amended array layout

[david lanyon]

Hello. we are in Cornwall and had to remove 14 South facing panels for building modifications. We can now only get 10 on a West facing slope and 4 on the East. Should i have 2 equal strings of 5 from the West face in series with 2 from the East or, a string of 7 on the west face and a second string made up of the remaining 3 from the West face and the 4 on the East. We have a Sunny Boy SB2.5-1 VL-40 inverter and Suntech 190w panels. Max current 5.2A Max voltage 36.6V thanks

 

[binky]

Never mix panels on different orientations on the same string, it will work badly.

There's a label on the back of the panels, can you post a picture of it.

 

[johnb2713]

Hello. we are in Cornwall and had to remove 14 South facing panels for building modifications. We can now only get 10 on a West facing slope and 4 on the East. Should i have 2 equal strings of 5 from the West face in series with 2 from the East or, a string of 7 on the west face and a second string made up of the remaining 3 from the West face and the 4 on the East. We have a Sunny Boy SB2.5-1 VL-40 inverter and Suntech 190w panels. Max current 5.2A Max voltage 36.6V thanks

You need to change the inverter for one with 2 x MPPT inputs, also lookout for the startup voltage with the 4 panels.

 

[david lanyon]

You need to change the inverter for one with 2 x MPPT inputs, also lookout for the startup voltage with the 4 panels.

the 14 were arranged in 2 strings of 7 so has 2 inputs

 

[david lanyon]

Never mix panels on different orientations on the same string, it will work badly.

There's a label on the back of the panels, can you post a picture of it.

i cant but the info is - Model no- Suntech STP190S-24/AD+. Max power 190w. Current at Pmax 5.2A. Voltage at Pmax 36.6V. Short circuit current 5,62A. Open circuit Voltage 45.2V. Max system Voltage 1000V. Maximum series fuse rating 15A

 

[johnb2713]

the 14 were arranged in 2 strings of 7 so has 2 inputs

Hmm, how odd, the manufacturers spec says otherwise but no matter, the important thing is you have two inputs for your East / West configuration. The startup voltage is 80v by the way.

 

[truffle pig]

Worth looking at installing optimisers

 

[binky]

Hmm, how odd, the manufacturers spec says otherwise but no matter, the important thing is you have two inputs for your East / West configuration. The startup voltage is 80v by the way.

View attachment 15923

SMA did some unusual input configurations, including 3 MPPTs on some models, 2 'large' and a 'little' designed to take, say, 4 panels on an odd but of roof.

In this case, it is a single mppt, so probably better off selling off spare panels, or fitting a different inverter, or fitting 2 small inverters for the east/ west arrays

 

[david lanyon]

Hmm, how odd, the manufacturers spec says otherwise but no matter, the important thing is you have two inputs for your East / West configuration. The startup voltage is 80v by the way.

View attachment 15923

Thanks John. It is strange. There are 4 mc4 cables running to the inverter. I will see if i can get a better look at the input to the Inverter today. It seems to me that 10 panels would be within the optimum range but the 4 wouldnt yet be above the start up voltage on their own but the west face would be contributing to some degree. I am in a situation where due to an unexpected bereavement, i am completing the job for the widow who is selling the property so doesnt want to expand the set up, otherwise, i would just add panels or change inverters. From what i can tell, although not optimum performance, i could connect the 10 in one string and 4 in the other without suffering any harmful effect n the inverter

Edited to make it less confusing to read

 

[david lanyon]

Worth looking at installing optimisers

Will do some research on these for my grid tied system at home. Do they affect the agreement with the energy company ? If so, do you know if they (EDF ) are receptive to applications for these to be added ? thanks

 

[binky]

Thanks John. It is strange. There are 4 mc4 cables running to the inverter. I will see if i can get a better look at the input to the Inverter today. It seems to me that 10 panels would be within the optimum range but the 4 wouldnt yet be above the start up voltage on their own but the west face would be contributing to some degree. I am in a situation where due to an unexpected bereavement, i am completing the job for the widow who is selling the property so doesnt want to expand the set up, otherwise, i would just add panels or change inverters. From what i can tell, although not optimum performance, i could connect the 10 in one string and 4 in the other without suffering any harmful effect n the inverter.

some mppts have multiple connections, you don;t see that so much these days. . You cold try adding Tigo optimisers to the 4 off panels, in theory that should stop them taking the string down, and allow use of all the panels. Must on the high FiT rate judging by the panel wattages, so keeping production up will have good financial benefits for the customer.

 

[david lanyon]

having had a closer inspection today it is more clear. Each string goes back to the isolator and not 4 cables to the inverter as i initially said, where it then comes out as one feed to the inverter. A local installer i spoke to earlier in the week, suggested i spoke with SMA to be sure and they have responded by saying best consult a local installer. Ha