Portable Solar Panel Connected to Converter?

[Patandlinda]

Originally Posted by Jim Bennett

Mounting direct, one of the advantages of flexible panels.

Once I get the panels, and figure out how I will wire them in, along with the portable, I will post about the process. It should be fairly easy.

Now you have my attention . Can't wait for pictures of your installation . Every time I mention flexible panels I get flack.What do you think about not having a air space , between solar panel and fiberglass trailer ? In your professional opinion , is that a big deal now ? Pat

[alanmalk]

Originally Posted by Jim Bennett

You are correct with the PWM controller, but can go either way with MPPT controller. I am using an MPPT.

The big advantage with using MPPT controllers is being able to run the panels in series which avoids the potential voltage drop that you would get with wires that are undersized. For someone following this discussion - Jim's 4 panels in series would be roughly the equivalent of one panel's amps but 4 panels voltages added up. Taking a guess: 4 amps at 64 volts nominally will be coming down the wire. 8 gauge wire would be overkill for 4 amps. But the key is having an MPPT controller which very few of us have. The ordinary PWM solar controller that most of us have can not accept the higher voltage, nor can they convert high voltage into high amps like the MPPT (which has a DC to DC converter inside) can do.

But, like everything else, there can be a drawback. 4 panels in series will be shut down if 1 gets shade where 4 panels in parallel will produce 3 panels worth of power if 1 is shaded. Then again, panels in series could have diode bypassing added to minimize the shade issue.

--
Alan

[hollis]

This is an important clarification about my post which began this thread.

You may recall that, in response to my question to Escape about how the solar port for a portable solar panel was to be connected, they had said "the Zamp port is wired to the converter, where the battery charger is located".

After explaining my confusion about this to Escape they have cleared this up with the following:

"There are two types of wiring for the solar port one is if you have our solar panels and the other is if you don’t. If you have our solar panels it is wired to the solar controller. If you do not have our solar panels the wiring goes directly to the battery."

Such a good company to deal with, looking forward to finishing my build sheet.

Chuck

[Jim Bennett]

Originally Posted by freespirit

your project is interesting and look forward to its progress, but curious ....how do you replace a failed panel once it has been bonded to the fiberglass?

With the EternaBond tape I am considering you can cut the tape with a knife, then use heat to remove the tape off the trailer. Acetone will remove the remaining residue.

With either of the caulks, you could just cut it free, then cut and scrape the stuff off the trailer if desired.

Originally Posted by Patandlinda

Now you have my attention . Can't wait for pictures of your installation . Every time I mention flexible panels I get flack.What do you think about not having a air space , between solar panel and fiberglass trailer ? In your professional opinion , is that a big deal now ? Pat

Most folks that have used and tested them have had no issues with heat, at least none they have reported. My opinion is just one from doing hordes of research and reading. I am using a panel that has a thin ETFE coating from Japan, with helps absorb sunlight, and does not reflect like the PET coatings most flexible panels have used.

Originally Posted by alanmalk

The big advantage with using MPPT controllers is being able to run the panels in series which avoids the potential voltage drop that you would get with wires that are undersized. For someone following this discussion - Jim's 4 panels in series would be roughly the equivalent of one panel's amps but 4 panels voltages added up. Taking a guess: 4 amps at 64 volts nominally will be coming down the wire. 8 gauge wire would be overkill for 4 amps. But the key is having an MPPT controller which very few of us have. The ordinary PWM solar controller that most of us have can not accept the higher voltage, nor can they convert high voltage into high amps like the MPPT (which has a DC to DC converter inside) can do.

But, like everything else, there can be a drawback. 4 panels in series will be shut down if 1 gets shade where 4 panels in parallel will produce 3 panels worth of power if 1 is shaded. Then again, panels in series could have diode bypassing added to minimize the shade issue.

--
Alan

My 60W panels run at 17.6 Volts and produce 3.4 Amps. My portable runs at 18V with 4.4A.

