Flex v Fixed frame Solar panel

[daninPA]

I just received a set of Renogy 100w solar panels — 1 rigid frame, 1 flexible (order mistake. — one will go back).

But now that I have the flexible panel I am considering keeping it and mounting it on the roof with industrial strength Velcro. That way I can remove it for transport or whenever it’s not required.

But the flex panels are shorter lived and apparently not as effective.

Thoughts?

 

[pcg]

I've attended two seminars (pre-Covid) given by Jeff Cote of Pacific Yacht Systems and in both he raved about flexible panels, but he also stated that if you want quality you have to pay top dollar. At that time the flex panels he was discussing were made in Italy I believe.

At that time I was considering making my C-Dory into a hightop (along with other modifications I'm doing during a restoration project) so that I could store several thin flex panels in the cabin ceiling when not being used. I've since abandoned that idea after Will Prowse has started testing flex panels. He states that they are very fragile, prone to damage by handling, and cannot dissipate heat well.

https://www.youtube.com/watch?v=onMZ_dRSFUs

 

[Peter & Judy]

I have two sets of solar panels on Mistaya. Mounted on the radar arch are 2 10w hard panels, they are always in place mostly used as a battery maintainer. I also have two 30 w flexible panels that I tie on as necessary, mostly on top of my kayaks. Mistaya almost always has two kayaks on the roof. When I remove the kayaks, I simply tie the flexible panels to the roof hand rails. They are light and effective. I have also purchased a 50 square panel that I plan to mount on the Bowmar Hatch above the v-berth. I haven't quite decided how I am going to mount it there. This would give me a total of about 130 watts of solar capacity. I like to flexible panels as they are light, easy to store and remove.

 

[daninPA]

I've attended two seminars (pre-Covid) given by Jeff Cote of Pacific Yacht Systems and in both he raved about flexible panels, but he also stated that if you want quality you have to pay top dollar. At that time the flex panels he was discussing were made in Italy I believe.

At that time I was considering making my C-Dory into a hightop (along with other modifications I'm doing during a restoration project) so that I could store several thin flex panels in the cabin ceiling when not being used. I've since abandoned that idea after Will Prowse has started testing flex panels. He states that they are very fragile, prone to damage by handling, and cannot dissipate heat well.

https://www.youtube.com/watch?v=onMZ_dRSFUs

This is helpful, thanks!

The flexible panel certainly does not feel as substantial, but would the rigid frame be more or less subject to damage from bouncing across the waves?

 

[Captain Starbucks]

On my previous boat, I installed a single 175 watt panel to recharge my bow mounted 36 volt trolling motor via a Trollbridge. I can't compare what I had to a rigid panel, but I can say it worked quite well with my Renogy Smart controller and smart shunt. The system charged up my 3 x 12 volt 65 Amp hour lithium iron phosphate batteries. I'm hoping to install the system on my TomCat soon.

I wasn't sure about the mounting location on my previous boat so I installed the panel temporarily on the cabin roof with aluminum tape. It turned into the permanent location but the tape worked so good I just left it. I towed the boat at freeway speeds many times for hours at a time. No issues.

 

[daninPA]

At that time I was considering making my C-Dory into a hightop (along with other modifications I'm doing during a restoration project) so that I could store several thin flex panels in the cabin ceiling when not being used. I've since abandoned that idea after Will Prowse has started testing flex panels. He states that they are very fragile, prone to damage by handling, and cannot dissipate heat well.

https://www.youtube.com/watch?v=onMZ_dRSFUs

Very helpful link — thank you!

I’m leaning towards returning the flex panel and keeping the 100w regular size panel. I have rotor rails so I think the best option will be running the panel across the roof suspended on supports that are mounted to the grab rail. I can put some cutout PVC blocks midway to provide additional support and vibration dampening.

We have a Honda generator on board for the roof mounted A/C unit (which we used once this season). I haven’t yet figured out how to use the generator to top off the batteries (though I suppose I could just plugin my C-Tek battery charger to the AC outlet).

 

[ssobol]

... We have a Honda generator on board for the roof mounted A/C unit (which we used once this season). I haven’t yet figured out how to use the generator to top off the batteries (though I suppose I could just plugin my C-Tek battery charger to the AC outlet).

I have a Honda 1000 generator for running my AC when shore power is not available. I have found that running the outboard at about 1000RPM will charge the batteries a whole lot faster than the generator can. 1000rpm is much quieter than idle due to resonance of the boat interior.

