Have any of you solar pros run across safety or code issues with a higher than 40 volt output? Something less than 40 volts not requiring a permit?
My buddy normally only puts on rv voltage type systems. He mentions safety. Wind issues from a 61"x41" panel size? How many mounts needed stuff maybe.
He admits a higher voltage setup with the smaller wires would be better. But worried about safety and legalities. Should he be?
My power trace solar controller has a mid 80's volt mppt input needed. 60 volt minimum.
What kind of wind ratings are available?
Bob, you are aware we are talking about DC voltage. Not near as dangerous as A/C
Yes I know it's dc. A 360 watt panel puts out how many amps?
Crane man may need to talk to you as you are local.
I don't worry much about it as all my wire is fuse protected. Mine Are a bit over 73 volts ea 51"x81"doubt there are any "codes" to follow other than proper wire size and fusing as stated in the NEC ( National electric code) As far as anything flying off the top and damaging something, that liability going to belong to the owner I would imagine.
I dont remember now what the amps are on mine but one side is in the 70v range.. as for permits.. not sure what address to use for mine as sometimes its at the house sometimes its at the church where I park it and for the last 3 months its been down the street from my shop so I can use it to rest if needed after my back surgery..
Or it could be boondocking at the lake.. Wonder if it needs to be a moving permit included with the install permit..
4 mounting tabs ..1 on each corner... VHB tape holding them down.. have been in 50-60 mph wind while driving at 60 - 70 mph.... They are still on the coach... that tape is amazing.. did I mention the panels are huge?
Most are 36 to 40 volts and can produce up to 7 or 8 amps.
What do you mean when you say your solar controller needs 60 volts min. and mid 80's volt input?
I have the same question as jcus. What is the brand, model, and model number of your solar controller?
Mine is 36.6v @ 8amps each panel
Magnum pt100.
You wired your panels to get to 70 volts?
2 panels parallel and 2 panels in series
My four 300 watt panels have a nominal output voltage of 36 volts DC, very common. In a perfect world they can put out as much as 90 amps but that is never going to happen. Open circuit voltage can be 150 volts DC. Most contollers have a maximum voltage for use with panels in series. My panels are wired in parallel and individually fused before the solar controller. The output of the solar controller is also fused and switched.
Each panel has a 1-3/4"x12" mount at each corner with 1.5"x12" VHB tape. Use the VHB tape adhesion promoter/cleaner on the roof and the mount. Each mount is caulked with 3M Fast Cure 4000UV. No screws needed. Panels are bolted to the mounts with 5/16 SS bolts, washers and nylock nuts. Wires are 8ga UV protected outdoor solar cables. They go through the refrigerator vent and through the floor to the fuses, solar controler, more fuses and a switch.
Commercial panels are rated to at least 90 mph. 1.5"x12"x4 VHB tape is rated at over 6500 lbs (91 psi). Plenty of safety margin.
If you wire your panels in series voltage goes up but current does not, so you can use smaller wires after the combining ooint.Each panel wired in parallel and individually fused to the combing point can use #8 or #10 wires. Once to the combining point then whether on the roof or in the basement you need significantly bigger wire to the solar controller. And the probably bigger still to the batteries. There is not much money to save on wire from the panel to the combining point bu using smaller wire compared to all of the other costs, only voltage losses.
Generally, wired in parallel reduces the impact of shade on a single panel.
A well planned solar install is a relatively straight forward DIY project. There are lots of things you can learn from others who have done it but there are lots of great resources out there to help you understand what it does and how it works so that you can make quality choices for yourself based on your own knowledge.
Its not just having the solar but getting it into the batteries also... Good Charge controller is important. I have 2.. 1 for each set of panels. Just in case one fails
Read the spec's, where did you get the 40 and 80 volt figures? Looks like for MPPT operation, needs between 60 and 187 volt input. That means you probably need to run some big panels in series to get that min. of 60 volts. Seems strange to me, most of the mppt controllers I have seen only require 18 or so volts to work. If one panel was shaded, might have a problem making that 60 volts.