I plan to mount the four fixed panels, then play with the wiring to see what the output is at the batteries in both parallel and series wiring. I could also see what happens with shading one panel, whether it drops the output of the whole array, or just reduces the output by the loss of the one panel.

Either way, I would need to somehow (still working on this and looking for ideas) need to connect my portable in series to get the full 80W capacity it is capable of. I kinda wish now I did not have it, and instead use one or two of the 60W flexible as a portable solution. Not only would there be no conflict, they would store easier too.

Still on the learning path.....

[alanmalk]

Originally Posted by Jim Bennett

...
Either way, I would need to somehow (still working on this and looking for ideas) need to connect my portable in series to get the full 80W capacity it is capable of.

You can connect it in series but the output amps will be limited by the smallest panel in the string (3.4A), and the total voltage will add up to around 80V. This may or may not be over the maximum that your MPPT controller can take. Should be easy enough to determine from the manual. Not much you can do about the missing 1 amp however. (Otherwise you would be getting something for nothing. ) The same effect happens with shading in a series string - total output amps will be limited to what the shaded panel can produce.

I do know it's fun to play around with combinations and to learn what works and what doesn't.

--
Alan

[Patandlinda]

Jim do you have the name and source for your panels ? I found a 50 watt and 100 watt flexible solar panels on Amazon . I want to compare what you found and what I found . This has been trying to sort through this for a couple of years now . I really would like the flexible if the technology will work for me . Pat

[Jim Bennett]

Originally Posted by alanmalk

You can connect it in series but the output amps will be limited by the smallest panel in the string (3.4A), and the total voltage will add up to around 80V. This may or may not be over the maximum that your MPPT controller can take. Should be easy enough to determine from the manual. Not much you can do about the missing 1 amp however. (Otherwise you would be getting something for nothing. ) The same effect happens with shading in a series string - total output amps will be limited to what the shaded panel can produce.

I do know it's fun to play around with combinations and to learn what works and what doesn't.

--
Alan

That makes sense Alan, I had not considered it.

I have read conflicting info on wiring different sized panels like mine in parallel, as to whether the wattage seen is the equivalent to the lower sized one. I understand that they need to be similar voltages, or like in your example with amperage, they would operate at the lowest voltage in the array. To my thinking, in parallel, the wattage would be additive, no?

Either way, it is seeming more and more like parallel would be the most beneficial in most aspects, especially seeing I am well under the maximum amperage of the #10 wire.

I think I am getting smarter, miracles do happen. I imagine I will have a few more stumbling blocks along the way though.

[Jim Bennett]

One other consideration with the portable panel. Would it be fine to just plug it into the input of the controller, or would it be best to have it switched. As I am using a hatch for all my various inputs, it would be easy to add a DPDT inline with the input connector. This plug could also double as a DC out connection then too.

[Jim Bennett]

Originally Posted by Patandlinda

Jim do you have the name and source for your panels ? I found a 50 watt and 100 watt flexible solar panels on Amazon . I want to compare what you found and what I found . This has been trying to sort through this for a couple of years now . I really would like the flexible if the technology will work for me . Pat

In my searching I found lots of good reviews on Lensun solar panels, and decided the was what I would go with.
Lensun® 60W 12V Flexible Solar Panel,Only 2.5mm Thin, Light for battery charge RV, Boats

They are on ebay too, but shipping to Canada was too high.

If you search "Lensun ETFE fiberglass" you will find lots of hits on suppliers and reviews for the specific ones with ETFE coating and fiberglass backing.

I ended up finding them from another supplier not using the Lensun name, but the specs and everything were exactly the same. I imagine whoever is making them for Lansun is supplying other folks too. Shipped to Canada was substantially cheaper. I just ordered a couple days ago, along with a solar controller from another source, so it could be a while to get here from China.
https://www.aliexpress.com/snapshot/...Id=32676932632

[alanmalk]

Originally Posted by Jim Bennett

I have read conflicting info on wiring different sized panels like mine in parallel, as to whether the wattage seen is the equivalent to the lower sized one. I understand that they need to be similar voltages, or like in your example with amperage, they would operate at the lowest voltage in the array. To my thinking, in parallel, the wattage would be additive, no?

