Flexible Solar Panels: Want to communicate with those who have them installed

AldebaranJill

I'd like to hear from folks who have mounted flexible solar panels to their T@B's:

1. Which panels did you install

2. What method did you use to affix to roof

3. Where on roof

4. Which solar controller

5. What part of country you use them in

6. Typical output in Amps for sun and shade and clouds

Prefer comments from those who have actually installed them, no theories please :-)
I live in the Pacific Northwest, so it's rainy and cloudy often, but am planning more travel to eastern washington and southwest states. I'm looking for specific details from folks who have installed them and used them under various conditions and have the ability to measure the amps they are putting into battery, especially if you camp in shady and cloudy environments.

jkjenn

@Ratkity had them on her T@b.

Ratkity

1. I had one semi flexible Renogy 100W panel. It only had a 30% max bend to it, so I had even more limited area to place it. I set it up to have the potential to put up 2. It has to be in a place where there is no shading at all in your 4.5-5 hour premium sunlight time. You can turn off 1/3 to your entire panel power by simple shading from your vent cover.

2.  I fixed it permanently to the roof without drilling using 3M automotive trim tape (never see car trim fly off going 70 mph down the road). Make sure you position the trim tape so water and debris doesn't get trapped underneath when it rains. There were grommets on the panel to use for mounting, but I read they tore out easily even if I found aluminum cross braces to mount them to in the roof. 

3. Letsee, where? Driver's side, front - as far above the front window as possible. The bend is more than 30% if you go too low. 

4. I used a Trimetric monitor and controller, but would probably opt for a Victron brand after seeing V's set up. Both are good products!

5. I live on the right coast and used it mainly for battery maintenance while the camper was parked next to the house in full sun. I camp mostly in the shade. 

6. Very little amperage in partial shade or cloudy days. Not enough to even stop battery drain. Rainy days had no charging going on. Max amps were about 17, but the controller modulated amperage to my specific battery type in a 3 stage charge setup (like the converter, but more customizable) so there was no overcharging. Max light per day was usually 4 hours (the way I was parked). Winter sun is weaker and cooler temps needed more energy to charge the battery. Summer sun is very hot and panels lose efficiency rapidly, especially without airflow behind the panel. Max amps were obtained in Spring and Fall.

Because of how I used the panel, I permanently mounted it until there was a recall. Taking that sucker off was a lesson in patience, scraped knuckles, balancing on an 8 ft ladder in the snow and using a plastic spatula as so not to mar the gel coat/paint. I opted to go with the movable panels (suitcase) after that because the solar panel wasn't doing anything when I parked in the shade at a state or national park... put there were always points I could have used 15-25' of extension cables to aim a suitcase panel set in the sun. This was just to have an extended long weekend on battery power only up in my favorite mountains, not for the sole aim to boondock exclusively. 

I hope I answered all your questions!! 

AldebaranJill

@Ratkity awesome thank you so much! Follow up questions:

6. Spring and Fall... that's very interesting, so when it gets hot, they lose charging efficiency, even when the sun light is more direct, or was it because you actually parked in more shade in the summer time?

7. Recall:  So you had the ones that were recalled - what where they recalled for? Sounds like a total nightmare of getting them off, sigh, I can't even imagine how awful that must have been. I suppose it's very telling that rather than replace them with other flexible panels, you went with the portable. Did you stick with the same brand?

Ratkity

6. Spring and fall have the optimal temperature that solar panels operate optimally - about 77F.

7. Yes. Stayed with the same company. They had switched sources at one point and there was an issue with single cells getting hot (wiring issue?). I thought it was great they contacted me and offered to replace the panel from another source that wasn't defective or let me change to the suitcase panels. From other people's experience, I thought the suitcase was something I'd like to try. It's heavy (100W), but not the 50 lbs that the 200W weighs! I think it's 27 or 37 lbs (sorry, I can't remember). 

jkjenn

Ratkity said:

6. Spring and fall have the optimal temperature that solar panels operate optimally - about 77F.

You will lose some efficiency because of the lack of airflow and heat build-up.

Normfun

I have 2 Renogy 100w semi bendable panels on my T@b. They were NOT part of the recalled batch. I have them front to back on either side of the fantastic fan. They are attached using 3 m VHB tape. They have been on 2 years now. The most charge I've seen is 10.2 amps. We are in Utah so sun is plentiful. They do drop off substantially in the shade or rainy days. Outside Everett last year in deep shade I was only getting .5 amp. I also have a 100 watt portable that we can put in the sun when needed. We have 2 golf cart batteries that have held up well. I notice the hot sun does effect charge rate but not critically. 

Ratkity

jkjenn said:

Ratkity said:

6. Spring and fall have the optimal temperature that solar panels operate optimally - about 77F.

You will lose some efficiency because of the lack of airflow and heat build-up.

