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Topic: Seeking advice on several solar install aspects... (Read 2638 times) previous topic - next topic

Re: Seeking advice on several solar install aspects...

Reply #20 –
Quote from: Pierce & Gaylie Stewart –
In my opinion, tilting the panels is not necessary. Even if you tilt them. the sun will only be perpendicular for a moment during the day.
I have found that the sun is so low on the horizon during the winter that tilting the panels moves the needle quite a bit for us. This is with 740 watts + AGM batteries that don't charge as quickly (on our 5er).

Re: Seeking advice on several solar install aspects...

Reply #21 –
Quote from: Pierce & Gaylie Stewart –
In my opinion, tilting the panels is not necessary. Even if you tilt them. the sun will only be perpendicular for a moment during the day.

Except in this case where OP needs a means to create a path to the A/C units, etc. on the roof for servicing (and also for cleaning the panels).  With the proposed layout, if they are fixed, he cannot walk on the roof at all.

Re: Seeking advice on several solar install aspects...

Reply #22 –

Thanks Roger - all the parts are currently sitting here waiting for install, so the die has been cast, so to speak ;-)  part of the process of coming to our current plan was after taking comments like yours into careful consideration.  We went thru this planning process with our previous 500sf home when we had solar installed on it as well - it always generated much more than we had planned for or used, though that was in Hawaii and angled properly on a roof ... in a city that saw over 80 inches of rain a year (lots of cloudy days).

Our energy usage on our rig is based on 1/2 of our summertime residential use  while running a 14k window A/C 24/7 and all electric appliances (30kw/daily) in a 2500sf home-so I planned for a 20kw battery bank, running from 20-80% capacity daily with 15kw solar collection capacity, based on 5 hrs of sun exposure during peak of summer months when it will most likely be needed (where we work in the summer time it can be 110°-115°f) - I know that getting full capacity in reality will be "rare" and I do plan to install an 8k window A/C unit in our rig - not planning on the roof top air if the generator is not running.  The areas we work in 90% of the time have either no power or 15 amp on a looong extension cord (I set our inverter/charger to not draw more than 10 amps from shore power so we don't trip circuits when we are plugged in)  -  No residential fridge, running on LP but cooking is mostly electric (Induction/instant pot, toaster oven, etc... very little microwave)  For most of the year when sun exposure is much more limited (like right now)I would only expect 1-2 hours at most, our usage will be much lower and the extra battery capacity will give us multiple cloudy day use between solar/generator recharging.

This is our home, and I didn't want power to be a limiting factor, at least as much as possible.

So, that was the reasoning behind all this - I started thinking about this over a year ago (oddly, just before the covid issue came up) and when we spent 2 months, during the first shutdown last March, in our truck camper travelling to visit my parents on the east coast it confirmed to us that we wanted to move back into a much smaller living space and spend more time with both my Father in Law and my parents who live on the West & East coasts respectively.  God seems to be honoring this decision and allowing our work to expand geographically which makes this possible for us.

Grateful for your thoughts - can't tell you how many times I have scrapped my whole plan and started over from scratch during the last 6 months, but now it's time to move forward and let planning and reality meet (Collide?) :-)

Aloha, Tim

Quote from: Roger & Susan in Home2 –
There are many VHB tape variants, all have specific application objectives.  I used 5952 based on the advice I got from 3M friends who worked in the Automotive Divison.  It is a bit thicker, more adaptable to slightly irregular surfaces and slightly misaligned surfces (not quite parallel).  It has a 91 psi tensile strength and very good shear strength.

Amazon.com: 3M VHB Heavy Duty Mounting Tape 5952, 1.5" width x 5yd length (1...

This is the recommended surface cleaner/adhesion promoter. Petroleum based solvents are inot appropriate, they interfere with the bonding process.
Amazon.com: 3M 111 Clear Tape Primer - Liquid Bottle - For Use With 3M VHB...

A very light sanding with 320 or 400 grit paper where the mounts attach is sufficient.  Put the mounts on the oanel and put the panel in place. Blue tape around each mounting point, prep where the tape goes, don't forget the mount itself.  Tape on the roof, roll with a J roller, remove backing film and place the panel.  Press down firmly and let it sit over night.  Remove the panel from the mounts and caulk all four sides of the mount/roof intersection with 3M 4000 UV adhesive/sealant caulk.

I used 12"x1.75"x3" aluminum angles at each corner. The angles were bent at 92° to account fot the curvatur of the roof and the width of the panels so the they sat flat on the roof and the flanges are parallel to the sides of the panels.  The angle changes woth panel size. This gives me more than 6,500 pounds holding on each panel.  I think a 6" long one in each corner would be sufficient.

