Solar PV - Save Money & Shrink Carbon Footprint

Discussion in 'Business and Economics' started by NeilBlanchard, Mar 21, 2018.

  1. NeilBlanchard

    NeilBlanchard Well-Known Member

    We have been driving EV's for 3 1/2 years, and we are now using a heat pump for most of heating our house, as well. We got a solar PV system installed yesterday, and it should soon be generating a large amount electricity, to offset our use. The system is Sunpower 327 watt panels (about 20% efficient), and it is warranted for 25 years. The system will pay for itself in just over 5 years, with all the incentives, and in less than 10 years without them.

    It is a 10kW system on the AC output, and the estimated annual output is just under 13MWh.

    We have expensive electricity here in Massachusetts - we pay between 18¢ and 22¢ total per kWh (both generation and distribution costs); and we also have chosen to pay another 2.4¢ / kWh to support renewable generation. Even with these costs, driving our two EV's (Bolt EV and e-Golf) cost us only about 4.5¢ / mile.

    Here's the roof panels, on our reconstructed roof (which is still in process):

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    And the equipment in the basement:

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    I am really looking forward to our reduced electric bill, and our reduced carbon footprint.
     
    Last edited: Mar 23, 2018
  2. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    I have not seen the pics yet, but you've made some excellent choices. Thank you!
     
  3. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Yes, I don't see them , either.
     
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  4. NeilBlanchard

    NeilBlanchard Well-Known Member

    I will redo the picture links - I tried using Google, since my phone automatically uploads them.
     
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  5. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    You may have to "simplify" and download from Google photos, upload to CleanMPG, then delete from your phone. I haven't tried loading directly from Google so I can't help with that...
     
  6. NeilBlanchard

    NeilBlanchard Well-Known Member

    I fixed the pictures.
     
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  7. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    Thanks!
     
  8. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Very nice, Neil ! I'd love something like that. And the south side of my house is not bothered by any trees or taller buildings.
    Hmmmmm.........
     
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  9. NeilBlanchard

    NeilBlanchard Well-Known Member

    We had to take down three large trees to open up the sky - the maple logs are in the lower left foreground. There were two tall Norway spruce trees - the taller was about 75 feet tall.

    This entire project was started when our roof wore out. We demolished the roof down to the attic floor, reused the rafters to double the floor joists, put plywood down, framed the 12 pitch roof, and that work continues. We will also gain a larger fourth bedroom, and a large family room / office - and R72 roof insulation! I will be using blown in wool insulation.

    That's four major improvements in one project.

    Edwin, depending on your electricity use, and the space available, you can get up to 360 watt Sunpower panels, that are over 22% efficient. Our system will pay for itself in just over 5 years, and in less than 10 without any incentives. There is not many other ways you can get a better return than that.
     
  10. puddleglum

    puddleglum Well-Known Member

    Very nice! You're going to have a lot nicer home when you're done as well.
     
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  11. puddleglum

    puddleglum Well-Known Member

    Neil, can you disconnect from the grid or are you still going to be tied in? Even 10 years payback for a system that large would be wonderful but seems too good to be true. Then again, I do live in Alberta. Does your $.18-.22 in addition to your fixed costs of being on grid or is that included? You may have a very different billing system than we do here so I apologize if I'm asking a silly question.
     
  12. BillLin

    BillLin MASS: 2018 Bolt EV and 2017 Prime

    Kevin, I'll share my own solar setup in the interim. Until I integrate a battery system into my solar array, it remains a grid connected type system. Grid loses power, I lose power even if the sun is full strength. I don't have a gas/diesel/LP generator attached.

    With a net meter, the flow of electricity to my site is bidirectional. When the sun is out and I'm not consuming all the power, the excess flows out to the grid. At other times, the energy flows from the grid. The net meter keeps track. Each month, if the net usage is negative (produced more than used), then there is no bill. The credit is tracked by the utility company. If the net usage is positive *and* exceeds whatever credit is in the account, then there is a bill for that month. I usually have no bill about 8 months of the year and minimal bills for the remainder. Around November or December, all my credits are used up and with the weaker (actually just lower in the sky) sun, the solar PV system does not produce enough energy to cover our energy use.

    The cost of the net positive electricity usage is billed at the prevailing generation fee plus transmission and other miscellaneous fees. I figure it costs about 20-25 cents per kWh, and mostly about 25 cents/kWh.

    There are other financial benefits to owning the solar panels. There's something called SRECs (renewable energy credits) that are created and traded by the utility companies and other companies that serve the function of aggregating those credits from small generators like us. The power companies must produce a certain percentage of their power from renewable sources, and they purchase the right to use our little home generator as part of their mix. For that privilege, they pay us a dollar amount for each MWh that we generate. That dollar amount might vary from say $200 to double that or better, depending on the scarcity or glut of available SRECs. This SREC revenue stream only lasts for about 10 years from the activation of the solar PV system. This is above and beyond the tax incentives and the free use of the energy that we generate. I imagine this is one of the reasons there are solar leasing companies. They collect the SREC monies.

    One other thing that I liked about Neil's setup is that he runs his heating and cooling using heat pumps. So no added burning of fuel oil or natural gas to heat his home. Most of the energy can come from the PV panels. His system is a little bit bigger than mine. I have 40 ground-mounted panels (250W) driving 40 Enphase microinverters rated at 210W each, so a 8.4 kW AC output system. We went with geothermal heating and cooling, which uses a form of heat pump.

    I'll add more if I think of it, or if there are any questions.
     
    Last edited: Mar 25, 2018
  13. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Neil , thanks for that info. It's nice to get some facts from someone who isn't trying to sell me something. :)
     
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  14. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Ooops , I meant , thank you Neil and Bill.
     
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  15. NeilBlanchard

    NeilBlanchard Well-Known Member

    It is grid tied, for the time being. If we add battery storage (which we hope to do), then we will save even more money, and we can still have power while the grid is down.

    Since we are driving EV's, we save money on gas (and maintenance!), in addition to saving on electricity.

    I am hoping to switch to a biochar retort / rocket stove as backup / supplemental heating. We currently have to use a gas fired steam boiler a few weeks a year, when the heat pump can't keep up with the loss during the coldest days and nights.
     
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  16. puddleglum

    puddleglum Well-Known Member

    Thanks Bill and Neil for the good explanations. I can certainly see how the systems would payback much faster if you are already driving EV's and using electricity for at least some of your heating. Your high rates make a big difference as well.
    I believe having a Solar system here works very similar but the numbers are different of course. You inspired me to look into it a bit again on the weekend. Found out Alberta has implemented a solar rebate program now That's encouraging, but with high up front cost and cheap electricity, I think payback would still be pretty long. I am hoping it's a sign that things are changing though. An EV and solar array have been on my bucket list for a long time
     
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