Cohousing-L Mailing List: Re: Solar microgrid, anyone?

[Bryan Bowen (bryan]

Hey David,

I believe your thinking is spot on. Also, I fear it may be too great a cost
to retrofit an ideal system into older existing residential buildings, but
it's totally dependent on factors that vary quite a bit project by project,
including the utility provide/regulatory environment. If we're repurposing
an old building to become cohousing, it's usually pretty easy since we're
upgrading everyone already.

What we tell our forming communities:

   - If you're able, meter the project as a whole or building by building
   (instead of unit by unit)
   - Definitely need to understand utility billing and electrical codes to
      make this determination.
      - Plan for rooftop solar (rough in) as well as solar gardens on
   garage/carports/the CH, or ground mount to meet a NZE level of production.
   - Sub-meter individual units (e-gauge
   
<https://store.egauge.net/?gclid=Cj0KCQiAubmPBhCyARIsAJWNpiPoEhrNnArd5pdQBrKwZQZV6ahgo1UHXRDU_jFgi0yVkELuL6vYH70aAnM9EALw_wcB>
   etc) for your own billing purposes if you'd like (same with domestic water,
   actually, it's more important)
   - Go all electric and plan for a future increased share of electric
   vehicles.
   - And while you're at it, plan for tons of bikes of different
   configurations to be parked in ways that really work for people. You want
   to encourage as much of a mode shift as possible.
   - Make a resiliency plan that includes consideration of what natural
   disasters etc you might have to survive and for how long, and size a
   battery back up to meet at least your critical loads.
   - Include all of this thinking in your decision making process, through
   one of the usual workshops or a stand alone series on
   sustainability/resilience.

Having meters on each unit usually means you're locked in to providing PV
on a unit by unit basis. Metering more collectively allows the highs and
lows to balance out better and to keep system design less redundant and
expensive.

- b

BRYAN BOWEN    |    PRINCIPAL   |    AIA   |    LEED AP

*caddis collaborative*
1521 Easy Rider Lane #102
Boulder, CO 80304
303 443 3629
caddispc.com


On Mon, Jan 24, 2022 at 12:30 PM David Mandel <dlmandel [at] gmail.com> wrote:

> The great information about EV charging prompts me to ask this question
> that I've been starting to explore for my community.
>
> More than a quarter of our households already have EVs and that is sure to
> grow. We've installed a couple of shared L2 charging stations using
> existing meters (one common, one at a household -- users reimburse for the
> cost) and are looking into ways to install more.
>
> But this begs some other urgent questions. EV charging increases our use of
> electricity, as does the gradual replacement of gas-powered appliances
> (heating, stoves, dryers) with electric that is happening or contemplated
> in individual homes and the common house.
>
> And we have been warned that the transformers supplying our electricity,
> installed when we built the community 29 years ago, are likely insufficient
> to handle the extra demand. To merely find out the degree of the eventual
> shortfall would cost thousands of dollars, our utility tells us, let alone
> to upgrade/replace them.
>
> Moreover, our units were all wired with only 90 amps of service, low by
> today's standards and insufficient, some tell us, to operate the additional
> chargers and appliances many of us would like to install unless we take
> care not to use too much simultaneously.
>
> This leads to consideration of how else we could both increase supply and
> spread out demand. And the obvious answer is rooftop solar.
>
> Two households have already installed panels, but doing it individually
> does not really seem the best way. Some of our roofs are a lot more
> suitable than others (shade, direction, configuration), and for any that
> are highly suitable, the utility doesn't allow you to generate more power
> than you already use. (How shortsighted!) This is on top of a major push by
> California (and probably other) utilities to drastically lower the rate
> they pay for net metering, as well as imposing a high fee for solar users
> to maintain "their share" of the grid. (Another shortsighted approach
> seemingly driven by the current economics, not the pressing need to
> decarbonize.)
>
> A great answer in theory would be to develop a community microgrid, which
> would involve:
>
>    - Maximizing the amount of generation by installing panels on the most
>    suitable roofs, individual households and common structures.
>    - Using batteries to store the power, enabling its accumulation and use
>    at the most appropriate times of day.
>    - Finding a not-too-complicated way to distribute the energy and share
>    the costs and benefits among households.
>
> I'm engaged in early conversations with some solar designers/installers who
> are interested in the idea, and with a board member at our (publicly owned)
> utility about getting its cooperation and assistance.
>
> So my question is whether any of you have accomplished or are contemplating
> such a project. If so, let's compare notes and ideas.
>
> One more thing: It's clear that accomplishing this would be very expensive,
> probably beyond our community's ability to finance fully even with a
> long-term, low-interest loan -- which would make sense for part of it. What
> other possible sources of funding might be available?
>
> Thanks for any ideas,
> David Mandel
> Southside Park Cohousing, Sacramento
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