Five Questions To Ask About Grid-Interactive Energy

by | Nov 29, 2011

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Renewable energy is a market on the move. With announcements coming nearly every day about the latest advances in harnessing the elements for cleaner, cheaper power generation, it’s easy to see how something at the system integration level might get overlooked. But the industry should not make the mistake of ignoring what’s happening with battery-backed photovoltaic (PV) inverter systems. Grid-interactive PV systems solve problems that have long plagued both off-grid and grid-tied applications, providing integrators with previously unavailable flexibility and reliability for high-end deployments.

So what should these integrators ask to get up to speed on grid-interactive systems? Here are five key questions.

1. What does it mean for renewable energy to interact with the traditional grid?

Grid-interactive PV systems can tie into the local energy utility when it benefits users and opt out when it does not. So, if the traditional utility grid goes down, the user can still continue operating by drawing power from PV modules, a generator, a wind turbine or a backup battery system. Conversely, if the user wants to lower his energy costs and consumption, he can rely primarily on renewable energy sources, turning to the grid only when those more environmentally favorable methods fail. In this way, grid-interaction lets consumer and commercial users get highly reliable, cost-conscious energy while staying environmentally aware.

2. How does this differ from grid-tied systems?

Grid-tied PV systems use PV modules with high-voltage string inverters to convert direct current from the modules to the alternating current of the grid. The energy is then fed directly to the grid. There are cost benefits to that tied approach, but for users joined to the power grid in this way, there is no option to turn to renewable energy when the utility fails. If the grid has a problem or goes down, safety standards require the grid-tied system to disconnect. This raises reliability questions for users, who have few options in the event of a brownout or blackout.

3. What about staying off the grid altogether?

Off-grid systems were certainly the dominant choice among PV users a decade ago. They were used mostly in remote areas or places where the utility grid was too expensive of an option. These off-grid PV modules and inverter/charger power conversion systems had to be ultra-reliable because they offered the only means of power generation. That all-or-nothing option, however, came with risk. Outages could be frequent depending on weather patterns, and when the power went out, there were limited back-up choices.

4. Why isn’t grid-interactive already dominant in the market?

There is a struggle over this issue between proponents of off-grid and grid-tied PV systems. Early off-grid users created PV systems for their homes and businesses from scratch, but the components these hobbyists pieced together years ago are now mass produced, widely available and easy to install. The market has taken the best of the off-grid components and incorporated them into grid-interactive systems. As solar energy production goes mainstream, the availability of pre-assembled systems, such as grid-interactive inverters, will become more prevalent.

5. How can system integrators communicate the value of grid-interactive PV systems to customers?

Users can commit themselves to a renewable energy future without suffering the risks that come with completely off-grid power consumption. The option of grid interactivity lets businesses and consumers rely primarily on the cleaner, less expensive options of solar, wind or hydro power, while keeping open the option of going to the grid when necessary. The outcome: greater energy reliability, lower bills, smaller carbon footprints and happier end users.

Increasing flexibility in power generation

Whether they were tied to the grid or completely free of it, most energy consumers have suffered the effects of power outages. To lose a refrigerator full of groceries or lose a day of productivity when the business goes dark is a frustrating experience that sparks conversation about better options. Adding further to grid-tied power generation frustrations, developing parts of the world often only have access to the grid for part of the day. A grid-interactive system can provide continuous access to electricity with additional compatible and connectable sources. The market does not want to increase coal, nuclear or other controversial forms of power generation. The call is for greater reliability AND cleaner production. By providing ongoing cost savings and a reduced carbon footprint, grid-interactive systems answer that call.

As residential and commercial building owners increasingly adopt alternative energy for purposes of savings and environmental impact, they find that grid-interactive options let them simultaneously boost reliability. Building owners and facilities managers are turning to alternative energy sources such as solar and wind in order to offset rising utility costs. Grid-interactive renewable energy allows them to lower their utility bills and increase power reliability. These power users asked hard questions about grid interactivity, and those who adopted grid-interactive systems are today left with only one remaining question: why didn’t we try this sooner?

Harvey Wilkinson is the General Manager at OutBack Power, where he is responsible for increasing market growth and revenue expansion. With more than 25 years of experience in the energy and technology markets, his previous positions include Ioxus, Inc., A123 Systems, AVESTOR and Beacon Power Corporation.


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