Flexible Solar Panels

[ROBERT CROSS]

ROBERT CROSS - Nice set of 30 watt flexible panels. Where did you get them?

Thanks[/QUOTE

They are ICP panels, got them from Northern Tool several years ago. Have there own controller. In full sun will charge 14.2v, 1.6 amps. Keeps the batts maintained, but where we camp not very efficient at the re-charge.

Plan to adapt the Maria Solution this season..stay tuned

BC

[dljosephson]

We looked at flexible panels some years ago and realized we just couldn't get enough of them on the roof to help at all when boondocking. What has worked for some years now is a ~80 watt panel on the roof, and another that moves around the campsite depending on where the sun is. This allows moderate light, pump, radio and furnace use at night so long as we are moderately diligent about chasing the sun in the daytime. Flex panels would be fine in the desert, or for keeping the battery charged with no load, but we are talking a maximum of 30 watts or so in the available space, versus about 200 if I were really wacky about hanging them wherever I could find space.

There will be more radios in the new(er) Airstream moho and I am planning to get closer to wacky in that installation.

The rule of thumb about needing a charge controller seems to be that if your maximum panel output is less than 1/20 of the amp-hour rating of the battery, a controller isn't needed. So for 225 AH batteries like we have (2 T105's in series), anything up to about 10 amps is OK. I have found this to be true. The batteries will need watering, but the trailer sat in a storage lot for nearly a year and all was well.

[joecolao]

Hello JD,
I first installed the flex solar panels almost 10 years ago. My first installation was 2 68 watt modules on a 1977 Airstream. I then sold the trailer to my buddy Gary. He sold the trailer to someone in Vermont about 3 years ago.
Up until that point they functioned fine.
When I first installed them I rivited a piece of aluminum threshold that I bedded into some silicone sealant at the leading edge of the module to prevent wind from up lifting it.
Along the upper edge of the module I installed a continuous caulked bead. Along the lower edge I installed a broken caulked bead, I thought that maybe it was best to allow moisture that may have come between the Airstreams aluminum skin and the module to escape.

I have since installed (about 5 years ago) a 68 watt flexible module on my 1991 34' Airstream.
In this installation I did not use any caulking at all except for the bedding of the aluminum strip on the leading edge.

Last year I did a "non-scientific" pull test and found no decrease or defect in the adhesion between the module and the Airstream skin.

I hope this info helps you in your decision.
Joe

[joecolao]

Originally Posted by dljosephson

We looked at flexible panels some years ago and realized we just couldn't get enough of them on the roof to help at all when boondocking. What has worked for some years now is a ~80 watt panel on the roof, and another that moves around the campsite depending on where the sun is. This allows moderate light, pump, radio and furnace use at night so long as we are moderately diligent about chasing the sun in the daytime. Flex panels would be fine in the desert, or for keeping the battery charged with no load, but we are talking a maximum of 30 watts or so in the available space, versus about 200 if I were really wacky about hanging them wherever I could find space.

There will be more radios in the new(er) Airstream moho and I am planning to get closer to wacky in that installation.

The rule of thumb about needing a charge controller seems to be that if your maximum panel output is less than 1/20 of the amp-hour rating of the battery, a controller isn't needed. So for 225 AH batteries like we have (2 T105's in series), anything up to about 10 amps is OK. I have found this to be true. The batteries will need watering, but the trailer sat in a storage lot for nearly a year and all was well.

I would strongly recommend a good MPPT charge controller. Before leaving on a 3 1/2 month 16,000 mile trip in 2006 I watered my flooded batteries for the fist time in more than 3 years!

12 volt batteries off gas at 14.4 volts. The new solar charge controllers deliver maximum current of the solar array and up to 14.4 volts and then let the voltage float to 12.9 volts - this cycle continues until the cycles become shorter and shorter.

My experience has been about 35% more power into the batteries and much less watering required.

