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Increasing Solar Capacity to Reduce Wall Cavity Size

avery_law | Posted in Energy Efficiency and Durability on

I am in the planning phases of a duplex in coastal Maine that I will be building myself. I have been working for a builder for about 5 years now.

Basic building specs: 1800 sqft, ranch style single story, 2x 2br units, concrete slab, energy heel trusses, 2′ overhangs all around.

Originally, the plan was to do a double stud wall similar to what Dan Kolbert does. That evolved into a “wrap and strap” with 2×6 exterior walls with dense pack cellulose and with 2×4 horizontal framing on the interior with Roxul.

NOW my thought is, why not go with a 2×6 wall with dense pack cellulose, be extremely particular with air sealing, and simply upsize the array of the PV panel which will provide power to the heat pumps to each unit. (Yes, I plan to include heat for each renter. Powered by Solar) Is this a solid plan? Upsize PV, reduce wall thickness, and AIR SEAL AIR SEAL AIR SEAL.

Has anyone tried reducing wall construction complexity and labor by upsizing mechanical and PV systems to create similar reductions in environmental impacts? Maybe I am just trading one for another and not really gaining anything in the end? Thanks in advance.

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  1. Expert Member
    NICK KEENAN | | #1

    There's definitely a point where a dollar more of insulation delivers less value than a dollar's worth of solar. Whether you're at that point is impossible to tell just from the description, you really have to do some energy modeling.

    Also, keep in mind that solar may be less attractive in the future as net metering by utility companies becomes less generous. The utilities are already beginning to balk, and net metering as currently practiced in many places is clearly something that couldn't work if it was broadly practiced.

    1. avery_law | | #2

      That is a good point about the net metering. Not something I had considered. Net metering can be taken away pretty easily. Insulation will also continue to do its work long after the life of a solar panel, inverter, or net metering agreement.

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