 

[daninPA]

Interesting. What do use to ascertain the battery charge status? I have a simple voltmeter display plugged into the power adapter but I’m sure it’s not adequate…

 

[Hunkydory]

I have a simple voltmeter display plugged into the power adapter but I’m sure it’s not adequate…

There’s almost always something better & usually more complicated. The simple digital voltage reader, plugged into my otherwise not used cigarette lighter plug has worked well the last 20 years for us for monitoring the charge of the two batteries. I alternate running the twin motors at displacement speed, while also switching between the two batteries for the house. With the change from twin 40’s to 60’s, I’ve doubled my alternator output, so now very seldom need to bump up the charge, while anchoring with my Honda 2000 gen. In fact, the generator now is pretty much solely for a ceramic heater back up in case the Wallas or alternator should fail. Towards the end of last summers SE Alaska cruise the old 12v digital reader failed & I sure missed it.

Jay

 

[daninPA]

I have a simple voltmeter display plugged into the power adapter but I’m sure it’s not adequate…

There’s almost always something better & usually more complicated. The simple digital voltage reader, plugged into my otherwise not used cigarette lighter plug has worked well the last 20 years for us for monitoring the charge of the two batteries. I alternate running the twin motors at displacement speed, while also switching between the two batteries for the house. With the change from twin 40’s to 60’s, I’ve doubled my alternator output, so now very seldom need to bump up the charge, while anchoring with my Honda 2000 gen. In fact, the generator now is pretty much solely for a ceramic heater back up in case the Wallas or alternator should fail. Towards the end of last summers SE Alaska cruise the old 12v digital reader failed & I sure missed it.

Jay

So true!

What voltage did you expect to see and at what point did you starup the engines or generator?

I’ve read all sorts of proclamations that this voltage means the battery is being overcharged, that voltage means the battery is 75% discharged…

Is there w widely accepted and demonstrated rule?

 

[Marco Flamingo]

I had a couple of flexible solar panels on a yurt for years. They got blown around, pitch on them, and mistreated. Still worked fine when I gave them away. I was impressed.

I put a flexible solar panel on the Limpet using SNADs. It is a small panel and is attached with only 4 SNADs. No drilling through the cabin top. By putting a stick-on rubber furniture pad on the back of the panel, it is held away from the deck, creating an air space and avoiding the problem of flexible panels overheating from lying directly on the deck. I was concerned about whether the SNADs would hold in a stiff wind, but have had no problems on the freeway. Good for sustained 70 mph wind.

Pictures in my photo album under Electrical Stuff - Solar Panel.

 

[Hunkydory]

I have a simple voltmeter display plugged into the power adapter but I’m sure it’s not adequate…

There’s almost always something better & usually more complicated. The simple digital voltage reader, plugged into my otherwise not used cigarette lighter plug has worked well the last 20 years for us for monitoring the charge of the two batteries. I alternate running the twin motors at displacement speed, while also switching between the two batteries for the house. With the change from twin 40’s to 60’s, I’ve doubled my alternator output, so now very seldom need to bump up the charge, while anchoring with my Honda 2000 gen. In fact, the generator now is pretty much solely for a ceramic heater back up in case the Wallas or alternator should fail. Towards the end of last summers SE Alaska cruise the old 12v digital reader failed & I sure missed it.

Jay

So true!

What voltage did you expect to see and at what point did you starup the engines or generator?

I’ve read all sorts of proclamations that this voltage means the battery is being overcharged, that voltage means the battery is 75% discharged…

Is there w widely accepted and demonstrated rule?

If the battery is pretty much fully charged & still connected to the running motor’s alternator or genset, mine will normally read out between 13.4 to 14.7v & will slowly climb to that if voltage is low & then begin charging. After shutting off whatever’s charging & the battery without a load it will drop to about 12.7v if fully charged. When not being charged & no or very low load, I don’t like my AGM batteries to drop below 12.3v though supposedly 12.2v is the 50% discharge recommended not to exceed.

If I’m putting the batteries under a heavy load, like when using the windless, then I will either combine the batteries or run both motors.

There’s good reasons for those who have onboard frig/freezer, lithium or other more complicated usage, perhaps such as solar, using the upgraded battery monitoring systems or for that matter those who just like to see the discharge rates & other data, the more complicated systems show. As for me & others who have basic set ups, the simple voltage readout is all that’s really needed. On my first three extended cruises to remote areas, all I had to monitor the batteries was the alternator gauges & a small handheld multimeter.

Jay

 

[ssobol]

I have a Honda 1000 generator for running my AC when shore power is not available. I have found that running the outboard at about 1000RPM will charge the batteries a whole lot faster than the generator can. 1000rpm is much quieter than idle due to resonance of the boat interior.

