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  • Hi I'm TAZ427

    Hi, I'm TAZ427. I'm a somewhat recent transplant from Houston, TX to Sacremento, CA area (technically Sugar Land, TX to El Dorado Hills, CA.)

    In TX with the low rates, I ran the numbers on Solar ever couple years, and they were always be > 20yrs to get the value back.

    Moved to CA in Sept 2015 for work. Electric rates were high, but I'm a low consumer (LEDs, CFLs, temp set high in Summer, low in Winter, Installed a Whole house fan, ...) then summer hit, and while my consumption was < 1/2 of my June, July, Aug in Houston (99% humidity and temps not falling below the high 70's at night keeps the AC cranking) I broke the $500 barrier on one month, and I had never exceeded $350 in Houston.

    I ran the solar numbers after I first got here, based on previous owners 1yr of consumption, was at about 8yrs to get a return (they're a slightly higher consumer than my family.) Did again about a year ago and was at about 7yrs. Now, I'm down to 6yr, the Tax Credit is going to start running out, California is about 1.5yrs from being forced to all new home builds having solar. And so many other things going on that I'm wondering if the cost of install isn't going to go up a bit in California for a few years, and the tax credit fades away. So it's time for me to jump in with both feet. Actually, I've taken the plunge, I signed a contract last night.

    8.04kW system
    24 - LG 335W NeON 2 (LG335N1C-A5) Panels
    Solar Edge P400 Optimizers
    Solar Edge SE7600H Inverter
    - Production and Consumption Meter included
    Mounting - ProSolar RoofTrac - 6" Standoffs
    Pricing $3.15/W (plus a bit of Marketing incentive to knock it a little lower post Tax Incentive for a final of ~$2/W)

    I read a lot on this forum as a Lurker before I made my decision. My only regret is not joining the forum earlier.

  • #2
    Welcome to the neighborhood.

    Busy just now, more later. In the meantime, see prior posts about considering an array as a revenue generator and using the output X NEM "income" to offset an electric bill. That is, with a lot of, but not all NEM tariffs, it's possible to treat and consider array output, and usage, as separate. PVWatts hourly output per hour X incremental rate/hr. = annual system "revenue" . As long as annual system output is < annual usage, and as long as T.O.U. rates are not f(billing period quantity used), different array sizes, orientations, etc., can be compared on the basis of how much annual "revenue" they might produce.

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    • #3
      Originally posted by J.P.M. View Post
      Welcome to the neighborhood.

      Busy just now, more later. In the meantime, see prior posts about considering an array as a revenue generator and using the output X NEM "income" to offset an electric bill. That is, with a lot of, but not all NEM tariffs, it's possible to treat and consider array output, and usage, as separate. PVWatts hourly output per hour X incremental rate/hr. = annual system "revenue" . As long as annual system output is < annual usage, and as long as T.O.U. rates are not f(billing period quantity used), different array sizes, orientations, etc., can be compared on the basis of how much annual "revenue" they might produce.
      Oh, trust me, I've spent a good amount of time with spreadsheets. Pulled in my Consumption for past year broken down to the hour, Pulled in PVWatts (had to time adjust for DST as I'll be on TOU), Have Peak and Off Peak, not just overall, but separate for Summer vs Winter months. Even two of the three plans there's a Baseline per month (of course different for summer vs winter) where the rate is pro-rated up until that has been reached (basically a 2 Tier TOU plan.) So, I've got it Consumed, vs Produced, down to the hour and exactly what I get charged and credited for it, and checked it out for all three TOU options I have available to me. Even calculated what I save by moving my pool pump earlier in the day so it's not impacted by Peak Rates. What's really funny is in the end with my current consumption it ends up being the two most common being within $5, the new TOU option which looks good initially, ends up being about $40 worse (that happens to be the one I took a snapshot of my spreadsheet for below.) Did analysis for all three faces of the house where panels might go. Talking again last night, we thing we can go 18 West (76deg) and 6 South (166deg) - Note, that's maxed out on that side as I've got a solar pool heater there...

      One last thing I need to do, is put in a extra consumption factor in the summer afternoon/evening if I end up using a bit more AC and see which plan comes out best there. I think I know which one it is, but I want verification.