Joe

[Crusty]

Originally Posted by dljosephson

... The rule of thumb about needing a charge controller seems to be that if your maximum panel output is less than 1/20 of the amp-hour rating of the battery, a controller isn't needed. So for 225 AH batteries like we have (2 T105's in series), anything up to about 10 amps is OK. I have found this to be true. The batteries will need watering, but the trailer sat in a storage lot for nearly a year and all was well.

This rule of thumb is a bit misleading and it could lead you to electrically damage your batteries and possibly even create a hazardous condition. The issue with the amorphous silicon panels is that in bright sun conditions they may output up to 18V, and it is this over-voltage which may damage less resilient battery types (such as AGMs) regardless of the output power.

The over-voltage causes corrosion of the positive plates within the batteries which depletes the plate material and may even cause the growth of dendrites between the positive and negative plates (causing an internal short) as well as excessive gas production (oxygen/hydrogen) which is explosive, and it also depeletes the electrolyte (which in sealed cells cannot be replenished).

In the case of Trojan T105s, the batteries themselves are one of the most durable batteries that have ever been made (I had a pair of T105s which lasted over 10 years) and can tolerate significant electrical abuse and continue to function, but that's not the case for AGM batteries (which are a good choice inside of a trailer because they typically don't vent hydrogen or corrosive vapors into the contained environment of the trailer interior).

So, always use a charge controller with this type of panel to control the output voltage, and the MPPT type is recommended because they result in up to 20% more charge into the battery from a given panel over the standard controllers.

[jimmini]

Here is solar at work.Note evan has panels on pick-up truck and used as awnings over the windows.
Photo taken this winter in Quartzsite AZ
CLICK photo to make larger.

[Fenghuang]

Originally Posted by jimmini

Here is solar at work.Note evan has panels on pick-up truck and used as awnings over the windows.
Photo taken this winter in Quartzsite AZ
CLICK photo to make larger.

A friend of mine recently got a mobile solar panel from "Solar" Mike Gohl, a dealer near Slab City The Sun Works
The business as an A+ rating from the BBB. I don't know if Mike deals with the flexible panels. Has anyone on the forum utilized his services? Our friends is happy with his mobile solar panel.

We are seriously considering getting a portable panel to supplement our two 53 watt panels, which are mounted flat on our trailer. Our panels are sufficient for 3-4 nights of dry camping. The extra panel would come especially in handy when camping in locations with limited sun light due to weather or trees. One objective is to get the trailer self sufficient off grid for a longer than 4 nights in case of a disaster.

Larry in San Diego

[AirsDream]

Seems to me that if you want to be certain of being "self sufficient off grid," then a) you need to shed electric load insofar as possible ... go with LED lighting, avoid / minimize furnace use, minimize water pumping, etc.; b) be in a sunny place so your solar panels can work; and c) carry a small generator to deal with those cloudy days when solar panels don't have enough output to keep up with usage ... this likely is not necessary if you've got enough panel output, charge controller works well, etc. and you are in e.g. desert environment where it's sunny pretty much every day. But once your electricity budget is under control, then fresh water and waste tanks will become the limiting factors.

[jimmini]

Originally Posted by AirsDream

Seems to me that if you want to be certain of being "self sufficient off grid," then a) you need to shed electric load insofar as possible ... go with LED lighting, avoid / minimize furnace use, minimize water pumping, etc.; b) be in a sunny place so your solar panels can work; and c) carry a small generator to deal with those cloudy days when solar panels don't have enough output to keep up with usage ... this likely is not necessary if you've got enough panel output, charge controller works well, etc. and you are in e.g. desert environment where it's sunny pretty much every day. But once your electricity budget is under control, then fresh water and waste tanks will become the limiting factors.

HERE is how you take care of fresh and waste water so you have no limiting factors.
Fresh and wast tanks go in TV
Fresh water tank has same pump that is in trailer it plug into power outlet in TV.I can then hook hose to my city water or fill my tank.
Waste tank goes into TV it is filled by use of macerator pump that is powered from trailer batteries. and dump like you trailer.

