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Old 02-24-2019, 12:49 PM   #1
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Micro Minnie DIY Solar Install

I've been researching solar install for a whole and finally last trip I completed my initial setup, so I thought I'd share.

Parts:

The goal:

I wanted to stat simple, with one panel, to evaluate durability, ease to remove, size, efficiency etc. I did not want to drill the roof. The primary need for the system was to top off the battery during the day when we are dry-camping, so I don't have to turn on/off the generator just to charge the battery.

Process:

After basic layout and measure, I washed a section of the rubber roof well and let it dry. I used strips of the rubber tape to establish adhering base between the panel and the roof. I then used the mounting tape between the rubber tape and the solar panels. I used some more rubber tape to strengthen the front edge, concerned that wind might affect it most. Finally I covered all edges with the white UV resistant duct tape.

I soldered my own cables to the battery with the MC4 connectors and the 12AWG silicone wire and mounted those with the sticky mounts down the front of the trailer towards the battery.

I installed the SAE connectors to the battery and to the charge controller. On the battery side, I used the 60A circuit breaker and the copper lugs.

First plugged the battery side to the charge controller, once it booted up and all looked normal, I connected the solar panels. SEA connectors are easy to work with, hard to flip polarity and weather-proof. On a sunny (SoCal) day I easily get 3 to 4 amps of charing most of the day. Cloudy I still get 1+ amps. Which keeps the battery topped off during daily use (water pump, lights, fans, even sound and USB charging)

For now, I unpack/plug the charge controller when we get to the site and put it back in when we leave. Again the SEA connectors are great. I have a spare AMG battery we use for charging drones and other mobile tasks that also has SAE, super nice to just plug the solar charger to it when we get back to camp.

The final result:
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Future plans:

I'll give the panel a few months to make sure it holds. I want to check if the rubber tape/mounting is easy to remove without damaging the roof. If all is well:
  • Enclosed box for the charge controller
  • More panels. I can easily fit 4, might even go for 6. Two pairs - parallel and serial
  • MPPT charge controller for the extra efficiency
  • Bigger trailer battery - deep cycle AGM, 120MAH+
  • Pure sine inverter, hoping for 1200W/2400W(peak) to keep basic AC stuff running like TV, coffee grinder, etc.

Let me know what you all think, feedback in any form is appreciated.
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Old 02-24-2019, 01:55 PM   #2
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Good planning.
Thoughts:
-- With panels on the roof it is not just the horizontal wind you have to contend with. Especially at the front part of the trailer there is a pretty good vacuum created as the wind hitting the front pushes up and over the top of the roof and then hits back down some several feet back. Just use that in planning on fastening down the panels.
-- When you do add additional panels, use a wire size calculator such as: Voltage Drop Calculator - for single and 3 phase ac systems and dc systems
It is best to size the wire for 1% loss. 12 gauge wire is too small for extra panels.
-- Consider larger panels, such as a 250watt or 325 watt panel. They produce the higher voltage needed for the MPPT controller and may be cheaper than multiple small panels. Space on the roof will dictate what can be used.
-- I know you don't want to put holes in the roof. However panels w/o any air space between the panel and the roof get hot and produce less power than those with air space for cooling.
-- Look at going with a pair of 6V golf cart batteries. That will give you about 220AH. They are about $90 each from Sam's Club or Costco. Mounted in a box on the hitch they will be easy to maintain the water level in the batteries and give excellent service. No need for expensive AGM unless you are going to put the batteries in an unvented box inside the trailer.
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Old 02-24-2019, 01:59 PM   #3
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Looks good!

We didn't do our research and just bought a two-panel 200W starter kit with a 30 amp controller;

https://www.amazon.com/Renogy-Monocr.../dp/B0718ZYX6Z And a couple of 30 amp breakers.

It does have Bluetooth but we still haven't figured out all the readings and setting in the App.

We used VHB tape on the fiberglass roof along with Dicor over the top of the brackets.

