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 > Project complete: 500w solar install, plus 2000w inverter

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SJ-Chris

San Jose, Ca

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Posted: 03/17/21 03:26pm Link  |  Quote  |  Print  |  Notify Moderator

Project complete: 500w solar install, plus 2000w inverter
(This is on one of my 2015 Thor Majestic 28a RVs)

I wanted to put this together in the hopes that some would find it helpful (...I know I've learned so much from these forums!).

Total cost:
- For the 500w solar:
$225 for the system, and another ~$150 in additional items
~$375 total
- For the 2000w inverter:
$240 for the inverter, and another $100 for cables, outlets, etc
~$340

Total time: ~20 hours

I finally had some free time to tackle this project...adding 500w of solar and a 2000w inverter. Happy to report that things seem to be working well. Here's what I did...

First, I wanted to start with a "clean canvas" (aka: roof). I had notice my Dicor caulking around my front/rear and also around the vents looked like it was starting to crack. I happened to have several gallons of Dicor roof sealant (step 1 and 2) from a previous RV I never got around to sealing, so I thought I'd start by resealing the roof. Here is a link to that project:

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30201452.cfm

With a clean canvas, it was time to start...

Background: My initial plan was to add 200-250w of solar on the roof, just to provide some modest boondocking capability. My RV has two 100AH Lead Acid (deep cycle) batteries (will be adding a 3rd battery soon). I also have a 4000w generator, but I hate running it while camping (…kills the peacefulness of the great outdoors). It is never my intention though to have a serious (large) battery bank and "live off the grid" for extended periods of time. I happened to be visiting Phoenix Arizona late last year and I had stumbled across SanTan Solar (www.SanTanSolar.com) (located in Gilbert, Az 10 minutes away) who sells used residential solar panels and all the components to make an RV solar setup. I had planned on buying a 250w system from them which included one 250w panel, an MPPT charge controller, fuse and a breaker, mounting hardware, and all the wiring (for $165). Seemed like a great price. Well, when I arrived I was surprised to see they were having a sale on their 250w panels and they were just $35 each(!). These are only 10 year old panels and I tested each of them. Soooo, I decided to bump my solar system up to 500w "just because". I was out the door with a complete 500w system with all the components for just $225 (two 250w panels required a bigger MPPT controller and one extra inline 15a fuse).

Here is a before picture of my roof:
[image]
On top of the AC is a disabled solar trickle charger that I will remove.

Advanced tip: Before I got started, I tested the entire system on the ground. Layed the two panels on the ground, connected the charge controller to the batteries, then connected the panels to the charge controller. Yep…everything seemed to work. I even did a test where I drained my batteries by ~80AH over night to see if the solar setup would properly do its thing. The test showed me that everything worked as planned. (I certainly didn’t want to attach some panels to the roof with tape and holes/screws, etc only to find out that the system wasn’t working). If you are doing a solar install, I would suggest you do the same.

I then started by mounting the two panels near the front of the RV. I wanted to make sure I had a pathway to walk between them. I also wanted them to be as far as reasonable from the AC to reduce any possible shading impact. My plan was to use five Z-brackets….Two on each side and one on the lead edge (front). I wanted to do everything possible to avoid these tearing off the roof while driving down the freeway at 65mph into a strong headwind. I used 3M VHB Tape between the bracket and the panel and between the bracket and the roof surface. For those who haven’t used 3M VHB tape before….it is STRONG. Since my roof is EPDM, I also bolted the brackets to the panel frame and bolted the brackets to the roof surface. Even though the VHB tape is strong, I would never trust it completely on its own (especially on an EPDM roof).

