Solar Panels on roof, wondering what size output they are

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Solar Panels on roof, wondering what size output they are

May 23, 2023, 04:09:58 pm

Hi All,
Was just curious about my solar panels and if anyone knows the technical specs on them. The LD is a 1999 RB 26.5, I purchased her in the spring of 2021 (the family loves her and so do I) and changed the charge controller to a BlueSky 3000i due to an issue with the old charge controller. The output of the panels (or possibly one panel? maybe one doesn't work anymore?) seems to be enough for us based on the things we use it for, but I have been thinking about upgrading parts of the solar system if it will be as easy as changing the charge controller was. I was curious if any of you have any information on these specific panels and what size they would be. The BP panel seems to be from the original LD build, I'm not sure when the Shell solar panel was added. What is the best (and least cumbersome) way of determining the output of one or both of the panels? If I wanted to purchase a new panel, is it easy to take one off and put another in it's place? I've been doing some research but am having trouble with these specific questions.
Thanks in advance for your time and knowledge, attached are some pics,
John

Re: Solar Panels on roof, wondering what size output they are

Reply #1 – May 23, 2023, 05:30:53 pm

Our 2003 LD had 85 watt BP panels.

Larry

Re: Solar Panels on roof, wondering what size output they are

Reply #2 – May 23, 2023, 05:52:50 pm

Thanks Larry, that was the kind of information I was looking for, typical panel installation on rigs close to the age of mine. Did you have two panels on your 2003? I was curious on ours if maybe one BP panel was switched out for the Shell panel, or if the Shell panel was added later.

Re: Solar Panels on roof, wondering what size output they are

Reply #3 – May 23, 2023, 06:16:59 pm

If your old charge controller was a Heliotrope, that is a factory install. Standard was a single panel, with a second optional. However, the original panel would be 24 years old, so performance would be reduced considerably. I would recommend you replace both, as current models are more efficient and much cheaper. For a self-install, Home Depot has decent prices on 100W or so models, as does Amazon.

Steve

Re: Solar Panels on roof, wondering what size output they are

Reply #4 – May 23, 2023, 06:20:21 pm

"Was just curious about my solar panels..."

Your forth IMG #8723 is of German manufacture! "5 Flachglas AG" can be Googled but unless you read Deutsch it probably won't be of much use.

I imagine that the manuf. supplys many users.

But perhaps it will give you a lead for further research.

Re: Solar Panels on roof, wondering what size output they are

Reply #5 – May 23, 2023, 07:10:34 pm

Thanks Steve; ya I was thinking the same thing, a 24 year old panel has got to be producing minimal output at this point right? And it looks kinda funky too, like the sun has really beaten it down. For replacing a panel, is it pretty much a plug and play type operation? Have you done it before? Are the connectors universal? Unplug the old one, plug the new one in and mount it? We are leaving on a 3 week trip on June 9th, so I'm a little hesitant to change anything before we go, but if it is really just a simple job I may be persuaded to jump in. It would be nice to have some new panels.
Thanks Lazy Bones, I actually looked that up first, didn't have much luck, but I didn't dive deep enough to see if I was getting a bunch of German hits. That fourth image is of a corner of the BP panel. I was hoping looking that up would lead me to the exact panel specs but it didn't seem it was that easy, but I'll try again and see if I can dig a little deeper.

Re: Solar Panels on roof, wondering what size output they are

Reply #6 – May 23, 2023, 07:33:40 pm

It's unlikely the new panels will line up to the old hardware, and most current models do use a standard connector arrangement, but you would have to purchase compatible mating connectors and splice them in. However you would likely want to upgrade the wiring from roof to the Blue Sky controller to take full advantage of the increased current. In addition, if the PO had not installed a 'battery monitor' such as the Victron BMV 700 series, this is also recommended. As such, I would not rush into this on a time-dependent schedule if your existing system is adequate for you at this time.

