Solar Panels Advice

[JCAvenger]

Hey!
I need some advice on which type of system I should use, serial or parallel.
I have two sides suitable for solar panels, South and West: My plan is to have 5 panels facing south and 4 panels facing west. Both sides of the roof have a 45-60 degree angle.

I have spoken to some solar panels companies and I've gotten contradicting proposals, so I'm here to ask you guys what to do!
The best budget I got was a serial system 9x panels URE 420 Wp Full Black N-type and the inverter would be Growatt MIN 3600TL-X, with a starting voltage of 100 V, would this work?

 

[binky]

Panels are always wired in series, but for your roof you would need 2strings to work properly.

Reckon if they supplied shorter panels, which they would have to shop around for, you could get 5 panels on the West roof. Have they actually physically measured the roof, or are they just working from Google images?

 

[JCAvenger]

Panels are always wired in series, but for your roof you would need 2strings to work properly.

Reckon if they supplied shorter panels, which they would have to shop around for, you could get 5 panels on the West roof. Have they actually physically measured the roof, or are they just working from Google images?

But I heard from one of the competing suppliers that if I get sun from the south that this serial system with two strings wouldn't work?
They're just working from their software that apparently gets 3d images.

In order to lock me in that company quoted me for 5.7k for that system and the fusebox that is required, seems like a pretty good deal.

 

[binky]

But I heard from one of the competing suppliers that if I get sun from the south that this serial system with two strings wouldn't work?
They're just working from their software that apparently gets 3d images.

In order to lock me in that company quoted me for 5.7k for that system and the fusebox that is required, seems like a pretty good deal.

They should fit an inverter with lower start up voltage then. Wire all those panels as a single string and it will perform badly. Have a read of other posts on here, there's loads of information.

 

[johnb2713]

Panels are always wired in series, but for your roof you would need 2strings to work properly.

Reckon if they supplied shorter panels, which they would have to shop around for, you could get 5 panels on the West roof. Have they actually physically measured the roof, or are they just working from Google images?

5 on each roof would be better, inverter size needs to be bigger and battery?

 

[binky]

View attachment 15596
5 on each roof would be better, inverter size needs to be bigger and battery?

Whose been playing with Photoshop .

Strictly speaking the corners are too close to the ridge, but I've never regarded that as an issue. Plus it's a flat image, in reality there's more space on the roof than shown, which is why I was asking if they have physically measured the roof. If panels were still 1.3m X 0.8m you could get six panels on there.

 

[JCAvenger]

They should fit an inverter with lower start up voltage then. Wire all those panels as a single string and it will perform badly. Have a read of other posts on here, there's loads of information.

When would it perform badly and why? I'll also check that but sorry, I'm new to solar panels!

 

[JCAvenger]

View attachment 15596
5 on each roof would be better, inverter size needs to be bigger and battery?

Nice job ahah! But would it be worth it (in 10 years) to upgrade to a paralel system?
When would the system not perform correctly?

 

[binky]

When would it perform badly and why? I'll also check that but sorry, I'm new to solar panels!

The MPPT tracker will be trying to find the optimum power point of two sets of panels behaving differently to each other, ergo, the tracker will be unable to find the most efficient output from the panels because it's trying to track two different power curves. Have a read. https://en.m.wikipedia.org/wiki/Maximum_power_point_tracking

Not being funny, but the company you are talking to seem incompetent, or just don't give a shit about how well the system works for you. Large national outfit by any chance?

 

[binky]

View attachment 15596
5 on each roof would be better, inverter size needs to be bigger and battery?

Two of my older jobs v national company https://maps.app.goo.gl/JGQGam2z2qmrf2gS8

 

[johnb2713]

Nice job ahah! But would it be worth it (in 10 years) to upgrade to a paralel system?
When would the system not perform correctly?

Two strings of 5 panels would work nicely with the appropriate inverter. It's a shame not to put 5 up there whilst the scaffolding etc is up. If you connect them as a single string, you will get higher voltage into the inverter BUT whichever roof isnt getting the best of the sun/daylight will restrict the performance of the panels so you have a lose / lose situation. During the morning time the South facing panels will be doing well but bottle necked by the West facing ones, later day it's the other way round. If you have them connected as two strings (mine are), during the morning through to mid afternoon the south facing roof is at peak performance, afternoon through into the evening the West facing roof becomes optimum. The two independent MPPT inputs in the inverter can get the best performance out of the panels.

I'm not quite sure what you mean about a 'parallel' system?

 

[binky]

I'm not quite sure what you mean about a 'parallel' system?

Think he means two strings

 

[Andy1733]

I'm no expert but from reading the forum frequently it's a no brainer when fitting panels on 2 different facing roofs to run them on different strings..

Binky/John. Is there any situation where a single string over 2 different orientations would be best???

 

[binky]

I'm no expert but from reading the forum frequently it's a no brainer when fitting panels on 2 different facing roofs to run them on different strings..

Binky/John. Is there any situation where a single string over 2 different orientations would be best???

Nope, although you can compensate using panel optimisers - I'm not a fan.

The only system where a single string is possibly better is using Solaredge

 

[DJN008]

Agree, two strings all day long. We have a similar set up at home, but only six panels with a 3.68kWh inverter. We are pulling in just over 10kWh at the moment. I would not use Growatt inverters though. In my experience their technical side of things are next to useless, and the WiFi dongles are just as bad. I've used Sunsynk and their technical is pretty good, as is Solis.

Off to light a barbecue...

 

[johnb2713]

Agree, two strings all day long. We have a similar set up at home, but only six panels with a 3.68kWh inverter. We are pulling in just over 10kWh at the moment. I would not use Growatt inverters though. In my experience their technical side of things are next to useless, and the WiFi dongles are just as bad. I've used Sunsynk and their technical is pretty good, as is Solis.

Off to light a barbecue...

My solar install has a Growatt Inverter and Battery, it's the only Growatt I have experience of and it's been rock solid, 100%. My DIY battery has a Victron Inverter, the amount of setup for that was horrendous but it has immense flexibility and anything you could want an inverter to do the Victron can do it.