diy solar

diy solar

Flexible Panels hit Prime Time?

Exciting news about these panels and very much looking forward to a future build with lower price points in the future. That being said even with the discount codes there are still around 4x increase above new / blemished Sunpower rigid panels at https://santansolar.com/. The last ones i snagged were the 370Watt for $150 each which was the premium A-spec. At the same time they had the 350W (same panel but 20 watts less for maybe ~$120 or less which were brand new. Pic below taken a week ago in west palm beach had 3@250W + 2@370w. Max output as indicated by Victron Cerbo was 1370w (1490 rated) @ 90ish amps. Would live to replicate this with new flexible panels as much less of an engineering challenge.
Travato  Palm Beach.jpg
 
Last edited:
I guess the CIGS Panels getting pretty hot if mounted directly an the roof of a Van. Doesn't it mean that the efficiency also drops more than on a classic Glas-Panel with air under it? Also I guess its getting hotter inside the van, right!?
Whats about the "plastic" surface of the CIGS Panels? Doesn't they getting much fast dirty and on the long run kind of "milky"?
 
That's what I thought too and why I was so surprised by a 25 year warranty.
Hmm... anyone tried purchasing a flex panel via their credit card, then add the panel to their credit cards warranty protection plan!??? If one could get the panel covered through a CC warranty plan... those CC warranty plans typically double the original manufacturer's warranty!
 
The Renology flex panels only have a 5 year warranty on material and workmanship. So if they fall apart in 61 months you are out of luck.

I have a project coming up that flexible panels would be perfect for, the target is for 1500W of solar generation, but really worry about having $2500 worth of problems with the Renology product.

The CIG's look interesting but pricey. Do they really truly last as advertised?
What about calling your credit card company and seeing if the panels qualify for your credit card's extended warranty plan!???
 
I am working on a design for my class A RV that will get me close to 4kw. Here's my plan:

I want 60 cell panels so that I don't need a solar controller. These are very common and are typically .5$ per watt, or even less when used.

Higher efficiency modules probably do me no good, because it seems that the module efficiency simply raises the Vmp, which means I gain nothing from higher efficiency cells because the cell is tied to the LiFePo4 battery voltage.

I plan on putting 6 fixed panels on slides, with 6 flexible panels of similar size and wattage below them mounted to the roof. I'll keep some of the existing 100w panels that I have on the roof for tighter spots for an additional 500w. This would be about 2300w when driving and about 4kw when parked and slides extended.

The idea with the flexible panels is less weight. The big ones are 40lb, plus slides and motors, puts maybe 400lb on the roof, which weighs heavily on my conscience. I'll remove maybe 150lb of air conditioning up there, but if I'm honest the 2 interior head units of the mini split will be up high too.

I found a supplier on aibaba that will sell me 60 cell sunpower panels. After panicking over the tariff issue which this thread raised, I am concluding that these are an exception to the tariff because the cells are USA sunpower cells. It seems I will be paying 300 per panel plus $1500 for sea shipping. Not cheap, but then not 40lb.
If you're determined to use large panels on RV's (for $/Watt reasons), install a few cross strips on the back to form an open lattice to support the glass & reduce unsupported span.
I have not found 30 cell fixed panels, so I'll want to run additional trusses under the fixed panels on the slides.

I figure the flexible ones will be rather protected while I am driving, and they won't be handled to be deployed. In theory, the sunpower cells are more durable than what Will has endured. I will want to close the slides when there are storms, which also covers the flexibles so there really should not be hail or rain whacking the ETFE.

Anyone have additional thoughts for me?
 
Sounds too complex and the flexi panels are not a good solution if you want max power density. They are good for roofs where a rigid panel is problematic but this is not a problem on a class-A.

I'd start with seeing how many rigid panels you can fit on the roof of the voltage you require to do your direct charge approach. If the power is not enough consider a two tier approach to get another similar sized set that slides out when stationary. If still not enough you can consider a 3 tier to get a passenger/driver slide out array. At some point the height becomes a problem as reasonable limits, but typically 2 tiers will be lower than a roof mount AC.

Use 8020 for the frame and slide outs. They make all the parts to make it easy, durable, and reliable. Use physical locks to ensure it doesn't deploy while in motion.
 
I have six 100 watt renogy flat panels on my roof, and two renogy 175 watt panels.

The flexible panels put out as much as the flat panels, despite being a little over half the wattage.