      Here's a snapshot of one of several spreadsheets I have calculating this. Did I mention I'm an Engineer, therefore I must analyze things to the max. I did leave the system losses and invert efficiency as the defaults, even though I expect better, just so I have closer to worse case production numbers. TOU-C3.JPG


      EDIT: To anyone whose on PG&E, ping me and I can provide a spreadsheet for each of the TOU plans (I'll be updating this as PG&E changes things.) You'll just need to replace columns A-K with those from PVWatts, and replace columns T-W with data from PG&E - this requires a slight massaging as you'll need to re-order so you get a Jan 1, 0:00am starting point for the PG&E data so it aligns with the PVWatts data. You could simply pick the Jan 1 - Dec 31st of the year before, and this will give probably a best approximation and no fiddling with the dates.
      Last edited by TAZ427; 05-16-2018, 02:38 PM.

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      • #4
        PG&E has a plan for electric cars that is amazing. With the high gas prices in California, the EV-A plan is something worth considering getting grandfathered into. There are amazing deals on used Leafs and huge subsidies on the Bolt and i3's. I have the same system as you, but it is 11.25 kW.

        Net Usage
        Peak -285.588800 kWh @$0.32987 -$94.21
        Part Peak -581.342400 kWh @$0.20417 -118.69
        Off Peak 517.181500 kWh @$0.13046 67.4

        I know the prices per kWh are insane, but with a plan like this you need to understand that there are no tiers and you get credit for the high price that you feed the grid. I ended up with a $145.50 credit with a net 350 kWh added to the grid. That works out to $0.42 per kWh credit that I put into the grid. I have to pay $18.93 in charges from using energy from the grid with my usage, but they do subtract with estimated $10 you need to be hooked up to the grid from that value.


        In May I will end up with an even bigger credit with the summer prices below.

        Peak: $0.47334/kWh
        Park-Peak: $0.25994/kWh
        Off-Peak: $0.12753/kWh

        Comment


        • #5
          Originally posted by TAZ427 View Post

          Oh, trust me, I've spent a good amount of time with spreadsheets. Pulled in my Consumption for past year broken down to the hour, Pulled in PVWatts (had to time adjust for DST as I'll be on TOU), Have Peak and Off Peak, not just overall, but separate for Summer vs Winter months. Even two of the three plans there's a Baseline per month (of course different for summer vs winter) where the rate is pro-rated up until that has been reached (basically a 2 Tier TOU plan.) So, I've got it Consumed, vs Produced, down to the hour and exactly what I get charged and credited for it, and checked it out for all three TOU options I have available to me. Even calculated what I save by moving my pool pump earlier in the day so it's not impacted by Peak Rates. What's really funny is in the end with my current consumption it ends up being the two most common being within $5, the new TOU option which looks good initially, ends up being about $40 worse (that happens to be the one I took a snapshot of my spreadsheet for below.) Did analysis for all three faces of the house where panels might go. Talking again last night, we thing we can go 18 West (76deg) and 6 South (166deg) - Note, that's maxed out on that side as I've got a solar pool heater there...

          One last thing I need to do, is put in a extra consumption factor in the summer afternoon/evening if I end up using a bit more AC and see which plan comes out best there. I think I know which one it is, but I want verification.

          Here's a snapshot of one of several spreadsheets I have calculating this. Did I mention I'm an Engineer, therefore I must analyze things to the max. I did leave the system losses and invert efficiency as the defaults, even though I expect better, just so I have closer to worse case production numbers. TOU-C3.JPG


          EDIT: To anyone whose on PG&E, ping me and I can provide a spreadsheet for each of the TOU plans (I'll be updating this as PG&E changes things.) You'll just need to replace columns A-K with those from PVWatts, and replace columns T-W with data from PG&E - this requires a slight massaging as you'll need to re-order so you get a Jan 1, 0:00am starting point for the PG&E data so it aligns with the PVWatts data. You could simply pick the Jan 1 - Dec 31st of the year before, and this will give probably a best approximation and no fiddling with the dates.
          Understood. But did or do you understand the idea of separating generation from usage and treating generation/hr. X rate/kWh as offset revenue that can possibly, depending on tariff, be considered a parameter to optimize or compare different orientations or array sizes ?

          Other: Do you have the experience level with PV systems to get some perhaps further insight from something called SAM from NREL ? If you're curious, might be worth a sniff.

          As for PVWatts, lots of informed opinion suggests and has found that the 14 % system loss parameter leads to a more conservative model output. Without getting into a discussion of what's conservative or non conservative with less output not necessarily being more conservative if it means winding up or pointing to a less cost effective system, many users have found that something closer to 10 % for a system loss parameter seems to often get closer to actual output more often, at least for systems less than a few years old.

