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Goal: Net Zero - Companies Suggesting Widely Varying kW Systems

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  • Goal: Net Zero - Companies Suggesting Widely Varying kW Systems

    After living in Central Florida all my life, I've decided to attempt to Net-Zero my power bill with solar installed by a company, by this I mean offset all the expenses of my bill to zero from ($155/mo avg w/ taxes and fees). What I've found strange is that after supplying my power bills, and last 12 months of energy usage, the various solar companies have given me a wide range of suggested builds - anywhere from 8.3 kW to 9.7 kW. In Florida it's either buy or loan, so there is no PPA.

    Here are my remaining contenders and what they suggest to Net Zero my bill:

    Vendor GuS , 8.960 kW , $23,385 , Solar Edge Inverter with Optimizers and Axitech 280W , est'd 15,124 kWh
    Vendor ESA , 9.690 kW , $20,552 , Solar Edge Inverter with Optimizers and Hyundai HiS-S285RG , est'd 14,122 kWh
    Vendor Sup , 8.120 kW , $28,444 , Solar Edge Inverter with Optimizers and REC Twinkpeak 2 290W Panels
    Vendor SCi , 8.450 kW , $27,462 , String
    Vendor Gol , 9.240 kW . $24,474 , Solar Edge Inverter with Optimizers and Hanwa Q 280W Panels , est'd 13,760 kWh

    My average monthly power usage is 1186 kWh or 14,232 kWh annually. Do any of these stand out to stay away from? Obviously the two smallest systems that cost the most were probably not going to win. The prices listed are before tax credit.
    Last edited by Nethers; 06-02-2017, 03:58 PM.

  • #2
    What does net zero mean to you? Net zero electric energy across a year? Net zero electric energy each month of the year? Net-zero energy all-in (all-electric house)?

    Are you expecting zero dollar or less bill every month?

    Would you expect to hold the contractor liable if they missed a month or year of net-zero? Would you rather be conservative and over-generate or be more economic in your decision making (net zero not usually the quickest payback).

    I'm not really looking for an answer to all these questions, but when you take it all into account the difference between 8.3kW and 9.7kW isn't all that great if these weren't well defined.

    Comment


    • #3
      Have you looked at the pvwatts.nrel.gov website to see what a system would generate in your neck of the woods?

      You can enter in a number of different multipliers based on which compass point the panels are facing as well as an efficiency value.

      You could then use the yearly kWh value from that calculator and compare it to the Vendor's estimate to see if they are under or over sizing their system.

      Comment


      • #4
        Download and read : Solar Power Your Home for Dummies". You will benefit from the education.

        A 100 % off set of your bill may not be the most long term cost effective way to go.

        After the book, run PVWatts. Read the help/info screens a couple of times and use 10% system losses instead off the 14 % default. With some better information and a more informed idea of how much of your bill you want to replace, you'll be better able to make a more informed decision.

        Do not buy anything until you understand what you're doing and what vendors are telling you. They make money by putting equipment on your property, not getting you the most cost effective way to reduce your electric bill.

        Comment


        • #5
          Originally posted by J.P.M. View Post
          A 100 % off set of your bill may not be the most long term cost effective way to go.
          What are you suggesting then? If a 9kW system is $113/mo to offset 97% of $152/mo...

          Comment


          • #6
            Originally posted by Nethers View Post
            What are you suggesting then? If a 9kW system is $113/mo to offset 97% of $152/mo...
            Usually the recommendation around here is to start from analysis of your current & projected usage, that's where the most savings are anyway. Do you know where those 14,000+ kWh go every year? Optimizing that would allow you to lower your required PV system size and create 'ripple' effect of savings. Ignoring that step creates the opposite effect . I dropped my monthly bill 50% before finally deciding to go with solar. Honestly at that point it wasn't that obvious I even need it.

            Comment


            • #7
              Originally posted by Nethers View Post
              What are you suggesting then? If a 9kW system is $113/mo to offset 97% of $152/mo...
              Depending on where you live and what your electric cost are it becomes hard to totally get rid of your electric bill by adding solar. There comes a point that getting the last 5% of your bill zeroed out becomes very expensive and drags out the ROI.

              Comment


              • #8
                Please pardon my ignorance, I am new to solar, have not read the Solar for Dummies book, and I don't totally understand the benefits of the Optimizers and the importance of the type of inverter. I checked the length of the book, and while it seemed solid, at 381 pages and with two kids, a full time job and graduate school, I doubt I'll get time to read the book.

                So I'm hoping I can look towards the extremely knowledgeable people on this forum: I've read people on this site saying people who go with Solar City are ultimately stupid, but their re-quote was surprisingly competitive - the one thing that gets me is that they don't tell me what equipment they're going to install, and from what I can tell, I won't have optimizers and will receive a basic string inverter. If they ultimately guarantee the performance, does the lack of optimizers and base string inverter matter (all the competitors had solar edge inverters with optimizers)?