If you can disconnect your panels from the roof physically and electrically, you can test for short-circuit current by aiming directly to the sun on a clear day while connecting an ammeter (at least 10 Amp range) from the positive to the negative terminal. Then connect a voltmeter from the positive to the negative terminal to get the open-circuit voltage. These two specs are among those listed for other panels, and by comparing, you can get an idea of how yours are performing, and what improvement new panels would give you.

Steve

Steve

Re: Solar Panels on roof, wondering what size output they are

Reply #7 – May 23, 2023, 08:19:52 pm

Thanks Steve, that makes sense; I was hoping I could find something where I wouldn't have to change the hardware but I can see that's probably a pipe dream. I think I will take your advice and hold off on this project until we get back from our trip.
I did actually install a battery monitor a few months back, cheaper version, not the Victron, but it seems to be working pretty good so far. Got a project box off Amazon and put the 12 volt and antenna connectors together with it and mounted it on the wall between the windows. Here's a pic of it.
Thanks for the help and info on this,
John

Re: Solar Panels on roof, wondering what size output they are

Reply #8 – May 23, 2023, 09:40:25 pm

Hi John; I just went through this with my '99 TK. The PV panels I had were older than '99 but still in bubble wrap, never used. I got them at a great discount, they were still available for $479 each in retail stores.(In 1999) 48 watt, monocrystaline, 36 cell. About 14% efficiency. With advanced age the rubber seals were leaking, and water and dirt intrusion had reduced the outputs. Time for a better built, higher efficiency panels.
   The German glass on your panel, is just the glass. The panels were BP. 'Beyond Petroleum' and the company went out of business around 2011. The Shell panel is no longer made either.
   I put in Renogy 100 watt panels. 4 at $100 each, (and a 50 watt, 1/2 size next to the passenger side escape hatch).
Amazon.com : Renogy Solar Panel 100 Watt 12 Volt, High-Efficiency Monocrystal... The description lists 18% efficiency. They are much better made than my old panels. Lighter weight even with the higher wattage. Now the Amazon price is $90. (it changes). They come with standard MC4 connectors. Stainless 'Z' brackets would be good.
While I bought the corresponding connectors. I am re-routing some cabling, and I'm going to cut out the connectors entirely, and just solder the ends together with the 10 ga. wire I used. I used wire loom under the panels and Bell boxes with 1/2" Liquatite 1/2" conduit. Joined up with multiple #6 wire down leads through the refrigerator vent. Your floorplan may do better with different routing. (Someone with an RB?)
   You have a good solar controller there. I used a SB3000i also. I reprogrammed it for the higher voltage LiF batteries. That feature can wait until you go Lithium. RonB

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Re: Solar Panels on roof, wondering what size output they are

Reply #9 – May 24, 2023, 02:31:01 am

Hi Ron! Thanks for the response, always appreciate your advice sir. I checked out the panels on that link, I think I will definitely go with at least a pair of these. As far as installing them on the roof, is there anything special I need to know? Or a good thread you can point me to on here that walks thru a best practices approach to it? I’m very hesitant to go drilling into the roof without a good guide on exactly how to do it. I assume it’s simpler than I think but I just would hate to do something wrong just because I didn’t find the right info before I started. Also sounds like you have 450 watts on your roof, I’m probably mistaken but I thought the SB3000i could only handle 400 watts max? Is 450 the true max or can it go even higher? Thanks for all the detailed info!

Re: Solar Panels on roof, wondering what size output they are

Reply #10 – May 24, 2023, 12:01:41 pm

Larry Wade has 560 Watts on the SB3000i. It will dissipate anything it can't use (within reason). Those ratings for Watt output are highly optimistic in general. Governed by rules for equal testing. Off angle insolation, dirt on the panels, dirty air and clouds, shadows, etc. all reduce the actual output. As Larry said, and I agree, the max solar panels are for the days in winter when when you need all the power you can get. Short days, rainy and/or cloudy with more tree cover, when you are inside using more heat, lighting, computer, and so on; make the extra bit of power a plus. I really don't like running the generator either.
The higher voltage requirement of the Lithium batteries, reduces the amount of current available from the MPPT controller. Watts is Watts.
The 'Z' brackets don't have much contact surface on the roof. You tube has lots of potential ways of mounting. Usually a pad of double sided tape (3M VHB), one short screw per foot and sealant over the top of that. One member here is using aluminum 'unistrut' rails screwed into roof rafters, with movable mounting brackets to accommodate future modifications. The struts add stiffness and lift the panels up off the roof to get ventilation under them. I believe he is going an even Kilowatt, with massive LiF battery capacity. Way past the capability of the SB3000i. RonB

