Simple Airstrteam Series/Parallel Solar System

[KSA63]

Originally Posted by Kalashnikov

These days the prewire is 8ga, wire itself seems to be of very high quality.

I hope that you are correct but I have not physically looked at the pre-wire yet. I have been making assumptions based on the AS owners manual.
The following is from a 2020 manual...



My plans may change if the wire is actually 8ga.
Thanks
Kevin

[GMFL]

Originally Posted by KSA63

I hope that you are correct but I have not physically looked at the pre-wire yet. I have been making assumptions based on the AS owners manual.
The following is from a 2020 manual...

Attachment 364222

My plans may change of the wire is actually 8ga.
Thanks
Kevin

Your 2011 will have 10Ga prewire. They started using 8ga in 2018

[KSA63]

Originally Posted by GMFL

Your 2011 will have 10Ga prewire. They started using 8ga in 2018

Thank you GMFL, i had been holding off on installing a solar system as I was unsure what I may need at first and because I was not certain the 28’ 2011 FC was our forever trailer. It turns out our forever trailer (we hope) is stalled on the assembly line till this COVID-19 business runs its course. We were to take delivery in May but right now we have no idea when delivery may be. [emoji848] Of course there is no rush but it would be nice to have it here to work on till travel can commence.

The new trailer will be the 2020 Globetrotter 30. Of concern is the 12 volt only refrigerator and my APAP device using all the power up. I am hoping the 400w solar will go a long way to alleviate my worry. Also of concern would be the shading issues as this trailer will have 2AC units which may impact significantly where the panels should go.

Btw, I’m not even sure that there will be a fridge vent since there is really no reason for it. So running new wiring through the venting is probably a no go. It is good to hear that the pre-wire is heavier than I thought. [emoji3]

[Garfish]

Installing two 100 watt with MPPT. Either series or parallel? Thought about just connecting each panel to own plug in combiner box, essentially parallel

Also using Renogy brackets and think it ok to not use curved brackets on lower sides. Cleaner profile if I just bend brackets some so they are square with roof. Sun rarely directly overhead anyway. Anyone mount that way?

[hotfoot88]

I’m a fan of all parallel panels
As few connections as possible
Each panel fused before combining
Wire gauge has to do with current, length and % of drop from length
There is always some compromise
Running 2 panels in series less current smaller wire, however, any blockage on one panel can shut down this group completely

[pteck]

Originally Posted by Garfish

Installing two 100 watt with MPPT. Either series or parallel? Thought about just connecting each panel to own plug in combiner box, essentially parallel

Also using Renogy brackets and think it ok to not use curved brackets on lower sides. Cleaner profile if I just bend brackets some so they are square with roof. Sun rarely directly overhead anyway. Anyone mount that way?

Parallel is the recommended setup. Even with an MPPT controller.

This video should help show why. Note they're using a big dollar MPPT controller no less. One can equate rigging on a boat, to fan covers, A/C shrouds, tree branches, etc. With the way panels are on different planes as installed on a curved Airstream roof, would also compromised output with one or another being caste in shade at low sun angles in early morning and evening.

Series installs continues to be a handicap against varied conditions that an RV would experience. Something static house installs can control which is why series installs are preferred there.

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

[Garfish]

Originally Posted by GMFL

Your 2011 will have 10Ga prewire. They started using 8ga in 2018

2020 GT manual says 10. Will check actual wires when I install Victron

[rdsyl]

Nice drawing - it very accurately represents our system self-installed in Dec-Jan and tested for 4 weeks in AZ this January. My only difference was that I followed AM Solar's advice and used heat shrink butt splices instead of MC4 connectors. Even in January with low sun angle we were able to charge our 2 x 100ah Battleborn Lithiums batteries fully almost every day. There is room atop our 2018 Classic 30 for another series pair of Renogy Eclipse 100w panels that I will install later if there is a need. Send me a private email if you'd like photos.

[rdsyl]

I was pleased to discover that our 2018 Classic was pre-wired with 8 gauge. Airstream will send you the detailed electrical drawings if you call them. The drawings for our unit showed a 2018 upgrade from 10 to 8 gauge part way through 2018, and we lucked in. As for the argument about curved roof and the impact of series-parallel, I find it a bit disingenuous. If the sun was digital and in its top dead centre position all the time, I wold buy the argument. Since the sun traces an arc across the sky there is no one position of panels or method of wiring that is optimum for all conditions. Our 2 sets of 100 w Renogy Eclipse panels connected in series-parallel with a Victron Smartsolar MMPT controller and BMV 712 monitor worked just fine in AZ this past January. It is more about positioning the trailer in a north-south orientation and away from trees in my view. I suspect that a thorough analysis may well show that there is a slight benefit to a parallel-only arrangement, but if you want to use the pre-installed 3 receptacle roof box and limit the current, series-parallel works fine. If I need more panels I will just install another series-parallel pair. I believe that the wiring choice has less influence than other factors that need to be considered.

