The Hut Hamlet’s kitchen/bathhouse — central distribution area for the neighborhood’s Microgrid.

In June, twenty-two residents of the Hut Hamlet neighborhood became owner/users of the first electric Microgrid at Earthaven! Chris Farmer of SunWorks Electric installed an 8.16 kW solar array and power system to serve 11 huts, and the neighborhood kitchen and bathhouse. The system will produce, on an average day, 31.5 kWh of electricity, which is what the average American house consumes.

After Chris and fellow valley solar electrician Brandon Greenstein had to troubleshoot, fix, or upgrade too many small, old, self-installed systems, they decided that to install one new, state-of-the-art system wired to code for the entire neighborhood.

One of the greatest obstacles to creating a shared off-grid power system is the different levels of electrical needs, as well as levels of consciousness around usage, people have. How does a group deal with this fairly? The Microgrid has a metering system that records different users’ true impact on the system, and charges users accordingly. Earthaven resident Jake Ferina wrote all the computer code for the weighted metering system, as well as for an Automatic Generator Start program better suited to off-grid solar than any offered on the market.

One perennial question in off-grid solar design is how big a battery to install. Too small, and it’s almost useless. Too big, and without an appropriately sized array, the batteries will not adequately re-charge after cloudy spells, But if the array is large enough to keep the batteries well charged, during sunny spells much of the energy from the panels will go to waste. We avoided this conundrum by installing a Diversion system that diverts excess electrical production to a conventional electric hot water heater. This 1) protects the batteries while 2) providing a freeze-proof solar hot water system.

Before the Microgrid, some residents had enough power for a light and a laptop, while others had upgraded to power refrigerators. The new plan, which took many minds over many months to work out, plus weeks of disrupted phone lines and paths, has been running smoothly for a few weeks and the future of power in the Hamlet looks, well, …brighter!

For the list of components in the Hut Hamlet Microgrid, see this entry in the Earthaven blog.

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