Problem with solar 2017 classic

[Lets travel]

Just got off the phone with Airstream Customer Service. The new Zamp 3 port cap is only being wired to the controller with 10 gauge wire!!! If you buy 3 160 watt panels from Zamp, you will have 480 watts on 10 gage wire. I hope they fix this or there is going to be alot of issues.

[lewster]

Originally Posted by Lets travel

Just got off the phone with Airstream Customer Service. The new Zamp 3 port cap is only being wired to the controller with 10 gauge wire!!! If you buy 3 160 watt panels from Zamp, you will have 480 watts on 10 gage wire. I hope they fix this or there is going to be alot of issues.

Don't hold your breath............

[Lets travel]

Lew, what size wire should they use from the panel to the controller and than controller to batteries.

[lewster]

Originally Posted by Lets travel

Lew, what size wire should they use from the panel to the controller and than controller to batteries.

If you are considering building a system that has potential for future expansion, then I would use 6AWG up to 400 watts and 4AWG up to 700 watts. This is for a 12VDC based system with all panels wired in parallel.

If you want to think about series connections, the wire gauge can be reduced, but then you also require a solar charge controller that will accept the now higher output voltage of a series solar array and one that will also be usable when charging a 12VDC battery bank.

The Blue Sky 3024iL does this nicely, but the Victron solar charge controllers have a much higher working voltage (up to 150VDC) range and lightning fast MPPT sampling as well. By that time, you have already totally redesigned the solar charging system, so you might consider doing that initially and not ordering Airstream's solar package at all.

[BAB]

Having done two solar installs myself on two Airstreams (well, with Lew's help -- albeit from afar!), I'd just say that if you are going to do this, do it for maximum benefit for the $. I just returned from 5 days at Shenandoah NP with no hookups. I do carry a Honda EU3000i Handi, but even with a fairly tree'd site, my 600W of AM Solar panels did a great job. I haven't run the cost per watt of my solar system vs. what Airstream is charging on the '17 Classic, but I know it'd make me smile. Solar is a great add-on if you don't plan on being an RV park inhabitant. I wish Airstream would take the subject more seriously than they seem to.

[ghaynes755]

Preinstalled solar wiring is 10 gauge, been that way for years. With the small panels supplied on an Airstream build, if you order the option, 10 gauge is probably ok. But not for anything more than the 100w or so with the option.

[wlanford]

Lew, other than a small reduction in the power going to the batteries, what other issues are caused by Airstream's use of #10 wire. Couldn't this be overcome by using slightly more wattage on the roof? After all, #10 wire is rated for 30 amps isn't it?

[lewster]

The voltage drop for 12 VDC is much more evident than for higher voltages like 120 VAC.

This can be overcome by series wiring of solar modules to increase their effective DC voltage output, but if any part of a panel in a series string gets partially shaded, you will lose the majority of that string's output.

Look at the tech manual for a quality solar charge controller like the Blue Sky 3024 iL and you will find a chart of what wire sizes Blue Sky considers acceptable for certain voltage/ length combinations.

And remember that a circuit length is for both the positive and negative cables, effectively double the length of the length of a single cable.

[wlanford]

Is the ONLY issue with voltage drop the decrease in watts reaching the batteries?

[lewster]

It's a MAJOR ISSUE.

[rmkrum]

When you buy a solar system it is all about the watts reaching the batteries. Why else would you do solar?

Why waste them by warming up an inadequate wire in the circuit?

This is exactly why I did not bother even looking for the other end of the too-skinny wires preinstalled in our 2007 AS. Our kit came from AM solar and is properly sized and then some.


Sent from my pocket Internet using Airstream Forums

[rvb]

I installed my own solar and originally had 2 100w panels with a short run of #10 wire down to the controller and it was barely adequate. I added 2 more panels for 400w with the usual line connectors and was very disappointed in the output. I pulled #4 wire and built a combiner box on the roof and immediately saw almost double the output from the panels.

[Pongo]

When I saw the original post, which expressed concern regarding solar hub gauge waiting, I contacted my dealer. (I've a 2017 International Serenity 27FB on order, with 160W solar on the roof and 160W of portable via the front solar connector for use in shade).

An Airstream electrical engineer responded back straight away. It's been a long time since I was a practicing electrical engineer, but I'm comfortable with his response. I've pasted a copy of his response below:



The 10 AWG wiring used by Zamp is sized correctly for the application and will support up to 3 x 200W panels running at 100% capacity with a 10% overhead. Note this also assumes that all 3 panels could actually run at 100% capacity, which is rare. While I understand the one forum poster's reasoning behind it, 6 AWG or 4 AWG in this application is not needed.

There are a number of factors that come into play when deciding the correct wire size, these are things like the length of the wire run, insulation size, air flow, ambient temperature range, proximity to other wires, breaker / fuse response time, etc.

In general use applications, like house wiring, the voltage is higher and most of these variables are not fully known or understood by the installer, or can be accounted for over the life of the house, so for a safety margin, the wire is de-rated to a smaller number.

14 Gauge = 15Amp Circuit
12 Gauge = 20 Amp Circuit
10 Gauge = 30 Amp Circuit

In Zamp's case, the application is known, the voltage range is known, and a number of other variables are also known, so it allows more freedom to better utilize the capacity of the wire safely.

