What is a DC Microgrid?
A DC Microgrid is a new approach to stand-alone renewable energy systems, that is much cheaper and more reliable than typical off-grid energy systems. This system was developed at Living Energy Farm, an intentional community and environmental education center in Louisa, Virginia, where a DC Microgrid has been successfully serving the energy needs of about a dozen people since 2011.
DC Microgrids are effective because they work with the strengths of renewable energy, instead of trying to make renewables behave like fossil fuels. The emphasis is on providing services, not bulk energy. For this reason we like to describe the DC Microgrid as a permaculture approach to renewable energy.
A DC Microgrid looks different in different locales, depending on wind and solar resources, local climate and energy needs, etc. But the design principles are the same everywhere. These principles are:
—First maximize conservation, efficiency and insulation. Solar energy is only useful when demand is minimized.
—Minimize battery size by storing energy in forms other than electricity. The bulk of the stored energy in a DC Microgrid takes forms such as a hot or cold thermal mass, pressurized water, or biogas.
—Operate high-demand electrical appliances as daylight drive only. In daylight drive systems, DC motors and resistive loads are wired directly to photovoltaic panels with no batteries or other hardware involved. These appliances are used only during the day.
—Keep electrical hardware as simple and durable as possible. A DC Microgrid uses no inverters or AC electricity, and use nickel iron batteries, a non-toxic battery technology that lasts 40 years or more.
Click here to learn about the DC Microgrid we have at Living Energy Farm in more detail.
Why are DC Microgrids Better than Grid-Tie Solar?
Grid-tie solar and wind systems work, as long as fossil fuels (particularly fracked natural gas) can make up for demand when the sun isn’t shining and the wind isn’t blowing. Because with grid tie there is no incentive to conserve at those times, phasing out fossil fuels presents a huge technical challenge. Large scale lithium battery facilities are very expensive and would have massive environmental footprint for the manufacture and disposal of the batteries, which only last 4-5 years. This is not a practical solution for the majority of humanity, which is not wealthy.
DC Microgrids have a drastically reduced cost and environmental footprint because they incentivize energy use when solar energy is most abundant, thereby minimizing the need for expensive energy storage. The majority of energy storage in a DC Microgrid is non-electrical storage, which is much cheaper and more durable than batteries.