Strings uneven MPPT Voltage

[garty611]

Hi all I have just had a 3920KW Sharp 16 X 245W panels fitted with a Solar River SR4K4TLA1 inverter.

There are 2 strings. One is currently reading around 330V and the other is just below 200V.

6 of the panels are landscape and 10 are portrait. I have since found out that 6 are on one string and 10 on the other.

Will that effect anything do you think or should the strings be matched in terms of input Volts.

The SolarRiver Product manual suggests that MPPT voltage range is between 200-500 V. The maximum DC Voltage is 550V. So therefore one of the strings falls below this minimum of 200V

Can anyone shed any light??

 

[SolarCity]

I'm not sure if the Solar River SR4K4TLA1 has two MPP trackers. If it doesn't, then you have problems.

The strings need to be the same if they are both installed on one MPPT.

 

[garty611]

Deffo 2 inputs (4 wires going in)

 

[garty611]

They are not the same but if one falls below the minimum (200 V) will that effect total output.

 

[JohnBoyZ]

I believe that inverter has 2 sting inputs but only 1 MPP tracker so would think uneven strings is not such a good idea

 

[garty611]

I know its not the best system all round as I originally wanted 250W Sharp panels and a 3000 sunny boy inverter but it all changed when the Gov cut the FiTs... Has anyone had any experience with the SolarRiver stuff?

 

[SolarCity]

I've never used them.

However, if your installer has installed uneven strings and the inverter is indeed a single MPPT inverter then he has installed you a poor system. I've found a spec sheet but I'm not sure it is for the inverter that you have.

Having two inputs does not necessarily mean two MPPTs

 

[SRE]

Solar Inverters - Solar Australia Wholesale

It's got a single mppt so the strings should be even 8 & 8 not 10 and 6. You'll need to get your installer to re-string it.

 

[garty611]

I understand cheers BiggsSolar, I'm trying to get them back ASAP as the roofer set the strings without telling the sparks (i'm led to believe). I know now that they need to be sorted.

 

[SRE]

I know its not the best system all round as I originally wanted 250W Sharp panels and a 3000 sunny boy inverter but it all changed when the Gov cut the FiTs... Has anyone had any experience with the SolarRiver stuff?

I wouldn't worry about Sharp being the best, we've got Sharp and lots of panels we install often outperform them/ SB3000 is under spec for that size system too imo.

On a more positive note - you've got panels installed and although you need a bit of reconfiguring with the strings you're installed and hitting the 43p - happy days

It could be worse - you could be an installer. :rofl:

 

[garty611]

Solar Inverters - Solar Australia Wholesale

It's got a single mppt so the strings should be even 8 & 8 not 10 and 6. You'll need to get your installer to re-string it.

Will it matter than 6 are Portrait and 10 are landscape.. IE 2 of the Portrait will have to be strung with 6 Landscape panels, to make it an even 8 a string??

 

[garty611]

I wouldn't worry about Sharp being the best, we've got Sharp and lots of panels we install often outperform them/ SB3000 is under spec for that size system too imo.

On a more positive note - you've got panels installed and although you need a bit of reconfiguring with the strings you're installed and hitting the 43p - happy days

It could be worse - you could be an installer. :rofl:

No I've still got Sharp 245 I wanted the Sharp 250's but beggars cant be choosers this late on eh?

 

[SolarCity]

Some installers insist that landscape and portrait panels shouldn't be installed on the same string but I'm unconvinced. They definitely need to be on a 8 + 8 configuration.

To be honest, I would say that a lot of the installs that have been carried out over the last few weeks will have similar issues.

Standards and good designs appear to have gone completely out of the window.

 

[garty611]

Some installers insist that landscape and portrait panels shouldn't be installed on the same string but I'm unconvinced. They definitely need to be on a 8 + 8 configuration.

To be honest, I would say that a lot of the installs that have been carried out over the last few weeks will have similar issues.

Standards and good designs appear to have gone completely out of the window.

Cheers guys for all your help I'll keep you posted what happens!!

 

[JohnBoyZ]

I was just wondering how are you measuring the voltages on the two strings, is it a function of the inverter? or are you simply turning off each of the DC isolators in turn. If the inverter has the ability to measure voltages on each string independently then it might have some clever optimization system even though the documentation I've found says it only has one MPP tracker.

 

[garty611]

I was just wondering how are you measuring the voltages on the two strings, is it a function of the inverter? or are you simply turning off each of the DC isolators in turn. If the inverter has the ability to measure voltages on each string independently then it might have some clever optimization system even though the documentation I've found says it only has one MPP tracker.

Good question... I was reading the Electricians meter whilst he was testing the system as originally he got the polarisation the wrong way around!! I may add that both strings are on the same DC isolator is that wrong?? Will it effect anything??

 

[JohnBoyZ]

There are many ways to configure the isolators I always like one isolator per string, you say there are 4 DC wires going into the inverter so maybe its a 4 pole isolator?

 

[garty611]

Yeah Im sure it's 2 positive and 2 negative from what he was telling me.

 

[SolarCity]

Judging from what I am reading, I will eat my thumb if a 4 pole isolator has been specd.

 

[dansk]

More like taken the links out...........