When I drilled the pilot holes for the brackets into the roof, I was a little surprised by how thin the plywood is. I can easily walk on my roof and it feels quite solid, so I thought it would be at least ¼” plywood, but honestly I think it is less. When I screwed the panels to the roof itself, I felt “okay” about the strength, but not great. I always try to think safety first, and I usually decide to overkill it rather than risk it. So, now the panels were VHB taped and screwed to the roof and I didn’t want to even attempt to take them off (…which I guess is a good sign that they were actually on there pretty good in the first place). So I bought some simple “L” brackets from Home Depot and I added 2 more brackets on the front leading edge and one on the rear edge. So in total, each panel has 8 brackets (16 screws total holding them down). Those panels seem like they are not going anywhere now!

[image]
I will probably hit them with another layer of Dicor and trim off those lengthy bolts.

Advanced tip for applying Dicor: After the panels were securely fastened to the roof (and once I retested the system to make sure it was properly working) it was time to use Dicor self leveling sealer/caulking. For a moment I wondered, “How am I going to apply this Dicor BEHIND the Z-brackets (underneath the panel). There is only about 1 inch of clearance between the roof and the panel framing. Then I came up with an idea… I bought a couple feet of plastic tubing (Like this: https://tinyurl.com/tubing4dicor) and a small hose clamp. Then I cut off a ~1 foot piece and fastened it to the end of the Dicor tube. Because this tubing comes wound up, it naturally has a curved bend to it. A one foot piece gave approximately a 180 degree bend. This made it simple for me to apply a healthy amount of Dicor BEHIND the bracket exactly where I wanted/needed to. [emoticon]

I wanted to keep all the wires very neat and tidy. So I used zip tie mounts in several places and zip ties. To keep the wires tidy underneath the panel itself (and not flapping around), here’s what I did:
[image]

I made sure I left a little bit of wire “slack” where the connections were made joining the two panels just in case I need to replace a fuse or possibly add another panel in the future (unlikely). Here is what the panels look like installed:

[image]
(I later Dicor’ed over the wire on the right coming from the panels down the right side of that picture).

[image]

When I put solar onto my other RV I plan on hitting this wire with another round of Dicor.

Because I am fairly certain I will never add more solar panels to this roof, I went with 10AWG wire. It is large enough to handle the ~16 max amps these panels could generate. I’ve got a ~40’ run to my solar charge controller, but 10AWG wire can do that with about a 3.5% drop in voltage. Remember…I only really needed 200-250w, so I didn’t need to worry about this relatively minor drop. I ran the wires down my refrigerator vent which was pretty convenient. During the stretch where the wire is running behind the refrigerator, I put it in electrical conduit and fixed it in place away from any hot components of the refrigerator cooling unit. From there, the wires went through the floor and popped out underneath the RV where I could route the wires (in flex conduit, wrapped in electrical tape) forward and to the driver’s side of the RV underneath the dinette seat. Zip-tied the wiring securely along the way. Under the driver side dinette…that’s where I put the solar charge controller and my 2000w inverter.

Side note: If you haven’t done this before, I highly recommend you grab 10-20 strong zip ties and you crawl all around underneath your RV. You will likely find PLENTY of wires you can secure better running all over underneath your RV.

From my 2000w inverter, I ran a parallel set (two positive/two negative) of 2/0 cables (~8’ long) to my battery connections (I’ll be adding a 3rd coach battery in the next couple of weeks). This should handle the large potential current draw from my batteries under the possible heavy load of the inverter. My inverter is mounted right next to my solar charge controller. From my solar charge controller, I have a ~2’ 6AWG wire (thickest that will fit in the solar charge controller) going to my inverter Pos/Neg posts (hence my batteries) with a resettable fuse in between (in case I want to disable the solar at any point while doing other work on the RV, etc). This makes my voltage drop between my solar controller and batteries pretty much negligible.