Interesting. What do use to ascertain the battery charge status? I have a simple voltmeter display plugged into the power adapter but I’m sure it’s not adequate…

I have a BMS that shows current in/out of the battery. The motor at 1K RPM can put about 30 amps into the battery.

 

[Pat Anderson]

We have 200 watts of solar in rigid panels on Daydream's roof. We also have a 2000 watt Wen generator. Our largest load is an ARB freezer. So far, the combination of the engine while cruising and the solar have been more than adequate on our 2017 Great Loop, at Lake Powell, and in the San Juan Islands. We did need to run the generator when we were sitting out some protracted periods of bad weather on the Loop when we were not able to cruise, but that was about the only time.

 

[daninPA]

This has been a helpful discussion — thank you!

I am sending the flexible panel back.

Current plan Is to mount the single panel on the roof using vibration-dampening bolt-on feet secured with Velcro to the roof, with shock cord running to each grab rail and to the radar arch.

I don’t intend to tow with the panel mounted in this position.

 

[thataway]

What loads are you going to be experiencing? The general experience is that 100 watts is not enough to keep up with a chest type freezer/refrig. (See Pat Anderson--2 panels), in Lake Powell area--lots of sun, but hot, PNW not as much sun, but cooler.

I have had good results in an alternate to the Victron 702 volt, amp SOC meter: (Although I used the Victron components on the boat), when I put together a "cheaper" version LIFePO4 system we use in the SUV with a freezer. I. used the
this Amazon volt/amp meter--it was $23, now $44 (although there seems to be another copy in the $36 range).

 

[daninPA]

We used electrical power (battery only) at a very low draw (stereo, VHF, Garmin 942, iPad charger). I only ran the A/C with the generator.

We still haven't used the frig -- we have a very good cooler that keeps ice overnight through very hot days (the key is to open it rarely! and pack it full!)

My primary interest in the solar panel is maintenance while in the slip and longer times at anchor (to avoid running the engine just to feel good about the state of charge).

My planned setup will allow the addition of another identical panel if we start using the boat differently. But so far we have had no overnights, and when we finally do I think First Mate (and putative CO) will insist on land accommodations -- for the time being.

 

[daninPA]

I have had good results in an alternate to the Victron 702 volt, amp SOC meter: (Although I used the Victron components on the boat), when I put together a "cheaper" version LIFePO4 system we use in the SUV with a freezer. I used this Amazon volt/amp meter--it was $23, now $44 (although there seems to be another copy in the $36 range).

Thanks for the recommendation! I have a Fluke Multimeter I plan to use until I install something like this (and replace the $12 power socket voltmeter).

 

[ssobol]

... My primary interest in the solar panel is maintenance while in the slip and longer times at anchor (to avoid running the engine just to feel good about the state of charge). ...)

If you have a BMS you don't have to run the motor "just to feel good about the state of charge". You'll know the state of charge and can make an informed decision to run the motor or not.

FWIW, the Norcold fridge that came with my boat only needs about 2.5 amps when the compressor is running. It worked fine when we used it for overnights in the mid-Atlantic region. I did add vents and a small fan to the compartment where the heat exchanger part of the fridge is. This compartment is normally fully enclosed. Don't know if this improves the performance of the fridge or not, but it can't hurt.

Typically, when anchored out I would run the motor for about 20 minutes before bed to top up the battery. If we weren't going anywhere I'd do the same in the morning. Normally all my electric power comes from one Group 24 FLA dual use battery. I have a 2nd battery in reserve that is just there for engine starting.

 

[daninPA]

If you have a BMS you don't have to run the motor "just to feel good about the state of charge". You'll know the state of charge and can make an informed decision to run the motor or not.

FWIW, the Norcold fridge that came with my boat only needs about 2.5 amps when the compressor is running. It worked fine when we used it for overnights in the mid-Atlantic region. I did add vents and a small fan to the compartment where the heat exchanger part of the fridge is. This compartment is normally fully enclosed. Don't know if this improves the performance of the fridge or not, but it can't hurt.

Typically, when anchored out I would run the motor for about 20 minutes before bed to top up the battery. If we weren't going anywhere I'd do the same in the morning. Normally all my electric power comes from one Group 24 FLA dual use battery. I have a 2nd battery in reserve that is just there for engine starting.

Right -- I thought I mentioned I plan to install a more accurate Battery monitor (I have the cheap power socket voltmeter but want more confidence than $12 part).

I'll have to check on the fridge -- it's what came with the boat when we bought it and we haven't used it yet!