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  • Small Grid Tied system for power offset

    Hello all,

    I've scoured the forum with both the advanced search and regular search and couldn't find a post/sticky that answered the questions I had about a small grid tied system. I apologise in advance because I know that these questions must have been answered somewhere before in pockets and I'm just lousy at searching I'd suggest. I'm finally building a small house and would like to use a couple panels (4 to start) to offset my power bills. I'm at work during the day Mon-Fri and expect that the panels should provide enough power for my network gear, a headless server that runs 24/7, my refrigerator, and any other electronics/appliances in a standby mode. My hope is that on weekends it would offset the use of the A/C units during the day and my music gear (studio monitors, board, couple pairs of turntables, mixer etc.). I've run the numbers and figured that 4 panels is a decent start with plans to get to 8/12/16 as budget and roof space would allow.

    First question: does any of this make sense or is this a POS idea to begin with?

    I have will have sun from 6:30am to 5:30pm and generally have clear skies outside of rainy season (10.6918° N) so I was looking at the Renogy 2 Pack 100W 12V Monocrystalline Solar Panel, Compact Design 42.2 X 19.6 X 1.38in, High Efficiency Module PV (cheaper to buy two, 2 packs funnily than one, 4 pack) and a 1000w Grid Tied Inverter unit. The Inverter would run to a main kill switch (just in case) before the 'solar breaker' in my main panel which will route power throughout my home's electrical system.

    sunshine chart.png

    Second batch of questions: Are the Renogy units ok units? Are there better from a cost/benefit position? Am I missing anything in my concept for how I would run this? Should I be looking at 12V or 24V for this kind of concept?

    I'm not too sure about connecting the panels but I'll not get there until I wrap my head around the basics first, establish cost, and choose what my best/optimum path would be.

    Thanks in advance for the help.

    Cheers.

  • #2
    Get educated on the basics before you spend money on equipment. Doing so will help avoid (but not guarantee) the POS part in the results. Reads like you have some equipment information but that's putting the cart before the horse.

    Start with a read of "Solar Power Your home for Dummies". ~ 20-05 $US on Amazon. Do so and you'll answer a lot of questions on your own that you don't even know exist at this time.
    Last edited by J.P.M.; 01-17-2020, 01:20 AM. Reason: spelling

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    • #3
      Do note that each addition to the system (adding more panels, upgrading the inverter) generally requires a NEW building permit and a NEW agreement with the electric company, so it's better to look up the electric company rate schedule and when their next increase/modification is set to happen and prepare to submit paperwork while you still can get a favorable plan.

      "Incrementally growing" your system is tough, as you have to plan for the final system, pull cables rated for that power, and at each upgrade, swap out breakers and such to maintain safety as well as finding out the gear you bought and planned with last year, is not available this year (no more blue panels, the new ones are purple with pink trim), and the net meter rate changed to allow you to sell back at $0.04 per KWH instead of the $0.12 is is today. Rates generally stay grandfathered in for 10 years unless you change something.
      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

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      • #4
        Originally posted by Mike90250 View Post
        Do note that each addition to the system (adding more panels, upgrading the inverter) generally requires a NEW building permit and a NEW agreement with the electric company, so it's better to look up the electric company rate schedule and when their next increase/modification is set to happen and prepare to submit paperwork while you still can get a favorable plan.
        Not an issue for me at all. Our regulations don't require permitting at all. Lawlessness is more the norm here than the exception. I do intend to reconfirm one item with the power company as I've heard that our archaic laws have us in a solar bind. Technically we are not allowed to generate power - no one is save the power company... but the government is encouraging the use of solar power... so that I need to have cleared up. The only things I'd really need is to ensure that we're safe and I don't burn down the house. Noooo paperwork here! LOL.

        "Incrementally growing" your system is tough, as you have to plan for the final system, pull cables rated for that power, and at each upgrade, swap out breakers and such to maintain safety as well as finding out the gear you bought and planned with last year, is not available this year (no more blue panels, the new ones are purple with pink trim), and the net meter rate changed to allow you to sell back at $0.04 per KWH instead of the $0.12 is is today. Rates generally stay grandfathered in for 10 years unless you change something.
        ...like I said above, there's no net metering or credits coming to me, I'm just aiming for an offset. If I can zero out grid use then my meter will be slow to none and my bill will be nominal. That's the goal. That's why I was aiming for a 1000W inverter vs going with a 600w and then having to buy another if I intend to max out my panel space later on. Thanks for the broad understanding though of the difficulties in an incremental upgrade...

        Get educated on the basics before you spend money on equipment. Doing so will help avoid (but not guarantee) the POS part in the results. Reads like you have some equipment information but thtat's putting the cast before the horse.

        Start with a read of "Solar Power Your home for Dummies". ~ 20-05 $US on Amazon. Do so and you'll answer a lot of questions on your own that you don't even know exist at this time.
        Not to be an idiot but after reading the book, I'm going to be able to answer all my questions for self? What's the point of a community of builders who have done and seen, know what works and what doesn't? I'm also asking hoping to allow the next person that's searching to get some updated answers and ideas to be fair. I'm less worried about particular equipment and more trying to understand if my idea broadly makes any sense, is feasible, is worth it, etc. Just telling me to go read 'for Dummies' really is no help to be fair. Thanks for the time?

