Solar powered grid-tied systems and safety.

[Hebrew]

Have a question for you guys and this is not a joke.We have a number of customers setting up solar powered grid-tied systems but had one feed back on to the system for about half hour.We are now required to ground the secondary.Personally,I think that the customer should have the system inspected by our engineers and tested periodically for correct operation.If they do not let us inspect the installation,disconnect the service from the secondary until they do.How do you guys handle the threat of a back feed from a photo-voltaic system at a customer?

[T-Man]

When I retired, we had customers on the system with photovoltaic systems. They had to have two meters and their system could send current on to our system, only when our system had potential. So if we switched a section out for an outage, or the section was out due to a fault somewhere, they couldn't back feed us because they didn't have our potential to close in to our system. Our engineers would inspect and ok any new customer operating this way. The customers with wind turbines and bio mass generation also had a similar system. Believe me our Troubleshooters were very concerned, and in a yearly Trouble Review we had the Engineer in charge of this process explain the systems and answer any questions the troubleshooters had.

[thrasher]

The key to the photo voltaic system not backfeeding is in the inverter. We require anyone installing such a system to pay us to inspect and certify the inverter. In the USA the inverter has to meet the requirements of UL 1741 which prevents backfeed to a dead system.

[Hebrew]

Problem is,Thrasher,we do not always know what kind of system the customers have.Some do get inspected by the Government agency here,some don't.

[Lineman North Florida]

Problem is,Thrasher,we do not always know what kind of system the customers have.Some do get inspected by the Government agency here,some don't.
Then your supervision should push to have the service dis-connected until the customer has their system inspected to verify that when there is an outage or the AC service is disconnected that there will be no output from the solar system, prior to connection to our system there is an inspection as described above also we require an outside disconnect so we can open when working on our facility's. It used to be so simple you knew your source and that's what you had to isolate from, now there can be many sources that you have to worry about.

[stulittle]

Over here, all distributed generation (pv/wind/biomass) has to meet standards laid down by the electricity networks association. Depending on the size of of the system the standards and inspection regime vary.

I do know that the lv fuses (secondary) are always pulled before working on the hv (primary) these days if working primary, and I have seen the secondary shorted too with all phases and neutral tied together to ensure safety.

Stu

[BigClive]

The solar power systems are not supposed to be able to backfeed the supply, so there may be an issue with non standard or defective equipment. Anything electronic should be regarded as a potential risk anyway, since a software or hardware issue could result in backfeeding.

This is something that should be investigated since backfeeds can cause lineworker fatalities, especially if the power is suddenly connected to a previously dead line.

Two things should be checked. The suitability of the equipment that feeds back to the network and the technical knowledge of the individuals who installed the system. Many are little more than roofers or labourers.

[lewy]

Have a question for you guys and this is not a joke.We have a number of customers setting up solar powered grid-tied systems but had one feed back on to the system for about half hour.We are now required to ground the secondary.Personally,I think that the customer should have the system inspected by our engineers and tested periodically for correct operation.If they do not let us inspect the installation,disconnect the service from the secondary until they do.How do you guys handle the threat of a back feed from a photo-voltaic system at a customer?

This is the way it is done here.
http://microfit.powerauthority.on.ca/faqs/connection-metering-and-settlement