No go on solar panels- Pittsfield Mass.

[BillK-AZ]

An article in the Berkshire Eagle:

http://www.berkshireeagle.com/local/ci_14487303

Claims that "But if someone was to mount solar panels on a building there, the power generated would not be able to flow back into the grid, because the redundancies and complexities only allow power to flow in one direction."

As a long term solar energy engineer, I have never of a situation that would allow power to flow in only one direction.

Anyone have an explanation for this claim?

 

[Sierrasparky]

An article in the Berkshire Eagle:

http://www.berkshireeagle.com/local/ci_14487303

Claims that "But if someone was to mount solar panels on a building there, the power generated would not be able to flow back into the grid, because the redundancies and complexities only allow power to flow in one direction."

As a long term solar energy engineer, I have never of a situation that would allow power to flow in only one direction.

Anyone have an explanation for this claim?

I might be short sided but I can't imagine a buisness not using all the power it is generatng. I would think the only case if it only operated at night! Most solar arrays are installed to offset the Higher tiers. Usually only residences will need to place back on the grid what is not used.

 

[BillK-AZ]

There is usually backfeed on weekends and in the spring/fall when heating/cooling loads are low. Just the possibility of a backfeed requires the utility permission. In most areas, conformance with Article 690 of the NEC and including a utility accessible PV disconnect switch is all that is required.

 

[SG-1]

The buildings are being supplied by network protectors. A network protector is a breaker with a protective relay that is piggybacked to the transformer feeding the building. Three such units are required for a true network.

In other words 3 or more separate unsync sources are available to feed the building. If one goes down the others supply the power. They open on reverse current. If the PV System tried to backfeed the network ( under ground system ) it would be interpeted as a fault and the utility sources would open. Network Protectors have been in use in this manner since before 1900.

The Network Protector only allows power to flow into the building. Forward current is limited by fuses. The reverse current required to open is less than the magnetizing current of it's transformer. Reverse trip is very sensitive.

In a nutshell the utility protection scheme used is incompatable with the green technology or any onsite generation.

 

[iwire]

In a nutshell the utility protection scheme used is incompatable with the green technology or any onsite generation.

Looks like they will have to change things.

We have done a couple of large PV installs that back-feed into the grid. 200 KW on a DPW garage that only has a small lighting load, and a 50 KW on a warehouse with very little lighting load.

There is also a capped hazardous waste site near by that has 425 KW of PV without any building load at all, every bit goes into the grid.

 

[don_resqcapt19]

Here is a paper with some details on what SG-1 posted. It is my understanding that network type distribution is common in bigger cities.

 

[SG-1]

Here is a paper with some details on what SG-1 posted. It is my understanding that network type distribution is common in bigger cities.

Usually cities with "Skyscrapers".

 

[iwire]

Here is a paper with some details on what SG-1 posted. It is my understanding that network type distribution is common in bigger cities.

Usually cities with "Skyscrapers".

In no way was I trying to say what you stated was not a fact, only that the power companies will have to come up with other ways.

When we fill out the forms for co-gen sites all these issues are addressed.

 

[jghrist]

In no way was I trying to say what you stated was not a fact, only that the power companies will have to come up with other ways.

When we fill out the forms for co-gen sites all these issues are addressed.

The power companies may have to come up with other ways, but the co-gen owner has to pay for any modifications needed. It's only fair. Otherwise, the power company's other customers would have to pay some of the costs to allow the co-gen operator to sell power.

 

[iwire]

It's only fair. Otherwise, the power company's other customers would have to pay some of the costs to allow the co-gen operator to sell power.

That is one way to look at it, or we could say the power companies original design was short sighted and lets face it, at least in my area the power companies are still trying to put the brakes on any change in the status quo.

 

[SG-1]

In no way was I trying to say what you stated was not a fact, only that the power companies will have to come up with other ways.

When we fill out the forms for co-gen sites all these issues are addressed.

Bob I did not take your comment that way. I was only clarifing that usually only large cities use them.

I can tell when you do not believe someone, believe me !