Author Topic: Solar planning thoughts  (Read 2045 times)

Offline freds

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Solar planning thoughts
« on: October 23, 2019, 10:30:48 PM »
As a new bus owner I have been kicking around a large number of items; with solar being one of them.

In my research the following items have popped out.

1. If only doing the summer season, just mount the panels flat on the roof.
2. If full timing and living off grid in dispersed camping during the winter you will want to orient the rig towards the east to catch solar radiation through the front windshield to warm up in the morning.
3. You should consider being able to tilt your panels for better power gathering during the winter as the sun will be low on the southern horizon.
4. Be very careful of any solar shading if you have panels wired in series as the full coverage of a single cell on a panel will take out all of the panels in the string.
5. Given point four do not put any panels when they might be shaded by the air conditioning units (except maybe for the right side of the bus when it faced to the east?).
6. Make sure the angle of the panels, do not shade other panels.
7. Maybe high wattage/high voltage panels in parallel would be better than any series array setup?
8. Plan some of the panels as dismount setups?
9. Keep all the above in mind when selecting the charge controller(s)? I.E. do not skimp of feed wire thickness or the number of controllers....

 

Offline chessie4905

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Re: Solar planning thoughts
« Reply #1 on: October 24, 2019, 04:14:54 AM »
I currently have no interest in using any, but may still consider some for my travel trailer for Alaska trip in 2021. However, for our coach, I would probably use the flexible ones because easier to attach, more coverage available on the roof surface without a bunch of brackets. I've read that they aren't as efficient as flat ones though. Figuring extra panels will help to offset that.
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Offline buswarrior

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Re: Solar planning thoughts
« Reply #2 on: October 24, 2019, 05:41:01 AM »
Definitely defend against shading, don't wire in series.

One giant seagull poop from above... there goes the charging.

Inspecting/cleaning the roof isn't the easiest job, and lends a degree of danger to your design that has to be managed.

Too many busnuts design on the ragged edge of a minimalist existence, and it is miserable when one teeters off that edge, not to mention those long suffering souls who are sharing that existence.

If catching the morning sun is your heating design, vs a nice way to save a couple pennies in  furnace fuel burn... Someone is going to be miserable...

If you didn't know, the front end of the bus loses a lot of heat, and many busnuts construct heavy curtains to completely isolate the driver's area, stepwell and windshields from the rest of the coach.

There's years worth of reading on here at BCM, just scroll back thru the forum.

Keep the neat ideas coming!

Happy coaching!
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Offline Dave5Cs

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Re: Solar planning thoughts
« Reply #3 on: October 24, 2019, 08:14:30 AM »
But if you used actuators to lift or tilt the panels then cleaning them would be pretty easy from the ground. ;)
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Offline Geom

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Re: Solar planning thoughts
« Reply #4 on: October 24, 2019, 09:03:29 AM »
FWIW, I just finished installing solar on my bus last month.
I went with 4 residential 325W panels.
There are a dozen reasons to choose residential panels vs the Amazon special dejour, but chief among them was better tolerance and handling of shading.
They are installed in a 2x2 parallel/parallel installation into 2 mppt controllers. Their naturally higher voltage negates the need for series. 
They do not tilt and I’ve gone back and forth and back again on that and decided to just hard-mount them. Waaaay easier and less PITA.  ;D
They’re on homemade brackets made of angle Al and 3” bar.
The panels are riding about 10” on the curve and 6” above center of the roof (that is one seriously curved roof :o)
I did this for several reasons but the main reasons are heat dissipation (you really don’t want to just stick panels onto or 1” above your roof) and to act as shading in hot weather (where it makes a huge difference in cooling the rig).

All in all I’m very happy with it. We’re producing ~ 6.5kw a day, during NM fall, and we’ve paid near 0 attention to orientation of the bus.
If I were to point the bus slightly north of west, I think I’d get an additional 1 to 1.5 kw.
We’re now able to boondock and have gone from running the gen two hours a day, to top-off batts and handle large loads, to about an hour a week :)

Hope that helps and regards,
George
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Offline freds

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Re: Solar planning thoughts
« Reply #5 on: October 24, 2019, 09:28:34 AM »
I currently have no interest in using any, but may still consider some for my travel trailer for Alaska trip in 2021. However, for our coach, I would probably use the flexible ones because easier to attach, more coverage available on the roof surface without a bunch of brackets. I've read that they aren't as efficient as flat ones though. Figuring extra panels will help to offset that.

