Solar Show and Tell

[batman]

Originally Posted by CarterKraft

I'll see how this goes but I could possibly rewire to parallel if needed with branch connectors no harm done but I think I'll get some data this way first.

I actually had daydreams of relays allowing me to switch from series to parallel, that's some serious overkill

I love the idea of relays to change from parallel to series with a flick of a switch.
If my panels were mounted on my trailer, That would be the way I would configure mine (king of overkill). However my solar panels are portable. The charge controller is inside the trailer. I can easily reconfigure my panels from full parallel to series/parallel in just 1 minute.

-Dennis

[CarterKraft]

Originally Posted by batman

I love the idea of relays to change from parallel to series with a flick of a switch.
If my panels were mounted on my trailer, That would be the way I would configure mine (king of overkill). However my solar panels are portable. The charge controller is inside the trailer. I can easily reconfigure my panels from full parallel to series/parallel in just 1 minute.

-Dennis

It sounds like we have a volunteer to test the series/parallel argument!

I wish I would have thought to pull a 16GA control wire when I ran my roof top wire...

[pcskier]

Well. When I went to bed last night, guess what was sticking out of the roof of my trailer


The rest of my odds and ends arrived so it was decision time. I decided to go for it and do full parallel with 6 ga wire and ran over to Home Depot to buy it. It required about 15 feet of wire from where the combiner will be to the controller, so my OCD about wire losses has been handled. Wasn't as difficult as I though, the worst moment was drilling through the roof. I didn't hit anything (I was very careful as Troutboy had mentioned a wire loom being in the area up there).
Have everything on the inside wired up. On to mounting panels and wiring in the combiner.

I should have a true "Show and Tell" system to "Show" in a couple days.
Thanks for the continued advice and feedback, airmiles and pteck, very helpful and informative. I'm excited to see watts flowing soon!

[AirMiles]

Originally Posted by pcskier

Well. When I went to bed last night, guess what was sticking out of the roof of my trailer

Attachment 346154
The rest of my odds and ends arrived so it was decision time. I decided to go for it and do full parallel with 6 ga wire. It required about 15 feet of wire from where the combiner will be to the controller, so my OCD about wire losses has been handled. Wasn't as difficult as I though, the worst moment was drilling through the roof. I didn't hit anything (I was very careful as Troutboy had mentioned a wire loom being in the area up there).
Have everything on the inside wired up. On to mounting panels and wiring in the converter.

I should have a true "Show and Tell" system to "Show" in a couple days.
Thanks for the continued advice and feedback, airmiles and pteck, very helpful and informative. I'm excited to see watts flowing soon!

I look forward to your Solar Show and Tell posts documenting how well your configuration performs. No doubt in my mind that you will be happy with your system. 400W of solar on the roof is like having a perpetual motion machine. I can use 100AH of power one day/night and have fully charged batteries again the next day to do it all over again on 97% of days. 400W of solar can turn an Airstream into a perpetual boondocking machine.

[pcskier]

Originally Posted by AirMiles

400W of solar can turn an Airstream into a perpetual boondocking machine.

That's a great way of putting it! I'll be posting as much data as I can for sure. Unfortunately I'm not able to do any long-term travels, but will track whatever usage I get. To your statement, this was the missing element to my frequent boondock adventures that was sorely overdue. I also switched to 6V Trojan T105s as part of this upgrade, so having 225 or so ah vs 160 with the old Interstates was a great improvement right off the bat...and now knowing that a majority of the time, I won't even have to think about batteries. They'll just stay charged for the most part. Super excited about that!

[daleyocum]

Airmiles:
In a previous post you included a screen shot of your phone showing sun locations. Is this just a photo you dit d to add the sun or is that a real app? Seems very helpful.

[Rdavenp3]

Originally Posted by daleyocum

Airmiles:
In a previous post you included a screen shot of your phone showing sun locations. Is this just a photo you dit d to add the sun or is that a real app? Seems very helpful.

The app is called Lumos and is in the Apple App store. Not sure if it's available on Android though.

[AirMiles]

Yes it’s the Lumos app for IPHONE. It really helps me choose campsites and position for maximum solar in tree-filled campgrounds. It’s a live picture with the sun track overlay.

[batman]

Originally Posted by Rdavenp3

The app is called Lumos and is in the Apple App store. Not sure if it's available on Android though.

Lumos for Android phone turns on the flashlight for the phone. lol

Lumos the sun tracking app is not available for Android based phones. There is a similar app from the google store called "Sun Locator" and the free version is "Sun Locator Lite".

[pteck]

Originally Posted by Wolfwhistle

pteck, I'm aware of that. Series produces less voltage drop at the same load compared to parallel, and since power (in watts) is volt x amps, higher voltage produces higher power. Even if it is only two or three watts.

My question was does panels (the source) in series produce more total daily power than parallel since it would seem they reach a higher and thus more usable voltage before parallel panels do. This is in low light conditions. I'm not talking shade that might only touch one panel, rather all of them... such as in early morning or late evening, foggy or hazy conditions. Or, complete cloud cover.