Re: Solar Panels on roof, wondering what size output they are

Reply #11 – May 24, 2023, 12:07:01 pm

For what it's worth (nothing, as far as this topic goes 😉) "Flachglas" is sheet glass, and "AG" is short for Aktiengesellchaft, which means corporation. In other words, it's the equivalent of our "Inc." You'll see that at the end of a lot of German company names, such as Volkswagen AG. The other one you'll see is "GmbH," which stands for "Gesellschaft mit beschränkte Haftung," or "Company with limited liability"--similar to our LLC.

Re: Solar Panels on roof, wondering what size output they are

Reply #12 – May 24, 2023, 12:15:09 pm

"It will dissipate anything it can't use"

And will run correspondingly hot--that energy has to go somewhere. It isn't likely to start any fires, but heat isn't good for electronics. But with that said, feeding 450 watts of panels into a 400 watt rated controller is probably OK, because most of the time those panels won't be putting out their full rated wattage. Just don't be surprised if the front panel gets warm to the touch on sunny days. 🙂 I experienced that with a Heliotrope HPV-30 controller in my first LD, when I hooked up way too many panels to it.

Re: Solar Panels on roof, wondering what size output they are

Reply #13 – May 24, 2023, 01:44:17 pm

"For what it's worth (nothing, as far as this topic goes 😉) "Flachglas" is sheet glass, and "AG" is short for Aktiengesellchaft, which means corporation..."

Thanks for that detailed explanation Andy! You saved me a lot of time and effort, I was not about to go into such depth even though I had the knowledge tucked away in my cobweb mind.

Re: Solar Panels on roof, wondering what size output they are

Reply #14 – May 24, 2023, 02:54:38 pm

Thanks Ron, I actually was looking thru the threads this morning and found people discussing the VHB tape (I had no idea you could do that, very intersting) and found that guys video on the unistrut thing (seems like its overdone, but still very cool). I also found someone saying not to screw into the thicker cross beam type wood, and that just going down into the plywood should do the trick and is the proper way to handle it (if I don't use the VHB tape I guess). And it makes sense what you and ANDY are saying about the extra panels on the 3000i not really being a problem. I think something in the neighborhood of 200 watts should be plenty for us, but maybe I'll do more, we shall see.
STEVE above mentioned upgrading the wiring possibly; honestly that sounds like it will make the job a bit more involved (maybe it's easy and just sounds hard?), do you guys think I can get away with the old wires? I don't want to do anything dangerous of course, but less efficient for a trade off to an easier job would be ok in my mind. I could always change out the wiring later too.

Re: Solar Panels on roof, wondering what size output they are

Reply #15 – May 24, 2023, 07:47:15 pm

These guys are your best help, but just FYI --
The wiring for solar was a huge discussion on the forum at the time I had mine installed ten years ago. Therefore I insisted on six-gauge wire (not cheap) so I'd never have to change it to upgrade anything. The Blue Sky SB3000i controller that was installed at the same time has been great. In fact, I usually don't plug in to AC.
Kristin

Re: Solar Panels on roof, wondering what size output they are

Reply #16 – May 25, 2023, 02:50:33 pm

Hi All.