I do attribute that extra wattage them being tilted into the sun on sunrise on the front of my fifth wheel. I never knew how tilted those roofs were until installed solar.

I also installed with the RVWithTito video with the tape bolts and nuts and locktite. Unlike when he tried to remove them, I plan on securing the bolt with pliers to keep it from spinning on the tape.

I see these flexible Renogy panels on Phoenix Craigslist, but the guy selling them is asking $10 less then whatever Renogy prices them at and won’t budge.

I also noticed Amazon is slower to remove the sale price than the Renogy website.
 
Why are you avoiding a solar charge controller?
Yes I have 60 cell panels going into 24 volt system but it seems like I would be creating all sorts of problems by skipping the charge controller.
 
Yes I have 60 cell panels going into 24 volt system but it seems like I would be creating all sorts of problems by skipping the charge controller.

Correct. You really want a solar charge controller. Figure out how many panels you can on the roof. That will dictate which solar charge controller you should get.
 
Sounds too complex and the flexi panels are not a good solution if you want max power density. They are good for roofs where a rigid panel is problematic but this is not a problem on a class-A.

I'd start with seeing how many rigid panels you can fit on the roof of the voltage you require to do your direct charge approach. If the power is not enough consider a two tier approach to get another similar sized set that slides out when stationary. If still not enough you can consider a 3 tier to get a passenger/driver slide out array. At some point the height becomes a problem as reasonable limits, but typically 2 tiers will be lower than a roof mount AC.

Use 8020 for the frame and slide outs. They make all the parts to make it easy, durable, and reliable. Use physical locks to ensure it doesn't deploy while in motion
I am working on a design for my class A RV that will get me close to 4kw. Here's my plan:

I want 60 cell panels so that I don't need a solar controller. These are very common and are typically .5$ per watt, or even less when used.

Higher efficiency modules probably do me no good, because it seems that the module efficiency simply raises the Vmp, which means I gain nothing from higher efficiency cells because the cell is tied to the LiFePo4 battery voltage.

I plan on putting 6 fixed panels on slides, with 6 flexible panels of similar size and wattage below them mounted to the roof. I'll keep some of the existing 100w panels that I have on the roof for tighter spots for an additional 500w. This would be about 2300w when driving and about 4kw when parked and slides extended.

The idea with the flexible panels is less weight. The big ones are 40lb, plus slides and motors, puts maybe 400lb on the roof, which weighs heavily on my conscience. I'll remove maybe 150lb of air conditioning up there, but if I'm honest the 2 interior head units of the mini split will be up high too.

I found a supplier on aibaba that will sell me 60 cell sunpower panels. After panicking over the tariff issue which this thread raised, I am concluding that these are an exception to the tariff because the cells are USA sunpower cells. It seems I will be paying 300 per panel plus $1500 for sea shipping. Not cheap, but then not 40lb.

I have not found 30 cell fixed panels, so I'll want to run additional trusses under the fixed panels on the slides.

I figure the flexible ones will be rather protected while I am driving, and they won't be handled to be deployed. In theory, the sunpower cells are more durable than what Will has endured. I will want to close the slides when there are storms, which also covers the flexibles so there really should not be hail or rain whacking the ETFE.

Anyone have additional thoughts for me?
IN

I am working on a design for my class A RV that will get me close to 4kw. Here's my plan:

I want 60 cell panels so that I don't need a solar controller. These are very common and are typically .5$ per watt, or even less when used.

Higher efficiency modules probably do me no good, because it seems that the module efficiency simply raises the Vmp, which means I gain nothing from higher efficiency cells because the cell is tied to the LiFePo4 battery voltage.

I plan on putting 6 fixed panels on slides, with 6 flexible panels of similar size and wattage below them mounted to the roof. I'll keep some of the existing 100w panels that I have on the roof for tighter spots for an additional 500w. This would be about 2300w when driving and about 4kw when parked and slides extended.

The idea with the flexible panels is less weight. The big ones are 40lb, plus slides and motors, puts maybe 400lb on the roof, which weighs heavily on my conscience. I'll remove maybe 150lb of air conditioning up there, but if I'm honest the 2 interior head units of the mini split will be up high too.

I found a supplier on aibaba that will sell me 60 cell sunpower panels. After panicking over the tariff issue which this thread raised, I am concluding that these are an exception to the tariff because the cells are USA sunpower cells. It seems I will be paying 300 per panel plus $1500 for sea shipping. Not cheap, but then not 40lb.

I have not found 30 cell fixed panels, so I'll want to run additional trusses under the fixed panels on the slides.

