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Yet Another Solar Hurdle from SCE

08/13/13

  09:17:00 am, by Jim Jenal - Founder & CEO   , 1062 words  
Categories: SCE, Residential Solar, Ranting

Yet Another Solar Hurdle from SCE

SCE logoOne of the greatest impediments to continuing to drive down the cost of solar are so-called “soft cost” - the nickels and dimes extracted from solar companies by nit-picking regulations and hoops that we are forced to jump through to get permits, inspections and interconnections accomplished.  Now SCE has added yet another pointless hurdle that is simply designed to drive up the soft-costs for larger residential installs - but the question is, why?

On Friday we got a notice from SCE about the latest revision to their Net Metering Interconnection Handbook and calling attention to changes in their requirements for what is known as a “line-side tap.” Now to explain why this is an issue, please bear with me as this gets a bit technical.

Normally, when we install a residential solar power system, the power comes down from the roof, to a “solar only” subpanel, to a disconnect with a performance meter and then “lands” on a circuit breaker in your main electrical panel.  Most recently built or remodeled homes in our service area have 200 Amp services which means that according to the National Electrical Code we cannot attach a larger breaker for solar than a 40 Amp breaker because the sum of all power sources feeding the bus bar that runs through your service panel cannot exceed the rating of that bus by more than 20%.  Assuming that you have a 200 Amp main breaker, then your bus is already fed to the 200 Amp rating by the utility.  That leaves 20% beyond the 200 Amps rating for solar and that gets you to the 40 Amp limit.  (There are exceptions to this, but that is the general rule.)  But the code limits us further since a circuit breaker intended for continuous operation has to be derated to 80% of its listed value.  Which means that my 40 Amp breaker becomes a 32 Amp breaker for continuous use (defined as a source where the maximum current is expected to last for three hours or more).  Since residential systems are running at 240 volts, that limits the maximum AC power of a residential solar power system to 7.68 kW.

Now that is rarely much of a limitation since the overwhelming majority of residential systems are smaller than that.  But what about those that aren’t?  What about the household that has two EVs (we have such clients) and lots of roof space?  How can they interconnect a larger system if the Code won’t allow a breaker larger than 40 Amps?

The answer is a line-side tap.  When you use a line-side tap, you avoid connecting to the service panel bus at all.  Instead, you tap onto the wires feeding your service between your meter and your main breaker.  This satisfies the Code and works just fine but it is a more complicated means of interconnecting your solar power system.  As a result, SCE has required that systems that call for a line-side tap have a Professional Engineer review and approve the single-line drawing (SLD) that shows how the interconnection will be made.  This adds to the cost of the system - PE’s have to make a living, too - but most installers have accepted that as a reasonable cost to insure safety.

But now SCE is requiring that in addition to submitting a PE-stamped as approved SLD, we must also submit a form letter, signed by the local Authority Having Jurisdiction, approving what we are going to do before it is done.  Now what is the point of that?  After all, before we can commence work we need to pull a permit, which means that the AHJ will have reviewed our site plan and SLD and deemed it acceptable.  Once the project is complete, again we have to interact with the AHJ, having them come out to our job site and inspect our work.  It isn’t as if we were trying to slip something past the AHJ.

So what is the point of this exercise?

Here is an excerpt from SCE’s letter that they are asking us to get the AHJ to sign:

If customer choses [sic] to continue to interconnect the generating facility on the source side of the customer’s main circuit breaker (tapping ahead of the main as defined by SCE), SCE must insure that the interconnection facilities continues to meet SCE’s safety requirements. Therefore in order for SCE to accept the modified equipment, SCE will require that this letter be signed by the inspecting authority. The Inspector for the AHJ acknowledges the following:

1. That the existing customer switchgear has been altered to allow the interconnection of the generating facility to the source side of the customer’s main breaker.

2. That the altered customer switchgear continues to meet UL certification requirements or that the modified equipment has been recertified for its new configuration.

3. That the modified equipment meets all the required NEC code requirements.

To reiterate, SCE considers the modification of the switchgear to be a safety issue and thus in order for SCE to approve the proposed generating facility, SCE must receive verification of UL and NEC compliance from the local inspecting authority prior to approving the generating facility for interconnection to SCE’s distribution system. It should be noted that in addition to this endorsed letter from the inspecting authority, the customer must comply with existing requirements including P.E stamped Single Line, plot plan, equipment requirement, etc.

Now in the first place, as a general proposition this really isn’t a modification to the switchgear (i.e., your service panel) at all.  Instead, this typically consists of clamping on to the existing feeder wires coming into the service - the switchgear isn’t touched.  But how many AHJs are going to be willing to sign this document - particularly when the utility themselves is now declaring this to be a safety issue?  How much iteration is going to be required between the installer’s PE and the AHJ to convince them to sign onto this letter?  And isn’t that the entire point of having the PE stamp the drawing to begin with?  The PE’s stamp is her way of saying that the proposed plan is safe and complies with the Code.

In our view this is nothing more than an attempt by SCE to complicate the process of installing larger residential systems and to drive up our costs to do so.  We have requested comment from SCE about their justification for this new policy - if we hear anything we will update this post.

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4 comments

Comment from: Sondra  
Sondra
Is this issue only a problem in SCE’s territory or have you had the problem elsewhere?
10/03/14 @ 16:02
Comment from: Jim Jenal - Founder & CEO
Sondra - it varies from utility to utility. We just heard of a jurisdiction in Texas where they aren’t allowing them at all! By comparison, this is just an annoyance. Jim
10/03/14 @ 16:07
Comment from: Brian Robbins
Brian Robbins
In Iowa under Alliant Energy, we aren’t allowed to line side tap at all.
05/30/15 @ 20:43
Comment from: Jim Jenal - Founder & CEO
Brian - what is the justification for that?
05/31/15 @ 08:16


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Jim Jenal is the Founder & CEO of Run on Sun, Pasadena's premier installer and integrator of top-of-the-line solar power installations.
Run on Sun also offers solar consulting services, working with consumers, utilities, and municipalities to help them make solar power affordable and reliable.

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