I just upgraded my solar on my 2000 LD. The original owner had solar installed by the factory. My BP Solar was only producing 3.5 watts at maximum. I took that off the roof and patched the holes. I installed 2 x 100 watt Rich Solar panels and attached them using plastic feet,HTTP://www.amazon.com/stores/CMYYANGLIN/page/562CBC13-1BD9-4755-854D-1AB95DE0A0CF?ref_=ast_bln. I also used VHB tape on the feet and then once on the roof and secure covered with Lap Seal Self-Leveling sealant. Very strong bond. AM Solar also uses their feet but I found expensive, like $80 a panel, and VHB tape. They have a video on their website showing it. The connections are MC4 so I added the BougeRV MC4 branch Y connectors also from Amazon to make the wiring connection to the solar panels. I also changed the Heliotrope controller to the Blue Sky 3000I controller. I am using 2 SOK 100watt Lithium batteries. Everything worked well at the start of the trip but due to really bad roads I had the battery wire at the solar controller come loose, once I fixed that the solar controller did not work. Since I was on my way to the PNW I called AM Solar and they fit me in, they found I had blown a fuse and they checked the rest of my connections. I was on my way in 1 1/2 hours. They are a tremendous group to work with. They will work on my inverter on my return back to AZ as that is not working as well. I loved a lot of money on installing by myself that I can afford to have them fix my mistakes. I also got a lot of help from this group which gave me the confidence to tackle this project. Thank you.

Re: Solar Panels on roof, wondering what size output they are

Reply #17 – May 26, 2023, 01:47:27 pm

Awesome, thanks for all that info KEVIN, much appreciated sir! Very helpful for what I'll be undertaking soon. I assume you had to splice in that Bouge RV Mc4 branch Y right? On my 1999 BP solar panel it looks like an old school connection. Pretty simple to add that Mc4 branch in?

Re: Solar Panels on roof, wondering what size output they are

Reply #18 – May 27, 2023, 09:58:39 am

I disconnected the wire going to the old solar panel and added the MC4 connectors to the wires coming from the solar controller on the roof, similar to this Amazon.com: BougeRV 12 PCS Solar Connectors with Spanners Solar Panel Cable.... The Y connectors were used to connect the two solar panels to the just completed roof wire connectors. There are many video on YouTube showing how to make the MC4 connectors to the roof wires. I am not an expert but the help on this form and YouTube really helped. The advantage of MC4 connectors is that you can disconnect them on the roof if you have to service the solar controller, which I had to do.

Hope that this helps.

Kevin

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Re: Solar Panels on roof, wondering what size output they are

Reply #19 – May 28, 2023, 03:49:34 am

Thanks KEVIN, helps a ton bro. I looked up a bunch of stuff on YouTube right after posting the question for ya, watched a bunch of videos describing what looks like the whole process you did.

Another question for everyone else, I looked up amps in relation to solar panel watts, and it looks like around 8 amps is what you get out of 100 watts. I was checking out my 3000i (its been pretty cloudy around here the past few days, but we had the sun break through a bit) and trying to watch the amps come in to see if I could judge how much the panels on the roof are putting out. It was hovering in the 3-5 amp range a lot, but at one point it hit 7.8 (maybe that was a fluke?). Am I right in assuming that if I see that many amps coming in then the panels up top must be giving me close to 100 watts? When we leave on our 3.5 week trip to NC in a few days I wanted to watch things and see just how much solar we actually need, and this will be the first long trip out with the new battery monitor install too so I should be able to get a good read on things. 100 watts may be plenty for us. We are doing a mix of campsites with hookups and boondocking with nothing so it should be a good test.
Thanks!
John

Re: Solar Panels on roof, wondering what size output they are

Reply #20 – May 28, 2023, 05:05:26 am

The 7.8 A reading is close to best case. Having the sun 25 degrees off of directly overhead would reduce the effective wattage to 90 W. The higher current might be in bulk absorption mode, and the lower current in float mode.

