Grid Interaction is Here. Are You Ready?

Your solar training today can prepare you for the grid tomorrow.

By Mark Cerasuolo

To fully understand the challenges facing the “next grid,” let’s step back a century to the original one. If we could somehow take one of the grid’s leading architects, Nikola Tesla, and bring him here, he would easily understand and, with a little training, even be able to service and troubleshoot a modern electrical station. Grid design is much the same today as it was almost 100 years ago, based on a geographically-dispersed network of loads powered by distant, centralized generation plants.

classroomSolar- and wind-produced renewable electricity sources are now challenging this grid “status quo,” as small rival generating stations. Grid architecture from the Tesla era was simply not designed with bi-directional energy flow from local sources in mind. While modern grids’ automatic and manual safeguards keep operations relatively stable, any extra renewable energy increases the risk of grid instability. Despite solar and wind energy being ideal for loads during periods of peak energy needs, when the wind stops blowing and the sun stops shining, power plants have trouble shifting production to make up the leftover power deficit. This is because centralized power plants are designed chiefly for baseline demand.

As renewable energy rises in use, it presents challenges and opportunities for the grid. One way to bridge the challenges and opportunities is local, deployable energy storage. For solar installers looking to cross that bridge, it’s time to make learning storage-based systems a training priority.

Nowhere is this need for storage more apparent than in the Golden State. California is well on its way to accomplishing its 2020 goal of having 33 percent of its electricity sourced from renewable energy, currently using 15 percent. The downside is that the state’s systems at times have 40 percent more renewable energy than can be used. Steve Berberich, the CEO of California ISO, the statewide system operator that runs California’s grid, was recently quoted by The Wall Street Journal saying, “The problem is we have a system now that needs flexibility, not capacity.”

California is not the only casualty of surplus renewable energy; the influx of power from new resources is also next on Europe’s list of concerns. Europe’s use of variable wind and solar power is introducing grid instability in addition to tectonic shifts in the economic landscape. Simply generating lots of renewable energy is not enough for a grid-stable future. Storing and using that energy is the next growth area, on a macro as well as a micro scale.

Diversify your know-how
According to research from IHS, the energy analysis firm, the global market for PV storage will reach $30 billion by 2017, up from $8.7 billion now. Additionally, solar research firm Photon predicts that battery-based solar inverters will surpass grid-tied string inverters within the next 36 months. The growth of energy storage is such that it will achieve peak penetration with residential installations, which we see coming within reach of practically all solar professionals.

AC Coupling Diagram

AC Coupling Diagram

While utility-scale storage is still being considered and debated, residential and commercial installers can take advantage of “microgrid” technology long proven in the developing world to power schools, hospitals and villages, and use it in their installations today. “Thinking locally” with storage means moving beyond simple grid-tied renewable systems to grid-interactive or grid/hybrid types, which not only save money when the sun’s up but provide off-grid independence when the grid is down, compromised or when renewable sources aren’t available (when the sun stops shining and wind stops blowing). Even existing renewable energy systems can get into the storage act with a technology called AC coupling which lets an owner retrofit a simple grid-tied system into a grid-interactive one by adding energy storage and augmenting the original grid-tied inverter with a second, smarter grid-interactive inverter/charger.

Learning from the pros
There are a lot of new concepts to be learned to cross this bridge, including bi-directional system design, battery chemistry, handling and sizing and more, but there are ample training and certification programs in place to meet the growing demand. OutBack Power is one manufacturer of components and systems using energy storage that’s providing comprehensive training in this area, which is registered with the North American Board of Certified Energy Practitioners (NABCEP). This is especially important in the residential building market, where builders and homebuyers are very focused on “turnkey” reliability and long service life with reduced system maintenance — for them, certification means assurance and ultimately acceptance.

“It takes more knowledge and planning to design a grid-hybrid system than a grid-tied system,” notes Brad Burkhartzmeyer, a NABCEP-certified trainer, project manager for the Solar Electric Light Fund and a technical project director for installations in Ghana, Nicaragua and Bolivia. “One must more precisely match arrays to the customers’ loads and energy priorities than one does when installing a simple grid-tied system, and selecting the correct battery for the customers’ needs requires knowledge of different battery types as well as learning appropriate wiring methods for battery banks to assure proper charging and longer service life. In addition to sizing the solar system to the customers’ loads, the integrator has to know how to size the battery storage bank to provide the power needed for the duration of power outages. Battery-based systems are OutBack’s core competency, and its program is the quickest, most effective learning path for installers who wish to increase their own level of expertise to enter and succeed in this important solar growth area.”

Burkhartzmeyer discussed his participation and teachings at OutBack Power’s training program, stating, “Installers who have primarily been working in the grid-direct solar market will appreciate the course as a way to expand their business into the grid-hybrid market.”

A successful hands-on training program for renewable energy systems designed for tomorrow’s grid that covers instruction in all balance-of-system (BOS) areas, including sizing design and battery technologies for system needs in addition to system setup and programming, is the key to bringing energy storage technology literally home and designing and selling smarter systems that can do much more than “make hay while the sun shines.” Tomorrow’s systems should be able to deal with everything from peak-shaving and offset to extended outages from life-changing events. And by being intelligently planned today around energy storage technology and effectively creating a “microgrid” for the home, they’ll be ready for whatever form the big grid ultimately takes.

To adapt to the energy needs around the world, people need to implement a system that is much more evolved from that of 20th century innovators like Tesla. The microgrid concept allows one to have the flexibility of storing energy to maintain everyday loads when the big grid is down, while also reaping the benefits of using power when it’s most convenient for the user.

Mark Cerasuolo manages marketing at OutBack Power, a designer and manufacturer of BOS components for renewable and other energy applications.

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