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  • first post looking at system from Tesla

    First post here lots of info to look at. We have been looking at solar for a little over a year now. Got some bids so far the best I have gotten was from Tesla. The system is for our winter home and or vacation Cabin in the rocky mountains of Colorado 8500 feet and lots of sun. When the Log cabin was built they put in a Electric Boiler with Radiant floor heat Excel is the electric co. . Had thought about putting in a propane boiler but it would also be expensive and hate cutting into a good working boiler system. The first system they came up with was a 10.4 KW system with a Estimated production of 13,156 KWH. It included 32 panels That would cover a little over 60% of our usage of 21,000 KWH we use in a year. Sounds like xcel gives you credit for excess power generated so in the summer when not there or not using heat it would xcel would credit me for power generated. The system would have left one part of my roof facing south without panels and it looked like they could add 9 more. So I asked to add more panels to the estimate and they did but not only did they fill all the south roofs they also added 9 panels facing the North west. I really didn't think that was a good Idea facing panels NW but they must have thought I wanted to supply 100% of the usage. I guess I would but not want the panels that are not getting much sun. That system with the extra 22 panels cost went up to 58,000 the system size was 17.55KW estimated production of 20,977 taking care of 97% of my usage. That seemed to get very expensive and I asked them for another plan with just 13 panels more than the first bid so they would all be facing south He thought that would be in the 40 to 45 thousand but is waiting for a plan from the engineer. All those costs do not include the tax credit so are full price. Does that first estimate seem like it is inline? At my age (60) not sure if the investment will return while I am still around and able to take advantage of the savings. Our annual use is 21,057 KWH and cost was last year of $2,197.73. What do you think practical or just kind of cool
    Last edited by Mbmaring; 03-27-2018, 10:07 PM.

  • #2
    Make sure they have a workable plan for how they will backfeed your electric panel with that much power. Code for a standard 200Amp service is 7.7kW max. To go more than that takes some modifications. Over 12kW with most utilities is a special case. Even if you have a 400Amp service, it can still be a problem as those are really just dual 200A busses.

    Not a fan of Tesla (SolarCity) - recommend checking out local solar installers found here on SolarReviews.com
    BSEE, R11, NABCEP, >1200kW installed

    Comment


    • #3
      off grid electric heat is a no-go. Propane or Solar Thermal water storage in a 500gal tank better chioce. Vacation home not likely to qualify for tax credit.
      And if you use the home part time, you have greatly increased the system cost, because it will be nearly totally idle when you are not using it. Batteries age (even tesla) and all the expensive solar PV is sitting on top of charged batteries doing nothing.
      Research the cost of installing grid power, and use simple grid tie with a backup generator.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

      Comment


      • #4
        Originally posted by solarix View Post
        Make sure they have a workable plan for how they will backfeed your electric panel with that much power. Code for a standard 200Amp service is 7.7kW max. To go more than that takes some modifications. Over 12kW with most utilities is a special case. Even if you have a 400Amp service, it can still be a problem as those are really just dual 200A busses.

        Not a fan of Tesla (SolarCity) - recommend checking out local solar installers found here on SolarReviews.com
        Looked at panel 225 main breaker so if that's the case wouldn't make much sense to go bigger 8 kw system?
        Last edited by Mbmaring; 03-26-2018, 12:30 AM.

        Comment


        • #5
          Originally posted by Mike90250 View Post
          off grid electric heat is a no-go. Propane or Solar Thermal water storage in a 500gal tank better chioce. Vacation home not likely to qualify for tax credit.
          And if you use the home part time, you have greatly increased the system cost, because it will be nearly totally idle when you are not using it. Batteries age (even tesla) and all the expensive solar PV is sitting on top of charged batteries doing nothing.
          Research the cost of installing grid power, and use simple grid tie with a backup generator.
          We live at the home 5 months in winter and a month in the summer tax person said we would qualify for tax credit as it is a second home. Is she wrong? As far as being idle I was told excel energy would credit me for power generated when gone in summer and fed back to grid and when we use the most electricity in the winter we could use that credit. Winter we use 4000 to 5000 in cold months. Maybe I should look at a propane boiler?

