A few years ago in a solar marketing department near you an enterprising executive had an epiphany: the word “microgrid” could be adapted to describe any system of any size and then used to confer a marketing advantage. Moreover, the more timely and part of the solar-lexicon the phrase microgrid became, the bigger and broader the opportunity it could describe potentially applying to everything from a residential PV system with a battery to a multi-megawatt installation. As long as the installation could be described as distributed generation (DG), it can be a microgrid.
The DoE defines a microgrid as “a group of interconnected loads and DG resources within clearly defined electrical boundaries that act as a single controllable entity with respect to the grid. It can connect and disconnect from the grid to enable it to operate in grid connected or island mode.” Under this definition, a forecast for microgrid deployment is roughly equal to global electricity demand.
Merriam-Webster defines “microgrid” this way: “The word you’ve entered isn’t in the dictionary. Click on a spelling suggestion below or try again using the search bar above.”
The microgrid concept has received considerable interest recently as incentives for grid-connected applications have decreased, changed and ended altogether. Microgrids, however, date back decades to when off-grid deployment was close to 100 percent of demand for solar technologies.
Of course, for microgrids to capture a major share of electricity production battery technologies (other than already mature lead-acid technology) need to mature rapidly with a cost structure that allows for sustainable profit margins. Battery technologies will need to be affordable as well as safe.
History and Future Growth of Remote Village Grids
Remote village grids are the great grandparents of today’s microgrids. In the pioneer days of the photovoltaic industry, solar technologies were viewed as too expensive and mostly regulated to deployment in the developing world. In these early days climate change was considered a myth and a PV system in the grid-connected world was considered a counter culture.
Remote village grids do not compete with utility-generated electricity and are competitive with small engine-driven and polluting gas generators. Cost sensitivity is a limiting factor in the rate of market penetration in the developing world, though not in the industrialized regions, where living-off the grid either for vacation homes, or for living year-round remains a matter of personal choice.
Village grid systems have traditionally ranged <10-kWp to 50-kWp, but are trending towards larger configurations with some systems >1-MWp, though systems in this range are in the minority. Storage for village grids is the mature though polluting lead-acid battery technology, though hybrid systems using polluting diesel generators are common.
Education as to what a photovoltaic village grid can provide as well as how to provide ongoing maintenance is crucial for successful deployment. Users must understand clearly what to expect and conservation as well as participation is crucial. In some cases, poorly set expectations have resulted in low user satisfaction. Payment methods remain a concern.
Portable generators used for emergencies or to power construction operations fit into the category of microgrids in developing as well as industrialized countries. Portable generators are typically, 5-kWp to 25-kWp off-grid units with battery backup built on trailers that can be linked together to form a larger generator or used singly, depending on the needs of the facility, requiring remote power.
Remote markets typically lack incentives and so avoid incentive risk and the headaches that come along with relying on government market-stimulating instruments. Unfortunately, government plans for PV in rural areas often fall victim to administrative and bureaucratic delays, which are an entirely different type of headache.
Figure 1 provides history and a forecast for remote village grids. Growth in this category is not of the roller coaster variety experienced by photovoltaic deployment in the industrialized, grid-connected countries. Deployment of PV in the remote village grid application has been and is expected to be stead – boring, but steady. Two scenarios are presented, accelerated and conservative. Over time this village grid application has most often performed in line with the accelerated scenario.
Figure 1: Village Grid Growth, 2004-2019 (Off-Grid)
Figure 2 offers grid-connected photovoltaic growth from 2009 through 2019. Two scenarios are presented with the accelerated scenario most likely for 2015 and 2016. Following 2016, significant changes to incentives should slow the market unless, that is, participants are willing to deploy unprofitably. As PV industry participants have a long history of willingness to eschew profit in favor of growth, the accelerated scenario is highly probably throughout the forecast period.
Figure 2: Grid-Connected Market Growth, 2009-2019
The Future of the Microgrid
Changes in incentive structures as well as the amorphous definition that applies to microgrids indicate that deployment (or at least projections of deployment) will be strong in this category for at least the next few years. It does not really matter, of course, what the installation is called as long as deployment is at a value that favors both sides of the seller/buyer equation. The concept of a microgrid, as defined by the DoE, requires storage. A PV system that can operate independently from the grid begins to fulfill the dreams of those pioneered the terrestrial PV industry. Fingers crossed that developers of battery technologies are not driven down the road to unprofitability as were the developers of photovoltaic cells and modules.
Lead image: Earth with solar and wind. Credit: Shutterstock.