Actually the wattage is essentially cumulative in series or in parallel. With one you get increased amps, the other, increased volts. And since watts = amps X volts ...

From my own experiments with different panels, minor differences in voltage has no significant impact. In fact, the more discharged the battery (or bigger load on the panels) the smaller the impact of different voltages. What happens with the higher voltage panel is that it gets pulled down from the "open circuit" voltage down to the working voltage of the smaller panels, so you would have essentially 5 panels at 17 volts. You will hardly miss the missing 1 volt. 1 volt times 4 amps is 4 watts - a couple of small LEDs worth.

Originally Posted by Jim Bennett

Either way, it is seeming more and more like parallel would be the most beneficial in most aspects, especially seeing I am well under the maximum amperage of the #10 wire.

I think I am getting smarter, miracles do happen. I imagine I will have a few more stumbling blocks along the way though.

The big "problem" with parallel panels is that not only do you have to worry about maximum amperage of a wire, but you also have to worry about voltage drop in *any* wire. Bigger becomes noticeably better in a high amp situation. Your 5 panels have a maximum potential (sunny Arizona in the summer at noon) of 18 amps. Look up voltage drop in a table and decide how much you can live with, and don't forget to measure distance in both directions - panel to controller and back again.

The other "problem" with parallel is now you have "wasted" the extra money on MPPT when you could have used cheaper PWM. Still, maybe someday in the future you will have a high voltage (24v and up) system.

Nothing major that can't be solved and have some fun doing it!

--
Alan

[alanmalk]

Originally Posted by Jim Bennett

One other consideration with the portable panel. Would it be fine to just plug it into the input of the controller, or would it be best to have it switched. As I am using a hatch for all my various inputs, it would be easy to add a DPDT inline with the input connector. This plug could also double as a DC out connection then too.

I'm not totally certain what is happening with a switched connection - but plugging into the controller is fine if all 5 panels are in parallel. If on the other hand you have 4 in series they will be providing over 60 volts and adding one 18 volt panel will add no power to the system. So if 4 are in series you should add the 5th in series, and that is not a simple plug-in. More like having one burned out light in a series. (Back to the "one shaded panel" scenario).

Now, being the expert in spending other people's money, I can suggest get another 17-18 volt 60 to 80 watt panel. Hook all 6 up as series-parallel so each pair puts out 34-36 volts. Now you can get your money's worth from the MPPT controller, you can use thinner wire, and you will have a total of around 400 watts of power and can supply all your neighbors with the extra. See, money solves everything.

--
Alan

[Jim Bennett]

Originally Posted by alanmalk

Actually the wattage is essentially cumulative in series or in parallel. With one you get increased amps, the other, increased volts. And since watts = amps X volts ...

Thanks, confirms what I was thinking.

Originally Posted by alanmalk

The big "problem" with parallel panels is that not only do you have to worry about maximum amperage of a wire, but you also have to worry about voltage drop in *any* wire. Bigger becomes noticeably better in a high amp situation. Your 5 panels have a maximum potential (sunny Arizona in the summer at noon) of 18 amps. Look up voltage drop in a table and decide how much you can live with, and don't forget to measure distance in both directions - panel to controller and back again.

I did try the calculations, and using 30' of #10 wire, in parallel there was a 1.1 V drop, and in series a .20 V drop, using all 5 panels. I just counted from the batteries to the entry point on the roof, and the portable would actually be right at the battery.

In parallel this should leave me with almost 16V, and my AGM batteries would never need this much.
(there would likely be a bit more counting the stuff on the roof)The other "problem" with parallel is now you have "wasted" the extra money on MPPT when you could have used cheaper PWM. Still, maybe someday in the future you will have a high voltage (24v and up) system.[/quote]
Most everything I read about said that even in parallel, that an MPPT in most cases will be more efficient, as it converts the full power from the voltage seen (say 17-18), instead of dumping the extra like a PWM would. Probably not huge amounts though.

