question

ckrohmer avatar image
ckrohmer asked

MPPT, PV input shorted ?

A customer has two SmartSolar MPPT 250/85´s each connected to 3 strings of 5 x 320 W 37(46) V solar panels that do not start up, blue LED blinks slowly. Voltage on PV input terminales is zero volts, but when connection is opened the solar panels show 207 to 214 Volts. On closing the switch PV terminals show zero volts. The PV input of the MPPT´s seems to be in short circuit. MPPT shows no PV current, I asume because measuring is behind the short. Can this be repaired ?

MPPT Controllers
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Have you checked the polarity of the PV cables?
If I remember correctly the MPPT showes 0V input if the PV polarity is reversed.

Edit:
What Panels do you have exactly?
With 46V + temperature coefficient (-0,XX%/°C) you maybe will be over 250V and that will kill the MPPT.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

ckrohmer avatar image ckrohmer commented ·

the panels are Yingli Solar (China) type YL320P-35b, temp coefficient is 0,148 V/°C, at 0°C voltage will be 248,5 V. We are aware that at temperature lower than 0°C and good sunlight the voltage can be over 250 V and can damage the MPPT, and we have told the customer so.

We will check polarity as soon as we can.

0 Likes 0 ·