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  • SF Bay Area 4.8kW System Review

    I'm looking for feedback on my thinking/choices/prices and any installation recommendations.

    I've been entertaining some solar options in the bay area based on an average 4.73 kW usage for the past 13 months. My average monthly bill is $136 for electricity.

    I'm thinking that due to my roof being fairly constrained as to where I can even put panels and still maintain recommended calfire setbacks, that the only real location for panels is on the first story roof towards the front of my home. I could maybe fit a few on the 2nd story but i haven't confirmed.

    Google Maps.png

    I'm thinking that to get to a system of that size i'll need to go with more expensive higher output panels.. Thus why the quote i'm sharing is for LG 320W 60 cell panels which unfortunately seem to be $1.13/W. If I can fit 15 of these on the first story, I get to 4.8kW.. If I go with a lower output panel, i'd have to put some on the 2nd story somewhere and get more panels.

    IMG_0181.JPG

    Similarly, i'm thinking micro inverters given that i expect the 2nd story to start casting shade on the leftmost panels starting around 3-4PM.

    Here are the financials of what i've been told so far by both the equipment seller and an installer that i spoke with..

    financials.png

    i'm wondering a couple of things..

    1. equipment wise, see any problems with the items picked or prices?

    2. installation wise, the $9k was only a verbal quote and frankly strikes me as high considering this seems like a relatively simply installation and some of the other posts that i've read here (~$1.88/W.. includes handling all permitting and so forth - i do nothing but pay). The conduit can literally just run from the roof, down the side of the wall to the panel some 30 feet away. no need to make it go through the roof or wrap around gutters or the like. so any feedback on what i should be paying and any references if anyone has them are welcome.

    Appreciate the looks/feedback!
    Attached Files

  • #2
    So you are going to spend extra to get LG 320W modules and then connect them to enphase M215 modules (limited to max of 225w).

    I would highly suggest that you either go with SolarEdge or switch to enphase S280 micros. You will need to go with two strings with the S280.
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

    Comment


    • #3
      By " average 4.73 kW usage " do you mean continuous, or 3450 kW hour a month? Bruce Roe

      Comment


      • #4
        I'll suggest go as large on each panel as you can base on limited roof space. What I see the problem is the shading in the afternoon since the 2nd floor is higher than your garage. SolarEdge or micro inverters were suggested.

        Or

        Go a little large system and place the panels on NW roof since your roof space without shade is limited
        Last edited by silversaver; 11-11-2016, 05:01 PM.

        Comment


        • #5
          I'd agree with silver that you'll have some shading issues in the afternoon depending on the elevation difference between the roof with the panels and the more westerly roof elevations.

          Also, Bruce's comment relating to usage makes me think your confused about how much electricity you use. I'm not super familiar w/ PG & E rates, but $136+/month from PG & E might indicate ~ 600 - 700 kWh/month average usage, depending on which tariff you're on. "4.73 kW usage for the last 13 months " makes no sense, unless your annual usage in kWh = (4.73)*(24)*(365) = 41,434 kWh/yr.

          Comment


          • #6
            Originally posted by bcroe View Post
            By " average 4.73 kW usage " do you mean continuous, or 3450 kW hour a month? Bruce Roe
            Average kWh usage seems to be 633 looking at the last 16 months. Average bill $140 for electricity. I ran an online calculator again which suggested 4.79kW system. I usually end each month in either tier 3 or tier 4 PGE usage. Here is the PGE data by month:

            PGE usage.png

            Comment


            • #7
              Originally posted by ButchDeal View Post
              So you are going to spend extra to get LG 320W modules and then connect them to enphase M215 modules (limited to max of 225w).

              I would highly suggest that you either go with SolarEdge or switch to enphase S280 micros. You will need to go with two strings with the S280.

              All panels would be LG 320W modules.
              All micro inverters would be enphase S280 micros.
              I'm confused as to why you're mentioning SolarEdge or M215 modules. Maybe i didn't communicate something properly?

              Comment


              • ButchDeal
                ButchDeal commented
                Editing a comment
                My mistake but you will still need two strings as the max string length for s280 is 14
                So you will need two termination caps, AC combiner box and some fuses.

            • #8
              Originally posted by gwichman View Post


              All panels would be LG 320W modules.
              All micro inverters would be enphase S280 micros.
              I'm confused as to why you're mentioning SolarEdge or M215 modules. Maybe i didn't communicate something properly?
              I think that the inclusion of "M215 Term" in the parts list was confusing.
              SunnyBoy 3000 US, 18 BP Solar 175B panels.

              Comment


              • #9
                Originally posted by inetdog View Post

                I think that the inclusion of "M215 Term" in the parts list was confusing.

                Ah.. i abbreviated the quote.. it actually says "Enphase Branch Terminator M215 Termination Cap".. quantity 1, cost $17.00

                Comment


                • #10
                  Some posters around you are seem to be getting closer to $3.50/Watt. $4.13 seems a bit high. The installation doesn't look or sound all that unusual.

                  On line calculator : PVWatts , or something else ?