[Kalashnikov]

Originally Posted by rdsyl

I was pleased to discover that our 2018 Classic was pre-wired with 8 gauge. Airstream will send you the detailed electrical drawings if you call them. The drawings for our unit showed a 2018 upgrade from 10 to 8 gauge part way through 2018, and we lucked in. As for the argument about curved roof and the impact of series-parallel, I find it a bit disingenuous. If the sun was digital and in its top dead centre position all the time, I wold buy the argument. Since the sun traces an arc across the sky there is no one position of panels or method of wiring that is optimum for all conditions. Our 2 sets of 100 w Renogy Eclipse panels connected in series-parallel with a Victron Smartsolar MMPT controller and BMV 712 monitor worked just fine in AZ this past January. It is more about positioning the trailer in a north-south orientation and away from trees in my view. I suspect that a thorough analysis may well show that there is a slight benefit to a parallel-only arrangement, but if you want to use the pre-installed 3 receptacle roof box and limit the current, series-parallel works fine. If I need more panels I will just install another series-parallel pair. I believe that the wiring choice has less influence than other factors that need to be considered.

That was my thinking as well.

My layout:

[Panel1] [Panel2][Panel3]
[Fan][Sunroof][AC] [AC]
[Panel4] [Panel5][Panel6]

My series strings:
- S1: Panel1/Panel4
- S2: Panel2/Panel3
- S3: Panel5/Panel6

Performance:
- Sun overhead: 100% performance
- Sun West or East: 100% performance
- Sun North: S3 both panels shaded, 66% output (AC shading)
- Sun South: S2 both panels shaded, 66% output (AC shading)

With 600W my system is likely overbuilt but will easily absorb poor trailer alignment at the campsite and also cloudy days.

[KSA63]

We picked up the new 2020 Globetrotter 30 on July 16th. A few issues on delivery and now waiting for a couple of replacement items to arrive but overall we are quite happy.
Solar bits and pieces have been waiting to be installed for months so I jumped in last week-end to wire the charge controller and breakers.

The hole you have to work in is pretty tight and so I worked left handed (fortunately I am left handed) to get it done. It took most of a day with a little finish up work on day 2.

Did a dry run of 2 of the panels in parallel to test things on last Sunday afternoon and found out the Renogy adapter (MC4 to SAE) is wired backward to what the Zamp roof top box is expecting. Changed the connectors and we were operating.

I let it run for about 6 hours or so and harvested 480WH. Nice.

[KSA63]

Yesterday I worked on getting the panels more permanently positioned. I was able to get the 2 driver side panels mounted and wired for series/parallel operation. I still need to Sikaflex the mounts and tie down the cables to finish up this side.

At 9am this am I am mostly underwhelmed by the S/P arrangement with tree filtered sunlight.

It worked much better last evening in low angle direct sunlight.

[gator.bigfoot]

Originally Posted by KSA63

Yesterday I worked on getting the panels more permanently positioned. I was able to get the 2 driver side panels mounted and wired for series/parallel operation. I still need to Sikaflex the mounts and tie down the cables to finish up this side.
Attachment 374436
At 9am this am I am mostly underwhelmed by the S/P arrangement with tree filtered sunlight.
Attachment 374437
It worked much better last evening in low angle direct sunlight.

Well you have mostly shade. Then the S/P has come to bite you. Once you get out of the shade it will work. You can add 4 more panels in the S/P configuration to try to balance it out. These are drawbacks of roof mounted solar configurations. Sun angle and placement are much harder to arrange. The good thing is that the sun shines for at least 12 hours a day this time of year. So you'll have a good chance of it working once the sun moves around.

[AirMiles]

Originally Posted by KSA63

Yesterday I worked on getting the panels more permanently positioned. I was able to get the 2 driver side panels mounted and wired for series/parallel operation. I still need to Sikaflex the mounts and tie down the cables to finish up this side.
Attachment 374436
At 9am this am I am mostly underwhelmed by the S/P arrangement with tree filtered sunlight.
Attachment 374437
It worked much better last evening in low angle direct sunlight.

There's nothing "special" about series-parallel connected panels except that it allows you to use up to 600W of solar efficiently on the factory prewire. Two 100W solar panels connected in series is just one big 200W panel. If you had one big parallel connected 200W panel in the same size/position, you'd also be getting 7W. Even if you had two 100W panels connected in parallel, you'd probably still be only getting 7W because one panel is completely shaded and the other is 95% shaded. Solar panels do not work well in shade, parallel connected or series-parallel connected.

Also, if you had two 100W panels with one in shade and the other in complete sun, you'd get the same amount of power out of either configuration. The MPPT solar controller is designed to optimize output for any given input. With series-connected pairs, you get double the voltage at half the Amps. If one series connected panel is in the shade and the other is in complete sun with only two 100W series connected panels, the voltage would cut in half and the Amps would stay at half, resulting in the exact same output as a single 100W panel. With two parallel connected panels with one in full shade and the other in full sun, again the output would be equivalent to a single 100W panel. I've tested all these scenarios and reported the results in the Solar Show and Tell thread:

https://www.airforums.com/forums/f44...ml#post2242341

https://www.airforums.com/forums/f44...ml#post2102863