I figure the flexible ones will be rather protected while I am driving, and they won't be handled to be deployed. In theory, the sunpower cells are more durable than what Will has endured. I will want to close the slides when there are storms, which also covers the flexibles so there really should not be hail or rain whacking the ETFE.

Anyone have additional thoughts for me?
In the picture above of my class B i am using a 3 tier system with slides but none of my panels are flexible. Three points you should consider factoring into your design are:
#1 Shading - The panels on the bottom need to slide out a minimum of 4" beyond the top panel and you need to minimize the height difference between the top panel and slide panel which all tie into the slide length which impacts the slide heights that will be available to you.
#2 Motors - My original design was to use actuators but thought the risk was too high for an accidental deployment at freeways speeds and imagined a panel flying through someones window. Mine are manual with manual locks.
#3 Rack Structural Integrity - The rack holding the fixed panels on top with slides on the bottom is more complex than you might think as you have to account for shading and the width on the slides as well as the strength of the rack which requires a lot of engineering. Taking this into account the fabricator that made mine used a fabrication technique called a "double pan" when you have a mirror image of the inside and outside of the rack that fit into each other which are then welded. This adds a lot of weight but exponentially increases strength so if you are ever in an accident the rack wont shear off.

Good Luck and please let me know how those panels work out.
Danny
 
Last edited:
Why are you avoiding a solar charge controller?
There is not much point to it. The 24 battery voltage is very close to the Vmp, so the MPPT part of the device, the dc-dc converter, is a waste of money, not to mention heat/energy. The battery side of the controller is pointless too. LiFePo4 does not need an interesting voltage/amps profile like lead acid.

The BMS turns on/off (disconnects the panels from the battery) charging when the batteries can take more or not. The only benefit to a charge controller would be to limit current to not exceed the equivalent of say 3.5v so that the battery can be run up to the full charge. But the sun tapers current nicely every day without any complicated circuitry. I charge to a SoC of 95%, which means the batteries almost never get near the knee where the voltage measurement is useful. I don't see the point of attempting to run these up into the knee. It's not like I absolutely have to have the rated 280ah from this pack. Who would, really?
Correct. You really want a solar charge controller.
No, I don't. I don't have one now and my system (1600w of 72 cell panels and 24v LiFePo4) is doing just fine without it. The most I can get from my panels is really 1333w, since the 12 extra cells effectively do nothing at the voltage of the pack.

A far better question is why, if you are using panels that cannot exceed say .5C and are matched near to the Vmp, does everyone have the belief that they are needed, except for the fact that everyone believes it?
 
Last edited:
the flexi panels are not a good solution if you want max power density. They are good for roofs where a rigid panel is problematic but this is not a problem on a class-A.
I don't see why the flexi panels are any different. They use the sunpower mono crystalline cells that are pretty much the same in terms of watts/area.

I agree that adding 500lb down near the chassis is irrelevant in my class A, but 500lb on the roof is significant. That's a lot of moment of inertia. The RV is already a pig when the rear wheels experience a rise at different times. This is roughly every entrance and exit from any parking lot turning onto a road. It is essential to hit speed bumps perpendicular. Mine has steel tying the roof to the walls, which sucks as far as weight goes.
#1 Shading - The panels on the bottom need to slide out a minimum of 4" beyond the top panel and you need to minimize the height difference between the top panel and slide panel which all tie into the slide length which impacts the slide heights that will be available to you.
#2 Motors - My original design was to use actuators but thought the risk was too high for an accidental deployment at freeways speeds and imagined a panel flying through someones window. Mine are manual with manual locks.
#3 Rack Structural Integrity - The rack holding the fixed panels on top with slides on the bottom is more complex than you might think as you have to account for shading and the width on the slides as well as the strength of the rack which requires a lot of engineering. Taking this into account the fabricator that made mine used a fabrication technique called a "double pan" when you have a mirror image of the inside and outside of the rack that fit into each other which are then welded. This adds a lot of weight but exponentially increases strength so if you are ever in an accident the rack wont shear off.
#1 I agree. I was planning on doing what RV with Tito did to mount the light weight panels. Note, that my rigid ones will be on top and do the sliding. I figure I can mount the rigid ones as low as possible to clear the fixed panels below.

#2, True, but I am not eager to have to get a ladder to extend them. Maybe, I can make a simple latch that can be tugged with a rod from the ground allowing the actuator to do its thing. Plus, I like the idea of doing something to measure the stress/wind and retract them automatically.

