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diy solar

Considering 400W to 600W upgrade

JBennettBus

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Oct 6, 2022
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I have a 400W Proswian solar setup on my short bus. Works great except in winter, when I'd like to have a little more power available. Main components:

4X 100W panels
10AWG connector cables (less than 18' foot run)
EPEVER 40A MPPT charge controller
3X Renogy 12V 100AH gel batteries

Main locations: Colorado in summer, south Texas or south New Mexico in winter.

I've been looking at options like adding alternator charging, a wind turbine, or a hamster wheel with big hamsters, but I think adding 2 more panels is the cheapest, easiest upgrade. That should get me through this next winter, and in spring I'll probably replace those gel batteries with a 24V lithium battery and a new inverter.

If I wire the panels for 24V, it seems like I can get by without any other changes to the current setup. Am I missing anything?
 
LOL... "Prowsian"... nice.

Flat panels are lucky to get ~40% rated at those latitudes in winter. Increasing your panel tilt to ~45-60° will likely get closer to 60-70%.

You can parallel to your existing array by matching the series Vmp. If your 400W array is 2S2P, then 2S 100W panels should be really close and can just be paralleled with your roof array.

Lightweight, flexible panels as a deployable array can be quite practical:

 
I have a 400W Proswian solar setup on my short bus. Works great except in winter, when I'd like to have a little more power available. Main components:

4X 100W panels
10AWG connector cables (less than 18' foot run)
EPEVER 40A MPPT charge controller
3X Renogy 12V 100AH gel batteries

Main locations: Colorado in summer, south Texas or south New Mexico in winter.

I've been looking at options like adding alternator charging, a wind turbine, or a hamster wheel with big hamsters, but I think adding 2 more panels is the cheapest, easiest upgrade. That should get me through this next winter, and in spring I'll probably replace those gel batteries with a 24V lithium battery and a new inverter.

If I wire the panels for 24V, it seems like I can get by without any other changes to the current setup. Am I missing anything?
Probably the hamster wheel would be more reliable and efficient than the windmill generator, but installing alternator charging would be a good idea.
Re-wiring your panels to 24V is another good idea, but swapping out gel batteries for lithium is not.
Search around in these forum pages for battery problems, and you will find the postings about lithium battery problems far outnumber the postings singing their praises.
Especially in a mobile application with all the road vibration and temperature variation, simpler is less vulnerable, when it comes to batteries.
 
Increasing your panel tilt to ~45-60° will likely get closer to 60-70%.
Tilting the panels is another good option. The only problem is that I don't want to have to drag out the ladder and climb up on the bus roof to adjust the panels every time I park and leave a place. Especially in winter. At my age. And weight. :)

I haven't really thought about adding deployable panels. I'll have to look into that. Thanks!
 
Probably the hamster wheel would be more reliable and efficient than the windmill generator, but installing alternator charging would be a good idea.
I love the idea of a wind turbine since I camp in a lot of windy places, but the thought of setting it up, taking it down, and figuring out how to store it hurts my lazy soul. Alternator charging still looks good, and since my batteries are installed on the wheelchair lift, wiring it in should be a breeze. The wires are already there.

btw, are you in an Arkansas cabin? I'm saving up to buy a place back there. I'll probably park the bus and turn it into a workshop.
 
IMHO, if you tend to move every day or two rather than stay in one place then alternator charging would be best. But if you are pretty certain you will be moving to 24v in the near future than I think the solar would be better because the alternator charger will have to be changed again and they ain't cheap if you're going from 12v to 24v.
And if you're going to move to lithium then it will require a different B2B charger to effectively charge to it's full potential.
The only problem I have had with LiPo batteries is when it gets too cold. I'm solving that now by moving them to another location where my house converter can fit so it should keep them relatively warm. Other than that, they have been noticeably better and worth the extra cost.
So if you are definitely going to do a major upgrade later then it's best to just upgrade the solar now because you will want that either way.
 
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Tilting the panels is another good option. The only problem is that I don't want to have to drag out the ladder and climb up on the bus roof to adjust the panels every time I park and leave a place. Especially in winter. At my age. And weight. :)

I haven't really thought about adding deployable panels. I'll have to look into that. Thanks!
If you use gas struts to lift the pannels and a rope and cam cleat to lower them there's no need to climb up although some other form of locking the pannels down would probably still require ladder climbing of some form ??
linear actuators are the expensive option for lift, lower and lock ? or hanging panels on the side (after parking up!) and hinging them is another option i've conciderd, i'm no lover of ladders and i'm not getting any thinner or younger LOL
 
IMHO, if you tend to move every day or two rather than stay in one place...
I generally stay at one spot for 10 to 14 days with about a 2 or 3 hour drive between. I was thinking of alternator charging mainly as a backup for those times where there's like no sun for a week, but that's not a common problem out west.

I'm a little worried about the cold. The bus is poorly insulated, and it frequently drops to 20 or 25F in there. (I don't run the heater when I'm asleep.) I think insulating the batteries and maybe adding a small heating pad might keep LiFePo batteries warm enough. I'll be adding some insulation and weather stripping to the bus soon, so maybe that will help too.
 
linear actuators are the expensive option for lift, lower and lock ? or hanging panels on the side (after parking up!) and hinging them is another option i've conciderd, i'm no lover of ladders and i'm not getting any thinner or younger LOL
I've looked into electrical actuators a bit, but I'm no engineer. Linear actuators? Some kind of scissor lift? I dunno. Seems like there's a business opportunity there though. Tiltable solar panel mounts that you can adjust from inside might be popular with the the van/bus/rv crowd.

We're on the same page when it comes to ladders. Not a problem when I was young, but I fell about 6 feet off one a few years ago, and my body came all unhinged. Ack!
 
Agreed, (sort of,) but every fiber of my rather fibrous being tells me to avoid lithium.
Why? After one season with lithium batteries I couldn't be happier. Smaller and lighter than lead-acid or AGM, and better performance too. I think they'll be cheaper in the long run too. What's not to like?
 
I think they'll be cheaper in the long run too. What's not to like?
I think they're close to cheaper at the time of purchase these days, at least at the low end of the lithium battery market. I have three 12V 100AH gel batteries, so about 1800WH of usable power at 50% depth of discharge. It would cost $650 (+/-$100) to replace them today.

A Chins 12.8V 200AH LiFePo would give me the same usable power storage at 70% DOD. That would cost $640. Same power storage and $10 left for a nice cheeseburger.
 
I think they're close to cheaper at the time of purchase these days, at least at the low end of the lithium battery market. I have three 12V 100AH gel batteries, so about 1800WH of usable power at 50% depth of discharge. It would cost $650 (+/-$100) to replace them today.

A Chins 12.8V 200AH LiFePo would give me the same usable power storage at 70% DOD. That would cost $640. Same power storage and $10 left for a nice cheeseburger.
Good point. For me the weight and space savings were the most important. I removed a 50 lb lead acid battery with 80 aH, and replaced it with 2 50 lb batteries with 400 aH. So I doubled the weight but got 5 times as much power.
 
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