I wonder about this because my new project with three 200W panels in series on an MPPT controller, I have seen a slight charge above the draw of a fantastic running, to the batteries under a street light; all night long. Could these in parallel do that, I wonder?

I have gone by Bogart Engineering specs when designing every system I have ever built. From their chart which is based on 12 volt nominal for calculation purposes; not whatever the panel voltage is we settle on buying, and with no more than 3% voltage drop (VD).

My factory prewire length is 22.5 feet or slightly more. AS ran it to the rear fantastic vent, ignoring the logical place for 2 panels would be in the front. I kid you not.

Adding 2 panels would be right at or slightly over 3% VD, but 3 drove me to run 6AWG to the roof just behind the front fan, 15 feet to the SCC, almost to the inch. Add 0.8 VD to the left rear panel I am still good to go. Four panels should be possible considering VD.

Clint

I believe it would be about a wash in that situation.

Interestingly, if you're talking about setting up 3x 200W panels in series, that is something I can get behind. Shade on any panel will only effect the individual panel or panel segment as MPPT will having the ability to seek the voltage at which peak power is produced in the overall array. With or without the shaded panel or panel segment.

It is specifically the parallel-series configuration that is particularly susceptible to shading and output losses. Because of the nature of inter-decencies among the panels, the single lowest panel output impacts the array twofold. As the array is interdependent between panels in voltage or current. This is not something MPPT can work around.

[TouringDan]

I have been following this thread and all the discussions on how to connect the panels together- series parallel, parallel or series. I have been confused at times by some of the discussions and come away with the bottom line that it just doesn’t matter all that much.

I am installing 4-100 watt panels on top of my bed cap. I can connect them series parallel, parallel or series. The panels will be feeding a Victron 100/50 controller in the bed cap then to two BB batteries through 30 ft of #10 wire. How should I connect the panels? Here are some photos.

Thanks, Dan

[AirMiles]

Originally Posted by pteck

I believe it would be about a wash in that situation.

Interestingly, if you're talking about setting up 3x 200W panels in series, that is something I can get behind. Shade on any panel will only effect the individual panel or panel segment as MPPT will having the ability to seek the voltage at which peak power is produced in the overall array. With or without the shaded panel or panel segment.

It is specifically the parallel-series configuration that is particularly susceptible to shading and output losses. Because of the nature of inter-decencies among the panels, the single lowest panel output impacts the array twofold. As the array is interdependent between panels in voltage or current. This is not something MPPT can work around.

I would like to see the real life data that supports this comment or a link that supports it. If this is true, then full series would be the ultimate configuration with four or six 100W panels. When you connect multiple panels in series, they become one large panel. It would not matter if they were 100W or 200W. A series parallel configuration of four 100W panels simply becomes two 200W panels in parallel.

[AirMiles]

Originally Posted by TouringDan

I have been following this thread and all the discussions on how to connect the panels together- series parallel, parallel or series. I have been confused at times by some of the discussions and come away with the bottom line that it just doesn’t matter all that much.

I am installing 4-100 watt panels on top of my bed cap. I can connect them series parallel, parallel or series. The panels will be feeding a Victron 100/50 controller in the bed cap then to two BB batteries through 30 ft of #10 wire. How should I connect the panels? Here are some photos.

Thanks, DanAttachment 346193Attachment 346194Attachment 346195

I would use series-parallel because the Victron owners manual recommends that configuration when using 100W panels. It recommends parallel when using larger panels. Configuring series-parallel with 100W panels is the equivalent of installing two 200W panels in parallel.

[Fair_Enough]

Originally Posted by AirMiles

I would use series-parallel because the Victron owners manual recommends that configuration when using 100W panels. It recommends parallel when using larger panels. Configuring series-parallel with 100W panels is the equivalent of installing two 200W panels in parallel.

Exactly.

If you elect to park under a canopy of trees, you have decided to not use your solar system, it probably won't matter a hill of beans how they are wired.

The situation where a strong moving shadow would negatively affect one panel (or one at a time) for several hours is possible, even likely one might say. During that event, parallel will give you a fraction of 100W for those minutes.

I've seen a test done by the altEstore that shows a shadow doesn't totally shut down a panels output.

We should consider our own trailer's landscape for obvious things that will shadow... TV antenna comes to mind, or placing one too close to the AC unit, or vent cover. At least consider these.

I say consider if that moving shadow and ask, does that justifies the expensive and the inevitable blood, sweat and tears, of rewiring. If you think it does, go for it.

I am a proponent of parallel (okay, I lost my mind for the cargo conversion), but the post started of with the premise of using the factory prewire with 4-100W with the included and extensive data, showing it to be an attractive solution. And, listening to the people who made your equipment seem like good advice.

I leave you with a quote from a guy named Lee Blake, "Build it, use it, change it".

Clint

[Paprika]

There's been a lot of discussion of a "Battery Smart" device. Victron does make a product called Smart Battery Sense, and I think that's what is being referred to here. I mention this because someone who reads this thread later is liable to be confused by references to a nonexistent "Battery Smart." It's helpful to use correct product names.