Roger, do you have a picture of the panel mount that you used?
Thanks Steve
Magnum pt100 is a residential unit. My buddy mentioned 70mph road speed and a 70 mph wind. Will they stay on? He bolts them on. Orders the tape mount without the tape
The panels I have been looking at are 22 plus efficiency and higher voltage.
41x61 inches, 360 watts
Easier wiring at higher voltages I understand.
Panels way more money. Crane man needs to show me his. Will drive....
Makes sense for very big panels, at a house. Not very practical for a motorhome. Have used VHB to hold the panels down, on last 4 coaches, with no problems. You can design a solar system for your house and know whether or not you will have shade from trees etc, but in a motorhome will never know when you will have partial shading. Would recommend a different controller.
Considering high efficiency panels for more power at the same size or less. Can anyone here high powered solar setups get to 100 amps dc to the batteries? What efficiency panels are you using?
My local metal bender makes them for me. About $10 per corner for the aluminum parts. The part that sticks on the roof is bent to 92° to get good contact with the curving roof and stay square to the panel.
The panels have 2 holes about 10" apart at each corner, pretty standard for commercial panels. The smaller 90° piece lets you set the offset from the roof at any height you want. The vertical part of the roof mounted bracket captures the panel side to side. Removing the bolts from the bracket to the panel lets you remove the panel without upsetting the bracket mounted to the roof.
An RV roof top solar application with maybe 1500 watts or more with the coach oriented perfectly and panels tilted to the exact angle needed for the location which would likely have to be at higher elevations and cooler temps might hit 100 amps to the battery for a very short time. In the real world probably never.
With three panels (900 watts) we have peaked at 5.1Kw in a single day. Maybe peaked at 50 amps. Averaged less than 40. One day, one time.
Typical performance for 1200 watts is going to be 2.4 Kw per day over a year. Less in the winter, more in the summer. Very location dependent.
You need to be very realistic in your expectations, know your usage and design accordingly. Your ability to get through the night and still have a 75% SOC in the morning to maximize battery life depends on battery capacity more than solar capacity.
Thanks for all your input. My thought was to max the amps so I can come closer to 1/5c charging.
With 1/5 th C as the design idea if a system can be made then the battery choices expand,
I have less objections to Lifeline agm's IF I can get to 1/5th C reliably.
The 255 amp hours with four batteries would be 90% of five gels at 225.
Plus 2 hour recharge versus 3 1/2
Tempted to go all in and use high voltage high efficiency residential type panels,
Way back of my mind is a residential refer setup for a prepper.
Extended use. No gen. Not limited by the 192 gallon fuel tank @ .44 gph.
Weird I know. Absolutely no need. Right? Maybe
More hassle and money is the balancing point. If you knew for sure you would need it most would do this?
Bob, why 100 amps? Considering the 22% efficiency panels cost close to twice the price of 16% efficiency panels, are you sure you need them? Most of us get by with 1200 to 1500 watts, even with residential fridges. If you had lithium that could take 100 amps till batteries were 100% SOC, would be a consideration, but with the lower amps necessary on absorption stage on gel cells, a different situation, and for me would not be worth the money.
With gels you are correct, but even gels like the 1/5 th C IF possible.
Thanks for the info. We have used coaches in true 4 season conditions. Minus 30 to plus 120.
Love the li-ion idea but the temp restrictions unless mounted inside and carefully monitored could limit our use.
Like we really are going to the extreme weather. Yea, sure.
The ability to do it is part of what the Fores built.
Looked closely at a north star li-ion setup 6 years ago. You needed two at $6k each.
Crazy for our uses.
But....
Bob, Foretravel had the best technology in the 80's and 90's, but in 2019, the new tech is working out very well. My thermostatic heater and ventilation fan in the battery bay insures that my lithium battery bank works in 4 seasons, and because of the built in BMS, I do not have to worry about batteries going dead, or anything else. If you find the battle born's on sale, not much more than your gel cells and have many more advantages, and of course, a lot longer lifespan.
