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Which type of system do I use? Suggestions

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  • Which type of system do I use? Suggestions

    Hello all,
    I've done some looking around here lately and it seems easier and easier for you to start putting up panels either on the roof or ground mount. I've got a new metal roof so I am thinking a ground mount system is more practical for me. Also I'm really needing to air out some idea's here about which type of system do I go with. I do know that I don't really want to jump in with both feet right now and do something with batteries. However I'm wanting something that could potentially be scale-able in the future if needed. I'm thinking about doing a grid tie inverter system.

    However I've seen some information about micro-inverters that you just attach to the back side of the panel's them selves. I guess I'm needing someone who has dealt with this before to lay out the pros and cons of what I"m wanting to do. Thanks in advance and have a good one.

  • #2
    If you can afford the extra cost, I have a list of 46 advantages to a ground mount. Net metering
    is easily the most economical approach, the only batteries here are for hand held tools or for
    starting engines. Micro-inverters are no brainers, but have many issues you may wish to avoid.
    Bruce Roe

    Comment


    • #3
      Originally posted by bcroe View Post
      I
      . Micro-inverters are no brainers, but have many issues you may wish to avoid.
      Bruce Roe
      Although, being on a ground mount makes the eventual change out of microinverters a piece of cake and IMHO worth the cost of a ground mount by itself.
      2.2kw Suntech mono, Classic 200, NEW Trace SW4024

      Comment


      • #4
        Originally posted by littleharbor View Post

        Although, being on a ground mount makes the eventual change out of microinverters a piece of
        cake and IMHO worth the cost of a ground mount by itself.
        Guess that should be reason # 47? I have been beating on my original string inverters 6 years
        with no failures. Bruce Roe

        Comment


        • #5
          Originally posted by bcroe View Post

          Guess that should be reason # 47? I have been beating on my original string inverters 6 years
          with no failures. Bruce Roe
          You would think that any ground mount would be optimally located and not give the owner a legit reason for panel level electronics. Given the choice myself, I would opt for a central string inverter too. Of course there will be the types who love all the graphs and charts whether there are shading issues or not.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

          Comment


          • #6
            Ground mount: More advantages than disadvantages.
            Pro:
            - Easier to avoid shading.
            - Easier to get optimum array orientation.
            - Easier to service and clean.
            - Probably ~ 44 other advantages (see Bruce).

            Disadvantages:
            - Takes up otherwize usable ground space.
            - May/Probably need a fence around it for safely.
            - Installation costs/labor will likely be higher.

            I'm not a fan of micros vs. simple string inverters as they violate the KISS rule, but if future expansion is a certainly, and depending on the size and nature of any future expansion, micros or optimizers may well be less troublesome to service with a ground mount.

            Comment


            • #7
              Definitely grid-tied. Batteries rarely make financial sense. What state do you live in? How many MWh do you use per year? Do you have enough property for a ground mount solution?

              What is your goal for adding solar? Have you already optimized / economized your consumption? How will your consumption change over the next 5 to 10 years?

              Speaking in generalities, SolarEdge optimizers have historically been more robust than Enphase Microinverters. But the Enphase product has been improving over the years, That said, SolarEdge is by far the market leader in panel level MPPT.

              As JPM rightly points out, adding electronics and components may/usually reduces overall system reliability. BUT, many of us feel that the added panel level monitoring that comes with SE and Enphase is worth this disadvantage in most cases.

              If your array is roof mounted, most states require rapid shutdown, so you will likely end up with an SE or Enphase solution. There are a few other options (TIGO, etc.) but the market share of these alternatives is very small. There are certainly racking solutions for metal roofs which clamp/fasten to the seams.

              If you prefer ground mount, with a String inverter (SMA, Fronius, ABB, etc.) or with SolarEdge you will likely require fencing (per your AHJ) due to the high (>300V) DC voltage and risk of electrocution. But, some places are still the "wild West." With Enphase each panel only puts out 240V AC, so fencing might not be required. Still you need to trench or run overhead wire back to your home's meter and electric panel.

