Offgrid Racetruck/ Motorhome

[MezzBatt]

Mission : to build me a stand alone self sufficient solar powered system for off-grid wild camping situations.

I'm seeking all the advice i can get to get it right first time round. I am almost autistic when it comes to perfection and with a decent budget available i want good components in the fold. I've not worked out load demand yet fully and instead am working back to front in so much as maxing out on the number of panels i can install on the roof. I have some new Dimplex 230w panels coming my way and availability to fit 8 of them up top. I will fabricate an articulating mechanism using 24v actuators to maximise panel function. Battery bank will be 24v.

What i seek is information to construct a layout drawing in the first instance so i can visualise the finished job before i start handing over the hard earn't loot..!!!!

Will, if your reading this feel free to chime in and share some of your knowledge as well as other members


Here's my truck, a little old and tired she's getting a full revamp, that roof is fully chequerplated and ready for solar....!!!!

 

[HRTKD]

Layout drawing of what? The roof? The components?

I used Sketchup to draw my roof and place my panels on it. I used draw.io to create a drawing of what components would be in the system. I then used Sketchup again to draw the compartment were my components were located, ensuring that I could fit everything within the restricted space.

If you can overpanel on your roof, then the tilt mechanism may not be necessary. Tilting is cool, but you can also cause shading of adjacent panels if you don't plan it right.

 

[MezzBatt]

Layout drawing of what? The roof? The components?


If you can overpanel on your roof, then the tilt mechanism may not be necessary. Tilting is cool, but you can also cause shading of adjacent panels if you don't plan it right.

A layout drawing of the components and a full understanding of what protection to apply and where to place it.

What do you mean by 'overpanel' please..?? (I'm a newbie so bare with me ok...!!)

The tilting and shading aspect IS something to contend with and I have considered this in pre design thinking. I was considering two banks of (x4 panels) port & starboard sides so if one bank was slightly shaded at least one full bank of (x4 panels) would be getting max output...??

 

[HaldorEE]

1840W of solar into a 24V system will require a solar charge controller rated for 70A to use all of it.

That solar array should be able to provide 5000WH of solar input per full day of sun.(conservatively rated). I would match that with no less that a 6000WH battery pack. Doubling that would give reserve capacity for cloudy days.

How large of an inverter do you plan to use?

You might want to consider a 48V battery. 16 of the 280 AH cells would give you a 14KWH, 48 V (51.2 V actual) battery pack. The DC current in everything will be half of what it would be in a 24V system, which makes wiring lighter, cheaper and easier to install.

Considering the scale of your intended system, I recommend you investigate building it using the Victron infrastructure.

 

[HRTKD]

What do you mean by 'overpanel' please..?? (I'm a newbie so bare with me ok...!!)

See this thread: https://diysolarforum.com/threads/help-me-understand-overpaneling.2425/

It goes into more depth on over paneling than I could.

 

[HaldorEE]

Overpanelling means using a smaller solar charge controller (SCC) than is required to handle peak solar power. SCC's are able to deal with this situation by converting the excess power to heat.

The only advantage is you get to save money on the SCC. If that doesn't matter then sizing the SCC to handle peak input will use all of the solar input. The SCC will handle higher ambient temperature better if it is not overpaneled.

 

[MezzBatt]

Overpanelling means using a smaller solar charge controller (SCC) than is required to handle peak solar power. SCC's are able to deal with this situation by converting the excess power to heat.

The only advantage is you get to save money on the SCC. If that doesn't matter then sizing the SCC to handle peak input will use all of the solar input. The SCC will handle higher ambient temperature better if it is not overpaneled.

I was advised (on another forum) to use 2 MPPT SCC's to split the solar load up and I asked 'why' but never did get a response. Do you see any sense in doing this or just use one SCC...????

 

[HaldorEE]

I was advised (on another forum) to use 2 MPPT SCC's to split the solar load up and I asked 'why' but never did get a response. Do you see any sense in doing this or just use one SCC...????

Could end up being cheaper to buy 2 smaller SCC than one bigger SCC.

Could be related to wiring issues. Staying within the max current limit in an MC4 connector.

Could work better if part of the system gets shaded. Depends on how the panels are wired.