Think that in 5 years, all higher end coaches, will have lithium of some sort.
Right now it is the price point, but that will change.
True. My gels are low cycles so I may be able to outwait the price point. I hope
My panels are afixed with VHBTAPE and in all the years they have been staying put. I did make and install a deflector in front of the panels to make the air pass over the top of them.
JohnH
Bob, let me look in my garage.. Might have some extra mounts that I used on mine you can have..If I didnt toss them. Probably didnt since I am a pack rat.. so I am told at least 2 times a month. :))
Bob,
I am leaning towards the pt-100 to integrate into my new solar setup. Is it overkill? Perhaps, as it's unlikely I will be installing a 6600 watt PV array, but I already have a Magnum inverter with the me-arc remote. The pt-100 networks seamlessly with the Magnum inverters and the me-arc remote will also allow complete control, monitoring and configuration of the pt-100. I am planning to use 24 v 72 cell panels and the pt-100 will work well with them. Support from Magnum is a breeze because I am using all their products in my setup (except for the panels). I will not have to upgrade my charge controller anytime soon as well!
Dave
Dave, a 72 cell, 24 volt panel is very interesting, who makes them? Thanks.
Solar charging is not something you get to have much control over. Watts into the batteries is pretty much a bell shaped curve during the day. You will not be putting in a uniform charge in over the day. If you believe you have to have 1/5C or nothing then solar is not the way to go.
This is another big plus in the Lithium column. LiFePO4 doesn't care about high charge rate (within reasonable limits that are way above my solar capacity), low charge rate or about being topped off. On a bad day my solar won't put more than 10 amps peak into the battery but it doesn't matter as long as I have enough charge to get through the night. No side effects from slow charging or storing for extended periods at low SOC. One less thing to worry about.
Dave thanks for your input. I bought the controller not knowing for sure if its correct so any details of how it integrates would help me.
I have a magnum inverter, ME-RC(To be changed out to a ME-ARC), and a BTMS abd to install all the parts listed as I go along ME-AGS-N(gen start), a ME-BMS(first thing), and a Blue-Sea auto battery combiner.
Without a residential refer my 270 watt current solar helps the batteries 3 mk 8g8d's recover and make sure in storage that the batteries never get discharged accidentally.
I run my chest refer when on the road so it's compressor load is noticeable but manageable but probably not as much as a residential refer. Probably 1/2 the amp hours?
Yes the PT-100 maybe overkill but that's ok as long as it works as the ARC panel can control everything.
Sure leaning to a higher voltage system if it will work and the more efficient 22% panels.
Can they take the windloads?
Back of my mind for extended rv use would be to have Tesla install a powerwall in our home then steal it and put it flat in a storage bay.
5k inverter built in. Lots of amp hours. Roof airs off the battery stuff. Probably a pipe dream
The help so far has been great. Keep it coming.
Bob
Jim,
I was looking at these panels. There seems to be quite a few people selling larger capacity panels in the Vegas area. These may be surplus from commercial projects and the like. The prices are great. I am in the Vegas area so no shipping charges. I like the idea of putting 1000+ watts on the roof using only 3 panels. The roof on my coach (entry side) is clear all the way back to the ladder so they will fit in there nice.
Trina 340 watt mono 72 cell Solar Panels - general for sale - by owner (https://lasvegas.craigslist.org/for/d/las-vegas-trina-340-watt-mono-72-cell/6808694779.html)
Dave
Dave
"Can they take the windloads?"
Yes.
Mounting large solar panels with 3m VHB at 4 corners has been a common installation method on flat, smooth, structurally sound RV's for years. I never heard of a properly mounted panel coming off. I also incorporated a wind deflector into the leading edge of my mounting hardware, as others have done, so as to not tempt fate but they are very solid. The deflector probably helps eliminate wind noise more than it helps reduce wind load.