#3, I agree. I figure with the thin panels below, I can really minimize height of rigid panels on the slides. The steel slides will be almost touching the roof, and the panel just above the thin panels. This should help a lot with the wind profile and the required structure to keep them on the roof, compared to 2 layers of rigid panels.

Thanks for the thoughts.
 
In the picture above of my class B
How much weight did you add to the roof? Can you feel it?

I am very tempted to throw 500lb on my roof then do some tests. Basically I would want to measure the amount of rocking when driving one rear wheel on a hump at an interesting speed.
 
There is not much point to it. The 24 battery voltage is very close to the Vmp, so the MPPT part of the device, the dc-dc converter, is a waste of money, not to mention heat/energy. The battery side of the controller is pointless too. LiFePo4 does not need an interesting voltage/amps profile like lead acid.

The BMS turns on/off (disconnects the panels from the battery) charging when the batteries can take more or not. The only benefit to a charge controller would be to limit current to not exceed the equivalent of say 3.5v so that the battery can be run up to the full charge. But the sun tapers current nicely every day without any complicated circuitry. I charge to a SoC of 95%, which means the batteries almost never get near the knee where the voltage measurement is useful. I don't see the point of attempting to run these up into the knee. It's not like I absolutely have to have the rated 280ah from this pack. Who would, really?

No, I don't. I don't have one now and my system (1600w of 72 cell panels and 24v LiFePo4) is doing just fine without it. The most I can get from my panels is really 1333w, since the 12 extra cells effectively do nothing at the voltage of the pack.

A far better question is why, if you are using panels that cannot exceed say .5C and are matched near to the Vmp, does everyone have the belief that they are needed, except for the fact that everyone believes it?

You are absolutely correct - if care is used to match the panels voltage to the system voltage you don't need a charge controller. A simple disconnect works to stop charge when battery full; or in a situation you don't want to charge.

The Electro-Dacus BMS has a module (DSSR) for solar to do exactly this and also diverts any excess power to a dump load if you have it.

It's a clever and efficient setup without extra complexity. But you should know most people on this forum like complexity :cool: as this is a hobby and we like to tinker away. It is not viewed as critical infrastructure which should fall under the KISS rules.
 
The Electro-Dacus BMS has a module (DSSR) for solar to do exactly this and also diverts any excess power to a dump load if you have it.
That's what I use. I don't use the diversion, but I do have my BMS turn on the water heater when the batteries are above 90%, so I have the poor man's version of that.
most people on this forum like complexity
Oh, that's a bit unfair. I find that most people have not really questioned the MPPT. I had an exchange on another forum where the arguments were essentially "because it is done this way". I think we are dealing with mental/marketing inertia from lead acid. Nobody seems to notice that they are effectively turning off the battery side of the MPPT settings.

The other source of the beliefs is probably from lousy BMS's that do nothing but disconnect the battery. In that situation, it is important to balance the batteries and make sure your charge controller is shutting off before the BMS kills everything. Maybe those are not used much anymore, but the belief that an MPPT is needed still lingers.
 
That's what I use. I don't use the diversion, but I do have my BMS turn on the water heater when the batteries are above 90%, so I have the poor man's version of that.

Oh, that's a bit unfair. I find that most people have not really questioned the MPPT. I had an exchange on another forum where the arguments were essentially "because it is done this way". I think we are dealing with mental/marketing inertia from lead acid. Nobody seems to notice that they are effectively turning off the battery side of the MPPT settings.

The other source of the beliefs is probably from lousy BMS's that do nothing but disconnect the battery. In that situation, it is important to balance the batteries and make sure your charge controller is shutting off before the BMS kills everything. Maybe those are not used much anymore, but the belief that an MPPT is needed still lingers.

I didn't mean a negative with the complexity comment. I mean that if something is a hobby the complexity usually grows with the tinkering and that these systems tend to evolve over time.
 
I didn't mean a negative with the complexity comment. I mean that if something is a hobby the complexity usually grows with the tinkering and that these systems tend to evolve over time.
Well, the electrodacus is a substitute for a controller. My primary concerns with going without a controller are (1) going without regulated input and having the ability to modify the input to coordinate with my other components even if they are close (2) I do not want to rely on a BMS for shutdown as they are intended in my system as a backstop last resort (redundancy) (3) may batteries could back feed to the panels at night. I think going without a controller actually adds complexity and risk to the system while reducing flexibility.
 
Back
Top