              So Ground mount is usually more expensive. While Ground Mount does enable you to orient and incline your array optimally for your Latitude (assuming you have space) improving production. Depending on your production needs, adding more roof mounted panels to make up the loss (due to suboptimal orientation and pitch) can often be less expensive,

              Lots of good panels these days. Panasonic, LG, Hanwha, Jinko, Trina, etc. Hanwha and Panasonic both have US mfg plants these days. But depending on the model and batch, any particular order could still come from Malaysia or Korea, or China, depending.

              As a very rough rule of thumb, a turnkey solution will usually be between $2.50 and $3.50 / W (DC STC) installed. Depending on where you live, complexity, and component costs.

              First step is to understand your current consumption in order to model what size array you need.

              If you really want emergency backup power. You should compare the cost of generator (usually cheaper and covers more loads) versus battery backup (usually more money and covers less loads / less runtime). If you want consumption shedding / time shifting due to PoCo TOU, then only batteries can do this. BUT, you might not save any money.

              Comment


              • #8
                Thank you for all the replies. To answer some of the questions you have posed. I have plenty of space, I live on 3 acres, however 80% of it is wooded. That doesn't mean that I am opposed to removing some trees and the like to achieve what I'm going after. I live in SW indiana and I anticipate my power consumption to increase as i have 3 young girls and a wife so lots of hair drying and curling irons in my future I believe. I currently average around 800 kwh/month. I've done about everything that I can right now short of bringing in a contractor to spray foam my crawl space and the basement. Everything in the house is LED and I've even had Duke Energy come in and give me an energy assessment of my house. They said that I'm doing about everything I can.

                I"m just wanting to have something in place to where I can easily scale it up to fit me and my families needs as the years go on. Thanks once again and any additional info would be greatly appreciated.

                Comment


                • #9
                  A ground mount will allow the solar system to be active every day of the year, with very
                  minimal effort if the design allows for snow.

                  Can you account for just how 800 KWH a month are consumed? Electric car, pool pump,
                  air conditioning? A good look at the specifics is worthwhile, I spent a couple years on it
                  and managed to greatly improve my efficiency. Bruce Roe

                  Comment


                  • #10
                    I don't have any of the "Kill-a-watt" plugs yet. I do know that our AC does run but not that much. We invested in spray foam on our addition and got a fairly efficient AC unit and furnace. The next thing that I see that draws a pretty decent load is the Oven. My wife does a lot of cooking with it. We have fans in nearly every room of the house which helps us keep the thermostat turned up a degree or 2 to stay comfortable. No pool, electric car or anything like that. Just every day usage stuff, we do have LED's in every socket in the house and we are fairly vigilant in keeping things turned off. Outside of the oven we have a deep freeze downstairs and a small fridge. We also have a large fridge in the kitchen.

                    The only other thing that I could think it could be is the water heater, it's been around 18 months or so since I've change out the elements on it.

                    Comment


                    • #11
                      Originally posted by bartiks View Post
                      I don't have any of the "Kill-a-watt" plugs yet. I do know that our AC does run but not that much. We invested in spray foam on our addition and got a fairly efficient AC unit and furnace. The next thing that I see that draws a pretty decent load is the Oven. My wife does a lot of cooking with it. We have fans in nearly every room of the house which helps us keep the thermostat turned up a degree or 2 to stay comfortable. No pool, electric car or anything like that. Just every day usage stuff, we do have LED's in every socket in the house and we are fairly vigilant in keeping things turned off. Outside of the oven we have a deep freeze downstairs and a small fridge. We also have a large fridge in the kitchen.

                      The only other thing that I could think it could be is the water heater, it's been around 18 months or so since I've change out the elements on it.
                      OK so far.