I removed and repositioned one panel. It was an all day job, tape and caulk are very tough.

Do your energy balance math again.  How much power do you use each day? What is the range between min and max?  How much battery capacity do you have? Are you running an LP refrig or residential?  Almost no one has sufficient battery or inverter capacity to run AC for any length of time so don't plan on it.    For most with a residential refrig, typical use will be about 3200 watts per day +/- a lot depending on user.  Without a residential closer to 1800 watts per day.  Same +/- specs.

Back of the envelope numbers are 1600 watts of non tilting panels on the roof of your coach will get you about 3200 watts or more on 1/2 of the days of the year.  A 1/4 of the year you will get an average of about 2,400.  The rest of the year will average about 1600 watts per day.  Where you are, what direction you are pointing, shade, clouds all make a difference.  Solar panels mounted on a motorhome are not ideal.  Tilting is dangerous, add more panels instead. 

Leave room to get around on the roof for normal service and maint. 

Panels in parallel are going to get you the maximum output especially relative to shade.  Each panel should be fused. I used 8 and 10 ga UV rated solar panel cables for ech panel, run them down behind the refrig through the ref vent, through the floor to a fuse block then to solar charger.  Output should be fused and switched to the batteries. At that end it should be fused as well. 

Your panels can be 2-2 1/2 " off the roof (room for getting your hand underneath). Any shading due to AC covers is minimal at most during most of the year.  When sun angles are so low that the AC cover's shade is an issue everything else will be worse.

I have 1200 watts now and will likely add 2 more 60 cell panels to get closer to 1900 watts and still have adequate access. They will add about 2 months to the time each year where we can be land line and generator independent.  All bets are off if you get a week of rain.

If you don't have to do this now maybe us the coach for a year or so and learn how it works and you do in it.  Good idea for almost everything.

Roger
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Re: Seeking advice on several solar install aspects...

Reply #23 –
I have 1400 Watts supposedly on the roof put in by two previous owners and AM solar did the final install with the controller and wiring including the lithium ion batteries. All of that is mounted where are the washer dryer used to be in the bathroom.
The panels were mounted using VHB tape and I have had one or two mounts come loose and need to be remounted. I strongly strongly strongly advise not to use the layout as you propose. there will be times when you will need to get up on that roof and you have no room to move around with that layout you will find that unscrewing the panels and lifting them up will be a major hassle for short trips up there. as it is it's dodgy getting around my roof but at least I can put my feet down in between the panels and things like the vents and air conditioners. with your proposed layout you will not have that ability and it will take you time to unscrew them and how are you going to get to the other side of the panel to unscrew it without standing or putting some kind of weight down on it?
As far as putting your controller and wiring underneath the couch I guess that would be a good place to do it but you do have a heater under there I expect. I also have my subwoofer there and the center drawer so there's not a whole lot of space under there now. If you do have a washer dryer in the bathroom and you don't use it much consider putting it in there or in the space above it if you have a similar arrangement as I do. That would make it much easier to run your wires. And if you decide to go with lithium, 600 amp hours plus a 3000 watt inverter plus a solar mppt controller and the BMS all fits in there nicely and there is a vented door and an air condition duct above it that can be blown into it to help cool things when you're charging. That's the way my previous owner did it with AM solar and I'm quite happy with that arrangement. Would I like to have more solder on the roof? yes. would I like to have less space to walk around in absolutely not. Why I don't like going on the roof often I've had to go up there several times in the last year to clean it to change out a fan and next year to paint it. When I do that I may change out some of my panels for newer ones with better energy density but I will be very mindful of being able to walk from the back of the roof to the front without having to tilt the panels or unscrew them. If you do want additional solar you could always take them out of the Bay and hook them up and tilt them on the side of the coach. A cable lock from the wheels to the back of the panels would secure them from theft. You couldn't add 3 320 w panels that way and just slide them into your Joey bed when not needed.
Anyway just a thought. Good luck on your install.
Bob

Re: Seeking advice on several solar install aspects...

Reply #24 –
Easy to run panel cables down behind refrig, through the floor to fuse block and charge controller above the water pump.  From there easy connections to battery points.  Your coach may have a different floor plan than mine but plan your use space carefully.

Mount parts on a panel and then the panel to the wall.

Re: Seeking advice on several solar install aspects...

Reply #25 –
This is my layout on the roof currently taken from just behind the rear air conditioner. There's room for additional panels while still having a space to move around or I could go with higher wattage panels to replace some of my lower wattage older panels and still have room.

Re: Seeking advice on several solar install aspects...