          BTW, and FYI, if pinging means PM's, there ain't none on this forum.

          Comment


          • #6
            Originally posted by J.P.M. View Post

            Understood. But did or do you understand the idea of separating generation from usage and treating generation/hr. X rate/kWh as offset revenue that can possibly, depending on tariff, be considered a parameter to optimize or compare different orientations or array sizes ?

            Other: Do you have the experience level with PV systems to get some perhaps further insight from something called SAM from NREL ? If you're curious, might be worth a sniff.

            As for PVWatts, lots of informed opinion suggests and has found that the 14 % system loss parameter leads to a more conservative model output. Without getting into a discussion of what's conservative or non conservative with less output not necessarily being more conservative if it means winding up or pointing to a less cost effective system, many users have found that something closer to 10 % for a system loss parameter seems to often get closer to actual output more often, at least for systems less than a few years old.

            BTW, and FYI, if pinging means PM's, there ain't none on this forum.
            I just now noticed this post. Yes, I definitely considered the treating generation at different times for different rates, and orientation... Actually if you look at the screen capture, one of the things I noted was that while the 166deg mostly South facing is 12% more in production, it's only 5.9% higher in value over the 256deg mostly West facing, do to time of production. Also, calculated shifting pool pump time (shifted i.e. the 4-9pm peak rate one, I subtracted out the pools average consumption from 4-6pm and added it to the 10am-12pm portion - was running it 12-6pm now running it 10am-4pm so that it's off peak.)

            I glanced at SAM, it really didn't have as much details in the analysis that I really wanted (at least as far as I could see.)

            I wasn't sure what the best true estimate for losses were, so I left that as is, I think from the little I've seen in the 4 days of production, that I do believe that 14% to be too conservative, also the default inverter efficiency of 96 percent was a bit too conservative. But I'd rather over produce than under produce... at least for the first several years.

            Too bad there's no PM on the forum. If anyone is interested in the spreadsheet the can e-mail me at c 1 courtney at g mail (well you should know how to string that together.)

            Comment


            • #7
              Originally posted by discodanman45 View Post
              PG&E has a plan for electric cars that is amazing. With the high gas prices in California, the EV-A plan is something worth considering getting grandfathered into. There are amazing deals on used Leafs and huge subsidies on the Bolt and i3's. I have the same system as you, but it is 11.25 kW.

              Net Usage
              Peak -285.588800 kWh @$0.32987 -$94.21
              Part Peak -581.342400 kWh @$0.20417 -118.69
              Off Peak 517.181500 kWh @$0.13046 67.4

              I know the prices per kWh are insane, but with a plan like this you need to understand that there are no tiers and you get credit for the high price that you feed the grid. I ended up with a $145.50 credit with a net 350 kWh added to the grid. That works out to $0.42 per kWh credit that I put into the grid. I have to pay $18.93 in charges from using energy from the grid with my usage, but they do subtract with estimated $10 you need to be hooked up to the grid from that value.


              In May I will end up with an even bigger credit with the summer prices below.

              Peak: $0.47334/kWh
              Park-Peak: $0.25994/kWh
              Off-Peak: $0.12753/kWh
              I had calculated with the TOU-EV-A and TOU-EV-B plans, and w/o an EV it was costing me about $100 more per year relative speaking than TOU-A or TOU-B, based on current consumption (and time shifting the pool to Partial Peak - Not running it at night for Off-Peak.) Now if I had an EV car and with current average driving, I'd save my self about $200 extra on this plan.

              I'm not willing to give up my SUV - and the Tesla X design doesn't appeal to me at all, the i3 looks nice but it's too small for me, the Bolt is way too small for me, I loved the Buick EV SUV Concept and would have been willing to go that route, but as of today, I'm probably 5yrs out from going to an EV car. At that point, I'll switch to an EV TOU plan.

              I also asked PG&E about it, and they said, if I don't have an EV, I'm not eligible anyway. It was down to TOU-A vs TOU-B plan. The difference by math was $5/yr. I would barely be pushing into Tier 2 during a couple days in June and July and I think it was 5 days in Aug but current consumption. But I figured, it's more likely that my consumption may actually go up a bit and be more likely to push further into the tier, so I went with TOU-B plan, which has no Tier, which is where my costs are most likely to go up.

              That said, I don't see the EV TOU plans going away, and while you can get grandfathered into one (if you have an EV) the rates are never grandfathered...

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