[pteck]

This is my last post on the entertaining parallel vs series-parallel. It will be as much show as possible while staying away from technical. I leave it to you, the individual to choose your poison. There are many many considerations in the overall install. Understanding the full trade space, yet weighing the significant factors is what's important here. So as not to make a decision for a red herring and invite other compromises (i.e. shade).

1) Main premise for series-parallel is to mitigate the factory pre-wire voltage loss due to a minor span of 10-gauge wire

This has shown to be in-material as discussed here as it represents less than 1 Ah on a great sunny day. When that extra 1 Ah is likely thrown away anyways.

Here's my all parallel 400W system over factory pre-wire putting up great numbers - 1780 Wh (148 Ah). On a partially shaded day no less. I haven't looked at all of AirMiles data, but this is a relatively higher watermark than anything I have seen in his data from his series-parallel 400W system. Factory pre-wire is not holding anything back here.


2) Series "can start earlier in the day"

Here's my all parallel system already generating at 5:30AM. In shaded light through trees no less.


3)

Originally Posted by AirMiles

I would use series-parallel because the Victron owners manual recommends that configuration when using 100W panels. It recommends parallel when using larger panels. Configuring series-parallel with 100W panels is the equivalent of installing two 200W panels in parallel.

Application (RV, lots of shade) is the most important consideration here. Professional solar installers including AM Solar and Lewster, some of the most experienced installers that also use Victron parts.

What do they do? All parallel. All the time.
http://www.airforums.com/forums/f448...ml#post2241991
http://www.airforums.com/forums/f448...ml#post1899387
http://www.airforums.com/forums/f37/...-a-195049.html
http://www.airforums.com/forums/f448...ml#post1965168



What I would do today... all parallel. But I would also just run my own wire completely and bypass the factory pre-wire because it's relatively easy and something I can do in 30 minutes behind cabinets and raceways. I've run way more other wire in my trailer since and it's probably the easiest part of a solar install.

[pcskier]

Well it's too early to really panic, but I got my first Renogy 100w panel on the roof and was a little crest fallen when I excitedly went to see what I was getting. Tough to say on this pic, but the panel is probably 50% filtered shade, maybe a little less ...the left 1/3 is in full mid day sun, the right half has 'patches' of sun though the pic looks really shaded. So I knew I wouldn't see optimal results...but 15 watts? I guess output is not tied to sun coverage in a linear way? Based on what I've read here about even dusk/dawn lighting getting a few watts...this seems really low to me. Connections are good, about 7 feet of 10 ga to the box, then 6 ga to the controller.

Should I be disheartened?

[pteck]

Originally Posted by pcskier

Well it's too early to really panic, but I got my first Renogy 100w panel on the roof and was a little crest fallen when I excitedly went to see what I was getting. Tough to say on this pic, but the panel is probably 50% filtered shade, maybe a little less ...the left 1/3 is in full mid day sun, the right half has 'patches' of sun though the pic looks really shaded. So I knew I wouldn't see optimal results...but 15 watts? I guess output is not tied to sun coverage in a linear way? Based on what I've read here about even dusk/dawn lighting getting a few watts...this seems really low to me. Connections are good, about 7 feet of 10 ga to the box, then 6 ga to the controller.

Should I be disheartened?

Attachment 346221
Attachment 346223

It's not linear unfortunately. Which is why shade is hugely impactful, and why it should be the primary factor to manage to the extent possible. RV life is full of shade. House installs have controlled placement so they can focus on other factors (voltage loss).

Even in this rather open spot with sun still relatively high in the sky. That's shadows for hours in the day to optimize for.



Don't be disheartened. RV solar is like the tortoise. Slow and steady throughout the day wins the race. It's exciting to see it sprint mid-day during the fleeting optimal alignment in an open space, but that's going to be the exception rather than the rule.

Other part of it to understand is if your batteries are fully charged already, solar charging will taper off. You need a load to see maximum output. Turn on all 12V things you've got. If you have an inverter, turn it on and put a load (hairdryer?). My inverter is wired for the whole trailer 120V, so I usually fire up the fridge on electric to test.

[rmkrum]

Understand that the 100 watt rating is under perfect laboratory conditions with absolutely no shade.

That said, with as much shade as you have on that panel, 15 watts is probably not bad. It’s enough to help keep the battery charged if you have everything else turned off in the Airstream.

My 150 watt rated panel in direct sunlight does not quite make full rated power, but keeps my batteries well charged in spite of having the 12 volt power fully turned on and running a FantasticFan in storage here in the SoCal desert.

[pcskier]

Originally Posted by pteck

Other part of it to understand is if your batteries are fully charge already, solar charging will taper off. You need a load to see maximum output. Turn on all 12V things you've got. If you have an inverter, turn it on and put a load (hairdryer?). My inverter is wired for the whole trailer 120V, so I usually fire up the fridge on electric to test.

Batteries are fully charged, AC power is now off. But wouldn’t that just impact the output of the controller? Don’t panels produce whatever watts they can in the moment, regardless of battery SOC, then it’s up to the controller to do what it needs with that power?