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  • #16
    Why don't you install south / west instead of east /west? You would have more production
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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    • #17
      I need to look into these rapid shutdown boxes a little to see if they're worth it.

      You're probabaly right about the south/west. I should just do it. It's a 10%+ difference annually. Black panels should look good on that roof.

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      • #18
        Originally posted by Nut&Volts View Post
        I need to look into these rapid shutdown boxes a little to see if they're worth it.
        .
        They are required by code. Micro inverters and solaredge have the feature built in though.
        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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        • #19
          JPM brought up a good point on page 1 - load calcs What he is referring to is to make sure you understand exactly if solar makes sense for your home.

          Assuming you have not already done this (and if you have - great) is to step back and understand your current energy usage with the goal of reducing your current usage by energy savings. Start by getting the historical usage from your PoCo (hopefully you can just download this online) and continues by looking at everything that uses electricity in your home and understand how much is uses and if there are easy ways for you to reduce that usage. It includes things like weatherstripping and sealing of openings. Looking at how the big uses of energy can be reduced. This can be a balancing act between lifestyle choices and energy cost but any savings or repairs you find will give you immediate payback.

          Then once you feel you have a realistic understanding of your current/historical usage and you feel that you have reduced the usage as much as your lifestyle dictates is to then understand what solar can do for you. This starts with knowing the rate programs for solar offered by your PoCo. Software such as SAM (which is free) can really help you with "what-if" type of questions to understand how long it will take for your investment to pay for itself. Without this process you have no idea if putting the effort into installing a solar system is even worth it to you.

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          • #20
            Originally posted by tyab View Post
            JPM brought up a good point on page 1 - load calcs What he is referring to is to make sure you understand exactly if solar makes sense for your home.

            Assuming you have not already done this (and if you have - great) is to step back and understand your current energy usage with the goal of reducing your current usage by energy savings. Start by getting the historical usage from your PoCo (hopefully you can just download this online) and continues by looking at everything that uses electricity in your home and understand how much is uses and if there are easy ways for you to reduce that usage. It includes things like weatherstripping and sealing of openings. Looking at how the big uses of energy can be reduced. This can be a balancing act between lifestyle choices and energy cost but any savings or repairs you find will give you immediate payback.

            Then once you feel you have a realistic understanding of your current/historical usage and you feel that you have reduced the usage as much as your lifestyle dictates is to then understand what solar can do for you. This starts with knowing the rate programs for solar offered by your PoCo. Software such as SAM (which is free) can really help you with "what-if" type of questions to understand how long it will take for your investment to pay for itself. Without this process you have no idea if putting the effort into installing a solar system is even worth it to you.
            I'd respectfully add:

            Having worked with POCO rates and SAM for some time now, I'd caution to be careful to confirm the rates that SAM uses. My experience is that, in the past, SAM's rates were generally incomplete and inaccurate. More recently, things w/the SAM rates seem to have improved with respect to accuracy, but they are far from complete, at least with respect to what my POCO is doing and what SAM thinks. Example: SAM still does not have my tiered rate daily allowance correct which throws everything off. T.O.U. rates as SAM uses them to be a better fit than before.

            I know a bit, but not as much about other CA POCO rates, and things look similar with them, but I could be wrong on that. In any case, caution may be advised on trusting SAM's bill estimating accuracy.

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            • #21
              I have done a bit of background research on my energy usage. I had an energy audit done last month helping me understand my heating/cooling/insulation. Everything was pretty good. Furnace and water heater are natural gas. All appliances are new Samsung units, energy star, etc. I also have a smart utility meter which features a solid smart phone app. Lets me know my instantaneous usage and records daily usage too. Super useful. All home bulbs have been updated to LED. My thermostat is an Ecobee3 smart unit, that automatically lowers temps when we leave. I havent gone to any extremes, but I believe solar is the

              One of the biggest reason I want solar is because I drive a Volt and use at least 10kWh a day for that. In general I have been using 1100kWh a month for the winter and expect closer to 900kWh this spring. Annually (which is what matters for co-generation vs net metering in my area) I should be between 10000-12000 kWh. I am looking at system that produce 6000-8000 kWh annually. If I over produce then I will get my wife a PHEV too. No TOU rates in my area, but I am at about $0.13/kWh right now. My payback time reported for a self install have been between 4-6yrs using SAM. Early on I also used Helioscope to calculate annual energy.

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              • #22
                Originally posted by Nut&Volts View Post
                I have done a bit of background research on my energy usage. I had an energy audit done last month helping me understand my heating/cooling/insulation. Everything was pretty good. Furnace and water heater are natural gas. All appliances are new Samsung units, energy star, etc. I also have a smart utility meter which features a solid smart phone app. Lets me know my instantaneous usage and records daily usage too. Super useful. All home bulbs have been updated to LED. My thermostat is an Ecobee3 smart unit, that automatically lowers temps when we leave. I havent gone to any extremes, but I believe solar is the

                One of the biggest reason I want solar is because I drive a Volt and use at least 10kWh a day for that. In general I have been using 1100kWh a month for the winter and expect closer to 900kWh this spring. Annually (which is what matters for co-generation vs net metering in my area) I should be between 10000-12000 kWh. I am looking at system that produce 6000-8000 kWh annually. If I over produce then I will get my wife a PHEV too. No TOU rates in my area, but I am at about $0.13/kWh right now. My payback time reported for a self install have been between 4-6yrs using SAM. Early on I also used Helioscope to calculate annual energy.
                Out of curiosity. With your estimated 12000 kWh usage and $0.13/kWh costs what did you determine you system installed $/watt would be to get that 6 year payback?