Totally. I think the suitcase (just my theory, mind you) is more efficient just because of airflow behind it.

jkjenn

Ratkity said:

jkjenn said:

Ratkity said:

6. Spring and fall have the optimal temperature that solar panels operate optimally - about 77F.

You will lose some efficiency because of the lack of airflow and heat build-up.

Totally. I think the suitcase (just my theory, mind you) is more efficient just because of airflow behind it.

I think the semi-flexible are a little less efficient out of the gate, and then when you permanently mount them, you lose a little more from lack of air flow. My DIY folding mounts worked fairly well, considering.

mash2

I'd like to hear from folks who have mounted flexible solar panels to their T@B's:

1. Which panels did you install

unisolar panels (no longer available)

2. What method did you use to affix to roof

Permanent mastic.

3. Where on roof

From fan to back of tab.  

4. Which solar controller

MPPT 30 amp.  Branded under many names.  Mine is no name.  MC5 remote port ....

5. What part of country you use them in

San Francisco CA.

6. Typical output in Amps for sun and shade and clouds

Depends on time of year.  Thru end of september 40+ daily (rain or sun).  Big drop off in late octover to november.  

AldebaranJill

mash2 said:

I'd like to hear from folks who have mounted flexible solar panels to their T@B's:

1. Which panels did you install

unisolar panels (no longer available)

2. What method did you use to affix to roof

Permanent mastic.

3. Where on roof

From fan to back of tab.  

4. Which solar controller

MPPT 30 amp.  Branded under many names.  Mine is no name.  MC5 remote port ....

5. What part of country you use them in

San Francisco CA.

6. Typical output in Amps for sun and shade and clouds

Depends on time of year.  Thru end of september 40+ daily (rain or sun).  Big drop off in late octover to november.  

Is 40+ in Amp Hours?

AldebaranJill

@Ratkity @Normfun @mash2 :

If my power consumption profile is 10AH - 20AH per day, and I live in Seattle, would two 100W flexible panels keep up, if I often camp in cloudy/rainy conditions.

Is there any conflict in having solar always connected when you're towing and charging via alternator?

Thanks!!!
Jill

jkjenn

AldebaranJill said:

@Ratkity @Normfun @mash2 :

If my power consumption profile is 10AH - 20AH per day, and I live in Seattle, would two 100W flexible panels keep up, if I often camp in cloudy/rainy conditions.

Is there any conflict in having solar always connected when you're towing and charging via alternator?

Thanks!!!
Jill

This is going to depend on your battery capacity. If you hit a streak of several days of mostly cloudcover, it probably will not keep up unless you have a larger battery capacity than 75ah or 100ah.

Ratkity

Jill, no conflict. The alternator provides a trickle charge - some smaller than others. Smaller alternators can't even keep up with the frig on DC power because of the amp pull. The alternator has to supply power to camper lights (always good to have running lights on, even in the day) and brake lights and turn signals. Some people have isolators on their tow vehicles so the camper doesn't pull battery power from the TV battery if they stop for lunch. With your TV alternator, unless you are driving 24 hrs straight in sunny weather (Alaska?), you can't overcharge your battery. 

The solar controller always keeps the battery from being overcharged. Solar is a type of trickle charge too. Just like the 24 hr optimal theoretical sunny day with your TV alternator, you can't overcharge your battery via solar (because of the controller).

ericnliz

@AldebaranJill, Jill, one thing I didn't see in your post is the amp hour capacity of your battery(s) as @jkjenn briefly mentioned. I'm thinking that would have a really big effect as to how long you could go in cloudy/overcast conditions with your amp hour consumption. I've gone two days straight in overcast conditions using just my 100amp solar suitcase panels and they seemed to "maintain" the battery ok, but we're pretty frugal with our electrical consumption. We have a single GP24 with 80ah capacity.

Normfun

Most days I think it would keep up. The only time I've had trouble getting back to a full charge each day was @ Flowing Lake. Very heavy dense forested site. The next trip there I had a site with 3 hrs of sun a was fine. 

Size of battery bank will determine how critical your daily recharge is. 

AldebaranJill

jkjenn said:

AldebaranJill said:

If my power consumption profile is 10AH - 20AH per day, and I live in Seattle, would two 100W flexible panels keep up, if I often camp in cloudy/rainy conditions.

This is going to depend on your battery capacity. If you hit a streak of several days of mostly cloudcover, it probably will not keep up unless you have a larger battery capacity than 75ah or 100ah.

My battery capacity isn't relevant - my question was regarding AH usage and maintaining the battery status quo.