                  Did you account for shading ? If so, how ?

                  An unshaded 4.8 kW system might offset your entire annual load at what looks to be a SSW orientation, but that shading will cut into the output some, depending on panel placement. You might check the CALfire setbacks. You may be able to get by with one (1) ea. 3 ft. access pathway depending on how the roof type is interpreted. If so, the array might be moved closer to the east edge of the roof giving less shading.

                  Comment


                  • #11
                    Originally posted by J.P.M. View Post
                    Some posters around you are seem to be getting closer to $3.50/Watt. $4.13 seems a bit high. The installation doesn't look or sound all that unusual.

                    On line calculator : PVWatts , or something else ?

                    Did you account for shading ? If so, how ?

                    An unshaded 4.8 kW system might offset your entire annual load at what looks to be a SSW orientation, but that shading will cut into the output some, depending on panel placement. You might check the CALfire setbacks. You may be able to get by with one (1) ea. 3 ft. access pathway depending on how the roof type is interpreted. If so, the array might be moved closer to the east edge of the roof giving less shading.
                    I don't recall which calculator i used previously. I went to PVWatts just now and plugged in what I knew and it spit up 5.35 kWh / m2 / day. AC Energy (kWh) 7,464. Energy Value $1,568

                    For shading, I went to the roof during the summer and noted where the 2nd story shade fell at 3, 4 and 5pm. I then compared this to the layout and it looked to my eye that 2 panels would start to get shared around 3-4PM with 2 more panels getting shade around 5PM. I don't know how to translate that to output but it seemed tolerable at the time.

                    Good point on the CALfire setbacks.. although i like the 3ft setbacks for another reason - makes installing xmas lights easy ..

                    Comment


                    • #12
                      Originally posted by gwichman View Post

                      I don't recall which calculator i used previously. I went to PVWatts just now and plugged in what I knew and it spit up 5.35 kWh / m2 / day. AC Energy (kWh) 7,464. Energy Value $1,568

                      For shading, I went to the roof during the summer and noted where the 2nd story shade fell at 3, 4 and 5pm. I then compared this to the layout and it looked to my eye that 2 panels would start to get shared around 3-4PM with 2 more panels getting shade around 5PM. I don't know how to translate that to output but it seemed tolerable at the time.

                      Good point on the CALfire setbacks.. although i like the 3ft setbacks for another reason - makes installing xmas lights easy ..
                      The 7,464 kWh/yr. is the figure of merit, and not too far off my SWAG of 1,600 kWh/yr. per installed kW = (1,600)* (4.8) = 7,680 kWh/yr., with neither # including the shading. I'd guess your eyeball estimate is probably sufficient enough.

                      If you could or chose to eliminate the 3 ft. setback on the east side, it might be worth a few bucks ($100 or so, maybe)/yr. in avoided electric bill, but that's a guess, pure & simple. I'd also think about micro inverter placement to minimize access hassles if/when they need service. Read the fine print on the inverter warranty. Forewarned is forearmed.

                      Comment


                      • #13

                        I agree $4.13/W is high for SF Bay Area. I am in the area and got $3/W and many others also got similar price. Also, I wonder if it's really cost effective to go solar with < $150/month electricity bill.

                        Originally posted by J.P.M. View Post
                        Some posters around you are seem to be getting closer to $3.50/Watt. $4.13 seems a bit high. The installation doesn't look or sound all that unusual.

                        On line calculator : PVWatts , or something else ?

                        Did you account for shading ? If so, how ?

                        An unshaded 4.8 kW system might offset your entire annual load at what looks to be a SSW orientation, but that shading will cut into the output some, depending on panel placement. You might check the CALfire setbacks. You may be able to get by with one (1) ea. 3 ft. access pathway depending on how the roof type is interpreted. If so, the array might be moved closer to the east edge of the roof giving less shading.

                        Comment


                        • #14
                          Originally posted by solardreamer View Post
                          I agree $4.13/W is high for SF Bay Area. I am in the area and got $3/W and many others also got similar price. Also, I wonder if it's really cost effective to go solar with < $150/month electricity bill.


                          with comparable equipment? it's quite a bit cheaper if i go with cheaper equipment..

                          even at my current costs which i expect to drop a little and financing the system with an equity loan, it'll pay for itself in 10 years if I pay no more then my current bill (less if i factor in the fact that electricity costs more over time). I would like that to be more like 7 years though personally.. but to make that happen i'd have to find $4k in savings someplace. maybe if i bought the equipment out of state and did a portion of the install myself or something but short of that it doesnt seem feasible.

                          Comment


                          • solardreamer
                            solardreamer commented
                            Editing a comment
                            Good point about equipment. I believe the best quote I got for LG300 with Enphase was about $3.40/W.

                        • #15
                          Originally posted by solardreamer View Post
                          I agree $4.13/W is high for SF Bay Area. I am in the area and got $3/W and many others also got similar price. Also, I wonder if it's really cost effective to go solar with < $150/month electricity bill.


                          I'd be skeptical of the cost effectiveness as well, but not my money/house/life.

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