Greenno,

How are your panels wired? Mixing them can be detrimental unless they are closely matched or have separate chargers.

 

I've used Bogart Engineering equipment for a couple of years. Seems really robust. About to add their WiFi module.

 

Continuing on this same thread, we were over to our fifth wheel this last week and having been up on the roof, I decided removing the 16 year-old panels I have seems like a lot of work. That means planning a new system. I know I intend to go with monocrystalline panels, but is there a source that has compared the different brands besides the link below? I am wondering if this is a "find the cheapest source" kind of task. I know from reading the range is reportedly 22%-27%, so who actually makes a 27% panel? I can't find any. It looks to me like they all fall with 21% and just over 22% and the difference in temperature coefficients is quite small between the best ranked panels. Has anyone already researched this topic?

I did find this article on the Internet, but who knows if it is valid? https://news.energysage.com/best-sol...plete-ranking/

 

I'm on a solar forum and rarely is the efficiency a concern. I don't know why other than the standard suggestion is to add more panels. On a slide-in you're limited on space so efficiency matters.

Matching the panel's output - and configuration (series/parallel) - to the Solar Charge Controller is more important than maxing out the solar panel's efficiency. I'm in the design phase for replacing my solar and battery. There is a lot that goes into the design, that's for sure.

 

RVWithTito has a website as well as a YouTube channel where he put flexible panels down with Eternabond. For a panel that has no air gap that seems reasonable. But a rigid panel that needs an air gap, that can catch the wind when you're on the road, Eternabond isn't going to cut it. On an EPDM roof it seems that it would just pull the EPDM off the underlayment. When I add panels, my plan is to ensure that the brackets are positioned such that they are secured into the roof's trusses, not just the underlayment.

 

May I ask which forum?

Thanks,
Jim / crewzer

 

https://diysolarforum.com/ It's the forum that was created by Will Prowse who has this YouTube channel: https://www.youtube.com/channel/UCoj...q8kmJme-5dnN0Q

FTE member scraprat is on that forum also, but under a different user name. I figured out it was him by his solar system configuration.

 

I’ve not seen a production module with an efficiency higher than the low 20s; SunPower and REC come to mind.

Renogy claims 21% for the modules I bought via Amazon:

https://www.renogy.com/content/RNG-1...-Datasheet.pdf

HTH,
Jim / crewzer

 

Hitting the trusses in the roof of a truck camper can be a challenge. I am going to use my stud finder and see what it can do.

On the issue of efficiency, what I find is the manufacturer gives a number, but then posts values that range around it so the companies often overlap. I know some folks get way deep into solar, but all I intend to do is keep my batteries charged and maybe at some point add a small inverter, although I installed a Jensen TV with a 28" screen that runs off the batteries and using the microwave is not a concern. Our laptops and phone chargers do fine off simple 12 VDC aux plug chargers.

I have to measure the space on my roof. If I can, I intend to go with a single large panel 200 watts on up and probably a Victron MPPT controller since that seems to be popular with a lot of folks, although that is subject to change. i am not sure if I will connect with my phone except if required. On our fiver I have monocrystalline panels and a mppt controller I got from AM Solar in the past. Greg Holder who started AM Solar was a good friend. I don't intend to go with LI+ batteries until the price comes down. At present, lithium prices remind me of time when cell phones were just catching on and cost a fortune.

Steve

 

I plan to order LiFePO4 cells direct from China and put together a battery. Probably a 2p4s arrangement for 12v and 560 Ah. Latest price for eight, 3.2v cells in $1076. That's total cost including shipping and duties. That price is only about $100 more than a BattleBorn 105 Ah battery. I'll have to procure my own BMS but the one I intend to get is only about $115. I considered the BattleBorn, but it just doesn't fit where I plan to put it.

 

If a person isn't in a hurry to get lfp you can certainly build yourself a nice modest system for a very reasonable price. As you see Jim it's really not rocket science.

 

using my stud finder, I found today it can detect rafters, but the spacing will make screwing into them a challenge.

 

Unistrut may be an easier way to ensure the system is securely fastened to the rafters.

 

This is a very interesting read-- thanks all of you for posting. I hadn't really thought much about solar for my slide in

 

Just mount your support legs with 5200 caulking and screw them down on all 4 corners. The 5200 will pull the roof off before it comes loose. Used all the time in the boat/marine world when a permanent mount is needed. As far as hitting the support members that would be ideal but screwing through the Luan top under the roofing material should be sufficient. I have had mine installed since June of 18' and probably have at least 20 trips under them. Good luck.