[dljosephson]

Originally Posted by Crusty

This rule of thumb is a bit misleading and it could lead you to electrically damage your batteries and possibly even create a hazardous condition. The issue with the amorphous silicon panels is that in bright sun conditions they may output up to 18V, and it is this over-voltage which may damage less resilient battery types (such as AGMs) regardless of the output power.

The over-voltage causes corrosion of the positive plates within the batteries which depletes the plate material and may even cause the growth of dendrites between the positive and negative plates (causing an ...

Good point -- but it would have to be a huge amorphous panel and a tiny battery to get to this condition. I would not recommend AGMs or gel cells to anyone unless there was an unavoidable hazmat issue that prohibited the use of flooded cells. A charge controller is always preferable, but if you keep an eye on the voltage it is possible to do without. I have never seen more than about 15 volts across a pair of T-105s with an 80 watt panel.

[JDL]

joecolao (Joe)

Thank you! Thank you! Thank you!

This is what I was looking for and why I stated this post up again.

I assume the panels you installed 5 years ago on the 34 are still working ok? Also, I assume it was a Uni-solar?? I have a white enamel roof on mine. did you do any special prep to the surface before mounting the Uni-solar 68 watt panel?

Again I really appreciate your reply! 73's jd

Originally Posted by joecolao

Hello JD,
I first installed the flex solar panels almost 10 years ago. My first installation was 2 68 watt modules on a 1977 Airstream. I then sold the trailer to my buddy Gary. He sold the trailer to someone in Vermont about 3 years ago.
Up until that point they functioned fine.
When I first installed them I rivited a piece of aluminum threshold that I bedded into some silicone sealant at the leading edge of the module to prevent wind from up lifting it.
Along the upper edge of the module I installed a continuous caulked bead. Along the lower edge I installed a broken caulked bead, I thought that maybe it was best to allow moisture that may have come between the Airstreams aluminum skin and the module to escape.

I have since installed (about 5 years ago) a 68 watt flexible module on my 1991 34' Airstream.
In this installation I did not use any caulking at all except for the bedding of the aluminum strip on the leading edge.

Last year I did a "non-scientific" pull test and found no decrease or defect in the adhesion between the module and the Airstream skin.

I hope this info helps you in your decision.
Joe

[Crusty]

Originally Posted by dljosephson

Good point -- but it would have to be a huge amorphous panel and a tiny battery to get to this condition. I would not recommend AGMs or gel cells to anyone unless there was an unavoidable hazmat issue that prohibited the use of flooded cells. A charge controller is always preferable, but if you keep an eye on the voltage it is possible to do without. I have never seen more than about 15 volts across a pair of T-105s with an 80 watt panel.

I lost a Group 24 AGM which was connected to a 5W amorphous trickle charger panel from a week of Texas summer sun, due to overvoltage output. I stand by my previous statements.

[dljosephson]

Originally Posted by Crusty

I lost a Group 24 AGM which was connected to a 5W amorphous trickle charger panel from a week of Texas summer sun, due to overvoltage output. I stand by my previous statements.

OK, that's a solid data point. A 24 isn't too big, but I wouldn't imagine that was possible, thanks for the info. There are good, inexpensive charge controllers available so I guess that would be a very important piece to add to the picture, especially for an AGM or gel battery.

[dljosephson]

So, we've determined that you definitely need a charge controller. I thought I would review the other things I "knew" about these amorphous solar panels. The 68 watt Unisolar panels are available online for $339 from Affordable Solar (about $5 per claimed watt). Their site also includes a lot of information on attaching the panels to roofing materials. These panels are 112" x 15.5" . Working out their specified numbers it looks like they convert about 5.8% of the sunlight to electricity. Big crystalline panels are around $4 a watt ($3 if you buy 20 at a time) and are 12 to 13% efficient.

The question for me is that, for the same money or a little more, is it really worthwhile to use up double the roof space for the same output?

[VIKING]

Additional things to consider:

appearance

durability

better low-sunlight power conversion

reduced airflow disturbance

the shape is probably more effective for placement on our Airstreams roofs. I could fit 2 on my Safari easily, and they would be rather unnoticeable.

I'm sure there are more..

