Designing Ecological Habitats - Gaia Education

enewable energy anD electric systems Design for ecovillages 171
alternative than allowing the local
power company to bring power to
each building. Depending on your
local utility’s policies, this may result
in more control over the power you
generate plus it can make backing-up
when the grid goes down much easier.
If you are off-grid, this ecovillagewide
mini-grid may be far superior
to an independent system for each
building. If your layout plan is in
three or four major ‘pods’, separated
by some distance, then maybe three
or four sub-systems would be best.
The ideal degree of centralization
depends on the amount of power each
building is using and/or generating
and on the distances between them. It also depends on how many renewable
source-sites you have.
In general, I’ve found that except for very large ecovillages of more than
one-hundred people, or where distances between settlements are more than
a kilometer, centralizing your renewable energy resources will pay in the
long run. That doesn’t mean that every little existing off-grid cabin system
or every building needs to be on this centralized ‘grid’; but generally, you
will leverage your sources as well as your backup and renewable energy
equipment resources more with a centralized system. This can be achieved
even if you are now operating separate stand-alone systems.
Systems Integration
The ultimate in integrating multiple sources of renewable energy – be it
solar, wind, hydro and/or Stirling – is to create a ‘backbone’ of utility-grade
power throughout your community. This mini-grid allows you to add loads
or renewable sources anywhere rather than having to bring all source inputs
to one central location.
If you are on-grid, this mini-grid simply becomes a ‘campus’ electrical
customer to the utility grid with a centralized meter. If the utility requires
individual building metering then you can still create this backbone for
backup and/or phasing off the grid. If you are building a new ecovillage,
it means running conduit between all buildings, and this is well worth it.
With this approach, grid-tie renewable energy inputs can be used to turn the
central meter backwards by feeding anywhere into the mini-grid with gridtie
solar, wind, hydro or Stirling inverters.
If you are off-grid then this mini-grid becomes a very sweet way to
leverage renewable resources. One company, SMA from Germany, offers
an integrated grid-tie/off-grid set of inverters that allow you to feed solar,
Installation at Rocky
Hill Cohousing
in Florence,
Massachusetts,
USA. That’s my
crew finishing an
installation there.