We just got back from Solar Power International 2017 and it featured all the usual players with lots of cool stuff on the (gigantic) floor of the Convention Center at Mandalay Bay. But the biggest deal of the show, from our massively solar geek perspective, came from a tiny booth that no doubt many folks missed altogether. But for many of the potential clients that we see, this was a really big deal! Here's our take...
The Sad State of Play
Here in SoCal, we find a great many center-fed service panels - that is, a service panel where the main breaker is located in the middle of the bus. Now in a truly rational world, that wouldn't matter, but around here, the prevailing view is that you cannot use the "120% Rule" on a center-fed panel. (I know this is totally in the weeds, but the 120% Rule says that the sum of all breakers supplying a service panel cannot exceed 120% of the bus rating, and that the solar breaker has to be at the opposite end of the bus from the main breaker.) So, on a 200 A bus, with a 200 A main, the PV breaker is limited to 40 A. All fine and good, but it is that "opposite end of the bus" that causes some AHJs misery - like LA County - who insists that with a center-fed panel, there is no "opposite end of the bus"! (Ignore for the moment that if I have a center fed panel with 10 slots above and below the main, I'm out of luck. But I could have a main panel with a total of 10 slots below my 200 A main, and no one would have a problem with my putting my PV breaker in the bottom slot!)
So, we are presently stuck with an ignorant interpretation of the Code and it has meant that some folks needlessly were forced to upgrade a perfectly good center-fed service panel just to go solar.
More recently, SCE allowed the use of the so-called Generation Meter Adapter (GMA) ring, that consists of a spacer between the utility meter and the meter socket, that allowed for a whip connection to the PV system's AC disconnect. That got around the 120% Rule since there is no breaker landing on the bus. BUT - you have an unprotected connection all the way from the pole to that disconnect - which creates a serious hazard, especially in a residential environment.
You can see the interconnection on the right - and the scary danger sticker that we added to provide a suitable warning. (Interestingly, while we have to add all manner of stupid signage - like that directory plaque that provides no useful information whatsoever - there is no requirement for a warning about the hazard presented by that interconnection.)
To be extra cautious, we also install a lock on the disconnect door to discourage the curious.
Oh, and it costs just under $500 to have SCE install the ring (and their service tech has to suit up to reduce the risk that he gets lit up like a Christmas tree while doing the install). Geez, all this because of a bad code interpretation!
To the Rescue - B3 Bypass!
Fortunately, there is now an alternative to this madness! A California-based outfit that goes by the not-so-catchy name of QFE002, has come up with a revolutionary product - that is now UL listed! (They have been coming to SPI for years, but they just got UL!)
So what is this game changer? It is the B3 Bypass breaker and it taps directly onto the main conductors going into the main breaker. Because the PV does not go through the bus at all, the 120% rule does not apply. This means that the amount of current that could be backfed by the PV array is only limited by the main conductors feeding that breaker.
In the picture on the left, the 200 A main breaker is on the bottom and the B3 Bypass breaker is above. The B3 Bypass clamps down onto two of the four conductors feeding the main. (They have a nifty tool that strips the insulation off without otherwise modifying the conductors, or unscrewing them from the main breaker. Per UL, this does not constitute a modification of the panel, so its UL listing is unaffected - meaning that there is no need for a field certification.)
The B3 Bypass comes in various configurations - the dual, twin-pole 20's shown here can actually be as high as twin 60's - meaning that you could install 120 A of solar - triple what could be normally connected to a 200 A service, and twice the 60 A rating of the GMA ring! It is even 50% more than you could install on a 400 A service! Yeah, this could be big!
They are taking order requests on their website, although we don't yet have pricing or timing for potential deliveries. (My guess is that they are just now trying to move into production mode, now that UL is behind them.) We passed along their info to both BayWa and CED Greentech - hopefully they will get a distribution deal going so that they can make this available far and wide!
We are definitely fans!