We also bought two new 6V deep cycle batteries.
All of which will we add to our labor and file for the Federal Tax Credit this year.

But we have already determined that we may need to upgrade to 300 or 400 watts later this year. The more the better!
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Old 02-24-2019, 02:39 PM   #4
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Fiberglass roof would be much easier to mount, I saw the difference with the front wall compared to the rubber roof. It is very hard to adhere to the rubber roof, and if something does stick to it I am concerned it will pull the rubber if I try to remove it. I have to look into the 6V batteries, few folks are suggesting them.

I was not planning on Tax Credits, didn't know anything like that applies to RV, do you have more info or links? How much do you expect to get from it? Thanks!
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Old 02-24-2019, 02:50 PM   #5
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Wow, al1florida thanks! Awesome ideas. I am around 1-2% voltage drop right now, which is not too bad, but yeah I was planning on going 10 AWG, shorter cables and even maybe running another set of wires in parallel to the charger. Was going to do another panel in series for 36v idle voltage first to offset the drop, especially with MPPT.

Do you have recommendation for larger panels? There is space on the roof so that might be the way to go. I just didn't want to go big starting up as I learned the quirks with solar setup.

Great tip on the 6V batteries. I assume you split them in two groups in series to get to 12V?

Roof drilling is my biggest scare. I have background in electronics so that part is less scary, but mechanical work, especially something so critical terrifies me. Thanks for the info on the vacuum, didn't know that. We often get good amount of wind, tho probably less than the steady 55mph when towing, so I didn't want to risk panels lifting/ripping with a gap. Do you recommend to drill yourself or is there a good professional service place that can do that, without voiding warranty etc.?

Last question: When setting up an inverter, I was hoping I can just plug it in the AC port of the trailer. However, the trailer has a built-in battery charger. Is there a concern of the current circulating back, any type of weird feedback loop, other than some loss of efficiency of the system trying to charge itself?
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Old 02-24-2019, 03:09 PM   #6
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Quote:
Originally Posted by jaisor View Post
Fiberglass roof would be much easier to mount, I saw the difference with the front wall compared to the rubber roof. It is very hard to adhere to the rubber roof, and if something does stick to it I am concerned it will pull the rubber if I try to remove it. I have to look into the 6V batteries, few folks are suggesting them.

I was not planning on Tax Credits, didn't know anything like that applies to RV, do you have more info or links? How much do you expect to get from it? Thanks!
Our last RV had a rubber roof and it was a lot different. Our first motorhome had a smooth aluminum roof!

http://www.winnieowners.com/forums/f...it-353693.html

Not sure how much we will claim for labor. There's still time to 'create and inflate' our labor costs.
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Old 02-25-2019, 08:10 AM   #7
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Quote:
Originally Posted by jaisor View Post
Wow, al1florida thanks! Awesome ideas. I am around 1-2% voltage drop right now, which is not too bad, but yeah I was planning on going 10 AWG, shorter cables and even maybe running another set of wires in parallel to the charger. Was going to do another panel in series for 36v idle voltage first to offset the drop, especially with MPPT.

Do you have recommendation for larger panels? There is space on the roof so that might be the way to go. I just didn't want to go big starting up as I learned the quirks with solar setup.

Great tip on the 6V batteries. I assume you split them in two groups in series to get to 12V?

Roof drilling is my biggest scare. I have background in electronics so that part is less scary, but mechanical work, especially something so critical terrifies me. Thanks for the info on the vacuum, didn't know that. We often get good amount of wind, tho probably less than the steady 55mph when towing, so I didn't want to risk panels lifting/ripping with a gap. Do you recommend to drill yourself or is there a good professional service place that can do that, without voiding warranty etc.?