From my inverter, I created three 120v outlets (two near the dinette, and one all the way back in the bedroom). For the rear bedroom outlet, I used 14/2 outdoor Romex and put it in flexible conduit and routed it mostly underneath the RV fastening it with plenty of other wires running under there. Here is a picture of the outlet added at the dinette.
[image]

Here is my Aili battery monitor I installed previously. It now shows me that my 500w of solar constantly keeps my batteries at 100% [emoticon] If you don’t have a battery monitor, you should get one. It is the easiest way to know at all times what is happening with your batteries/solar/charging/etc. Very handy, and this one only costs ~$45.
[image]

For the places where I was going to be routing several wires (primarily under/through my dinette…Solar wires from the panels, 2 sets of thick cables from my inverter to the batteries, one wire in conduit to the rear bedroom outlet from inverter) I had to drill a sizable hole through the floor and out the bottom of the RV. I found that if I use a 1 5/8” drill bit it makes a nice size hole and then I use one of these 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes (https://www.homedepot.com/p/Everbilt-1-1-2-in-x-6-in-White-Plastic-Flanged-Strainer-Sink-Drain-Tailpiece-Extension-Tube-C9800/205154040) cut so that it sticks out about an inch out the bottom of the RV. I could glue this in place and it provides for a smooth exit out of the bottom of the RV (instead of rubbing on the metal undercoating that was drilled through. Once all the wires were done and the system was complete, I stuffed some steel wool inside this tubing so that it was about halfway between the floor and the bottom of the RV, and then I filled the rest (top and bottom) with some sealant foam (like this: https://www.homedepot.com/p/Loctite-TITE-FOAM-Window-and-Door-12-Fl-oz-Insulating-Spray-Foam-Sealant-2260115/302135916?ITC=AUC-62427-23-12140). This sealing (and steel wool) should make it rodent proof and air-tight.

Here is a fairly complete list of components:
- Two 250w residential panels (https://store.santansolar.com/product/santan-solar-t-series-250w/)
- Two 15amp inline MC4 fuses (Amazon.com: Renogy 15A Male and Female Connector Waterproof in-Line Fuse Holder w/Fuse, Black: Garden & Outdoor)
- One Y-branch MC4 parallel wire connector
- 40’ of 10AWG wire with MC4 connector ends
- Two 6”x16” screens from Home Depot to re-cover the refrigerator screen that I cut to gain access to drop the wires without having to pull the refrigerator (Gibraltar Building Products 14 in. x 6 in. Galvanized Steel 2-Way Reversible Vent-TW146-1/8 - The Home Depot)
- 5’ of electrical conduit to run behind the refrigerator to keep the wires away from the hot components of the cooling unit of the refrigerator
- Zip tie mounts and zip ties to keep the wires tidy along the way (https://www.amazon.com/gp/product/B07M69LTLJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 20’ of 2/0 cables to cut and double up and run two pairs from inverter to batteries (https://www.amazon.com/gp/product/B07FZWBKNZ/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1)
- Bag of copper lug connectors for making custom length cables (https://www.amazon.com/gp/product/B08R6TX3XM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
- Crimper tool for making custom length cables (https://www.amazon.com/gp/product/B07V6V7XZC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 5 tubes of Dicor self-leveling sealer
- 1’ plastic tubing and a small hose clamp (to apply Dicor BEHIND the Z-brackets)
- Two 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes
- Steel wool and foam sealant (to seal up any openings made in the bottom of the RV)
- Romex, 3 junction boxes and outlet receptacles and cover plates.
- Plenty of electrical tape
- 30 amp MPPT solar controller (https://store.santansolar.com/product/epever-3210-30a-mppt-solar-charge-controller/)
- 2000w Pure Sine Wave Inverter
- Two 40amp resettable fuses…one between solar panels and the controller, and one between the solar controller and the batteries. These are located right next to the solar controller so I can effectively enable/disable the solar anytime I need (https://www.amazon.com/gp/product/B07KF2PV6V/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 )
- Misc: Screws, washers, nuts, bolts

I didn’t really keep track of how many hours this project took me. Probably ~20 hours, which included lots of trips back and forth to Home Depot for misc items. I had fun (mostly) doing it, and learned a lot. The good news is that I’m putting another 400w solar system on my nearly identical Majestic 28a. While I was performing this current 500w install, I bought double the supplies/parts knowing that I have another one to do. I suspect I’ll be able to install the next solar system on my other RV in probably half the time now that I know all the tricks (and have all the components on hand). This was my first solar project and I’m very happy with the results. Can’t wait to head off-grid somewhere soon!