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                • #23
                  Originally posted by SunEagle View Post

                  Out of curiosity. With your estimated 12000 kWh usage and $0.13/kWh costs what did you determine you system installed $/watt would be to get that 6 year payback?
                  Or another way to check it out as long as the OP is using SAM: Change the # of years in the analysis until the "real LCOE" = $0.13. Not the same number as current per kWh cost, but maybe a more realistic way to look at years to cost effectiveness than the simplistic initial cost /current annual electric bill method. Besides being a pretty good tool for sizing, SAM's also a pretty good tool for learning stuff, in this case about ways to estimate cost effectiveness and something of process economics. One of several reasons to use SAM over PVWatts.

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                  • #24
                    Originally posted by J.P.M. View Post

                    Or another way to check it out as long as the OP is using SAM: Change the # of years in the analysis until the "real LCOE" = $0.13. Not the same number as current per kWh cost, but maybe a more realistic way to look at years to cost effectiveness than the simplistic initial cost /current annual electric bill method. Besides being a pretty good tool for sizing, SAM's also a pretty good tool for learning stuff, in this case about ways to estimate cost effectiveness and something of process economics. One of several reasons to use SAM over PVWatts.
                    It is just that I am using about 15000kWh per year with a cost of ~ $0.12/kWh and unless I can get an installed cost down below $3/watt before the FED rebate I get an ROI of around 8 years so 6 years seems pretty short even at $0.13/kWh.

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                    • #25
                      Originally posted by SunEagle View Post

                      It is just that I am using about 15000kWh per year with a cost of ~ $0.12/kWh and unless I can get an installed cost down below $3/watt before the FED rebate I get an ROI of around 8 years so 6 years seems pretty short even at $0.13/kWh.
                      It would be hard to imagine how the DIY grid-tie install the OP has described could exceed $3 / W. With the parts mentioned, it could be substantially less than $2 / W.
                      CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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                      • #26
                        Originally posted by sensij View Post

                        It would be hard to imagine how the DIY grid-tie install the OP has described could exceed $3 / W. With the parts mentioned, it could be substantially less than $2 / W.
                        Ah. I missed that in the OP first post. Yes I can see the price of a DIY being that low and having a much quicker payback then one for me.

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                        • #27
                          Originally posted by SunEagle View Post

                          Ah. I missed that in the OP first post. Yes I can see the price of a DIY being that low and having a much quicker payback then one for me.
                          Yes exactly self-install is key here. I also noticed a flaw in my use of the SAM parametric simulation feature (inverter parameters). So my break even is definitely not going to be below 5 years. My cost per watt is nice and lower around $0.7/Wdc (excluding my labor). This is with the old stock M190 inverters, C-grade panels from Sun Elec and Unirac racking. I have an unshaded roof, but have to live with the less sunny weather of Ohio.

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                          • #28
                            Discovered another issue with SAM and micros. Say I have 10 panels and 10 inverters in my system and two different arrays (so 5 on each). For one it seems like the software only allows you to put arrays in parallel on the DC side. This seems to decrease output. I may just be using this aspect incorrectly. The other issue is that it seems to lump all 10 inverters as one large on instead of applying each on to each panel. This means you'll rarely see clipping when you have arrays in different directions. Makes it difficult to find the reasonable limits for panel sizing

                            My solution is to simulate with a single panel/micro. I can do for each array layout (ie south roof and then one for west roof). Then just multiple the annual output by the number of panels I plan to have on each array. These results seem to make a lot more sense.

                            Anyone else experienced this problem? Am I just using the system design functions of SAM wrong?

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                            • #29
                              Originally posted by Nut&Volts View Post
                              Discovered another issue with SAM and micros. Say I have 10 panels and 10 inverters in my system and two different arrays (so 5 on each). For one it seems like the software only allows you to put arrays in parallel on the DC side. This seems to decrease output.
                              Microinverter arrays *are* in parallel. Any attempt to treat them as series systems is incorrect, unless you are looking at using something like two 36 cell panels in series to create the equivalent of a 72 cell panel.
                              CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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                              • #30
                                Hey all,
                                Been away for awhile. Project is still moving forward.
                                • Roof Inspection Completed - everything is good to go
                                • M190 inverters purchased - 20 are brand new, so 15yr warranty for only $25
                                • 245W all black Astronergy panels purchased - pallet of 25 for $0.43/W shipped
                                I have been able to answer a lot of my own questions, but I'm still struggling with a few on the wiring side. I plan to have two arrays, one of 12 and one of 13 panels. Each one will have two strings of M190s that are btwn 6-7 inverters long to reduce voltage drop. Usually called a center tap I've learned. So this will leave me with 4 interconnect cables which need to go from PV cable to Romex wire (or other house wire).

                                What I want to do... Run Enphase interconnect cables (PV cable) through wire glands into junction box mount on the end of my rail. From here those same cables will run through EMT conduit (4-6ft) into the siding of a roof gable. This puts the conduit in the attic. I will then the run the PV cable into a standard blue box as a junction box. This is where I will wire nut connect the PV Cable to Romex cable. The Romex cable will run through my attic/down wall into the garage subpanel.

                                Is that feasible? If I cant run the PV Cable into the attic, can I run the Romex cable in the EMT out to the array mounted junction box??

                                I understand the AHJ will have final say, but I would like to know if I'm missing something before I ask.
                                -Kyle

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