable Amps. Now track the amperage being used by your batteries used to run lighrs, fans, tvs, inverter, possibly you also have the residential refrigerator.

From the way you conduct your survey...you can calculate
accurately how much power is needed to run your coach off of battery power. This power needs to be replaced each day. Either with Solar...or like many of us...Solar augmented by some Generator time.

If I'm off grid...my plan is to program the generator to start in the morning and run for two hours. I'll have the water heater element turned on. So...when I get out of bed...the water will be hot...we can use the induction cooktop, coffe maker, microwave for breakfast, and take a hot shower...It will charge up the batteries some...and then turn off and handoff the job of completing the charge to the solar.

The information you get from this survey will be most valuable in deciding what and how many panels to get.

[C.Martin]

Here is the stuff for everything below the roofline...

I installed a plywood mounting for the solar between the frame rails...on the front bulkhead of the pass thru storage bay. This puts it as close as possible to the battery bank.

The solar prep wires are mounted across the top in the photo...with the positive lead going thru a disconnect switch...and then thru a 72v/60A renogy fuse...to the charge controller.

The output from the charge contoller goes to the battery bank using #2 AWG welding wire. The positive lead passes thru a disconnect...then on the battery bay wall thru a 125A fuse. Label the wires so a technician can see that solar is installed.

Leave the disconnects off...while you install the PV array. You can turn on the switch to the batteries for programming the controller....and the battery side should be ON before turning the Photovoltaic cell input.

I know red is usually positive and black is usually negative...but I wanted contrasting switches...to help be able to explain to a techniciam over the phone in simple non-confusing terms. IE turn off the TOP -BLACK switch first...then Turn off the BOTTOM - RED switch. Two ways to identify the switch to them.

Sorry...the orientation of my photos don't always come out correctly when I submit to a post.

[C.Martin]

I originally wanted to use the PT-100 charge contoller...but it was too big to fit where I wanted to mount it. The Victron Energy unit is a very good charge controller. Had I used the PT-100 from Magnum Energy...I would be able to program it thru the remote. Albeit, anupgraded remote.

The ME-RC remote that came with my coach doesn't provide PT-100 support. I elected to upgrade the remote to the ME-ARC remote. It has many advanced features that you're sure to want now that you have the ME-BMK installed...along with the ME-AGS-N networked Auto Gen. Start. The suite is amazing!!! On older coaches...you have to be aware of the firmware revisions. Magnum has a PDF of each feature and what revision is required. It may NOT be worth the bother if your Firmware is an early revision.

The Victron unit has the advantage of being able to interface thru a smartphone app. No running wires to a wall or panels somewhere for a remote display. I really liked that feature. It's one drawback is the lack of an external temp probe for the batteries. It uses it's own internal temperature. They recommend mounting them in proximity to the batteries. It's not practical with a flooded lead acid battery bay. So, if needed...I can adjust my charge voltages manually to correct for temp differences between the two bays. Victron is working on an add-on remote temp sensor as we speak. I think they already have one for one of thier other product lines.

[C.Martin]

The photo of components on the carpet have the 4/0 shunt to battery wire...and some inline fuses used above the roofline. Another very estute IRV2 contributor pointed out that I had selected the wrong amperage fuses. The decal on your panel will list the rated series amperage. Usually, 10A for 100w panels or 15A for 160-180w panels. Mine requires 15A. He noticed I had purchased 20A. I corrected the fuse size before installing the panels.

[C.Martin]

Now for the roof..

I ordered hardware from AMSolar.com. Yes, there are less expensive mounting options. If you are doing the install yourself.. you will thank youself later for spending the extra money.

They have youtube videos explaining thier system. The rocker feet mounts make it easy to mount, easy to wire, easy to tilt, easy to get underneath for roof cleaning and maintenance.

I'll also say thier customer service is second to none. Outstanding support for the RV community. Do a search for AM Solar on IRV2 and you'll see many others that feel the same way.

You kinda need to go with what fits. 100w or 160w...Grape Solar had just released a 180w panel thru Home Depot. The panels is great. Thier packaging stinks. Of the 6 panels 2 came too bent to use. I ordered two replacement panels..One was passable...the other needed to be replaced. Hopefully, the next one I get I can accept and mount on my roof.

MPPT controllers work best at higher voltages. So my 12v output...needs 24v input to work best (it's actually getting over 42v from the panels... To achieve this...AND also stay within the capacity of my #6 solar prep wire...I have three "strings" of two panels. Each set of two panels are wired in series. This combines thier voltage...while keeping the amperage the same. Then each pairs output goes to the combiner box...the connection there is parallel. So the voltage remains the same...and the amperage becomes the sum of the three. If I want to later...I can add two more of the same panels to make a 4th string. That would bring me up to the limits of my controller, fuses, and wiring that I have used. I am going to test the 6 panels...to see how well they meet my needs before adding two more. I prefer to have some space to walk up there if I need to.

The positive lead that goes to the combiner has a 15 amp inline MC-4 fuse. This is to prevent the other strings from being able to backfwed a shorted panel...and exceeding the current capability of that panel. The fuse will interrupt the current before it becomes a fire hazard on the roof.

[C.Martin]

Well thats all there is to it. I did usd VHB tape for mounting...cleaned the fiberglass roof very well with alcohol...gently scrubbed with purple scotchbrite (not recommended for all types of VHB tape) and I elected to use an adhesion promotor...3M Primer. Full strength requires 72 hrs. I am happy to report...We drove 177 miles today and they are still up there.

After they are stuck down...you go back over sith Dicor to keep out the elements so hour tape doesn't deteriorate.

It has been difficult to get a performance measure...as the panels have been topping up and going into float before the sun gets up high enough to produce peak energy. I will do some test after programming my inverter's charger to stay idle longer. That way the solar might actually take long enough to allow the sun to get up higher in the sky.

[C.Martin]

That's the quick and dirty.

If you are planning on your own...it's important to know and understand the safety factors. They all use formulas...you plug in the Open Circuit voltage Voc and Short Circuit current..Isc. You will multiply times 1.2 or 1.25...and some breakers rated at 80% need another 1.25 or 1.56 of the original.

I recommend downloading the Magnum Energy manual for the PT-100. There is a whole section for planning with all of these formulas.

Hope you enjoyed the tour...

Open to answering questions ...if you have some that I can answer.

[vito.a]

Very nice.
Can I ask why you chose Grape 180w solar panels?
Also, is your battery charge controller MPPT?

[C.Martin]

Originally Posted by vito.a

Very nice.
Can I ask why you chose Grape 180w solar panels?
Also, is your battery charge controller MPPT?

Home Depot was offering them at a special price of $199 per 180 watt panel. Although I don't expect to see 180W...they did have good specs...although the high temperature performance will probably fall below the higher tier panels.

I especially like the fact that when UPS gives you a bent panel...it's easy to drive over to my local Home Depot to get the situation rectified.

Anywhere I would order a panel...I will have to deal with our UPS gorillas. You should have seen how they had them stacked...with other boxes on them at any old angle.

The charge controller is a MPPT. IF I were to run my own wires...I would have probably preferred to run a conduit with pairs of wires going down into the basement and used a combiner box with string circuit protection and GFCI protection all in one. Save that...heavy enough wire to run all my panels in parallel. I opted to go with the #6 wire that had already been run...so to get more potential from that wire...I decided for me...the series+parallel option would be better...and an MPPT controller would be necessary. Absent shading...this arrangement will produce more charge amperage than a PWM charge controller. If I get panels with shading...my performance will diminish.

[We_B_Tripn]

Well done! I will be subscribing for future reference.