What I have heard from multiple places is that the flexible panels cost as much or more than the house panels and then only last a couple of years before they start degrading badly, because of that they come with a very short warranty period.

A decent YouTube channel mostly oriented towards RV:  https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q


Offline freds

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Re: Solar planning thoughts
« Reply #6 on: October 24, 2019, 09:45:48 AM »
But if you used actuators to lift or tilt the panels then cleaning them would be pretty easy from the ground. ;)

Any suggestions on actuators?

Offline freds

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Re: Solar planning thoughts
« Reply #7 on: October 24, 2019, 10:22:09 AM »
Still doing research but for tilting panels I was thinking of something like the latch assembly for a swinging gate.

Attach multiple panels together with a pivot point that fits into the latch, then you unlock one side of the other to point left or right with an actuator.

 

https://www.amazon.com/Weatherables-Polymer-Key-Lockable-Keystone-KLADV-P2-BK-KA-WEA/dp/B07CJHYQSX/ref=sr_1_6?keywords=electric+gate+latch&qid=1571333131&sr=8-6

Does anyone know the name of this type of capture latch or a boating equivalent?


Offline windtrader

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Re: Solar planning thoughts
« Reply #8 on: October 24, 2019, 11:06:44 AM »
Solar remains on the "to do" list, like anything tech, times offers better and cheaper products. Your report is encouraging and impressive, generating over 6kw.

Placement of panels off the vehicle is a requirement if the bus is located where it is shaded. How are panels mounted and connected to allow removal?
Second consideration for my design is energy storage. Lithium today offers the best performance but most costly. I'd bet it would be used more if the cost was closer to other formulations. The key reason being lithium takes charge at a far greater rate (1C) so more energy can be stored during the day, further reducing the need for supplemental use of generator, not that is all bad, just desirable
Don F
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Offline richard5933

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Re: Solar planning thoughts
« Reply #9 on: October 24, 2019, 11:22:30 AM »
We went with three ground-deployed 180-watt panels for our first round. My thought was that if we're operating on solar, I'm most likely not going to be running the a/c. With that being the case, it seemed that being parked in the shade was advantageous. Our three panels are wired in series to keep the current lower, allowing us to run a 50-foot cable between the bus and the panels. That keeps us fully in the shade while the panels are fully in the sun.

Eventually we'll be adding panels to the roof as well.
Richard
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Offline neoneddy

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Re: Solar planning thoughts
« Reply #10 on: October 25, 2019, 10:16:53 AM »
I have 1950 watts on my rig, 6x 320 watt panels.  I run 3 groups of 2 panels in series for 80v nominal PV voltage.   I can run the cheaper 8-10 ga wire.
If I could do it over again, I might have done smaller panels so I could go around vents and AC units, instead of looking at building a rack to go over it all.


I run the Victron MPPT charge controllers, I run 2 because I want to add 2 more panels here soon and in the summer I would max out on amps at 1400 or so using a 24v system.   I recommend a 24v house bank, you save on wire and charge controllers, a dc->dc converter for house 12v stuff is cheap and works great.

On avoiding series connected solar, I have not had issues.  In direct sun, yeah I'll lose some with partial shading on a panel, but in my experience I only lose that panel, the MPPT charger tracks it and it pulls power at 40v rather than 80v, I see it bounce around to 55, 60, 70, whatever to get the most it can.

On tilting - I've considered it, but the risk reward on a bus doesn't add up for me.   I want mine locked down, I don't want something to come lose and loose a panel or two.  I'd rather add a few more panels to make up for the lack of tilting.   If you want to tilt, I admire it and will be a bit jealous, it's just too risky for my taste.

Ground Deploy - I want to add some of this , maybe add a 3rd charge controller and a string of parallel panels I can setup and tilt while boondocking in the shade.   Now even in the shade  / partial shade in a wooded campspot I'll get 700-1000 watts out of my 1950, during mid day usually, with peaks and valleys as the sun moves.

