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In Bay Area, CA with PG&E NEM 2.0, I'm confused on what size system to install

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  • In Bay Area, CA with PG&E NEM 2.0, I'm confused on what size system to install

    Currently I'm on the EVA plan with 13,895 kwh used in last 12 months. Most of the usage is for charging my two volts at night with off-peak rates. I am a bit confused on how much i get back from PG&E for excess energy. I read that it was around $0.04/kwh for the excess sent back to the grid. Then I'm told by one solar installer that excess are sold back to PG&E at peak rate and my usage is bought mostly at off-peak and partial-peak. I therefore will bank the difference by buying low and selling high. So which is correct? Thanks


  • #2
    You will get the ~ $ 0.04 rate or less for excess generation. See the PG &E website for details.

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    • #3
      The installer showed me his PG&E bill and told me he will get back $500 from PG&E...surely that can't be from $0.04/kwh...
      Attached Files

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      • #4
        Originally posted by maximus96 View Post
        The installer showed me his PG&E bill and told me he will get back $500 from PG&E...surely that can't be from $0.04/kwh...
        Suit yourself, but I'd analyze his bill and get the details and particulars of how NEM is working for PG & E these days. SDG & E is currently paying $0.027/kWh for any excess annual generation at trueup. Other I.O.U.'s, including PG.& E are paying about the same.

        Be aware that what the bills you're seeing may show under any column headed with things like "NEM credits" has nothing to do with what you will see in terms of an actual year end credit or a check the POCO will cut you for annual excess generation at trueup. What that peddler is showing you may well be the retail value of how much electricity can be used before all the current year's so far accrued excess generation is used up.

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        • #5
          Originally posted by maximus96 View Post
          The installer showed me his PG&E bill and told me he will get back $500 from PG&E...surely that can't be from $0.04/kwh...
          without knowing more that bill doesn't look right to me- for the months May and after Net Usage column is exact sum of Net Peak & Net Off Peak but before May Net Usage has some arbitrary numbers. The bill doesn't show some very straight value like 'Balance Due' and simply invites you to assume the Total is what it is going to be. Sounds like common low level seller's BS to me and I'd drop the vendor on these grounds alone. Have you seen the entire bill or just this portion?

          Regardless of what you might be shown you need to figure out what rate schedule you are going to be at after the install and calculate those things yourself. You'd most likely need to contact your utility for help as your vendor will be tempted to present rosier picture.

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          • #6
            Can the $ credits be applied to the gas portion of the bill? or does it only apply to the electric portion?

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            • #7
              You are confusing, or at least not specifically identifying, what "excess energy" you are talking about in your firat sentence. Your installer is correct in one scenario, excess energy unused in a specific day will earn you credits at whatever peak period they are sold back at, if you are on a TOU plan and at retail rates less NBC charges. At your TrueUp, if you have banked dollar credit, it is wiped away unless you are a net generator of total kwh over the year (many people are not, this is called oversizing your system if you are). To qualify, you must Export more kwh than you Import, aka net generation, to be entitled to the small pennies per kwh rebate, but you only collect on amounts above their 120 per year bill minimum. Under nem2 NBC rates also will affect monthly carryover balances, but tbis is a little harder to explain and is outside answerjng your over generation credit anyway.

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              • #8
                Originally posted by maximus96 View Post
                The installer showed me his PG&E bill and told me he will get back $500 from PG&E...surely that can't be from $0.04/kwh...
                He will have the option to use up those $ 500 in electricity credits over the next few months until his TrueUp. No, he will not get a check for 500 even if it still shows $500 in that Total box at the end of the year. The ETOUA rate plan still has the $120 annual bill mininum attached, and if his Total Line still shows negative for Total Kwh Used, only then will he get a small reimbursement for those kwh.

                No, the $500 nem credit cannot be used as credit against the gas, it is wiped away.

                AFAIK, that 500 credit will be wiped away if unused by year end, whether he gets a small credit for excess generation or not.

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                • #9
                  Got it. So since I will also be on ETOUA, selling high and buying low, I should not size my system for 100% kwh offset. How do I determine/guess properly how much to offset? 80%, 85%?

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                  • #10
                    Researching some more, seems I should not be sizing to offset 100% kwh usage, but instead to offset 100% electric bill cost, or come close to it.

                    I currently have the EVA rate. Will I be moved to ETOUA or ETOUB once I install solar? The installer said I will be, but I can't find any info confirming that. If not, it seems that on average, a 7.59 kw system (23 panels at 330w each) will generate enough to zero out dollar-wise a day of use. At least per the estimated production shown in PVWATTS. I'm also showing I'm buying in summer rate and selling in winter rates to be conservative and production split evenly between peak and partial peak.

