Positive Energy Homes
Positive Energy Homes are Zero Energy Homes that are so efficient that the homes produce more energy than they consume. They are the gold standard for green homes. A home can be designed and built as a Positive Energy Home from the start, or homeowners can gradually transform their Zero Energy Home into a Positive Energy Home. The excess energy produced can, in some states, be sold back to the grid, or it can be used to power solar vehicles or tools.
Paths to a Positive Energy Home: There are several paths to creating a Positive Energy Home. The first and most obvious is to oversize the solar collectors so that they produce more energy than the home consumes. A second path is to start with just enough solar panels to create a Zero Net Energy Home with a solar photovoltaic (PV) system that can easily be expanded if an electric vehicle is purchased. The use of micro-inverters allows for more panels to be easily added, smoothing the path to creating a Positive Energy Home with the addition of more panels in the future. A third path to a Positive Energy Home involves starting with a Zero Energy Home and then utilizing an energy monitoring system to systematically monitor and reduce your family’s energy consumption, so that it is lower than your home’s energy production. A fourth, related path is to continue living in your Zero Energy Home once your children have grown and left home. At that point, your energy consumption will drop, while your home’s energy production stays constant and the home’s energy production moves into positive territory.
Examples of Positive Energy Homes: A pioneering Positive Energy Home was built as a ranger’s residence by the National Park Service at the John Day Fossil Beds National Monument in the Painted Hills of Oregon. This home is described in the National Park Service’s Painted Hills Briefing and in a Project Description for the Presidential Green Government and Green Innovation Awards. Carter Scott of Transformations in Townsend, Massachusetts has built affordable Positive Energy Homes, called Net Plus Homes™.
How to Use Excess Energy Production: In some states and power districts, people can actually sell their excess electricity back to the power company to make a profit and more actively contribute to the reduction in greenhouse gas production. In many locations, however, once you have achieved net zero, you cannot sell your excess production to the electric company. In that case one of the most economically sound ways of utilizing the excess electric production is to power an electric vehicle, so that your Positive Energy Home provides you with Zero Net Energy local transportation. If the excess energy produced is more modest, another possibility is to power an electric leaf blower and electric lawnmower so that you no longer need the highly polluting and noisy gas-powered versions.
Solar Powered Vehicles
All-electric vehicles can meet all of a family’s local driving needs, while plug-in hybrids can meet long-distance driving needs as well. In some communities and family situations, electric bicycles and road-worthy golf cart vehicles can be utilized for a significant portion of local transportation needs. With a Positive Energy Home you may have sufficient excess solar electric production to power one of these vehicles. For example, with the kilowatts produced by a 3 kWh solar PV system in northern Oregon, you can power an electric car, such as the Nissan Leaf, for approximately 10,000 miles a year. In other words, your car can be powered by the sun that hits the roof of your home. With an electric car like the Leaf, depending on driving conditions, you can travel up to about 90 miles per charge, which could allow for commuting to work and doing all your local travel. A simple rule of thumb for the northern U.S. is that 1 kWh of electricity will power an electric car about 3 miles. A 2 kWh PV system will produce about 8 kWh per day on average, which will power a car for 24 miles per day. A 3 kWh PV system will power a car for about 36 miles per day. In the southern U.S., photovoltaic systems will produce even more kWh each day. Utilizing a positive energy home to power your electric vehicle provides free transportation and frees you from gas price hikes and possible shortages, and helps to reduce your overall carbon emissions to Zero.