For much of renewable energy’s history, consumers adopting renewable energy systems faced have two very different options when it came to solar power. They could remain tied to the power grid and use their renewable energy source to offset their electricity use. Or, if they were brave enough, could take the plunge and try going completely off-grid.
The first option has limitations, including a big one: for safety-mandated as well as performance reasons, a “grid-tied” system has to disconnect during a power outage—no fridge and no TV even in broad daylight. And while second choice may be an idyllic one as part of a “cabin by the lake” scenario, off-grid is not a practical solution for most urban and suburban dwellers.
Today, there is a better choice, and it’s making renewable energy more attractive to a wider base of consumers. Grid-interactive photovoltaic (PV) systems are capable of bi-directional energy transfer; they can tap into the local utility when their owners need to do so and switch off when renewable sources are preferable. The result is that consumers can lower their energy costs, cut their consumption, and gain the option of greener living while also gaining the security and reliability of a back-up power source.
In terms of overall savings, green living, and resale value, grid-interactive energy is a win for consumers. Grid-interactive systems save users money on utility bills and take advantage of net metering (running the meter backward), which is offered to some degree by almost every state. During times of strong sunlight and relatively light load demand, net metering makes solar power systems especially compelling, as users can sell surplus power back to their utilities. There is an additional financial incentive from production credits, as well. In Washington State, for example, the government pays grid-interactive users up to .54 cents per kWh for producing electricity, even when the system owner consumes that electricity, as long as the main components (panels, inverters, controllers, etc.) are made locally.
For users seeking a greener lifestyle, a grid-interactive system is a reasonable next step after adopting high-efficiency lighting, improved weather sealing, and other essential upgrades in sustainability. Unlike wind turbines and micro-hydro installations, solar power doesn’t need sustained breezes, understanding neighbors or running water on the property. Sunlight is everywhere, and solar power has zero impact on the environment as a solid-state, low-impact energy source with no moving parts or complex transmission systems—solar energy is made locally and used locally. It’s an easily deployable form of renewable energy, and the grid-interactive option of harnessing solar power makes it low risk in terms of reliability, as well.
A grid-interactive system also pays off when a consumer is ready to sell his or her property. According to a recent Forbes article, solar energy system owners can regain as much as 97 percent of their renewable energy investment when they sell their property, higher than almost any other popular home upgrade. Perhaps most important in this slow housing market, solar energy system-equipped homes can sell twice as fast even in depressed markets, according to a U.S. Department of Energy study. One more bit of good news for homeowners who adopt greener living through grid-interactive solar power systems: a study in Southern California by the National Renewable Energy Laboratory found that solar-equipped new homes increased in value at a faster rate than non-equipped comparable homes.
Grid-tied systems can offer many of these benefits, as well, but with caveats. When the local power grid is operating normally, grid-tied systems have the same advantages as grid-interactive. However, when the utility goes down or its output fluctuates, grid-tied systems are incapable of delivering power. Users of these systems must disconnect from the grid during brownouts or blackouts, and even if they could remain connected their systems simply aren’t equipped to harness raw solar power on their own.
Grid-interactive PV systems give consumers the best of both worlds – the choice to connect to the grid or rely on solar backed-up power, depending on which is more preferable at any particular time. While the grid-interactive option essentially delivers twice the system, it doesn’t cost twice as much. The difference between grid-tied and grid-interactive inverters starts at 15 percent with essential back-up capability (this generally powers the furnace, some lighting, refrigerator, TV and Internet/computer).
To be tied to the grid is to know the frustration of its limitations. The same can be said of renewable energy systems that are completely free of utilities. Grid-interactive energy delivers uninterrupted electricity while maintaining a focus on renewability. Users save money, reduce their carbon footprints and gain peace-of-mind with a back-up power supply ready for any emergency, making grid-interactive power an energy option with wide appeal.
Article by Mark Cerasuolo who manages marketing at OutBack Power, a designer and manufacturer of balance-of-system components for renewable and other energy applications. Previously, he held senior marketing roles at Leviton Manufacturing, Harman International and Bose Corporation, and was active in the Consumer Electronics Association (CEA).