                      Two more tasks:

                      1.) A book: "Solar Power your home for Dummies". At bookstores or a slightly outdated but still relevant on line, free PDF. a good primer for homeowners considering PV. Helps avoid getting ripped off or self screwing from solar ignorance/bad assumptions/bloviating hearsay from either side of the solar is good/solar sucks camps.

                      2.) PVWatts: A residential PV sizing model from NREL. For homeowners and the not too technical. Read all the help info screens a couple of time, use a 10 % system loss parameter (you'll learn about that from the help screens) and get your array orientations right.

                      Good Luck.

                      Comment


                      • #12
                        Ok, thanks for the info. I'm looking at doing quite a bit of work myself as to keep the overall costs down. I'm somewhat electrical intelligent, and by that I know how to run wires and hook them up. Now all the terminology that goes along with the watts/volts/amps and the like I need to get familiar with. I have always just wired up a breaker and run a string of switches or outlets.

                        Need to get intimate with the whole sizing of the micro inverter and the size of the array and the like. Thanks once again and if anyone else has any further input or potential pitfalls to avoid please let me know. I don't see anything happening this year, looking later next year to get the ball rolling. Want to make sure ALL ducks are in a row with what I need for the house and any wrangling I will need to do with Duke.

                        Comment


                        • #13
                          My apologies if I missed it earlier. Have you considered using gas for your water heating and cooking needs? Sounds like you already have gas service from your reference to a furnace.
                          If not relatively new , your refrigeration could be costing you more than newer top rated energy star fridges and freezers.
                          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                          Comment


                          • #14
                            Originally posted by bartiks View Post
                            I don't have any of the "Kill-a-watt" plugs yet. I do know that our AC does run but not that much. We invested in spray foam on our addition and got a fairly efficient AC unit and furnace. The next thing that I see that draws a pretty decent load is the Oven. My wife does a lot of cooking with it. We have fans in nearly every room of the house which helps us keep the thermostat turned up a degree or 2 to stay comfortable. No pool, electric car or anything like that. Just every day usage stuff, we do have LED's in every socket in the house and we are fairly vigilant in keeping things turned off. Outside of the oven we have a deep freeze downstairs and a small fridge. We also have a large fridge in the kitchen.

                            The only other thing that I could think it could be is the water heater, it's been around 18 months or so since I've change out the elements on it.
                            You are started down the right road, but need to pin down individual consumers. Here is a 2000 sq ft ranch
                            with a fully conditioned 2000 sq ft basement. Insulation is mediocre 1978, but my AC is rated 33 SEER, my
                            earlier equipment used nearly 3 times as much energy (including a compressor heater that ran 8766 hours a
                            year.

                            My old fridge used 2.4 KWH hours a day, my ancient freezer even more. I replaced them both with an
                            Energy Star fridge-freezer that used 1 KWH a day. Your Kill-A-Watt meter will soon tell the story.

                            The oven here was found to use 12 KWH a month, heavy use but only on intermittently. Yours
                            might be a lot more, but likely not your biggest load. This surplus $20 meter got the info. I just
                            wired into the oven circuit breaker output, but a male-female 60A cord set could be made for the
                            oven to plug into.

                            ENEmeter.png

                            The AC could get a similar treatment, esp in the heavy use season. Another problem is vampire
                            loads, that is older equipment that draws watts of power even when it is turned off, to the tune of
                            3/4 KWH a month per watt. Example, wall warts (BIG OFFENDERS) for a couple printers were
                            using 10W continuously; I put them on the light switch so they only came on when the room was
                            occupied. I put the doorbell on the furnace transformer and got rid of a 5 watt trans, there are
                            door openers, central vac, alarm systems, security lights (my 9 are all motion activated), any
                            WARM wall wart is wasting energy. There must be reasons your use is nearly triple mine, find
                            them. Then come back here and see if someone has found a cure. good luck, Bruce Roe
                            Last edited by bcroe; 06-28-2019, 09:05 AM.

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                            • #15
                              Does anyone have a particular site that you get your supplies from or could you recommend one for me to start looking at? Thanks in advance.

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