Thanks, but appears these panels are 36 volt and not 24 volt, but they are a good deal.
http://sepbatteries.com/media/add_info/Tallmax.pdf
Seeing the PT 100 needs at least 60 volts to operate in MPPT mode, you should be okay unless you have shading on two panels.
Bob,
When you connect the network cable from the inverter to the pt-100 they will "link" to each other. You will have new menus available in the ME-ARC. There are a few settings that need to be changed. I believe I saw a YouTube video on networking the two devices and also the menus in the ME-ARC remote. The nice thing here is that I already have the remote installed in the coach (looks OEM) so NO reason to cut into anything else to add another monitor. With the FAVS button feature on the ME-ARC, you can program custom views and easily reference them (like amps in / out).
With regard to whether the larger panels will stand up to the wind, I don't know for sure. From what I have read, the 3M VHB tape is pretty robust and should hold them in place (if installed / applied correctly). I really don't want to put any holes in my roof but if I had to I might.
Dave
Your absolutely right Jim. Since I was looking at that Magnum PT-100 MPPT controller, I can take advantage of these panels.
Dave
Both the above my last comment are helpful.
As far as the 1/5th C I appreciate the bell part of the charging curve. Thanks for the refresh.
The easy simple way is just to add a couple more gels as they are not as affected by the slow charge rate.
Versus spend a lot of coach bucks to be able to run Lifeline AGM's
The higher capacity and quicker charging versus just adding gels.
Sure seems to not pencil well doesn't it.
My current need for the quicker charging and higher capacity of the Lifelines is not very high.
Bought the heavy slides that were posted here in preparation for adding a couple more mk gels maybe in a vented box to be installed in the big compartment next to the current battery area.
As my Magnum inverter in the same area is not non spark certified I would need to enclose the batteries.
Mk states no battery boxes but a vented box might work.
Two mk 8g8d's added to my three should allow a possible future refer change out.
The Tesla's powerwall seems to have a wider operating temp range. I understand it has a liquid internal cooling system with a circulating motor and maybe a fan.
Would be a fantastic rv power system but TESLA only installs in single family residences.
Probably worried about crashes.
Hard to have a runaway fire with gel batteries with marine UL listed fire retardant cabling with its pvc covering.
It been reported that Panasonic has been researching a new battery design.
Hopefully that's dr goodenoughs silicone based battery for his li-ion design he did 37 years ago.
Triple the Energy storage. Cheap. Ten times faster recharge without damage. 20k cycle life. No lithium
That might allow a electric wheel driven rv or car or truck. Like a locomotive?
The high efficiency panels are way more money but are 62" x 41". Not sure how important that is.
Going to Vegas at the end of the month where we have a family townhome being updated so maybe I will look
Anyone with a 40' figure out how many panels at either size would fit.
The high effeciency panels I thing are 96 cells. But many times more money for "trick"
Versus these for this price the ability to add even more capacity by using the high efficiency may not be needed as much.
Especially if using gels or li-ion batteries as at that point the need to use the 1/5th C to extend the battery life on AGM'S can be factored out.
Lifeline AGM's can be used in extremely low temps better than gels and charge quicker and have more capacity seems to be offset by the damage that slow charging my induce and the possible much shorter cycle life although Lifelines web site show a similar cycle life to mk gels
Seems the pt100 has an auxiliary adjustable output.
Can be set for many things but the adjustable high voltage turn on would seem to be able to be set to turn on a small fan in a battery box when under charging voltages only
I have not looked at the inverter but I think it does have the same auxiliary output.
So under charge either the solar or inverter could be run to a relay to power some kind of fan(s).
Foretravel installed a fan on the bulkhead on later coaches than ours to furnish cooling air to the inverter. Mounted on the wall.
More paranoid about putting batteries in the same area as a possible spark generating inverter.
Outback sells sealed inverter/chargers for this safety idea.
Bob I have 8 of these and if you need more I can make some for you.. Let me know ^.^d