                Comment


                • #9
                  Originally posted by Nethers View Post
                  What are you suggesting then? If a 9kW system is $113/mo to offset 97% of $152/mo...
                  I'm not suggesting anything other than to do what you want, but get educated and walk in with your eyes open.
                  Where did the $113/mo. come from ?

                  - The output/Watt for those systems where you've listed an estimated output is similar for 2 of the systems but different for the 3d. Without information on location and array orientation it's not possible to corroborate estimates. That's what PVWatts is for. If vendors ESA and GOL, which are close to one another in annual output estimates are reasonable, then vendor GUS is overestimating output. If GUS is closer to the mark, the other two just might be underestimating output to sell more product, a B.S. trick played on the solar ignorant. .
                  - ($1,860/yr.)/(14,232 kWh/yr.) = $0.131/kWh.
                  - The cheapest system you've listed, vendor ESA at $20,552/9,690 W = $2.12/W or X 0.70 = $1.48/Watt after tax credit gives a payback using the simplistic moron method of ($ 20,552 *.70)/($1,860) =~ 11 years. Kind of a long time these days. Those per Watt prices seem low, but I'm not in FL. Perhaps SunEagle could enlighten me on market price in/around central FL. Also, and while not being familiar w/ FL real estate, but I'd probably not expect an 11 yr. old PV system to add much of any value to a house any more than an 11 yr. old air conditioner, at least not without a lot of objective analysis, which FWIW, seems hard to find.

                  - My suggestion is predicated on the idea that most folks want the most bang for their long term buck, or at least want to know where that point is for sound decision making and tradeoffs like "more money spent or better aesthetics ?" or "More annual savings or less upfront out of pocket ?" Or, "If I put the $$ in some other investment, will I be, or what are my chances of, coming out ahead after "X" years ? ". Solar process economics sometimes uses something called the Levelized Cost of Energy (LCOE) analysis as one way to analyze costs and is a useful tool. The names of these things are more intimidating than the practice and the math. If you can do high school math, know how to read and have one eye and one balloon knot, a few hours of reading and number crunching will give reasonable outputs for reasonable assumptions about rates, alternate investment opportunities, future electricity costs etc. Seems worth the investment on a per hr. basis maybe.

                  There is a long list of things a homeowner can do to lower an electric bill, starting at the most cost effective and easiest is simply turning things off. Each measure taken has a $$ cost and a convenience cost. Those two things are somewhat inverse to one another. Going without something is often viewed as inconvenient, but it's very $$ cost effective. On the list of measures that are $$ cost effective, solar PV is usually and often at or near the bottom in terms of $$ cost effectiveness. If I'm suggesting anything, it's self education and saving money through informed choices is most of the reason behind it.

                  From what and how you write, you seem, to me anyway, to have all or most of the characteristics of folks who are running in some combination of panic and anger from perceived high electric bills with no idea of what to do other than throw expensive PV at the symptoms (high bills) rather than toward more cost effectiveness in ways to use electricity through education and in doingh so minimizing the long term costs of paying those bills. Start by downloading and reading the book. A slightly outdated version is free on the net. An updated version is ~ $25 at bookstores or Amazon. Then do PVWatts. Come back here and ask questions to fill in the blanks after that.

                  BTW, welcome to the forum of few(er) illusions.

                  Take what you may want of the above. Scrap the rest.

                  Comment


                  • #10
                    Originally posted by J.P.M. View Post

                    I'm not suggesting anything other than to do what you want, but get educated and walk in with your eyes open.
                    Where did the $113/mo. come from ?

                    - The output/Watt for those systems where you've listed an estimated output is similar for 2 of the systems but different for the 3d. Without information on location and array orientation it's not possible to corroborate estimates. That's what PVWatts is for. If vendors ESA and GOL, which are close to one another in annual output estimates are reasonable, then vendor GUS is overestimating output. If GUS is closer to the mark, the other two just might be underestimating output to sell more product, a B.S. trick played on the solar ignorant. .
                    - ($1,860/yr.)/(14,232 kWh/yr.) = $0.131/kWh.
                    - The cheapest system you've listed, vendor ESA at $20,552/9,690 W = $2.12/W or X 0.70 = $1.48/Watt after tax credit gives a payback using the simplistic moron method of ($ 20,552 *.70)/($1,860) =~ 11 years. Kind of a long time these days. Those per Watt prices seem low, but I'm not in FL. Perhaps SunEagle could enlighten me on market price in/around central FL. Also, and while not being familiar w/ FL real estate, but I'd probably not expect an 11 yr. old PV system to add much of any value to a house any more than an 11 yr. old air conditioner, at least not without a lot of objective analysis, which FWIW, seems hard to find.

