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.
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!
We have just learned that Pasadena Water and Power (PWP) will slash its residential solar rebates by 30% effective June 1, 2012. The reduction only affects EPBB rebates and will lower the amount from $2.00 to just $1.40/Watt. Potential clients who wish to secure a rebate under the present rates must have complete and correct rebate applications on file with PWP by May 31, 2012. Partial or incorrect applications will be rejected and will have to be re-submitted at the lower rate.
(Interestingly, PBI rebates are not declining which would mean that for clients who can tolerate waiting to receive their rebate payments over five years, they will do much better than clients needing the lump-sum EPBB rebate after June 1.)
UPDATE - Turns out that after we wrote this, PWP decided to also slash its PBI rebates for residential customers from the current $0.302/kWh down to $0.212/kWh effective June 1. Did our previous suggestion (now in strike-out type above) contribute to this policy change?
Unaffected are commercial and government/non-profit rebate rates, which were most recently reduced as of December 1, 2011.
We always experience a crush of inquiries about possible solar projects in advance of a major rebate reduction like this one and potential clients are encouraged to act quickly to avoid the hassle of trying to get necessary paperwork completed at the last minute.
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!
A bit off-topic, but given the wide-spread existence of downed power lines throughout the LA Basin, we thought it would make sense to include this timely advice from LADWP:
LADWP strongly encourages the public to stay away from any downed power lines and poles as well as downed trees and limbs, and protect children home from school today from the same. Beware of traffic signals that may be affected by power outage and proceed with extreme caution. Allow access for uniformed LADWP crews, all of whom carry Department-issued identification cards, so they may service infrastructure in need of repair.
In the event of a power outage:
•Have a flashlight and extra batteries nearby. Don’t use candles in a power outage.
•Turn off lights but leave one light turned on so you will know when your service is restored.
•Turn off and unplug appliances and other electrical equipment. Unplug heat-producing items like irons and space heaters. This helps prevent circuit overloading, which could delay restoration of service.
•Call us and report your outage at 1-800-DIAL DWP (1-800-342-5397). If you encounter a downed power line:
•Report any downed power lines immediately by calling the LADWP at 1-800-DIAL-DWP (1-800-342-5397). If you or someone else is in danger, call 911.
•Do not touch a downed or dangling wire or anyone or anything in contact with it. Always assume a downed line is still energized.
•If a power line falls on your car, stay in the car and wait for help. If you must get out, make sure you do not touch the metal parts of the car and the ground at the same time. The safest exit method is to open the door, stand on the door sill and jump free without touching the car.
•Stay away from metal fences, such as chain link fence, as there may be a power line down and touching the fence somewhere beyond your sight.
•If there is damage to the connection from the power pole to your house, you should go to the electrical box and turn off the main switch or shut off the fuse switch. Again, always assume electric lines are live.
•In case of an electrical emergency, stay calm and think before you act. Don’t become a victim while trying to help others. Call 911.
•If someone is shocked or not breathing, apply cardio-pulmonary resuscitation (CPR.) Then cover the victim with a blanket, keep their head low and get medical attention.
The public and members of the media are encouraged to check the Department’s news site at www.ladwpnews.com and Twitter page, @LADWP, for updates.
For folks not served by LADWP, you can report downed power lines by calling:
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