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        • #5
          Originally posted by djcarbon View Post

          Not an issue for me at all. Our regulations don't require permitting at all. Lawlessness is more the norm here than the exception. I do intend to reconfirm one item with the power company as I've heard that our archaic laws have us in a solar bind. Technically we are not allowed to generate power - no one is save the power company... but the government is encouraging the use of solar power... so that I need to have cleared up. The only things I'd really need is to ensure that we're safe and I don't burn down the house. Noooo paperwork here! LOL.



          ...like I said above, there's no net metering or credits coming to me, I'm just aiming for an offset. If I can zero out grid use then my meter will be slow to none and my bill will be nominal. That's the goal. That's why I was aiming for a 1000W inverter vs going with a 600w and then having to buy another if I intend to max out my panel space later on. Thanks for the broad understanding though of the difficulties in an incremental upgrade...



          Not to be an idiot but after reading the book, I'm going to be able to answer all my questions for self? What's the point of a community of builders who have done and seen, know what works and what doesn't? I'm also asking hoping to allow the next person that's searching to get some updated answers and ideas to be fair. I'm less worried about particular equipment and more trying to understand if my idea broadly makes any sense, is feasible, is worth it, etc. Just telling me to go read 'for Dummies' really is no help to be fair. Thanks for the time?
          Getting educated is the best first step anyone can take. That book is just one place to get that education.

          The problem with slow incremention of a solar pv system is the hardware costs. I do not know of any small legal 1000w grid tie inverters so you might have to go with a larger one but then you need enough panel voltage to make it work. And if you started with a smaller inverter you would then have to replace it with a larger one. That adds to the overall system cost.

          Even going off grid with a battery system is not conducive to growing the system because you have to keep the panel wattage and battery Ah balanced or you kill off the batteries. Starting with 200 watts would require around a 12v 160Ah battery system. If you decide to increase your panel wattage that battery system may no longer work.

          Finally even if you do not have any requirements for permitting you still need to follow all local electric codes for a pv installation. If you just DIY one and there is a problem that causes someone to get hurt or worse the authorities may look at your system and determine it was installed poorly. Especially if you need to not send any power back to your POCO. That requires a special inverter that can be programmed to not Net Meter.

          IMO if someone wants to save money on their power bill then finding ways to conserve power is the first and best thing to do. Once you can afford a full system and understand the ins and outs of owning one you can pull the trigger.

          Oh and those small "kits" are just a tease to get people to spend their money without understanding what they are getting into.

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          • #6
            Originally posted by SunEagle View Post
            ......The problem with slow incremention of a solar pv system is the hardware costs. I do not know of any small legal 1000w grid tie inverters so you might have to go with a larger one but then you need enough panel voltage to make it work. ..........
            One approach to incremental growth of a solar system is microinverters. At some point they get more expensive than a string inverter. I added 1000Watts of additional capacity to my string inverter by adding some used panels and 4 microinverters.

            9 kW solar, 42kWh LFP storage. EV owner since 2012

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            • #7
              Originally posted by Ampster View Post
              One approach to incremental growth of a solar system is microinverters. At some point they get more expensive than a string inverter. I added 1000Watts of additional capacity to my string inverter by adding some used panels and 4 microinverters.
              I agree but you have to start with the micros and then expand. The OP is looking at those Renogy "kits" with 100w panels. That is not the way to start building a system.

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              • #8
                Originally posted by djcarbon View Post
                Not to be an idiot but after reading the book, I'm going to be able to answer all my questions for self? What's the point of a community of builders who have done and seen, know what works and what doesn't? I'm also asking hoping to allow the next person that's searching to get some updated answers and ideas to be fair. I'm less worried about particular equipment and more trying to understand if my idea broadly makes any sense, is feasible, is worth it, etc. Just telling me to go read 'for Dummies' really is no help to be fair. Thanks for the time?
                No, that's why I wrote " 'start' with a read...".
                It's a beginning, not an end.
                Doing so will also give you a better insight as to the suitability and efficacy of your ideas and if they make sense to you and if they are a good way to meet your goals.

                If you're thinking this is a community of builders, allow me to disabuse you of that notion. Some folks here are knowledgeable about some aspects of alternate energy. Most are not. Many are like you, except maybe they are not necessarily lousy at searching it seems.

                As for how helpful my suggestion might be, take it or leave it, but the way I learned it, the best help is self help.

                If you do begin your knowledge quest by starting at a reliable source for the basics (and many well written sources besides the one I suggested exist) and doing some learning on your own you'll waste less of your time and that of others. You'll also be better equipped to separate reality from some of the B.S. that goes around - some of it here.

                Also, any questions you do ask here after getting some of the basics down will be better formulated and also have more meat on them.

                That will make any answers you receive here all that much better. You might even wind up with a better outcome for the effort.

                Welcome to the forum of few(er) illusions.

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