I see that the Smartsolar 250/100 has 3 pairs of PV connectors. are these all going to the same internal connection but avoiding overloading the MC4 connectors by using multiple?
If i have 11 400w panels, would i be best to connect these as 3 strings of 4, 4 and 3 panels? would they be ok like this in parallel but different lengths/wattages? The manual and the videos that i've watched don't go into this.
thanks,
Die 3 Eingänge sind intern zusammen geschaltet, es gibt nur einen tracker, die Stringspannung muss identisch sein.
thanks Ludo,
so my 11x 400w panels could not be connected to this charge controller in any configuration?
i will have to buy another panel to have 3 strings of 4x 400w panels but the last panel's position will be shaded sometimes. That's not good either!
Please advise me which chargers to use for my 11 panels. They will be linked to a Multiplus II 5kw.
so my 11x 400w panels could not be connected to this charge controller in any configuration?
11 is a prime number, and as such it is only devisable by 1 or 11.
12 is a much better number. 12 is devisable by 1, 2, 3, 4, and 6 !!! A much more flexible number :) !
You have not mentioned the battery voltage, or panel specs.?
Cant really give advice without knowing the panel specs, and the battery voltage.
Run your panels through the Victron online MPPT calculator.
The problem is a 12th panel would be behind the chimney for some of the day. I believe that would affect the whole string.
My panels are Trina Vertex S 405w
Batteries will be 2 or 3 US2000C at 48v but for now just some 'dummy' battery set-up to make things work until i get enough wongas for the real batteries.
The 4/4/3 setup would still work, but the detected mpp won't be optimal for all strings. So you'll lose some power, but it may even be better than an extra panel in shade. Just try it..
So 4 (or 3) panels in a string at 165V Voc and 12A Isc (124v, 12A for 3 panels),
I would need 3x 250/70.
Or, 4 strings of 3 panels i would need 4x 150/35.
It's getting complicated!
That's a lot of mppt ($$) for not a lot of panel, you're right it is complicated and inefficient.
Maybe take a moment and go and revisit if you have chosen your panels wisely.
There is always some compromise in a design.
You also don't have to jump into the deep-end, you can start with X and finish with Y if you weren't happy with the results.
It's getting complicated!
Kiss, 2 strings of 5 panels on a 250-70 mppt.
Another scenario would be to have 3 x 3 panels on a 150-70 mppt, and 2 series panels on a 100-20 (48) mppt.
Plenty of ways to implement 11 panels on Pylontech batteries.
TCO and redundancy also come into play. 2 strings of panels on a mppt = good. 3 strings of panels on a mppt = ok, but at the cost of string fusing.
Would i be better to just forget the 11th panel though? There is only 1 input on the Multiplus and I don't want the 'weak' input to affect the other 5 or is that not a problem?
So what would be better:
3 strings: 2 with 4 panels and 1 with 3 panels
or:
4 strings: 3 with 3 panels and 1 with 2 panels ?
Without having a detailed view of what the layout, orientation, shading etc is - this is guess work.
Better is an abstract term.
More panels = higher string voltage = better performance in lesser conditions.
Shading has to be taken into account.
Mixed sizes are not a problem in itself, though symmetry is always nice.
There is a reason this forum is not meant for design advice as design is nuanced and affected by context - detail the internet just can't communicate.
This stuff costs money, get someone in person to help you do the best fit so you don't throw away cash on stuff that you don't need or won't work optimally.
Panels come in many flavours, so if these aren't a good fit, pick another.
I'm a bit stuck as the panels are already here. They were ordered with a Fronius inverter but that seems like it will never be delivered due to components unavailable. I've waited 5 months. The Fronius would have accepted two strings of 6 and 5 panels each without problems I think.
Anyway, the plan has evolved a bit and now we will install batteries so i've gone down the Victron Multiplus route which can work Pylontech batteries because they are so much cheaper than BYD which the Fronius required.
The site is pretty south-facing, pretty much unshaded but there is a chimney which makes the 12th panel less worthwhile.
If the 11 are mostly unshaded then see if you can reduce the number of mppts without going beyond the mppt voltage limits- considering cold weather impact.
It may turn out that 2 x 5 is the best answer.
Its a bit cart in front of the horse designing this way round so a compromise may be unavoidable.
Remember, you can always change it later.
By providing open voltage, optimal voltage/current and shortcircuit current
got it now, it suggests the 250/85 for an array of "4 series" and "3 parallel" which i think is 3 strings?
Symmetrical strings are best practice on the 150/250 volt MPPTs.
VOC of the string at minimum temperatures is important. The 150 or 250v max is a hard limit max
The mc4s on the bottom of the mppt can take up to 30A (so you can y connect 2 strings onto one mC4 set)
See the tech specs.
11x400W is 91A so use 100A if you dont want any solar peak shaving.
Your other option is a 450/100 where there are two trackers so asymmetry is not a problem. Sizing for max VOC per string here now is 8 x float of the battery. They are a neat competitor for the Fronius. It also has partial shading detection. And you will only need 2 strings. So if it was already installed and set up for the Fronius, you can (almost) just drop it in its place. It is just DC connected not AC. Use a lynx power in or distributor for all the battery and mppt connections.
There is free training on victron professional for users , if you want to get a bit of training and understanding.
Yes two trackers is what i need. That was the benefit of the Fronius.
Thanks Alexandra, the two-tracker is what makes sense to me. Like the Fronius would have been able to do.
I will be getting the RS 450/100 which is a bit dearer than the 250/100 single tracker but then i can use the 11 panels without losing any sleep.
I can get the 150/35 for 335euro and i'll need three of them plus a 100/20 for the short string. About the same price overall as the TR450/100.
More reliable though? That's interesting.
No one buys multiple mppt's for reliability. That is nonsense advice.
2 smaller ones are more expensive than one larger one, wiring, joins, fuses, switches all add additional complexity, cost and the possibility to for something else to go wrong.
Keep it simple.
This is the internet, and while there are many opinions, they all aren't equal.
As moderators it is part of our responsibility to remind you of this.
Properly installed, a failure is very, very, very rare.
Victron units are (originally) mainly made for use on ships. These can be used for long trips offshore, where redundancy is life saving. Sure, most ships spend their lifetime in the marina, but that's not what they were designed for.
If you want to get a real life feeling for component failure, spend a winter-season on a large Spanish campsite wearing a victron t-shirt ;)
Or ask why repair times at transwatt are so long.
2 or 3 units would have to be the 250 series which would work out more expensive both ways.
For me the 450/100 costs 1425, two 250/60 637 each.
The wiring solar to mppt is identical, you'll need two extra wires and one fuse more from mppt to battery
For me redundance has a value
How does two 450/100 compare to one 450/200, or 2 x 250/60 to 250/100?
There are always pros and cons of going multiple smaller units or one larger one.
Simplicity of the wiring and switch gear, battery fusing, costing for the 450/100 is a big plus in my book. Then there is always the option to go to the Fronius if you still want to do that without major changes and another cost.
Then there is the multiple mppts as mentioned by ludo. Increased wiring cost and switch gear with fusing to install and labour as nickdb mentioned. But the benefits are really, if there is a faliure then its only a part of the entire array. So if distributor/warranty support is harder where you are, is a consideration if their are long waits. Good wiring set up is important here such as using bus bar particularly on the battery side, which is also an added cost.
To be honest we have not had a 450/100 fail to date. And the 150/35 are also solid units. So that is not a factor for consideration for me.
One should also bear in mind that using two units instead of one doubles the chance of failure. Albeit only half the system.