Rich

[ROBERT CROSS]

Maria arrived to-day!!!

Rigging-up the pole to mount her on.

[joecolao]

Originally Posted by VIKING

Additional things to consider:

appearance

durability

better low-sunlight power conversion

reduced airflow disturbance

the shape is probably more effective for placement on our Airstreams roofs. I could fit 2 on my Safari easily, and they would be rather unnoticeable.

I'm sure there are more..

Rich

Dear Rich,
There is also the temperatrue tolarance advantage. As glazed solar modules become heated they lose much of thier effeiciency even when elevated from the structure they are mounted on. The power factors stated on the rating plaque of a module is usually at 70 degrees F.

Amorph. are much more tolorant of heat.

I am not suggesting to anyone that amorph are superior to other modules. I have a blend of both and they compliment one another very well.

Modules should be chosen by the end user to better improve and achieve whatever it is that they are looking for.
Joe

[VIKING]

Thanks Joe.
I remember reading about that also.

I concur, amorph panels are not a perfect solution. Just another tool in the arsenal.

For those who are interested in this area of solar, I suggest doing some reading on the couple who is responsible for it, along with MANY other amazing developments in the areas of cd's and dvd's, batteries, hydrogen storage. The list goes on and on. I encourage you to follow the link below, and learn about one of the greatest inventor-developer couples of the century, Stanley and Iris Ovshinky.

The Founders of ECD Ovonics — Stanford R. Ovshinsky and Iris M. Ovshinsky founded Energy Conversion Devices (ECD Ovonics) in 1960 to use science and technology, based on Stan's discoveries, to solve serious societal problems in the fields of en


Enjoy, Rich

[joecolao]

Originally Posted by dljosephson

OK, that's a solid data point. A 24 isn't too big, but I wouldn't imagine that was possible, thanks for the info. There are good, inexpensive charge controllers available so I guess that would be a very important piece to add to the picture, especially for an AGM or gel battery.

Dear camping buddies,
It is important to properly interprete the voltages listed on the back of the modules. Most cyrstal modules are 21vdc and the amorphs about 18vdc. If you look carefully the manufacturer has ocv after the rated vdc.
Oc stands for OPEN CIRCUIT VOLTS.
When you place a battery in line with the PV module it has much greater mass and and will "drag" the voltage down to a useble level.
At 14.4 volts a battery will "off gas" or "boil" - absorbed glass mat or "agm" batteries has a slightly lower internal resistance and will charge a little faster. They also have a better soc life, whereas flooded batteries self discharge.
I don't know what happened to your 24 series battery but from my experience it is highly unlikely that a 5 watt module could have damaged it. The amps from a 5 watt module is about .3 amps.
In the hot summer sun a cyrstal module would generate significantly less power since the pv ratings are at 70f.

I hope that I am not confusing the issue more.
Joe

[MontanaArgy]

I put a 68w Unisolar unit on my Argy 20 two years ago. I have a controller, the MPP type from Blue Sky Energy which increases the amperage. I did not caulk or protect the front edge or do anything but just clean the surface (painted) well and stick it down. I got it all except the (two Optima) batteries from Infinigi. They were very helpful, and the best prices i was able to find at that time.

As Joe mentioned early in this string, getting the backing off was difficult, I did it when it was cold. Not that bad, but awkward on top of the ladder in the wind with 10 feet of it rolled up in your arms. I certainly recommend an assistant. It is installed high along the road side. I ran the wires down along side the tank vent pipe. I have two big Optima batteries. I know these are less efficient, but the don't gas into the trailer, and they don't need to be filled, as one of them is very difficult to reach. Similar to the Unisolar, they may not be as efficient at peak, but in cloudy or partially shaded conditions they continue to produce power when the solid type may not, at least these are my understanding, and seem to be accurate from what I am seeing.

I have had no sign of the panel pulling up, it seems to be stuck for life so far. The only interesting thing I have noticed is the trailer roof under the panel wrinkles just a bit in the hot sun on very hot days due to the expansion of the panel.

I will post a photo soon of what it looks like.