Originally Posted by alanmalk

I'm not totally certain what is happening with a switched connection - but plugging into the controller is fine if all 5 panels are in parallel. If on the other hand you have 4 in series they will be providing over 60 volts and adding one 18 volt panel will add no power to the system. So if 4 are in series you should add the 5th in series, and that is not a simple plug-in. More like having one burned out light in a series. (Back to the "one shaded panel" scenario).

I was going by the fact that breaking DC current cause more arcing than an AC circuit, where it hits a zero point many times. This may not be much of a factor here.

Originally Posted by alanmalk

Now, being the expert in spending other people's money, I can suggest get another 17-18 volt 60 to 80 watt panel. Hook all 6 up as series-parallel so each pair puts out 34-36 volts. Now you can get your money's worth from the MPPT controller, you can use thinner wire, and you will have a total of around 400 watts of power and can supply all your neighbors with the extra. See, money solves everything.

--
Alan

I am a pro at spending other folk's money, it is what I do for a living.

That is another consideration. I could do it with rewiring the portable I have, as it is actually two 40W panels in parallel. One consideration too, is that I would only bring out the portable if the fixed were not producing enough. I already own the portable, otherwise as mentioned, I would consider two of the thin flexible panels as spares.

It would be interesting to try the various arrays, whether all parallel, all series, or the three sets of parallel panels hooked in series.

Thanks again Alan for your input, you put things in a very easy to understand way.

[Patandlinda]

Originally Posted by Jim Bennett

In my searching I found lots of good reviews on Lensun solar panels, and decided the was what I would go with.
Lensun® 60W 12V Flexible Solar Panel,Only 2.5mm Thin, Light for battery charge RV, Boats

They are on ebay too, but shipping to Canada was too high.

If you search "Lensun ETFE fiberglass" you will find lots of hits on suppliers and reviews for the specific ones with ETFE coating and fiberglass backing.

I ended up finding them from another supplier not using the Lensun name, but the specs and everything were exactly the same. I imagine whoever is making them for Lansun is supplying other folks too. Shipped to Canada was substantially cheaper. I just ordered a couple days ago, along with a solar controller from another source, so it could be a while to get here from China.
https://www.aliexpress.com/snapshot/...Id=32676932632

Jim , PatThanks for the information . Will definetly check this out .

[Jim Bennett]

This is a good read on mixing solar panels. It helps explain a lot of what has been discussed.

Mixing solar panels – Dos and Don’ts • SOLAR PANEL SECRETS EXPOSED

[thoer]

Originally Posted by Jim Bennett

I already own the portable, otherwise as mentioned, I would consider two of the thin flexible panels as spares.

You could make it simpler if you sell your portable panel and get the 2 flexibles. Somebody at the rally will probably be glad to get a good deal on a portable. I'm not a pro at it but I too love to help other people spend their money

[Jim Bennett]

Originally Posted by thoer

You could make it simpler if you sell your portable panel and get the 2 flexibles. Somebody at the rally will probably be glad to get a good deal on a portable. I'm not a pro at it but I too love to help other people spend their money

Sold! You can pick it up and pay me at the rally.

Off to order two more flexible panels now.

[thoer]

Originally Posted by Jim Bennett

Sold! You can pick it up and pay me at the rally.

Off to order two more flexible panels now.

You missed that part about "other" people's money!

[alanmalk]

Originally Posted by thoer

You missed that part about "other" people's money!

We all should define Success as having others spend the money - not ourselves.


--
Alan

[PGDriver]

Originally Posted by Jim Bennett

Sold! You can pick it up and pay me at the rally.

Hey now here's a great idea, someone should start a "for sale, pick up and pay at the rally" thread.
Cheers
Doug


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