Happy Camping all!
Chris

* This post was last edited 03/17/21 08:26pm by SJ-Chris *   View edit history


San Jose, CA
Own two 2015 Thor Majestic 28a Class C RVs

Lwiddis

Monterey, California

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Posted: 03/17/21 03:40pm Link  |  Quote  |  Print  |  Notify Moderator

Very clear, detailed report. Excellent photos. Not sure why you used 10 gauge wire but it works for you.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watt solar-parallel & MPPT, Trojan T-125s. TALL flag pole. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist14 yr. Army vet-11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad


pianotuna

Regina, SK, Canada

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Posted: 03/17/21 04:12pm Link  |  Quote  |  Print  |  Notify Moderator

Hi,

Thanks for sharing your end results with us.

Are the panels in series or in parallel?

He chose the Epever 3210 30A MPPT Solar Charge Controller

https://store.santansolar.com/product/ep........r-3210-30a-mppt-solar-charge-controller/


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

jdc1

Rescue, Ca

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Posted: 03/17/21 04:31pm Link  |  Quote  |  Print  |  Notify Moderator

Nice set-up.

SJ-Chris

San Jose, Ca

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Posted: 03/17/21 05:23pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Hi,

Thanks for sharing your end results with us.

Are the panels in series or in parallel?

He chose the Epever 3210 30A MPPT Solar Charge Controller

https://store.santansolar.com/product/ep........r-3210-30a-mppt-solar-charge-controller/


Good question. I ran them parallel based on some videos I saw regarding shading and efficiency.

After I read your question, it made me wonder...I could run them in series. This would double the voltage and cut the current in half. My voltage drop % would go from ~3.5% down to ~0.86%. My current solar charge controller could handle this if I wanted, but it is not big enough of a difference for me to worry about doing for now. But what also occurred to me is that if I wanted to expand my system in the future to 1000w, I could run a 2x2 (parallel/series) setup and still use the same 10AWG wiring I have as the max current would still only be ~16amps. I would need to upgrade my solar charge controller to a larger output capability. I don't anticipate doing this, but just a thought.

Happy Camping!
Chris

SJ-Chris

San Jose, Ca

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Posted: 03/17/21 05:24pm Link  |  Quote  |  Print  |  Notify Moderator

jdc1 wrote:

Nice set-up.


Thanks!

I've learned a lot from these forums, so I want to give back whenever I can.

Happy Camping!
Chris

Lwiddis

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Posted: 03/17/21 05:32pm Link  |  Quote  |  Print  |  Notify Moderator

RV Tito did a video a while back showing no difference between parallel and in series.

time2roll

Southern California

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Posted: 03/17/21 07:10pm Link  |  Quote  |  Print  |  Notify Moderator

Beautiful work [emoticon]


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

2oldman

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Posted: 03/18/21 12:23pm Link  |  Quote  |  Print  |  Notify Moderator

SJ-Chris wrote:

.I could run them in series. This would double the voltage and cut the current in half. My voltage drop % would go from ~3.5% down to ~0.86%.
Nice job!

Yes, series cuts the wire size, the voltage loss and the combiner box. It isn't as big a deal with shade as you might think, provided your panels have bypass diodes. Inverters come in higher voltages too.

For your next install you may want to consider being able to tilt the panels. Makes a big difference in winter.

* This post was edited 03/18/21 03:00pm by 2oldman *

John&Joey

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Posted: 03/18/21 02:54pm Link  |  Quote  |  Print  |  Notify Moderator

What was the logic for running so much wire on top of the roof vs plunging inside?

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