Reply #26 –
This is my 2030 watt set up.

final solar upgrad.

Re: Seeking advice on several solar install aspects...

Reply #27 –
Kidspot, the links below to my approx 1800 watt system may be of help to you, or maybe to others that follow your awesum solar install.

Be careful with your high voltage, you are not dealing with a more safe 12 or 24 volts anymore.

Reply #2
3M VHS tape, brackets, wire, misc parts 2019
Adding solar

Reply #4
added used 600 W, now 1800W in 2019 for $220
Solar Upgrade

Reply #26
Calculating mixed panels 1200 W 2018
Solar Battery Charging

Pictures of my 1200 watts, 4 LG panels  2017
Shared album - John Lewis - Google Photos

Re: Seeking advice on several solar install aspects...

Reply #28 –
Quote from: Elliott –
I have found that the sun is so low on the horizon during the winter that tilting the panels moves the needle quite a bit for us. This is with 740 watts + AGM batteries that don't charge as quickly (on our 5er).
True for me too with 720 watts. I get 9 extra amps from tilting my 3 panels. The extra amps help on those short winter days. I also park east west when possible to get the most out of the southern sun.

see ya
ken

Re: Seeking advice on several solar install aspects...

Reply #29 –
Thanks for the great pictures and reference links - there are some great systems out there.

btw - I realized if roof access becomes more important than power we can always remove 2-4 panels and ground mount them - the mounts will just be in place, should they ever go back up on the roof and I'll just feed them into the charge controller from the ground - been considering a remote 45 amp powerpole connection for future expansion anyway - I've got lots on hand to do that with. 

Grateful for all the shared wisdom from y'all - many thanks - I started mounting the 3 charge controllers yesterday to a big piece of aluminum (From the old TV mounted up front) to help with heat dissipation.  and hoping to start getting the other components installed inside next week so they are ready for the panels & batteries - I'll keep you posted of the progress (I'll start a new thread for the actual project) 

Thanks again, Tim

Re: Seeking advice on several solar install aspects...

Reply #30 –

This is an update to my reply #27 in this thread.  After seeing the following video of a solar fail, I wanted to post what I noticed when I did my install.  Also please note I recommend nothing in the following video except, to see how not to install brackets.  It includes a good warning to definitely use larger washers, and also shows a possible shortcoming of using too few inexpensive aluminum brackets compared to the more expensive stainless steel brackets sold by AM Solar.

All VHS is not the same, do your own research.  It is easy to find the 3M spec chart for various VHB 3M tape, which I checked and 4950 excelled in adherence.  Also AM Solar used 4950, included with the stainless steel brackets I purchased from them.  I used a combination of the brackets,  Eight less expensive aluminum brackets on each panel in the rear, with large backing washers, and six stainless steel on each of the front panels, as I did my solar install over a period of two years.  This you can see in my previous reply #27 in this thread.  The front two panels are mounted using six brackets each of the stainless steel AMSolar brackets  I did this following their recommendation because of the size of the panels I used.  After seeing this video below, I am glad I did.  I used primarily VHB 4950 tape only.  I use screws only on the center, side brackets of the front two panels, as they due to the curvature of the roof there, appeared to need them.

He admitted failure due to using only eight brackets total, to hold down three panels, that is fewer than three per panel, which created nothing less that a big sail to be ripped from his roof.  Stainless steel would have helped, however even AM Solar recommended not using too few brackets.

3M 4950/WI15 Scotch 4950 VHB Tape: 1" x 15 ft, White
Amazon.com: 3M 4950/WI15 Scotch 4950 VHB Tape: 1" x 15 ft, White: Industrial...

AMSolar stainless brackets.
Mounting Hardware

My 1200W solar panels before adding another 600W.
Shared album - John Lewis - Google Photos

https://youtu.be/hCtmycZ4zZM


 

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Re: Seeking advice on several solar install aspects...

Reply #31 –
Jack, the only thing that is obvious from this video is a failure to prep the surfaces correctly.  When I moved one of my panels I had to cut the caulk off and use a wire saw to cut through the VHB tape and then an half hour or so on each corner to get all,of the remnants of tape off.  If this guy's mounts tore off leaving. Ot VHB tape residue, even the ones with screws then they were done improperly. 

Re: Seeking advice on several solar install aspects...

Reply #32 –
That's why I used a stud finder and drilled into the aluminum tubing below to mount the panels. The commercial panels should have at least three mounts on each side of the panel. That goes for the shorter 65 inch panels too.

With just two mounts on a side, if a panel lifts in the front, it will rotate up and destroy any kind of mount in the back of the panel. The middle mount really help distribute the load.

Pierce