The outhouse, with our tents and hogan in the distance.
We pitched our tents outside our host family’s hogan outside Sawmill, AZ on day one of CataCAMP. Our hosts, the Begay Family, had a generator to power a refrigerator, a kerosene lamp, and a small propane tank with a hose snaking through a kitchen window to a stove range. We could see and hear the buzzing of a distant high-voltage power line from our tents, but the Begay’s home was just out of range for access to electricity or running water.
According to the the Navajo Tribal Utility Authority (NTUA) – the entity responsible for providing the Navajo reservation with electricity, water and natural gas – 18,000 people on the reservation still do not have electricity in their homes. On day four of CataCAMP, we drove an hour down a bumpy dirt road with the NTUA to reach a home just west of Monument Valley with a hybrid wind-solar energy system, one of the off-grid renewable systems the NTUA turns to for its most remote customers. The distance alone makes servicing the system a large time-commitment, but it also requires a heavy-duty truck to take on the nearly impassable “roads.” The system size (880W for a hybrid system) these families receive are standardized to reduce costs. However, this means that when a family plugs in their refrigerator the electricity “stops working.”
Solar system for a remote family.
It was interesting to listen to the NTUA’s reasoning behind the use of standardized systems when we have tried so hard with our clients to produce custom-sized systems that anticipate future energy needs. The systems on the reservation were lacking, but they adequately performed the main job they were there to do: provide immediate power for moderate energy needs at a cost cheaper than running a electrical line to a house.
System sizing can be a tricky business. Before visiting with the NTUA, our team went through a basic energy assessment workshop called “Present and Future Power Needs” (PDF, 225KB), based on our experience with our Rwanda Solar PV project. The workshop outlines the process of cataloging appliances to understand how much power you need, and uses that number to derive how many solar panels and batteries you need in your energy system. However, what we have witnessed (and what the Solar Electric Light Fund [SELF] has witnessed) is that once we have electricity we tend to over use it if a feedback loop is not in place. Our sizing template accounts for that anticipated over use with a formula supplied to us by SELF.
While the second half of the workshop is specific to solar, the first half is relevant to any entity that wants to understand what size energy system they need. Knowing that number will affect your cost and your choice in technology (wind, solar, biogas, etc). Regardless of what technology you choose, it should be accompanied by training, maintenance and feedback loop that educates the user on consumption.
System sizing references: Green Empowerment