                    - My suggestion is predicated on the idea that most folks want the most bang for their long term buck, or at least want to know where that point is for sound decision making and tradeoffs like "more money spent or better aesthetics ?" or "More annual savings or less upfront out of pocket ?" Or, "If I put the $$ in some other investment, will I be, or what are my chances of, coming out ahead after "X" years ? ". Solar process economics sometimes uses something called the Levelized Cost of Energy (LCOE) analysis as one way to analyze costs and is a useful tool. The names of these things are more intimidating than the practice and the math. If you can do high school math, know how to read and have one eye and one balloon knot, a few hours of reading and number crunching will give reasonable outputs for reasonable assumptions about rates, alternate investment opportunities, future electricity costs etc. Seems worth the investment on a per hr. basis maybe.

                    There is a long list of things a homeowner can do to lower an electric bill, starting at the most cost effective and easiest is simply turning things off. Each measure taken has a $$ cost and a convenience cost. Those two things are somewhat inverse to one another. Going without something is often viewed as inconvenient, but it's very $$ cost effective. On the list of measures that are $$ cost effective, solar PV is usually and often at or near the bottom in terms of $$ cost effectiveness. If I'm suggesting anything, it's self education and saving money through informed choices is most of the reason behind it.

                    From what and how you write, you seem, to me anyway, to have all or most of the characteristics of folks who are running in some combination of panic and anger from perceived high electric bills with no idea of what to do other than throw expensive PV at the symptoms (high bills) rather than toward more cost effectiveness in ways to use electricity through education and in doingh so minimizing the long term costs of paying those bills. Start by downloading and reading the book. A slightly outdated version is free on the net. An updated version is ~ $25 at bookstores or Amazon. Then do PVWatts. Come back here and ask questions to fill in the blanks after that.

                    BTW, welcome to the forum of few(er) illusions.

                    Take what you may want of the above. Scrap the rest.
                    You are correct, I am completely ignorant. I wasn't really looking at the payback period of 11 years, but received a new quote with a 20 year term that put the monthly price at $113/mo and a 9KW system. It was from Solar City, which everyone here seems to despise. I simply saw it as an option to trade my $152/mo bill for $113/mo. I wasn't really panicked or angry, but simply excited to save the difference.
                    Last edited by Nethers; 06-02-2017, 09:02 PM.

                    Comment


                    • #11
                      Originally posted by Nethers View Post

                      You are correct, I am completely ignorant. I wasn't really looking at the payback period of 11 years, but received a new quote with a 20 year term that put the monthly price at $113/mo and a 9KW system. It was from Solar City, which everyone here seems to despise. I simply saw it as an option to trade my $152/mo bill for $113/mo. I wasn't really panicked or angry, but simply excited to save the difference.
                      Understood. Enjoy the book and PVWatts. Looking forward to your enlightened questions.

                      On SolarCity: My experience w/SolarCity from being the guy in my HOA that reviews and recommends to the Arch. Rev. Comm. is that they are one of the bottom feeders to avoid. Personally, I wouldn't let them on my property for any reason.

                      As for savings, there's a pretty good chance you can squeeze ($ 152- $113) = $39/mo., or a significant portion of that amount out of your current electric bill with some informed and determined conservation efforts and a bit of lifestyle adjustment.

                      Good luck.

                      Comment


                      • #12
                        Originally posted by J.P.M. View Post

                        ...
                        - ($1,860/yr.)/(14,232 kWh/yr.) = $0.131/kWh.
                        Wow ... does solar make economic sense when the grid electricity price is so low? Of course if the Florida utilities are like the ones in California the price won't stay low for long.

                        Comment


                        • #13
                          In this area 'net-zero' usually means a house that powers itself, heats / cools itself without consuming any outside energy. [no grid power, no fuel consumption].
                          4400w, Midnite Classic 150 charge-controller.

                          Comment


                          • #14
                            Originally posted by solardreamer View Post

                            Wow ... does solar make economic sense when the grid electricity price is so low? Of course if the Florida utilities are like the ones in California the price won't stay low for long.
                            That depends on how many days each month you expect the grid to be available.

                            Here on the East Coast you should expect the grid to be up and functional 20 days of every month. Sometimes more, sometimes less.

                            The greatest asset of solar power is power when the grid is down, each month.

                            4400w, Midnite Classic 150 charge-controller.

                            Comment


                            • #15
                              Originally posted by organic farmer View Post
                              Here on the East Coast you should expect the grid to be up and functional 20 days of every month. Sometimes more, sometimes less.
                              were exactly on the east coast are you that the grid is down 1 out of 3 days? I live and have lived in several east coast states and never had power close to that bad.

                              Originally posted by organic farmer View Post
                              The greatest asset of solar power is power when the grid is down, each month.
                              Solar power in and of itself does not have this capability. Thus the vast majority of installs do not. You can get a bimodal inverter ( with batteries) that does have backup capabilities but that system does not NEED to have solar added to it.
                              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                              Comment

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