Last question: When setting up an inverter, I was hoping I can just plug it in the AC port of the trailer. However, the trailer has a built-in battery charger. Is there a concern of the current circulating back, any type of weird feedback loop, other than some loss of efficiency of the system trying to charge itself?
I bought my panels in 2016, as well as inverter and solar controller from Northern AZ Sun & Wind. My RV was 30' long so I had room for two 325watt panels like these: https://www.solar-electric.com/resid...price_per_watt
I do have to mention the shipping costs on the large panels are higher since they have to be shipped via freight. They are too large for UPS, etc. However the shipping costs are much less if you are willing to pick up the panels at the freight company loading dock. The last few miles to your house generally costs $130 or more and then they just drop the pallet on your driveway. The shipping for my panels was $138 as I picked them up at the freight office. It would have been closer to $300 if I had them delivered to the house.
Yes with 6V batteries, you wire two 6V batteries in series to make a 12V battery pack. Note that when batteries are wired in series the voltage adds, but the amp hours (AH) don't add. Same with solar panels. Also miss matching voltage or current on solar panels defaults to the lower number.
About wires, I would go with #8 or #6 depending on what the wire size calculator shows. Or as you mentioned, run a second set of #10 wire. If you go with #8 or #6, go to Amazon and search for welding wire(cable). It is so much more flexible, much, much easier to work with.
I dont know what to say about the rubber roof. On my 3 RVs I have installed solar panels on, all have had fiberglass roofs. Much easier to work with and when I have removed solar panels or Sat TV dishes I just patch the holes with Bondo and some white paint.
What I use to attach the Z brackets to the roof is: https://www.amazon.com/120-Pieces-Drilling-Drywall-Capacity/dp/B075QM4FYQ/ref=sr_1_10?crid=3U3DP3UP3D9TZ&keywords=drywall+an chors&qid=1551094208&s=gateway&sprefix=anchors%2Ca ps%2C239&sr=8-10 The shank on these anchors is 5/16 in diameter so instead of using the self drilling ability I first drill a 5/16 hole to keep from tearing up the very thin Lauan board. Before I insert the anchors I put a squirt of Dicor in the hole. When I install the panels with Z brackets attached I first lay down a layer of Dicor for under the brackets, then once the screws are tightened, I cover them with Dicor.
The last RV I installed the large 66 by 52 325 watt panels on, I used the above method to attach them to the roof. I put over 40,000 miles on the RV and panels, including about 600 miles of gravel road and minor pot holes on our Alaska trip. Note, the gravel road was not the AK Hwy or the Cassiar Hwy to/from Alaska.
I cant see that drilling holes in the roof will void the warrant unless your holes leak. Sealing with Dicor will prevent leaks.
One of the things I love about Dicor is it never hardens, it is always flexible. Additionally, at least with fiberglass roof, the Dicor comes off with paint thinner. However you cant use paint thinner on a rubber roof.
I have always hard wired my inverters and used a combination inverter/charger. Many converters which come with RVs are single stage chargers which take a very long time to charge batteries, like 24 hours for a battery 50% discharged. You really want the 3 stage charger for dry camping or boondocking.
You must disconnect the converter if you charge with the inverter/charger. Otherwise the 120V from the inverter will go to the converter which will charge the battery which is feeding the inverter and you get into a loop.
I know you are experienced with electrical stuff, but there are a lot of unique details with RV electrical systems, battery charging and solar.
So here are some links with great info. Even if you already have knowledge about this, it never hurts to read more about it.
The 12volt Side of Life (Part 1) Be sure to click on the link to part 2 at the bottom of the above link.
RV Electrical
http://handybobsolar.wordpress.com/t...ging-puzzle-2/
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Old 02-25-2019, 07:01 PM   #8
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al1florida thanks again for the awesome detailed info, tips and links, much appreciated!
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Old 02-25-2019, 07:30 PM   #9
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Quote:
Originally Posted by jaisor View Post
al1florida thanks again for the awesome detailed info, tips and links, much appreciated!
You are quite welcome.
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Old 02-26-2019, 09:04 AM   #10
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Since 2019 is the last year for a 30% credit, you should plan on upgrading before the end of the year. In 2020 it drops to 26%, to 22% in 2021 and expires 12/31/2021. Hopefully there will be something new in 2022 but who knows?