Realistic Expectations - This was the biggest for me, I have a post on here where I went into more detail, but  to be fully solar sufficient you need  2x your daily consumption in realistic harvestable solar capacity.    My 1950, in clear skies, I'll see max 1700-1800 in June.  With wispy cirrus clouds and whatnot, I'm looking at 1400-1500 most days.   Right now I'm seeing 1200-1300 peak, and that doesn't last long in these shorter days.   So for me, I need 5 to 10kw of power per day if I'm running AC much.   I can maintain just fine if I show up charged, but by the time morning comes and I'm sucking juice as fast as the sun can produce it, I don't gain much. This is why I need those other two manels, maybe another four, but I've only got so much room, so back to ground deploy too.   Also, a good generator should be part of the plan, I finally am happy with a 7kw Onan gas genny that meets my needs perfect when catching up on a few cloudy days.

I also didn't see anything there about batteries.   In a bus you have options.  A lot of people recommend Battle Born batteries and they are good for the lithiums, but super expensive.   I'm really impressed with these Valence Batteries right now https://www.ebay.com/b/Valence-Rechargeable-Batteries/48619/bn_114829959   130+AH@12v for $450  Most of these are testing at 95% capacity.  The medical devices they come from are switched out yearly or something.   I ended up with 6  Telecom AGM batteries I got for $150-ish each or so.  210 AH @12v , yeah they weigh 130lb each, but $1000 for 14kw of battery storage is hard to beat even if it's an older chemistry.
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Online Jim Blackwood

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Re: Solar planning thoughts
« Reply #11 on: October 25, 2019, 11:03:44 AM »
Eddy, what would you think about a site deployable folding rig with powered actuators? My thoughts are, maybe you could have a center stick of panels a few inches off the roof laid flat as a rigid base and then a pair of hinged "wings" with robust frames and pivot points that would swing up and out to deploy, folding in to a 3 layer stack with alignment pins in the folded position, and it shouldn't be too hard to add powered safety latches. Acordian type links could be used to hold the weight when deployed. Something like a small HF winch could be used to deploy each side, and with shafting used to form the winch drum as well as the hinge pins, several sticks could be linked to a single pair of winch motors. You wouldn't get any charging while on the road, but the solar cells would be more protected. Plus it would give you more shade.

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Offline richard5933

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Re: Solar planning thoughts
« Reply #12 on: October 25, 2019, 11:34:40 AM »
Eddy, what would you think about a site deployable folding rig with powered actuators? My thoughts are, maybe you could have a center stick of panels a few inches off the roof laid flat as a rigid base and then a pair of hinged "wings" with robust frames and pivot points that would swing up and out to deploy, folding in to a 3 layer stack with alignment pins in the folded position, and it shouldn't be too hard to add powered safety latches. Acordian type links could be used to hold the weight when deployed. Something like a small HF winch could be used to deploy each side, and with shafting used to form the winch drum as well as the hinge pins, several sticks could be linked to a single pair of winch motors. You wouldn't get any charging while on the road, but the solar cells would be more protected. Plus it would give you more shade.

Jim

If you haven't already see it, you'd enjoy seeing the YouTube videos done by Beginning From This Morning about their solar array. They have panels on the roof which are moved by servos - they tuck in for travel and extend out for use. If I understand your idea it sounds similar to what they did.

Here's the 4th video in their series on the install: https://www.youtube.com/watch?v=wQRnECDIQ8E
Richard
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Offline chessie4905

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Re: Solar planning thoughts
« Reply #13 on: October 25, 2019, 04:49:56 PM »
Just pull a small trailer that you can deploy as many panels as you need.
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Offline freds

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Re: Solar planning thoughts
« Reply #14 on: October 25, 2019, 05:30:45 PM »
If you haven't already see it, you'd enjoy seeing the YouTube videos done by Beginning From This Morning about their solar array. They have panels on the roof which are moved by servos - they tuck in for travel and extend out for use. If I understand your idea it sounds similar to what they did.

Here's the 4th video in their series on the install: https://www.youtube.com/watch?v=wQRnECDIQ8E

Yes I have seen that video, it covers deployment, not tilting.