Re: Solar Panels on roof, wondering what size output they are

Reply #21 – May 28, 2023, 09:41:09 am

Quote from: JohnDon - May 28, 2023, 03:49:34 am

Am I right in assuming that if I see that many amps coming in then the panels up top must be giving me close to 100 watts?
Quote
You will never see the rated power out of the panels for several reasons:
1) The panels are rated under lab conditions of 1 sun at about 70 degrees F. That luminance is found at high noon at the equator, not at these latitudes, and not only are they likely to be at higher than 70 F air, but at about 20% efficient with an anti-reflection coating, that means 80% of the absorbed energy is converted to heat - they get hot!
2) Highest available power is obtained when mounted at right angles to the direction of the sun - not flat on the roof. I.e, you are not intercepting as much solar energy.
The way panels are rated is not a scam - reproducible conditions are necessary in order to compare products, so rating actual power in the U.S. mounted on flat roofs is NOT the data provided with your panels. For instance, the panels on my home are on a roof canted at 20 degrees to the horizontal. Max power is achieved sometime in April, though due to shorter days, maximum daily energy is during the summer.

Steve

Re: Solar Panels on roof, wondering what size output they are

Reply #22 – May 28, 2023, 07:21:28 pm

Quote from: JohnDon - May 28, 2023, 03:49:34 am

I was checking out my 3000i (its been pretty cloudy around here the past few days, but we had the sun break through a bit) and trying to watch the amps come in to see if I could judge how much the panels on the roof are putting out.
John

Your Blue Sky is an MPPT unit, which tracks the maximum power point of the panels' production. If the panel is putting out 18 Volts at 4 Amps, that is 72 Watts. If the Blue Sky is outputting 13.5V to the batteries, the current will be 5.3 Amps, because of its MPPT conversion. The output current you read is NOT the panel output, but the Blue Sky output to the batteries and accessories. Although there is some small conversion inefficiency, it is a pretty close approximation of the current output power of your panels to multiply the battery voltage by the output current of the Blue Sky. If the batteries are nearing full charge, they won't accept the full current, but you can turn on stuff to increase the current flow until the voltage starts to drop, and measure the voltage and current at that point.

Steve

Re: Solar Panels on roof, wondering what size output they are

Reply #23 – May 28, 2023, 07:41:37 pm

To expand on what others have said: the only accurate way to judge a panel's output is in watts, as shown by your solar controller. Amps alone don't tell you, because they are dependent upon the panel's output voltage, and output voltages vary. For example, I have some old AM Solar 100 W panels that are rated 4.54 amps at 21.5 volts; and I have some Renogy Eclipse 100 W panels that are rated 5.7 amps at 17.7 volts. Both panels put out exactly the same amount of power--100 watts--but at substantially different amperages.

I have panels sitting around from various projects that are rated anywhere from 17.7 volts (Renogy Eclipse) to 29.4 volts (Sunpower). Obviously if I compared amps out, I'd be mislead. You can't judge by amps alone. (Or volts alone, although I don't see people making that mistake.) You have to look at watts.

"You will never see the rated power out of the panels."

I've said that myself many times, and it's true more often than not, but there are exceptions. I recently mounted two Renogy Eclipse 100 W panels and two Zamp 90 W panels on my 19' Airstream. (The odd mix was because that was the only way I could fit the maximum amount of power on a small and crowded roof.) So, total rated output: 380 watts. But I've seen as much as 420 watts from this setup at noon on a sunny day in late May. In other words, at least some of these panels are over-performing. (I've heard that many Zamp panels do that, and I've seen a panel exceed its rated output power in at least one other case: a Zamp 190 W panel.)

So it is possible for a panel to beat its ratings... but it's not common. In my experience, you can typically expect to see 85% to 90% of rated output (in watts) at best, and less than that much of the time.

Re: Solar Panels on roof, wondering what size output they are

Reply #24 – May 29, 2023, 06:58:16 am

Older solar panels.
I have been wanting to test my panels. You always hear how they age out and don't put out like they used to after a while. I think they are original, from 1999. We just got back from a two week trip and 7 nights was at a Harvest Host (dry camping). Our panels seemed to keep up with our light and fan usage. Of course the two trojan batteries were fully charged from the 5+ hours of driving. I need to read up on what voltage I should be getting when in sunlight. For now they do the trick.

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