Could be to provide redundancy (if one SCC dies, you still have the other).

 

[MezzBatt]

Ok, so I'm going to have two banks of panels (2S2P) that will tilt but only one at a time (in opposite directions) so that I'll always have one bank picking up a super efficient angle to the sun. This will give different charging currents back down to the battery bank, will this kind of setup be ok ?? The theory being that I don't have to focus too much on parking up in order to get the required position for tracking the sun. Anything to consider or be aware of having one of the banks being a 'lead' bank and the other a trailing bank (as in power/current)..?????

 

[Hedges]

No problem paralleling strings of different orientations. It's only a couple percent lower yield than having separate MPPT for each.
All panels in series as part of one string should be same orientation.
All strings should be the same length (or similar total Voc & Vmp if different models in some strings.)

 

[MezzBatt]

No problem paralleling strings of different orientations. It's only a couple percent lower yield than having separate MPPT for each.
All panels in series as part of one string should be same orientation.
All strings should be the same length (or similar total Voc & Vmp if different models in some strings.)

I will be using two MPPT SCC's for each separately tilted bank and all panels are the same spec.....

 

[Hedges]

That will work too.
Some inverters can talk to each other, agree on charge mode.
Batteries will have a maximum charge rate, sometimes minimum desired (FLA probably wants 20% sometimes to mix electrolyte.)

With 2P into each charge controller, no PV panel fuses needed.

I like strings of multiple angles on one charge controller (inverter in my case) as a way to put 50% more panels on it without clipping, and get more watt-hours per day. With sufficient SCC each can have a single direction.

 

[ianganderton]

Where are you planning to use the truck and at what time of year? This can have a significant bearing on whether tilting panels are worth the effort.

Also because you haven't done a power audit as yet you are also groping around in the dark guessing whether something is worth it or not.

The most elegant and reliable systems are typically the simplist. Complications add failure points and reduce reliability.

 

[JoeHam]

Or get more complicated, your choice ?

Here is one example:

Stacked Panels with a slide out feature when parked.

I saw this video on YouTube and my mind went into overdrive. In the video they have a slide out panel for when you're parked, that slides to the rear. Then I thought slide out to the side and drop down at the end. Have panel #1 flat mounted on the roof with a raised stand. Then under it a 2nd...

diysolarforum.com

There is an extremely slick overland van guy with videos of a remote actuated slide out panel setup but I cannot find it now. Hopefully someone will add it.

 

[BiduleOhm]

This one maybe? https://www.youtube.com/playlist?list=PLq1-J1YKxmjoVol7zRL89DvemKUnbjdAR

 

[JoeHam]

This one maybe? https://www.youtube.com/playlist?list=PLq1-J1YKxmjoVol7zRL89DvemKUnbjdAR

No it was a giant off-road military looking vehicle. I’ll look around some more.

 

[JoeHam]

Here it is, about 3:30 into the video:

 

[fat_old_sun]

Mission : to build me a stand alone self sufficient solar powered system for off-grid wild camping situations.

Others have already given good suggestions. Mine is: build the electrical system (& other aspects of your rig) for reliability & simplicity so that you have a level of redundancy, instead of focusing on efficiency. If something breaks down, you'll have to fix it yourself.

 

[chrisski]

I will be using two MPPT SCC's for each separately tilted bank and all panels are the same spec.....

When I installed my tilt panels, I never took into account the few extra inches I needed between panels so I could get my hand in and tilt up the panel. With six 100 watt panels on my roof, I'm sure I lost space where I could put panel #7 and #8. With a bit better planning on my part with measuring, I could have fit 400 more watts on my roof with the space I took up for 600 watts.

I'm not sure what you have in the likes of plumbing, and if that's not up top, where those pipe vents will go. Gotta save room for those.

 

[chrisski]

Here it is, about 3:30 into the video:

I like the vehicle, I wonder if he has any protection for those panels for off road use. Even in the Sonoran Desert in AZ, there's plenty of branches while off roading. For my pickup, there's enough people going through with those, they cut so I have clearance, but the tops are scraping.

THere's never any trees in the desert that will effect off roading until you get to the washes, and then there's plenty of them. A lot of the trails go down the washes for miles.