AldebaranJill

ericnliz said:

@AldebaranJill, Jill, one thing I didn't see in your post is the amp hour capacity of your battery(s) as @jkjenn briefly mentioned. I'm thinking that would have a really big effect as to how long you could go in cloudy/overcast conditions with your amp hour consumption. I've gone two days straight in overcast conditions using just my 100amp solar suitcase panels and they seemed to "maintain" the battery ok, but we're pretty frugal with our electrical consumption. We have a single GP24 with 80ah capacity.

For me, my battery capacity is not relevant for this particular thread, as I'm only interested in seeing if solar could actually provide enough power to maintain the status quo of my batteries, whether they're 80AH or 100AH or 200AH capacity. My goal to adding solar, would be to simply keep up with my power consumption usage, regardless of what the state of charge of the batteries, or their capacity. I have a Trimetric meter, and so am extremely miserly with power usage, and so for me, the goal would be to have solar maintain battery status quo only.

jcfaber1

The only way to know if a solar setup will work for you is to do the following:
1). Estimate your daily AH draw from all of your uses of power.2). How many cloudy rainy days in a row are you likely to have.3) Multiply 1x2 = AH capacity required.  Now double that so that you only draw your batteries down to 50%.  This is your battery requirement in AH.  Now how fast do you want to charge your batteries? One day or 5-6 hours?  This is how you back into the size of your PV.  Make sense?  Also, while others are mentioning portable PV system, the reason they're​ heavy is the glass.  I made 200 suitcase using the flexible PV and it weighs 20 lbs.

jkjenn

Normfun said:

Most days I think it would keep up. The only time I've had trouble getting back to a full charge each day was @ Flowing Lake. Very heavy dense forested site. The next trip there I had a site with 3 hrs of sun a was fine. 

Size of battery bank will determine how critical your daily recharge is. 

You have to bear in mind that you are quite a bit further south than Washington and that they may encounter several days of heavy cloud bank - such is life in Washington and Western PA. :(

Using 30ah from a 75ah battery, has it almost down to the 50% threshold - and you are not going to get a ton of juice on a day with a heavy cloudbank. I ran 2 100w semi-flexible panels (not permanently installed) last summer in Colorado. I had one day of solid cloud and I was OK because I have 225ah of battery. The sun came out the next day and I was fine. If it would have been a second day of cloud cover, I would have gone into conservation mode.

wizard1880

A 100w panel provides roughly 5-6 amps of charging 12v power in full direct sunlight, with other sizes proportionately higher or lower.

The advantage of suitcase panels is you can move them to follow the sun.  This potentially gives you 8-12 hours of sunlight in an open site in mid summer.  Fixed panels will produce less, but if you upsize enough you can compensate.

mash2

40 + amp hours -  As I recall my yield under perfect circumstances is 8.2 Amps per hour.  

My system is 2 68 volt unisolar panels mounted to vehicle permanently with a third that can be unrolled for placement within 30 feet of the vehicle.  Batteries are 2 12v 100 amp (200 total).  In winter in the redwoods (where mine is stored), I can do a sustained draw of about 30 amps in the winter (my critical low point), as long as the trailer is oriented with the 2 panels south facing (don't leave the 3rd installed when in general minor use mode).  By March, my daily sustained yield is 30-40 by March and this holds until November.  Critical months for me are Dec-Feb where solar yields are weakest.  

There are a couple of resources that would help.  To start with, I think several of us have identified the solar calculator site which gives a good gauge of the basic solar yield, depending on panel specifications and time of year (both impact the potential output.  

http://www.where-rv-now.com/Notes/Solar/index.php?lat=32.63851&month=November&mday=7#Calculator.

Several folks have developed spreadsheet calculator that take into account your estimated demand for usage and the capacity of your system and your batteries (basic supply/demand for electricity).  I'm in the process of moving so don't have access to my hard drives that hold the spreadsheet....maybe others will chime in with samples.    

pthomas745

The link to Jkjenn's blog that holds the Power Consumption Worksheet she developed:

https://jenngrover.com/2015/11/guilty-as-charged-rv-battery-use-management/

If I ever meet her, I'm going to have her autograph my copy......

Ratkity

I've met jkjenn!! Didn't get her autograph though. LOL. We did chat a bit *snort* Cracker Barrel folks were wondering if we were going to stay for another meal time.

jkjenn

Ratkity said:

I've met jkjenn!! Didn't get her autograph though. LOL. We did chat a bit *snort* Cracker Barrel folks were wondering if we were going to stay for another meal time.

Don't pass up the chance to meet @Ratkity - just don't! One of the most interesting people I have ever met! It was a blast. WE have such awesome T@b people.

Ratkity

One day..... I will get to all the cities where my T@B and tiny trailer friends live to just say hello and enjoy some outdoors. Bucket list item!!! One that makes me smile big