Help design my adventure van power system please

[DiploStrat]

I'll check, but hopefully this is what Peter Kennedy is doing for me. Making sure all this works.

My compliments to M. Kennedy, I have bought from him before. This sheet gives you the info: https://www.victronenergy.com/upload/documents/Datasheet-Cyrix-Li-ion-120-A-EN.pdf

Basically, a normal VSR is set for a battery voltage of about 12.7v. With LiFePO4, you have a resting voltage of over 13v. Hopefully, Victron have matched, and tested, their relay with their batteries.

Final note: LiFEPO4 batteries can suck a lot more power than lead acid - watch your amp flows and alternator temps. Don't let the smoke out!

Best wishes!

 

[djb_rh]

My compliments to M. Kennedy, I have bought from him before. This sheet gives you the info: https://www.victronenergy.com/upload/documents/Datasheet-Cyrix-Li-ion-120-A-EN.pdf

Basically, a normal VSR is set for a battery voltage of about 12.7v. With LiFePO4, you have a resting voltage of over 13v. Hopefully, Victron have matched, and tested, their relay with their batteries.

Final note: LiFEPO4 batteries can suck a lot more power than lead acid - watch your amp flows and alternator temps. Don't let the smoke out!

Best wishes!

Thanks. I checked and yes, we have the proper charge relay *and* the proper combiner. I'll definitely do the wiring right, and I have the beefiest alternator I could get. This is basically the ambulance package.


--Donnie

 

[djb_rh]

So anyone here have experience using dissimilar solar panels together? Here's the deal...I wanna fill the roof as much as I can reasonably. Here's the roof:



Renogy has panels sized fairly good, but I'd end up with 5x100W panels and then 3x50W panels. But obviously those aren't quite the same voltage nor amperage (the 50W and 100W), you can't really combine them into one MPPT controller. I'm not opposed to going to a two MPPT controller setup (already have one 100/50 Victron and everything else is Victron), but it SEEMS to me like the only sane way is to put the 3x50W into a smaller controller (they could go in series to keep the current down assuming I get a controller capable of 75V). But that leaves 5x100W going into the first controller and my understanding is the only way to connect FIVE into the 100/50 would be in parallel. You can't do them all in series since the voltage ends up a tad too high (they are over 20V each) and since it's an odd number there's no way to do them otherwise.

So do I drop back and just do 4x100 and 3x50 for now? I hate leaving that extra 100W on the table, but I don't know any way other than doing them all in parallel, which I think just ends up needing crazy big wire for the current. Or I go to THREE controllers.

Thoughts?

(And yes, I'm just now actually getting to knocking this project out.)


--Donnie

 

[luthj]

I would just pick up another controller for the non matching panels. As long as its programmable to basically match your victron unit, it will work. Doesn't need to be same brand, or a high end model either.

 

[pdavitt]

So anyone here have experience using dissimilar solar panels together? Here's the deal...I wanna fill the roof as much as I can reasonably. Here's the roof:
--Donnie

Not sure from the picture the actual dimensions of the available roof area. But let me make a "way out there" suggestion. Why not use two 350W 36V panels? I just bought four LG Solar NeON R LG350Q1CA5 350 Watt 36V panels for a project I am working on. Each panel is 40" x 67" and weighs 40 lbs.
Wire the two panels in parallel with a suitably sized charge controller.

Speaking of Peter Kennedy, I am working with him on this project and found him to be very knowledgeable and a great help. I recommend him highly.

Pat

 

[djb_rh]

I tried to put the fans as far forward and backward as I reasonably could, but that still only left 76" between them. And I have basically 66" of roof width. While I'm sure 67" panels would have been fine on top that direction, I can't fit two of them between the fans. I maybe could put the second one at an angle above the fan, but I don't really love that idea.

Also, curious why you say "wire in parallel" on those. With most MPPT controllers, you should be able to reasonably get a 100V side and then you go in series. That way you keep the current in half and have less loss due to cabling (and the cable size needs stay lower). Or am I missing something?

--Donnie

 

[pdavitt]

Also, curious why you say "wire in parallel" on those. With most MPPT controllers, you should be able to reasonably get a 100V side and then you go in series. That way you keep the current in half and have less loss due to cabling (and the cable size needs stay lower). Or am I missing something?
--Donnie

There is a lot of discussion about the efficiency benefits of series or parallel wiring, I'm not going there. In this case my reasoning is much simpler. You only have two panels, if you wire them in series and one goes down, you have no panel output. If you wire them in parallel and one goes down, you only lose half your solar output.

Pat

 

[Rando]

The Vmp of the 50W panels seems to be close enough to the Vmp of the 100W panels that there shouldn't be any issue putting them all in parallel. Alternatively you could put two 50W in parallel then in series with the 100W panels.

 

[djb_rh]

The Vmp of the 50W panels seems to be close enough to the Vmp of the 100W panels that there shouldn't be any issue putting them all in parallel. Alternatively you could put two 50W in parallel then in series with the 100W panels.

Yeah, I wondered about that. Basically it seems like these particular panels (the 50W and 100W Renogy) do provide a lot of options thanks to that. What you *can't* do is deal well with odd numbers of panels terribly well. As long as you stay with even numbers, the options are much better. I'm just conflicted with my want to cover the roof. I want that for two reasons...the obvious is to maximize solar electricity output, the other is to cover the roof with a layer of "insulation" from sun.

To be clear, my idea of layout is three strips down the van. Two long strips that are 1x50W and 2x100W on each side of the fans, then one strip in the middle that's 1x50W and 1x100W. But that gives me an odd number of 100's and an odd number of 50's. As you say, I could possibly get away with turning two 50's into looking like a single 100, which evens things up. And if I give up that odd 50W in the middle, then I can still use one controller. Those voltages are CLOSE, but not the same, so it bugs me to maybe lose a tad of efficiency there.

My temptation is to put 4x100W on my current controller and buy another identical controller. It's only $300. Then I would parallel two 50W and add them to the left over 100W on that controller, so any inefficiencies are minimized and I have some redundancy.


--Donnie

 

[djb_rh]

So I started looking through my electrical road map from Peter and the stuff I have and....he forgot to sell me a Color Control GX! He didn't ship one because he didn't sell me one. And it's just as much my fault for missing it, too. But I am going to order it and another MPPT 100/50 and at least some of the cabling I'll need this week. I ordered the solar panels (5x100W and 2x50W) today along with what I think will do on the wiring and MC4 connector side. And glands.


--Donnie

 

[mezmochill]

Dont know if this was said but dont let your maxairs cast shadows on your panels.

 

[luthj]

Dont know if this was said but dont let your maxairs cast shadows on your panels.

Even antenna shadows can impact output significantly. I generally only have maxfan shadow issues in winter, as it is fairly low profile.

 

[djb_rh]

Most people use Z brackets and just VHB them to the roof. I'm thinking I'm going to go a tad higher and use the factory bolt points up there to make a frame and get the panels a tad higher than the Z brackets would. And I'll use some sheet metal to cover the areas that the panels don't for sun insulation. I think some aluminum rectangular tube will be strong enough and not add enough weight to be a problem.

That'll help with the shadow issue, and I'll definitely place the panels as far outboard as I can from the fans, too.


--Donnie

 

[mezmochill]

Vhb is probable enough but when you get into strong gusty side winds you may find yourself cringing at times.(4 brackets will give you maybe 12 -16 sq inches of adhesive area to the top of the van) If it were me id run at least one bolt through each bracket( 2 would be better) for saftey backup. Im a big fan of 3M adhesives but thats quite a bit of liability and money up there on top.

Good luck youll like that dual fan setup