Here a couple of links to websites that attempt to explain these ratings and what they mean. This information has been around a long time and is published in Handbook of Electronic Tables and Formulas for American Wire Gauge. 10 Gauge, non-bundled, open air wire is capable of handling 55 Amps for Chassis wiring, which is a conservative rating. 55 Amps in a solar application equates to around 660W, which is 10% more than 3 x 200W Zamp panels operating at 100% capacity.

http://www.coonerwire.com/amp-chart/
http://www.powerstream.com/Wire_Size.htm[/B]

[ghaynes755]

For a most excellent video on series vs parallel and impact of shadowing see this video from a few weeks ago from the GonewiththeWynns. The impact of even a small shadow on a single panel in a two panel series was MAJOR as Lewster said. Video is better than a thousand words sometimes.

https://www.youtube.com/watch?v=1qD3mN8VotQ

[Al and Missy]

Originally Posted by Pongo

When I saw the original post, which expressed concern regarding solar hub gauge waiting, I contacted my dealer. (I've a 2017 International Serenity 27FB on order, with 160W solar on the roof and 160W of portable via the front solar connector for use in shade).

An Airstream electrical engineer responded back straight away. It's been a long time since I was a practicing electrical engineer, but I'm comfortable with his response. I've pasted a copy of his response below:
....

It is interesting that, despite his response, if you look at the table in the reference it clearly states that #10 wire in a power transmission application is rated for 15 amps.

His response is based on what is safe for the wire. Ampacity is a term from the National Electrical Code and is predominantly about AC power distribution in homes, businesses and industrial applications. It is essentially the electrical building code.

Lew has it right, as usual. Voltage drop in wires is all about resistance and current. The voltage drop in a wire at a particular wire size and current will be the same in a 12V circuit as a 120V circuit, but proportionally it is 10x larger in the 12V circuit. Depending on the charge controller, the impact can be even greater.

Series connection can help, but makes the shading problem worse. If I install solar, I will be replacing the existing wiring and running panels in parallel.

Al

[wlanford]

It looks like to me the Airstream engineer above is using 120v values for his conclusion. Does anyone agree that he is correct?

[wlanford]

One more thought. Does anyone know if Airsteam will install #6 or #4 wire in place of the #10 to the batteries during construction of a new trailer if paid to do so?

[beetlebob]

Airstream doesn't do anything from their build at the factory. I have the factory installed solar and have found it works good for me. I also have 150 watts of portable panels. We always look for shade so having the panels on the roof is somewhat not good. I am looking into a small wind generator and maybe another set of portable panels but only have 2 AGM 12 volt batteries in the trailer so can only use so much at night anyway Boondocking is our way on the road and we know that so if you learn how to conserve and think you don't need a lot of solar to survive

[Lets travel]

Thanks for the info, I read your post and was confused because before starting the post I called both Airstream and Zamp. I talked to Jeff at Zamp in technical services and he was very helpful and provided a wealth of information. He stated as far as he knows no one has contacted them from Airstream for advice on the solar package that airstream has put together. Jeff explained to me that 10 Gage wire is NOT what they recommend for solar installs if you have the ability to add more solar panels to the system. No one knows what the Airstream Engineer is talking about 10 Gage wire being able to handle the amps that the 3 port can be connected to. If you buy 3 160 watt solar panel you'll have 480 watts thats about 27 amps, 10 gage is only rated for about 30 amps you would have a very high resistance with this set up. I'm sure many who view this know alot more than I do about solar install but I'm learning quickly with all your advice and help but one thing I do know Airstream is not doing it right.

[OSIN]

Originally Posted by Pongo

When I saw the original post, which expressed concern regarding solar hub gauge waiting, I contacted my dealer. (I've a 2017 International Serenity 27FB on order, with 160W solar on the roof and 160W of portable via the front solar connector for use in shade).

An Airstream electrical engineer responded back straight away. It's been a long time since I was a practicing electrical engineer, but I'm comfortable with his response. I've pasted a copy of his response below:



The 10 AWG wiring used by Zamp is sized correctly for the application and will support up to 3 x 200W panels running at 100% capacity with a 10% overhead. Note this also assumes that all 3 panels could actually run at 100% capacity, which is rare. While I understand the one forum poster's reasoning behind it, 6 AWG or 4 AWG in this application is not needed.

There are a number of factors that come into play when deciding the correct wire size, these are things like the length of the wire run, insulation size, air flow, ambient temperature range, proximity to other wires, breaker / fuse response time, etc.

In general use applications, like house wiring, the voltage is higher and most of these variables are not fully known or understood by the installer, or can be accounted for over the life of the house, so for a safety margin, the wire is de-rated to a smaller number.

14 Gauge = 15Amp Circuit
12 Gauge = 20 Amp Circuit
10 Gauge = 30 Amp Circuit

In Zamp's case, the application is known, the voltage range is known, and a number of other variables are also known, so it allows more freedom to better utilize the capacity of the wire safely.

Here a couple of links to websites that attempt to explain these ratings and what they mean. This information has been around a long time and is published in Handbook of Electronic Tables and Formulas for American Wire Gauge. 10 Gauge, non-bundled, open air wire is capable of handling 55 Amps for Chassis wiring, which is a conservative rating. 55 Amps in a solar application equates to around 660W, which is 10% more than 3 x 200W Zamp panels operating at 100% capacity.

http://www.coonerwire.com/amp-chart/
http://www.powerstream.com/Wire_Size.htm[/B]

Well Said!...In my previous life i've battled California State Authorities (OSHPD) over voltage drop, also worked closely with U.L. In one instance I even had to bring in actual wiring lengths and end devices on a backboard connected to Power supplies all the way to Sacramento, to prove their voltage drop methods were incorrect. It's a widely misunderstood subject. In Airstream trailers, as in most manufactured products these are not guesses, but engineered systems with life safety in mind.

Note: Belden was an excellent resource.