Panels series vs parallel 80v vs 40v benefits ?

denmonkey · Senior Member

Panels series vs parallel 80v vs 40v benefits ?

swamp · Senior Member

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 .

Peter_n_Margaret · Guru

swamp wrote:
... wire in parallel for better shade tolerance .

Yep.....applies to any size system.

The only up side of series is lower current in the wires and lower voltage drop - not an issue with what you propose.

Cheers,

Peter

denmonkey · Senior Member

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

Jaahn · Guru

Hi smile

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. hmm

Jaahn

Warren-Pat_01 · Guru

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.

Aus-Kiwi · Guru

Our solar wires run down through old 3 way fridge vent . Note . Often when running parallel? The wires are too thick to fit into regulator . So either a line connector or link box to connect them .fuse, breaker not bad idea to isolate when required ., Then one sort wire correctly sized . In my case 6mm sq did fine .

denmonkey · Senior Member

Jaahn wrote:
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

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:
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.

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 biggrin

AK.

The battery and feed will be on the other side to my fridge cry 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 biggrin

thanks everyone.

T1 Terry · Guru

As long as the panel voltage is greater than 5v higher than the battery voltage then the closer to the battery voltage the higher the output. I'm assuming the panel Vmp is around the 36v mark and the controller has a max input voltage of around 50v and a max output of better than 30 amps for a 12v set up or 15 amps for a 24v set up, then all should work well. The added cost etc for an MPPT controller that will handle the roughly 100v if the 2 panels were in series can't be justified, but be careful with the arcing at the solar panel Anderson plug and be sure to plug the battery Anderson plug to controller together first and wait for the controller to start up before plugging in the solar Anderson plug. If possible a blanket over the panels before plugging in or unplugging will extend the light of the Anderson plug contacts and hopefully avoid them welding together, 36v plus @ 30 amps will weld them together with enough of an arc first to get them warm

T1 Terry

denmonkey · Senior Member

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 biggrin

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

Jaahn · Guru

Hi Brett smile

Some good points by Terry about plugging and unplugging the solar input. You will have the regulator permanently installed so that is good !! You can always do the connecting and disconnecting at the evening/night or when the sun is not directly on the panels., eg in shade.

When I buy a regulator I usually try to buy one over rated so it is likely to have a better life, rather than running at the maximum all the time. The Tracers have 150V rated units instead of 100V in some models for not a lot more. I have bought one of those as a bit of extra insurance for a 24V system. And buy a bigger amp rating than you need perhaps too. Just as a general rule for item selection, which has served me well in my engineering life too. biggrin The Tracers work OK.

For another bit of information not asked for, but for general information, some 24V panels may be wired in the junction box (on the back of the panel), as two 12V halves which can be rewired as two 12V in parallel or 24V in series. Just saying. aww

Jaahn

-- Edited by Jaahn on Sunday 26th of August 2018 02:50:46 AM

denmonkey · Senior Member

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

Warren-Pat_01 · Guru

denmonkey,

Here are the promised pictures (hot off the camera today)

Hope they are of use, contact me if you need clarification.

Warren

denmonkey · Senior Member

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

Warren-Pat_01 · Guru

Hello Brett,
Gee, I LOVE computers! I had your reply all typed out & touched something & it's GONE!

The channel is stuck on the side with the same glue as I used on the panel feet - Soudal Fix ALL - High tack. Other forum members prefer one of the Sikaflex products.

I don't see an issue with sticking the channel to your ridged side, just fill the gaps with the glue & smooth it out down the edges. In hindsight, I should have put the channel in front of the awning metal work (the length of the cable would have been the same & one side would have been free of any boxing on it.

The join in the cables (commercial solar cables to HD twin) is somewhere down towards the bottom of the channel. The HD twin feeds a plug that can be plugged into the battery/controller via a socket mounted in a protected area under the floor so I can either feed the on-top panels or the portables into the van.

I have another picture to download (possibly Thursday as we're getting home tomorrow (shorts on tomorrow!!!) - of the roof erected. You probably saw the loop in the cables - with my built-in ladder (long legs), it's not hard for me to push it down a bit into the channel for a tidier travel "look".

You say your roof is thin corrugated tin (aluminium, I guess) - my roof is flat ?? (suspect very thin plastic/fibreglass).

PeterD · Guru

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

denmonkey · Senior Member

Cheers W&P very helpful.
Not sure when I'm going to get a chance to start of this but the more info I have before hand the better off I am.

Hey Pete. Thanks for the tip. I guess that's another reason to run them in parallel.
I'm actually thinking of setting up 1 panel as a tester, see how it goes and then add the second down the road.
See how it pans out.

T1 Terry · Guru

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

I think it's 120vdc with a max of 5% ripple, but that one seems to be all over the shop from one state to the next. It certainly rules out using the higher voltage MPPT units for a DIY install though, something I'm sure the sellers don't mention.

T1 Terry