                    I'd appreciate any feedback on my estimation, especially if I made a major mistake somewhere.


                    Attached Files
                    Last edited by maximus96; 09-11-2017, 02:28 PM.

                    Comment


                    • #11
                      Originally posted by maximus96 View Post
                      Got it. So since I will also be on ETOUA, selling high and buying low, I should not size my system for 100% kwh offset. How do I determine/guess properly how much to offset? 80%, 85%?
                      Sort of. The most cost effective size is hard to nail down, but it may likely be < 100% of your usage.

                      Getting close to a better estimate, as with most things, requires knowledge. In these situations that knowledge is of how your POCO charges you for what you use and how it pays you for what you send back. Start digging. I'd not rely too much on what your vendor is saying until you get yourself more informed and able to separate fact from assumption and incorrect info.

                      Getting all the info, and getting it right is a real PITA, been there a lot. Don't shoot me as I'm only the messenger on this, but there's a lot more that's necessary to know to get an understanding of what to do than can be explained in this venue.

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                      • #12
                        Originally posted by maximus96 View Post
                        Researching some more, seems I should not be sizing to offset 100% kwh usage, but instead to offset 100% electric bill cost, or come close to it.

                        I currently have the EVA rate. Will I be moved to ETOUA or ETOUB once I install solar? The installer said I will be, but I can't find any info confirming that. If not, it seems that on average, a 7.59 kw system (23 panels at 330w each) will generate enough to zero out dollar-wise a day of use. At least per the estimated production shown in PVWATTS. I'm also showing I'm buying in summer rate and selling in winter rates to be conservative and production split evenly between peak and partial peak.

                        I'd appreciate any feedback on my estimation, especially if I made a major mistake somewhere.

                        I don't think you'll be forced off the EV-A rate... it is not a closed tariff, and since it is TOU, it meets the requirements for NEM-ST.

                        I would download your actual consumption history, and run the PV watts hourly output against the TOU periods. Simple assumptions like 50% partial peak/50% peak are hard to make accurately.
                        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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                        • #13
                          Originally posted by sensij View Post

                          I would download your actual consumption history, and run the PV watts hourly output against the TOU periods. Simple assumptions like 50% partial peak/50% peak are hard to make accurately.
                          You're right. Looking at the hourly output for the year, PV Watts shows nothing after 4 to 5 PM. My 50/50 was too optimistic. I changed it to 30/70 peak/partial peak. If I increase the generation rates slightly by $0.02/kwh each as I'm not generating at Winter rates all year long, it shows a 7.59 kw system should still be sufficient. Furthermore, it seems the Panasonic panels could generate up to 10% higher than rated.
                          Solar 3.JPG

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                          • #14
                            SensiJ is right, youll just check the box that says Stay on Current Rate Plan on your A&A agreement and authorizations nem2 interconnect document. EVA is a TOU rate plan and you will not be forced off of it. You either are misunderstanding these statements or you really should be questioning having this installer do the work; I would question his experience, lack of understanding of previous interconnect agreements or his ability to remember.

                            Yes 50/50 is too optimistic for today's available rate plans for many, but might be accurate if nobody is home during day and you have no AC and use a gas oven. But "nothing after 4 to 5pm" doesnt sound right. Which way are the panels facing and at what tilt to show that?
                            Are you using the 2-9pm peak time period?

                            Is that table supposed to represent an average day of generation and usage profile or did you just pull up a random day from this month?

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                            • #15
                              Originally posted by cebury View Post
                              SensiJ is right, youll just check the box that says Stay on Current Rate Plan on your A&A agreement and authorizations nem2 interconnect document. EVA is a TOU rate plan and you will not be forced off of it. You either are misunderstanding these statements or you really should be questioning having this installer do the work; I would question his experience, lack of understanding of previous interconnect agreements or his ability to remember.

                              Yes 50/50 is too optimistic for today's available rate plans for many, but might be accurate if nobody is home during day and you have no AC and use a gas oven. But "nothing after 4 to 5pm" doesnt sound right. Which way are the panels facing and at what tilt to show that?
                              Are you using the 2-9pm peak time period?

                              Is that table supposed to represent an average day of generation and usage profile or did you just pull up a random day from this month?
                              This particular installer was one of many companies that submitted a quote, but not the one I chose for the install.

                              The panels are southeast facing and all the wattage numbers pretty much drop off after 5pm for most months out of the year.

                              Yes, using 2-9pm for peak time period, so I only get about 3 out of 11 or 12 hours of production in peak.

                              Yes, the table shows average daily generation based on the annual estimated generation from PVWatts. The daily kwh usage is the average daily use in July per my latest August PG&E bill. The bill shows about 18% usage in peak and 17% in partial peak, rest in off-peak.

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