          Comment


          • #6
            Originally posted by mike90250 View Post
            off grid electric heat is a no-go. Propane or solar thermal water storage in a 500gal tank better chioce. Vacation home not likely to qualify for tax credit.
            And if you use the home part time, you have greatly increased the system cost, because it will be nearly totally idle when you are not using it. Batteries age (even tesla) and all the expensive solar pv is sitting on top of charged batteries doing nothing.
            Research the cost of installing grid power, and use simple grid tie with a backup generator.
            +1. Get rid of the electric heating. Now ! That's like cutting butter with a chain saw.

            Comment


            • #7
              Definitely putting the cart before the horse. You didn't say where the vacation home is, but switching to minisplits are the way to go for heat as long as your seasonal temps are above zero. The hyperheat units work down to -12 F but the output is quite limited. There is also a fairly new to US technology which are minisplits that are air to water. They can be plumbed into an existing hydronic system, but unless the existing system was designed for the lower temps produced by these units, it may not have the response and capacity required.

              Comment


              • #8
                Originally posted by peakbagger View Post
                Definitely putting the cart before the horse. You didn't say where the vacation home is, but switching to minisplits are the way to go for heat as long as your seasonal temps are above zero. The hyperheat units work down to -12 F but the output is quite limited. There is also a fairly new to US technology which are minisplits that are air to water. They can be plumbed into an existing hydronic system, but unless the existing system was designed for the lower temps produced by these units, it may not have the response and capacity required.
                The cabin is in the Colorado Rockys 8500 feet in elevation West of Denver. Have large south facing windows the sun has lots of power up there. The electric boiler only runs a hour or so at about 4am we have a nest thermostat. when the sun comes out we open the blinds and the sun heats the house sometimes so well we even have to open some windows in the dead of winter.
                Forgot to mention there is no need for air conditioning here we seldom get over 75 degrees and nighttime temps are ways cool.
                Last edited by Mbmaring; 03-26-2018, 09:08 AM.

                Comment


                • #9
                  Originally posted by Mbmaring View Post
                  ..........As far as being idle I was told excel energy would credit me for power generated when gone in summer and fed back to grid and when we use the most electricity in the winter we could use that credit. ...
                  No business with batteries, grid tie, and a backup generator is what you need

                  Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                  || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                  || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                  solar: http://tinyurl.com/LMR-Solar
                  gen: http://tinyurl.com/LMR-Lister

                  Comment


                  • #10
                    Originally posted by Mbmaring View Post

                    Looked at panel 225 main breaker so if that's the case wouldn't make much sense to go bigger 8 kw system?
                    All right! - they put in a "solar ready" panel with an oversize 225A bus. (they don't make breakers with 225A ratings) So you should have a 225A bus with a 200A main breaker that can handle 70 amps of backfeed which is derated by 20% to 56amps or 13.6kW at 240Vac. You can go as high as about 15kW of array on that much Inverter output.
                    BSEE, R11, NABCEP, >1200kW installed

                    Comment


                    • #11
                      Originally posted by Mike90250 View Post

                      No business with batteries, grid tie, and a backup generator is what you need
                      Yes we have a 10kw Miller bobcat welder generator up here never had to use it in the last 4 years but it's a piece of mind as if the power lines go down here in the mountains it would take a long time to fix them.

                      Comment


                      • #12
                        Originally posted by solarix View Post

                        All right! - they put in a "solar ready" panel with an oversize 225A bus. (they don't make breakers with 225A ratings) So you should have a 225A bus with a 200A main breaker that can handle 70 amps of backfeed which is derated by 20% to 56amps or 13.6kW at 240Vac. You can go as high as about 15kW of array on that much Inverter output.

                        Don't understand we have a main breaker in our main service panel that is 225 amp? Or are you talking a breaker somewhere else?

                        Comment

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