Home » 2022 » November

Monthly Archives: November 2022

3 Solutions for MOV damage problem in Solar inverter

Recently we visited a site where the solar inverter was damaged for third time. Both solar EPC as well as the client were distraught as all remedies had not worked and the solar inverter was damaged again. This is a common complaint by Solar EPC as well as the customers who have got solar power plant installed.

The response by Solar inverter companies was evasive and pointed out to things that are inconsequential and problem repeats after some days or months.

Many solar companies question the make of SPDs, ask for another make of SPD to be installed or ask to have another set of SPDs to be installed. They talk about grounding issues and connection problems. In one of those sites they recommended type 1+2 or class B+C surge protection, but that is something that should have been in place in the first place as the Type 1 responds to lightning impulses and type 2 is not meant for lightning protection. A normal ACDB does not have type 1 surge protection meant for lightning protection.

Root cause of problems -MOV damage

In all the occasions , MOVs ( Metal Oxide Varistors) are damaged. MOVs do not get damaged due to spikes , they merely stop conducting the spikes under normal conditions. MOVs burst is caused by over voltage and is not desirable as it damages the complete circuit and creates an internal short circuit. MOV damage will lead to downtime and brreakdown of machinery which in no way can be termed as voltage protection

If you look in picture above, the MOV rating is 420V and supply voltage is 415V. The voltage recordings for 48 hours revealed that phase voltage reached peak of 460V which is equivalent of 265V in single phase. This happened multiple times in 48 hours and also remained for considerable time – 15-20 mins each time.

SPDs and MOVs respond to spike only. They do not respond to continuous over voltage. If the continuous over voltage is beyond its threshold, like in the case above, the MOV will burst causing breakdown of solar plant.

Our solution for this problem

Our solution was offered as 3 options.

Option 1: Go for inverter with better specification

When we say better specification, we meant with internal MOVs rated for 500V and higher. This is however a bit difficult as the solar inverter companies would normally not disclose this information. Most Solar inverters are white labelled products manufactured in China. So it will also be difficult for them to change the specifications. Also one more problem is about neutral open or double phasing problem that happen on site. In all such situation even 500V MOV would get damaged.

Option 2: Complain to (DISCOM) authorities in documented form

In this option one has to file a written complaint to the DISCOMs and get an inward stamp. Anything that is documented needs to be closed. If not it is a big problem for concerned department. Verbal complaints over the phone are not entertained.

Did you know that as per Indian Electricity rules 1956 the supply voltage should not exceed 6% under normal and 12.5% under extreme situation? Did you know that you could use this as reference and make a big case if you had voltage recordings which proved that voltage exceeded 6%? The DISCOM would be deemed liable for the damages caused by this problem and would be held accountable.

The problem with this option is that it will involve courts and matter could takes months and years to resolve. But considering that you have some strong point here, one can and should take this option

Option 3: Go for voltage protection for solar inverter

This option is the most simplest and no brainer actually. Go for voltage protector with 10% cut off setting. In this case we have our product – Power kavach which can be offered with high voltage setting of 255V on higher side.

Only limitation to be taken in to account is that there will be a generation loss when the Power kavach shuts off the supply in case of over voltage.

There is always limit to courtesy extended by solar inverter or solar EPC. Free service and free replacements cannot be done indefinitely. It is always better to protect your equipment from such problems by using Power kavach

Have you faced similar problems ? Talk to us on 9769996205 or email on

%d bloggers like this: