UPDATE - Citing technical issues, PWP has informed us that for now, these rates are NOT available for solar customers. Apparently the Meter group does not yet have a TOU meter that will properly account for energy generation as well as energy consumption. We will report back when PWP has this resolved - hopefully in a couple of months.
Pasadena Water & Power (PWP) is rolling out on a temporary, experimental basis, new Time-of-Use (TOU) based rates for customers with electric vehicles. The new rate structures, designated EXP-TOU-EV-1 and -2 are available to existing residential customers (either single family or multi-family service) who can demonstrate proof of ownership of a plug-in electric vehicle.
The two TOU rates differ from the existing R1 residential rate structure in that they provide discounts for energy consumed during mid- or off-peak hours. (Mid peak runs from 8 a.m. to Noon and from 9 p.m. to midnight. Off peak runs from midnight to 8 a.m.)
Here is how the two rates compare:
|TOU Period||Rate 1||Rate 2|
(Noon - 9 p.m.)
(8a.m. - Noon; 9 p.m.- Midnight)
The second rate has much greater discounts for energy use outside of the On Peak window, but it is combined with a significant penalty for energy use during the On Peak window.
Of course, this is where a solar power system comes in. Since a solar power system produces the bulk of its energy during the On Peak window, it could prove highly beneficial to EV owners who add solar to their homes. We will do a more complete analysis of how these two rates could work for a solar powered home in a future post.
To learn more about the program, check out PWP’s webpage devoted to these new rates.
Readers of this blog will know all about the 52.3kW solar project that Run on Sun just recently completed installing at Pasadena’s renowned Westridge School for Girls. Now that project has become the cover story in the Annual “Green Issue” of Pasadena Weekly.
Titled, “Solar Flair: New solar installation at Westridge School brings environmental lessons to life,” the piece features interviews with Westridge’s Head of School, Elizabeth McGregor, Facilities Manager Brian Williams, and three students who are part of the school’s environmental group known as the Green Guerrillas. The story reveals the school’s deep commitment to sustainability in everything from solar power to drought tolerant plants.
This first of what we hope will be many solar projects at Westridge really highlights the value of these projects for all schools, especially those in the Pasadena Water and Power service territory. Good rebates and a solar company that really understands your goals makes a solar power system installed by Run on Sun a “no-brainer.”
In Part 1 of this series about Installing Solar at Westridge School, we looked at the process of putting our materials together for the rebate application. With the rebate safely reserved, it was time to turn to pulling the permits for the job. A solar project of this size involves two separate permits - building and electrical - but four points of inspection - fire, electrical, building, and utility. We had already provided the utility, PWP, with the materials they needed but now we needed to load up for the permit center.
The permit process addresses an entirely different need than does the rebate application. The permit process is intended to guarantee that the proposed system, as designed, satifsfies all applicable codes and standards. In theory, once you have successfully pulled the permit, the inspection process should simply be a matter of showing the inspector that you built the system as it was approved when you pulled the permit.
This project presented one signficant challenge - the actual attachment of the system supports to the roof. While the roof looked conventional enough, that was not a wooden truss underneath those shingles. To the contrary, our roof was built from a 20 gauge “Type B” steel deck with two layers of 5/8″ plywood, followed by 3″ of solid foam insulation, followed by 3/4″ of plywood to which the roofing materials themselves - membrane, felt and shingles - were attached. So the question arose: what would be a sufficient way to attach our standoffs to this roof to provide the requisite resistance to wind loads - the effect of which had recently been demonstrated in Pasadena in such a disastrous fashion?
To help answer that question we turned to the structural engineer (SE) who had originally done the load calcuations for our building. Could we use a “FastFoot” and simply put multiple screws into the wooden decking materials? Surely with enough screws - the FastFoot will allow for up to eight - we could reach the required pull-out resistance. Unfortunately, that wouldn’t work since the engineer could not guarantee the manner by which the plywood materials were secured to the underlying steel deck. In other words, while we could be sure that our array would remain attached to the plywood, we couldn’t be sure that the plywood would remain attached to the building! Images of Wizard of Oz roofs flying through the air filled my mind - clearly we would need another way!
The engineer suggested that we could use carriage bolts that ran all the way through the steel roof and were bolted together on the back side. Certainly such an approach would guarantee that our array and the roofing materials stayed connected, and indeed, you would have to separate the steel deck from the steel framework of the building for that method to fail. Unfortunately, that wouldn’t work either since there was no way to access the back side of the roof in order to complete the connection.
There was one other approach - a company by the name of Triangle Fasteners sells some very strong, very long, self-tapping screws (called “Concealor screws“) that could drill their way into the steel deck and provide us with the required pull-out resistance. The bad news - our distributors only sold screws up to 7″ long - and that would not be long enough to guarantee that our screws made it through the decking. A call to the manufacturer revealed that in fact, they did make 8″ screws, they even made 9″ screws! Excellent! We now had a solution that our SE could bless. It was time to go pull our permits.
Anyone who has ever pulled a permit knows the combination of emotions that you encounter upon entering the building: fear that something you haven’t considered will suddenly become A Really Big Deal, loathing for the interminable waiting, and of course, the pain of paying for it all. Dentists’ waiting rooms tend to be cheerier places.
Pasadena’s permit center is certainly better than most: it is a comfortable old building across the street from the beautiful City Hall. They have a clever scheduling system that routes you among the different windows: Building and Safety, Zoning, Historical Preservation (very big in Pasadena but not a factor for solar projects), Fire, Permit Processing and, last but certainly not least, the Cashier. A solar project applicant must navigate their paperwork through every one of those windows before exiting with your Grail - a stamped set of plans and a bright Yellow permit folder where inspection sign-offs will be recorded.
First stop - Building and Safety.
The building and safety folks are responsible for reviewing your plans for conformity with state and local codes and standards - a really important task. First, however, you have to speak with someone who knows what you are showing them and on our first trip to the permit center, no such person could be found! The gentleman behind the B&S desk was very polite, and you could tell that it pained him to inform us that after our thirty minute wait, he couldn’t help us. Moreover, none of the people who “understood solar” were available - we would have to come back tomorrow.
Tomorrow dawned cloudy but we were determined to press forward. This time our 35 minute wait was rewarded with an appearance before someone who was prepared to pass judgment on our plans! We walked him through each of our sixteen 24″ x 36″ pages, explaining as we went exactly what we were doing and where the answers to his questions could be found.
All seemed fine, but then he started throwing us some curves.
Our SE had done his calculations for a basic wind speed of 85 mph - the same wind speed we had always used for load calculations in Pasadena.
“No,” said the man behind the desk, “You have to use 100 mph.”
“Really? Since when?”
“Since the windstorm in Pasadena at the end of November,” we were told. (Never mind that the wind speed never reached 85 mph in Pasadena, let along 100 mph, during that terrible event.)
“Really? Where was that published?”
“It wasn’t,” he conceded, but simply told us that we needed to revise our calculations for 100 mph or he wouldn’t approve them. That meant another iteration with our SE and another trip back to the permit center.
Now the good news here is that we were certain that our system would easily handle 100 mph winds (or 120 mph, for that matter) so this change in policy did not pose a danger to the project going forward. But changing the basic wind speed for an area from 85 to 100 mph is something of a big deal and will add to the expense of many projects that need permitting. Shouldn’t there be a more public process before such a change is implemented?
The other curve sent our way was really just odd.
We did a detailed drawing showing our attachment method as it penetrated the various layers of roofing materials and made contact with the steel deck beneath. We drew that straight up on the page and included multiple elevations in our sixteen pages that showed the pitch of the roof and indicated that the array was installed on top of our attachment method, parallel to the roof.
“Not good enough,” we were told.
“Why? What’s missing?”
“You need to show the attachment at the slope of the roof.”
“Really? We show you the slope of the roof, we gave you the detail of how the attachment connects to the roof and we told you that the array is parallel to the roof. How is that not sufficient?”
“You need to add a drawing that shows the array attachment and which reflects the slope of the roof.”
“Really? So what you want is for me to rotate the image of our attachment 13° to reflect how it will be pitched on the roof?”
Sigh. Ok, back to the drawing board (or more accurately, the computer screen).
Fortunately, our SE was able to redo his calculations in short order. And not surprisingly, it was also pretty easy to take our attachment image and rotate it. We printed up the revised plans and headed back to the permit center.
Surprise - there was yet another person behind the counter this time. Whereas his predecessor seemed to be actively looking for little things to complain about, this fellow could not have been more helpful. He looked at our revised load calculations - veryifying that they had been done for 100 mph and that the SE had concluded that all was well - and then proceeded to stamp our plans. (I had pointed out our added, rotated drawing, but it was clear that he wasn’t interested in that at all.) After he stamped our plans, he then took them himself to the zoning and historical preservation desks and secured those sign-offs as well! Wow! He saved us an hour of waiting in those queues and he seemed genuinely helpful and concerned. What a pleasant contrast! We were well on our way with just one real substantive hurdle remaining - the Fire department.
The California State Fire Marshall developed a set of guidelines that provide guidance as to how fire departments should permit and inspect solar installations. The guidelines call for space to be set aside for pathways around the array and for venting of smoke in case of a fire. The guidelines call for different restrictions based on the size and shape of the roof and whether it is a residential or commercial building.
(While the document from the Fire Marshall is labeled “guidelines", most localities seem to treat it as gospel. Even more curious, the guidelines clearly say that they are just that, guidelines that do not have the force of law until a local jurisdiction passes an ordinance adopting the guidelines as regulations. We have yet to see such an ordinance.)
Our building plan included a three-foot set aside around both sides of the array and from the ridge, and was augmented by automatic smoke ventillation devices already built into the roof. But that was not sufficient - the fire official wanted us to provide a four-foot clearance on all three sides. Yet another trip to the computer.
We returned with our revised drawing, showing four feet of clearance as requested. But now there was another concern - the same fire official now wanted us to open a walkway in the middle of the array. (We already had access paths for potential maintenance, but they were not wide enough to be considered a walkway.) No matter that our roof was not at all like the flat roof with parapet shown in the guidelines, we still needed to provide a walkway. There was only one way to do that - take out a column of panels. Together we X-ed out seven panels and thereby created a walkway. The fire official was now satisfied - she signed off on our plans.
And just like that, we were done. Well, not quite - there was still the little matter of paying for all this. Here we made out surprisingly well. Unlike some cities that gouge solar applicants (and you know who you are!), Pasadena’s fees were quite reasonable. Total cost for our now 52.25kW solar project? $732. Sadly, we know of residential projects one tenth that size in other cities where the permit fees have exceeded $1,000! (But that’s a story for another day.)
Altogether, it took us four separate trips to the permit center, three plan revisions, and a little over $900 in expenses to secure our permit.
Now all we needed to do was get the materials to the job site on time, and complete the installation in the two week window that we had to mesh with the School’s schedule. The real work was about to begin…
In November of 2011, Run on Sun was hired by Westridge School for Girls to install a 54 kW solar system on the roof of the school’s Fran Norris Scoble Performing Arts Center (the “PAC” as it is known on campus), and that project was just recently completed. This multi-part series will document the process by which we went from a signed contract to a signed-off solar power system. Not surprisingly, there were a few twists and turns along the way that had to be resolved before we could deliver a successful project, and this series will showcase those developments in the following five parts:
Part 1 - The Rebate Application (this post)
Part 2 - The Permit Process
Part 3 - On the Ground
Part 4 - On the Roof
Part 5 - Putting it All Together
The rebates being offered from Pasadena Water & Power (PWP) for this non-profit project were scheduled to step-down on December 1, 2011. Indeed, this was a substantial rebate reduction - 26% - such that failure to secure the existing rebate rates would have amounted to a hit of tens of thousands of dollars for our client. And PWP had made it very clear - unless applications were 100% complete and correct, they would be rejected and when resubmitted would be subject to the reduced rebate rates. Clearly the pressure was on to get this right the first time!
The application package consisted of eight parts - most of which were straight-forward, but a couple required substantial work to guarantee that the application as submitted would be acceptable the first time. Here are the parts that went into the rebate application: 1) Signed Rebate Application (PWP’s form, signed by client and Run on Sun under penalty of perjury!); 2) Single Line Diagram for the electrical components of the system (more on this below); 3) Site Plan; 4) CSI Report (as produced by the California Solar Initiative’s rebate calculator); 5) Shading Analysis (i.e., a Solar Pathfinder report to support the shading values used to create the CSI Report); 6) PWP’s Net Metering Agreement (executed by the client); PWP’s Net Metering Surplus Compensation form (for AB 920 compliance); and 8) Installation Contract between the client and Run on Sun. Also, since this was a non-profit client, proof of non-profit status was also required.
PWP wisely requires the submission of a shading analysis in addition to the output from the CSI rebate calculator. Since the amount of shading at the site directly impacts the performance of the system - and hence the CSI AC Watts of the system (or the predicted annual energy output in the case of a PBI rebate) - it really doesn’t make sense for a utility to simply trust that the installer is telling the truth about shading.
The output from the Solar Pathfinder proves that the shading numbers claimed are the shading values present at the site.
The site plan needed for the rebate application is a much simpler plan than what will ultimately be required for the permit, really only requiring an indication of where the various components of the system will be relative to the overall site. However, our system occupies three different areas of the PAC: the roof where the array itself is located, a ground-level storage area where our step-up transformer will be, and the utility switchgear, located on the far north end of the building. Thus our site plan included drawings for each location.
The array drawing showed the three sub-arrays and the clear space allocated for fire department access. Each sub-array consisted of three branch circuits, each of which was “center-tapped” to reduce the voltage drop in the associated branch circuits. Each branch circuit landed at a sub-array service panel which then fed a master “solar-only” sub-panel in the transformer area.
The transformer area drawing detailed the conduits coming down off the roof (one each from each sub-array sub-panel), the master sub-panel which feeds our step-up transformer (to change the 208 VAC three-phase power coming from the roof to 480 VAC three-phase supplied by the utility service) and then a safety disconnect switch located adjacent to the transformer. From the safety switch a fourth conduit carries the required conductors back across the roof to our service switchgear area.
The service panel area drawing showed the placement of our lockable PV AC Disconnect, the associated performance meter, and our circuit breaker for the system located in the existing service switchgear.
Our most significant deliverable in the rebate application packet was the single line diagram (SLD) for the electrical circuits. Since this diagram shows how all of the electrical components of the power generating system interconnect - including the tie into the utility’s grid - we knew that this would be the most closely scrutinized piece of the submission. To be sure, PWP has a generic SLD that installers can use (in fact, we helped develop it!) but that drawing does not cover the use of Enphase Micro-inverters which we were featuring on this job, nor does it allow for a step-up transformer.
Fortunately, we had developed a very flexible SLD format from prior jobs that we could readily adapt for this project. However, before we submitted it to PWP, we forwarded it to the application engineers at Enphase Energy to make sure that they were comfortable with what we had designed. Enphase was more than accomodating - given our tight time frame they bumped us to the front of their engineering review queue and came back promplty with the good news - the design was good as we had drawn it and no revisions were needed. Of course, that was no guarantee that the utility would agree, but it is always nice to have a P.E. on your side!
Included in the SLD preparation was a complete set of voltage drop calculations. This was complicated by the fact that we had 9 different branch circuits, three different sub-panels and two different operating voltages! Good design calls for limiting total voltage drop to less than 3%. To keep our worst case scenario within that limitation (covering the branch circuit farthest from the main “solar-only” sub-panel) we ended up with 4 different gauge sizes of conductors at different legs of the run: #12 in the branch circuit cables (supplied by Enphase), #8 from branch circuit jbox to sub-array sub-panel, #2 from sub-panel to main “solar-only” sub-panel, #3/0 from that sub-panel to the transformer and then #2 from the transformer back to the service equipment area. (One change that occurred during the install process increased the length of some of these runs - and that necessitated some wire size changes to insure that we stayed comfortably below our 3% limit. Those will be discussed in future episodes.)
All of those documents, plus pages and pages of cut sheets describing all of the key products being used, were then submitted to PWP - one day before the deadline! With no margin for error, our submission had to be perfect. Thankfully, it was - PWP gave us their official blessing to proceed three weeks later, just three days before Christmas. One big present, indeed.
Our first hurdle successfully surmounted, it was time to prepare for the most nerve wracking part of the process - pulling the permits! That’s the subject of our next installment - stay tuned!
In the first installment of this series, we looked at the solar system of Mrs. C which had been entirely destroyed in Pasadena’s terrible windstorm. Given that the racking itself was still securely attached to the roof, the critical question was: Why had this system failed?
As we began to dismantle the now scrap system, we examined the panels, the railing and the bolts that had held the system together. This array had been crafted out of a hybrid combination of unistrut steel parts - that created a 26° tilt - with Unirac rails and clamps. The array was on a flat roof on the northern section of the house - which meant that it was completely exposed to the full force of the wind with no other part of the roof to interfere with the flow. Under such circumstances, any mistake in the installation would be put to a very extreme test.
Our examination revealed that the forces on the panels had been so intense that the railing itself had failed.
This is how an end-clamp normally appears when holding a panel to the rail. You can see how the edge of the clamp grips the panel, the base of the clamp rests on the rail, and the bolt coming up from the rail is tightened down to hold the panel securely.
The portion of the clamp at the bottom right of the picture was supposed to grip the side of the panel but now it is gripping nothing.
Let’s take a closer look at this point of failure:
The t-bolt is made of stainless steel, whereas the rail in which it sits is aluminum. Under the extreme forces that occurred that night, the uplift from the panels caused the t-bolt to chew its way completely through the rail! You can also see how the bottom of the end-clamp had started to deface the top of the rail, as well as the scratch marks created by the solar panel (to the right of the rail failure.)
That answered the question of what had failed, but it didn’t answer the question of why. After all, when properly installed, that rail combination is designed to withstand forces far beyond what were experienced that night. In the days following the windstorm, Run on Sun inspected all of our projects that used this same combination of bolts and rails and none of them showed the slightest sign of failure. So why was this installation different?
We brought this system failure to the attention of Unirac and Pasadena Water and Power. We wanted Unirac’s sense of why this had failed and we wanted PWP to encourage its solar customers to have their systems inspected for possible signs of unexpected wear.
We got a great response from Unirac, who took this issue very seriously and helped us diagnose what had ultimately caused the failure. One possibility was that the last person that worked on those panels might have over-torqued the bolts. Unirac provides specific torque settings for the clamps used to hold the panels to the rails. Those setting have been tested to assure the maximum strength without running the risk of damaging the parts. But not all installers use a torque wrench when they are tightening their panels to the rails. Without a torque wrench, an installer has to tighten by feel alone, and a careless - or harried - installer could easily over-tighten the bolts which could weaken the rail and lead to a possible failure. Did that happen here? We will never know.
And yet, a different culprit ultimately emerged which almost certainly played a major role in the failure of this system. Indeed, it was right in front of us all along (you can see it if you look closely at the first picture in this post), but we didn’t notice it until we were starting to take the damaged panels off the roof.
Did you figure it out? Take a look at this photo:
Right there in the middle of the photo is a nut on the end of a bolt - these two panels were bolted together! Indeed, the installer had bolted all of the panels together into pairs. Why was that done? No idea - but the impact of that decision was profound. Now each panel - as “seen” by the rails - was twice as wide as normal. For each row of 10 panels, the number of mid-clamps available to resist the uplift force dropped from 18 (two each in the nine gaps between panels) to just 8. As the wind force increased to historic proportions, the loading simply exceeded the down-force that those 8 mid-clamps could provide. The result was a smashed solar power system with panels flung across the roof.
We were pleased to have discerned why Mrs. C’s system had failed and she was eager to get it replaced. She contacted her insurance company which contacted us and asked us to provide an estimate to repair the system. Given that there was lots of old gear to be removed and hauled away, in addition to installing what was pretty much an entirely new replacement system on a tilt-up rack, we gave them what we considered a fair bid that worked out to ~ $7/Watt. Not surprisingly, the insurance company informed us that since the amount was so large, they would need to get a second bid. Which they did - and that bid came back $11,000 more than ours! What’s more, they charged $250 just to provide the bid!
Mind you, we proposed using Sanyo panels and Enphase micro-inverters for this project - which is the absolute top-of-the line gear that we could have chosen. So how on earth does a competitor look at the same project and propose a system price nearly twice what we did? One can only assume that they saw that an insurance company would be paying for this and so they decided to go for a jackpot. To which we have just one response: PATHETIC!
Happily, the insurance company stepped up to the plate and Mrs. C awarded us the contract to “repair” her system. The folks from Unirac chipped in and agreed to provide the replacement racking for the project. In the final installment in this series, we will tell you about how that system came together and we will even have a totally cool video to share. Stay tuned!