You can claim the full amount of your purchase and installation in the year you spend the money but you can't place a value on your own labor. Here's the info on the tax credit:

http://www.winnieowners.com/forums/f...it-353693.html

Note that this is a credit, not a deduction, so you don't have to itemize deductions to receive it. You just need to complete a very simple form.
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Old 02-26-2019, 10:01 AM   #11
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Our RV came with an OEM Solar system. It cost something like $850 on the RV's invoice. I added some more panels for $250 and we submitted the $1100 cost on my 2017 1040. This actually saved more than the cost of the two new panels in total. So, WIN!

As to holes in the roof. Don't worry!! It's no biggy if you are careful and don't make any holes bigger than needed. For solar panels it's simple - put down a blob of Dicor, put the solar panel mounting bracket into the Dicor, screw in a short 1/2" or so wood screw so that you're screwing through the Dicor. Then when done liberally coat the top of the bracket with Dicor covering ALL of the screws. Done.

Running wires from the roof to inside takes a lot of preplanning unless you can use an existing hole in the roof. Those with RV fridges use the Fridge vent. In the past I've used the hole where my TV antenna came into the RV. On my newest motorhome I just measured 10 times and drilled a small whole just behind the front cap into the space behind the front cap and into the cabinets that were installed there.

You simply make sure that any hole is Dicored good both under any cover plate and then over the screws. There must be hundreds of Youtube videos on this process.

You should also expect that frame mounted glass solar panels are more efficient and will last 10 times as long as "flexible" flat mount solar panels. There are many Youtube videos about this as well.

Here's one:
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Old 01-28-2020, 11:01 AM   #12
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solar watts

How many watts do you need to maintain two 12 volt batteries?
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Old 01-28-2020, 02:25 PM   #13
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Quote:
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How many watts do you need to maintain two 12 volt batteries?
There is no one answer to that question. Your question is missing usage info, battery amp hours, amount of sun, amount of rain/snow, a dozen things that make each day of charging with solar a special day.

100w will keep fully charged batteries all charged if there is plenty of sun and no obstructions and zero parasitic load.

600w is not enough to charge fully discharged batteries with 1 foot of snow on the panels.

Here's two ways of getting this info:

1. get a Battery Monitor Kit and track your usage over time to know how much power you require in a day. Then attempt to size your batteries and your solar system to meet that need.

OR

2. Put a couple hundred watts of solar on your roof and go camping and see how it does. Then you'll have some real answers based on your actual usage and location.

We have 4-100aH 12v batteries and 300w of Solar panels. We live in South Texas where it's pretty darn sunny. I have a Battery Monitor Kit installed and I know that my batteries stay completely charged in storage all the time. When boondocking with a residential fridge and running the heater at night we use about 30% of our battery charge overnight and on sunny days the panels can get my battery bank up to full charge by about noon.

So, you see there is not one single answer to your question.
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Old 01-28-2020, 03:48 PM   #14
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A good place to start is to have at least as many watts of solar as you have AH (Amp Hours) of battery.
To determine how many AH of battery you have, go to this link and look for the group sizes.
Common sizes are:
24: 70-80AH
27: 80-90AH
31: 110-125AH

The number of watts of solar I gave above is roughly based on only discharging (using) about 20% to 25% of the battery by the time the sun is up high enough to start doing some decent amount of solar panel output. That is generally 9am to 10am and continuing to about 2pm to 3pm. That is full sun conditions from about early April to early October.
If you discharge more than 20-25% you need more solar or run a generator for 1-3 hours early in the day to get some charge back in your batteries.

As was mentioned in an earlier reply a battery monitor is an absolute must if you are going to do more than 2-3 days of dry camping before going back on shore power.
A battery monitor that a lot of RV'ers use is a Trimetric Battery Monitors - Bogart Engineering

I have been using the Trimetric I have for the last 12 years, moving it between my last 4 RV's.
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