Hi Keith, Many of the mainlanders opt for a "supply-side" interconnection (tap service conductors between meter and main breaker). There are a number of touchy issues with this method if it's in a single box, and it certainly isn't a "1 size fits all" kinda thing. In case nobody has said it on the list yet, I'll go ahead with the prediction that we are likely to see this method become a lot more rare in the future... Unless of course, your local PV installer has a UL Listed sticker in his back pocket... In most cases, my preferred option is to install a main breaker with a lower rating... i.e. Replace the existing 200 Amp breaker with a 150 Amp breaker. Be sure that the maximum continuous load of the residence does not exceed 80% of the new main breaker. (80% x 150A = 120A max continous load) This example gives you up to 90A of PV Breaker capacity on a 200A buss. The vast majority of homes with 200A services don't come anywhere near 120A continous. There are some that do, so make sure you understand their big electric loads and how they use them. Otherwise, you can upgrade the service, as you mentioned. Aloha, Matt Lafferty [email protected]
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Keith Cronin Sent: Monday, February 09, 2009 2:41 PM To: RE-Wrenches Subject: [RE-wrenches] Point of connection Hello With the growth of the solar industry coupled with the generous incentives now offered on fed part of the equation, we are seeing some trends here and wondering what the approach has been in other areas. What kind of feedback are you receiving from the AHJ? There are some integrators who now are installing "systems" meaning, multiple small inverters that are married to smaller arrays as opposed to one large array with one large inverter. So, it is quite conceivable to have, for example, 3- 3000 W SMA inverters on a customers home. So, the point of connection issues arise. When you look at 690.64B, it speaks to the 120% of the busbar rating. What are folks doing in other areas, for this above example to address the mechanical/electrical challenges associated with this situation, when if you had 1- 200 amp residential service? There is alot of discussion, like installing a 125 amp rated subpanel; interuppting the feeder from the electric service and installing a 225 amp panel with a higher rated buss (hard to find or custom made thru Cutler Hammer or others) etc. We can also see a trend using the enphase products as well, but not as much pronounced. It could be conceivable for a client to want to build their system up over a few years and have 15, 175 watt panels on a circuit (2P15 amp) and grow the system up to lets say, 45, 175 watt panels (3-2P15 amp). Same situation, different inverter manufacturer. My sense is this trend will continue for the forseeable future, and alot of wrenches will find orphaned systems out there and we should look at ways to address point of connection issues that are bound to present themselves. Thanks Keith
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