HI
In a small system under 800 watts wire in parallel for better shade tolerance . Wiring in series can greatlly effect output if shade is encountered .
MY system 6x 65watt panels in parallel 3panels roof top fixed and 3 panels as portable, tot of 390watt all 12 v panels . Mppt controller . It takes little shade on a panel to reduce output greatly .
Many seem to have 200--300watt on the roof with a 160watt portable

To put all your solar on the roof could be limiting [eg have to park in the sun all day]

different voltage panels combined donot mix so a portable will need its own regulator . Less than ideal but doable .

thanks for the input.

I've done the portable thing but am not a fan.
I understand the challenges of fixed panels but as I use minimal power anyway, have a dcdc charger which in theory should have me arriving topped up, they won't be responsible for charging a heavily depleted battery.
It's pretty much just lights and the usual device charging duties.
I 've gone full 12v so no requirement for an inverter either :)
I also have 250 on the top of the tug and can apply this via the dcdc charger remotely or start the car if I get desperate.
I have a genie too but don't want to be carting that about and really have no need.

I figured parallel would be optimal re shadowing etc but it's good to have it confirmed.

P&M cheers, that seems to be the only real benefit of the higher voltage system and as you said, won't be a requirement for the set up.
I just wanted to make sure I hadn't missed something.
The set up from a wiring perspective will be semi permanent in that I will have an anderson up top near the panels and one for input at the battery.
These will be connected on site or at home but not used during travel.
This approach will save me having to drill holes and managing cable routes, keeping the runs much shorter than they would need to be for a full permanent set up.


thanks again

G'day Brett,
You mentioned that your van is a poptop & has challenges in mounting panel(s) on the roof.

When I finally decided to put mine on the roof (as mentioned in my "can of worms" post), I used the mounts that Jaycar/RTM sell - the cable is fed in UV resistant flexible conduit + a 90 degree elbow to bring it over the roof edge & stuck to the roof. It feeds to a 50x25mm box section "conduit" that I stuck to the RHS of the van (my battery is on that side). I left a loop (straight, when the roof is up) in the cable that I partially push down into the box section when the roof is lowered. I'll try to add some piccies a bit later.

That way I didn't have to add holes in the roof/vinyl with the chance of adding leaks. I have a LV DC plug/skt underneath the floor - feeding into the regulator, etc.

Of course you have to consider the extra weight on your roof - more that you have to push up although being a "young fella", that might not worry you so much.

Jaahn wrote:

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Hi 

Others have said that in parallel is best for shading and me too ! However I also believe the MPPT will give more efficiency also. It is hard to get performance figures but I believe that converting at a lower voltage, above that required, will give more overall output current. IMHO.

Jaahn

 

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cheers Jaahn.

Yes, that is my belief too.

From my research they do better at voltages closer to the battery charge volltage.

What I like about mppt is that I can supply it at a higher voltage, avoiding some of the pitfalls of running higher current and get the benefits in charge rates at the battery.

I'll be doing a install video as per normal and if I end up with time to spare and have the motivation, I might do a set up where I can experiment between the 2 set ups and just see what the difference is in the real world.

I could see that taking up  a bit of time though.

 

Warren-Pat_01 wrote:

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G'day Brett,
You mentioned that your van is a poptop & has challenges in mounting panel(s) on the roof.

When I finally decided to put mine on the roof (as mentioned in my "can of worms" post), I used the mounts that Jaycar/RTM sell - the cable is fed in UV resistant flexible conduit + a 90 degree elbow to bring it over the roof edge & stuck to the roof. It feeds to a 50x25mm box section "conduit" that I stuck to the RHS of the van (my battery is on that side). I left a loop (straight, when the roof is up) in the cable that I partially push down into the box section when the roof is lowered. I'll try to add some piccies a bit later.

That way I didn't have to add holes in the roof/vinyl with the chance of adding leaks. I have a LV DC plug/skt underneath the floor - feeding into the regulator, etc.

Of course you have to consider the extra weight on your roof - more that you have to push up although being a "young fella", that might not worry you so much.

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Cheers W-P

Pics would be excellent.

I think I get what you mean though.

I did purchase some of those abs mounting brackets clamps that go on the corners and sides and one of those junctions where the cable runs into the box and then goes down through the roof.

On close inspection though, my roof is slightly corregated and very thin. I wouldn't be confident of it supporting the weight or what effects would be had if I drilled through it.

I plan to use 25mm square aluminium tube to brace above and below the roof in the area along the side between where the skirt sits and the outside edge.

Basically clamping the outter edge between the 2 and then running roof rack still accross the roof to support the panels.

Thats the plan at this stage.

and yes, I'm happy for them to remain flat even though they won't be at their most efficient. Life is about compromises

 

 

AK.

The battery and feed will be on the other side to my fridge so its a no go.

That and the vent is well down under the roof line, so I'd still end up with a length of cable hanging over the side that I want to avoid.

I'll use some decent cable but it won't have to be too substantial due to the lower current requirement. I still like to go heavier than needed though

 

thanks everyone.

Cheers Tez.
Yes, I think it's 37v.
I was considering a 100v input capable controller just to keep my options open. This would work for the current install and allow it to be future proof to some point for any upgrades or changes.
The epsolar tracer 40amp is what I currently have my eye on.
They seem to be well priced and have a good following.
Plus a mate has 2 smaller variants and is happy with them.

to be honest, I hadn't yet considered the plugging in and unplugging challenges like those you mentioned as yet. I'm sure it would have come up during the install process but thanks for reminding me.
I might even consider an external switch up under the panels or the like to break the circuit just to be sure.
If you can think of something like that which might work I'm all ears.

hmm maybe an inline switch on the cable might work too.
It will have to be able to handle being installed outside though. I like those types of challenges in projects, so I'm sure I'll come up with something suitable.
My short a$$ wouldn't manage throwing up something over the panels

The controller will be permanently mounted at the battery, so will remain connected.
So in theory, unless something goes wrong, it will always be active and thus plugging in the panels should in that order anyway.

 

cheers Brett

-- Edited by denmonkey on Saturday 25th of August 2018 11:21:58 PM

Thanks Jaahn,

I think I'll go the inline switch route. I'd want to put them to use on arrival at site rather than waiting til night to make the most of them.
I'm starting to think I might try just the one panel to start with to confirm my mounting etc it all going to work without any issue
Lifting the roof etc. I'll wire up and mount for the 2 but just throw 1 up to test. Safety first and all that.
frankly even 250 would be enough for my normal usage, but when I run amatuer radio from the van that little bit extra would be nice.
I may even go over to a compressor fridge at some point. These absorption units just aren't made for the aussie summers.

I wasn't aware of the 24v panel wiring thing. I'll keep an eye out for it in the future for curiosity sake. That sounds like a good idea from a flexibility perspective.

cheers Brett

Thanks W&P,

I do like the use of the channel down the side of the van.

Makes for a nice clean install.

Mine unfortunately has the cladding and as such has ridges all the way down the side. The roof is tin and slightly corrugated for the lack of a better term.

I'd love to use that channel but I'm not sure I could get it to stay.

How is it stuck to the van down the side ?

 

Still It's pretty cheap, so I might try and see what I can come up with.

It would certainly allow me to leave the panels permanently connected.

 

Thanks for the effort and pics mate. Tis much appreciated.

 

cheers Brett

One thing to watch is that when you go over 60 V DC you need an electrical contractor to install or maintain your system.