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Off-grid

In an increasingly tech-connected society, it’s ironic that there are more reasons than ever to live off the grid.

Some of those motivations haven’t changed. Homeowners might want to live in a site that’s simply unreachable by the electric grid, or they might be motivated to be independent in terms of energy and other factors, like food. But there are also new forces providing economic motivation to go off the grid. Interconnection fees from the electric or gas utility are now extremely high in some areas, while the price of on-site power systems such as solar panels and batteries is dropping. And in areas such as California experiencing public safety grid outages, homeowners want to be prepared for life on an unpredictable power grid.

With the potential for more customers to approach you about off-grid projects, the timing was right for the Propane Education & Research Council to build a new training course on designing off-grid homes. Developed in partnership with Newport Partners, LLC, an energy consulting firm specializing in housing, Energy Options for Off-Grid Homes: The Role of Propane in Off-Grid Designs evaluates the options available for renewable energy generation, energy storage, and backup power generators in off-grid homes.

The course identifies seven key features that builders and architects must consider when designing off-grid homes. For a more in-depth discussion of these topics, and to earn continuing education credit, check out the course at the Propane Training Academy.

7 features of off-grid living

On-site electric energy generation. Since off-grid homes can’t rely on the electric grid, they have to create their own power. And for the majority of projects, that means solar photovoltaic panels, says Jamie Lyons, senior consultant at Newport Partners. Over the past 10–15 years, solar panel prices have dropped by a factor of 2–3, he says, and due to that price drop, deployment of PV is on the rise. But while on-site energy generation is one of the most critical factors in off-grid designs, it’s not sufficient by itself. PV generation can drop during the winter or in cloudy weather. “It’s not going to provide all the power, on a daily or monthly or annual basis, the home will likely need,” Lyons says.

Source: U.S. Energy Information Administration

Battery storage. It’s not just power generation that can vary; usage will fluctuate as well. So off-grid homes will typically use batteries to support the home’s electric usage. The sizing of electric generation and battery systems has to balance several factors, including cost and the electrical loads on the home. Thoughtful design of the building envelope and use of propane for large thermal loads such as water heating can help avoid the need for an enormous solar PV and storage system.

Backup generator. During prolonged periods when the solar panels aren’t producing enough to meet a home’s electric demand, an off-grid generator provides a continuous supply of power to keep the home running. “Generator technology has evolved to the point where it’s not one size fits all,” Lyons says. Generators designed and warrantied specifically for off-grid applications integrate with the home’s battery and renewable systems to recharge the battery bank whenever the power level drops too low. A key benefit of propane generators over diesel is that propane can be stored for long periods without destabilizing. Propane is also more versatile in powering other systems in the home.

Building envelope design. Even more than grid-connected homes, off-grid homes must be thoughtfully designed to reduce heating and cooling loads. Designers should specify high levels of insulation, use rigorous air-sealing practices, and even consider reducing the size of the home. They should also take advantage of the characteristics of the construction site, Lyons says. “In many off-grid homes or in remote locations, they might have access to steady winds, which can be used for natural ventilation,” he says. “Some off-grid homes are built into the side of hillsides that take advantage of the thermal mass of the earth.” Passive solar techniques can help provide free heating from the sun in the winter while helping to avoid overheating in the summer.

Although outdoor clothes drying is preferred, propane clothes dryers remove a major electrical load from off-grid homes in rainy weather or during cold winters.

Mechanical systems. When it comes to mechanicals, the overall goal should be to reduce the electric budget, Lyons says. An effective strategy is to shift thermal loads from electric to propane and to focus on using high-efficiency systems. Some propane-heating and water-heating systems are designed to use very little electricity. Propane wall heaters, for instance, might rely on air convection to circulate heated air or use small, highly efficient fans. Some styles of propane tankless or tank-style water heaters do not require electricity to function.

Appliances and lighting. Some of the innovations in home systems over the last 5–10 years make it easier to reduce electrical loads. LED lighting, for instance, consumes 75 percent less energy than incandescent lighting, providing a very cost-effective way to trim electricity usage. In addition to using other high-efficiency electrical components, such as air conditioning, energy-recovery ventilators, and kitchen appliances, designers can consider specifying a propane dryer, which uses much less electricity than an electric dryer when outdoor clothes drying isn’t possible.

Homeowner behavior. Your clients have a huge impact on how their off-grid home will perform, Lyons says. “Off-grid homeowners are generally going to be fairly cognizant and aware of how they’re using the home, but there’s a learning curve,” he says. Architects and builders can help shorten that learning curve by providing guidance on heating and cooling set points and optimizing the use of electric appliances to avoid prolonged cloudy periods when the batteries are low. Implementing system monitoring can help homeowners understand how much power they’re consuming and generating at different times of the day or year.

Energy Options for Off-Grid Homes: The Role of Propane in Off-Grid Designs provides a deep discussion on these topics and more, including incentives for off-grid technologies and examples of builders with successful off-grid projects. Visit the Propane Training Academy to claim your continuing education credits and get prepared to discuss the energy options for your next off-grid client.