Hi Joel, Here's a link to utility requirements in VT as of 1/8/08. See drawings #405 & #406 at the end of the document. Looks like a PITA for existing structures where a backfed breaker won't work.
http://www.cvps.com/CustomerService/Book01-08.pdf Dick Dick Ratico Solarwind Electric Bradford, VT 05033 VT #EM-4156 NH #10483 M --- You wrote: Hello Matt, Thank you very much for your detailed reply. In case you missed my first post on this issue, here it is again with the details. January 1, 2009 LADWP added another interconnection requirement. See page 8-11 at http://www.ladwp.com/ladwp/cms/ladwp004344.pdf Here is how a PV contractor project manager working on a commercial project in LADWP territory described this new requirement: When a customer, any customer, generates electrical power with the intention of supplying that power to the electrical grid, the connection to the grid has to be made below, or on the load-side, of one main switch for the property. In other words, the policy seems to be that the total electricity supplied to any building or property must be disconnected from the grid by one main switch. This policy is in place for emergency situations, to where fire fighters or persons on the scene during an emergency would be able to completely shut down building power with one switch. This describes a scenario whereby the grid is disconnected from the building circuits, but the solar PV is still connected to the building circuits. Therefore, there is a basic flaw in this requirement; this scenario is only possible at nighttime- during the daytime, the solar PV system is energized and may still feed to the building electrical circuits, unless the main PV disconnect switch is opened. Therefore, during emergency situations in the daytime, a minimum of TWO switches are needed to completely disconnect power from the grid AND from the building circuits. This effectively negates LADWP's one-switch policy. Referencing (an LADWP letter dated 23 January to the project manager) "the generator supply circuit shall be tapped on the load side of the customer's main service disconnect device". This may be accomplished by either connecting the solar PV circuit, 1. Via a circuit breaker inside the existing customer service panel (circuit breaker panel), which is a load-side tap, or 2. By tapping into the incoming electrical service above the service panel, which is a line-side tap. This is the result of both options: 1. In most cases, this will result in the service panel being replaced, and upgraded to a larger capacity. All existing circuits in the building will need to be re-fit with new circuit breakers, in addition to the solar PV circuit breaker. This can cost upwards of $10,000 on average, of additional expense per property. 2. Above the solar PV line tap, a new main circuit breaker must be installed, complete with an enclosure. This will then disconnect the LADWP incoming electrical service from the building service panel and the solar PV circuit. This will add from $3,000 to $6,000 to the project budget. My comment: This situation is hard to describe in words, but picture a utility revenue meter feeding power into a customer service panel. The service panel cannot accommodate a PV system backfeed meter so the project manager submitted the interconnection 1-line drawing with the PV system feeding into the required solar performance meter and then into the required lockable fused disconnect switch and then into a line-side tape between the revenue meter and the service panel bus. Now picture this new requirement's additional disconnect switch and circuit breaker between the line-side tape and the revenue meter. Do any other electric utilities require an additional disconnect switch on a PV system with a line-side tap? Joel Davidson --- end of quote --- _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
