The Advances and Advantages of Solar Power and Battery Energy Storage
by Mark Hanson PhD LEED AP BD+C and Jody Andres AIA LEED AP
This article originally appeared in the December 2021 School Business Affairs magazine and is posted with permission of the Association of School Business Officials International (ASBO). The text herein does not necessarily represent the views or policies of ASBO International, and use of this imprint does not imply any endorsement or recognition by ASBO International and its officers or affiliates.
No matter where you live, you’ve likely heard your local weather service describing an “unprecedented weather event”, a “100-year storm”, raging forest fires, or depleted reservoirs.
Rising sea levels, extreme weather events, and the degradation of natural resources are a direct result of carbon and other greenhouse gas emissions, which threaten global economies and national security.
In the United States, approximately 40% of greenhouse gases are attributed to carbon produced by buildings during construction and by everyday heating, cooling, and lighting. These emissions can compromise our future as they irreparably transform our planet.
"Climate change is an issue for everyone, and how we construct and manage our buildings can be a part of the solution."
K-12 Market Leader
Climate change is an issue for everyone, and how we construct and manage our buildings can be a part of the solution. The American Institute of Architects has challenged architects worldwide to support humanity’s collective call to climate action through an unrelenting commitment to sustainable and resilient design.
One approach is to aim for net-zero energy (NZE) school buildings. In an NZE building, the total amount of energy used by the structure is equal to or less than the amount of renewable energy produced on the site annually.
By their nature, district leaders are thought leaders, shepherding the community toward a brighter future. Education leaders and architects, engineers, designers, and builders can provide leadership on important issues like climate change, resilience, alternative energy, and sustainability.
Within the past 10 years, solar and battery energy storage technologies have evolved, drastically reducing energy costs and becoming feasible options for school systems. Two significant trends that are becoming relatively mainstream for schools are on-site solar photovoltaic (PV) systems that convert sunlight into electricity and, more recently, on-site battery energy storage systems (BESS).
Battery energy storage systems are charged from excess solar production when more power is generated than the building’s systems need at that moment. This stored power can be used later, during the night or during higher-cost on-peak power periods. Batteries can also be charged from the electrical grid during nonpeak, low-cost hours.
Integrating energy storage with solar PV systems enhances flexibility to a building’s energy management system, delivering cost savings through peak demand reductions and providing power when the sun is unavailable. With the addition of microgrids, battery storage can also be used for emergency power during outages on the electrical grid, such as the one Texas experienced in February 2021 and areas in California experienced during the 2020 fire season.
Demand management strategies–with or without solar PV systems and BESS–seek to reduce peak demand charges. As utility provides introduce smart grids that send a real-time price signal from the power grid, automated adjustments can control the operation of the building’s equipment.
For example, when electric rates are high, such as during peak demands, some equipment (for example, chillers and lighting) can be adjusted to be limited for certain time intervals. Such enhancements require additional programming of the heating, ventilation, and air-conditioning (HVAC) and lighting controls.
If a school’s electrical consumption can be controlled to diminish the demand peaks, the building might use the same quantity of electricity annually while reducing the electricity bill by 10% or more.
The overall objective is to move toward net-zero energy and achieve financial savings along the way.
Reaping the Benefits
Northland Pines School District (NPSD) in Vilas County, Wisconsin, recently received bids for a 70-kilowatt-DC PV system and an approximately 60-kilowatt-AC, 150-kilowatt BESS to be installed at the St. Germain Elementary School.
NPSD had previously installed 430 kilowatts-DC of solar at its three other schools (Northland Pines High School/Middle School, Eagle River Elementary School, and Land O’Lakes Elementary School). The success of these projects encouraged NPSD to add a solar PV/BESS system at its only school without solar.
The district capitalized on its experience with BESS as it planned for NZE in the future. The benefits of the previous solar projects included financial savings as well as on-site platforms for renewable energy education.
Because of limited school use during the summer, an important feature of the St. Germain design is its ability to generate power during the winter with the use of bifacial solar PV modules set at a steep angle (approximately 50 degrees).
Bifacial PV modules produce additional power from reflected light on the backside of the module. This backside power, combined with the steep angle, sheds snow that might impede winter power generation.
To spread the power generation over more hours during the day (reducing the need to store energy or sell power to the grid at midday), the project uses three orientations: southeast, south, and southwest. The BESS stores excess generation for later use. Because the size of the PV system is limited, monthly generation does not exceed the amount of electricity used by the school monthly.
Another example can be found in a 400-kilowatt-DC solar PV system and an approximately 100-kilowatt-AC/200-kilowatt-hour BESS system planned for the new Clintonville Middle School and the adjoining high school in Clintonville, Wisconsin.
The ground-mounted solar PV field is similar to that of the St. Germain Elementary School, but it is much larger to emphasize winter solar power production. The middle school installation will also feature a geothermal system (ground-sourced heat pump HVAC system), which will make it the second NZE school in Wisconsin. The BESS will store solar energy for peak demand shaving and arbitrage. Arbitrage is the purchase of less costly power overnight for peak shaving the following day.
Making the Finances Work
The primary economic advantage of an on-site solar PV system is the lower cost of power. This advantage includes low maintenance and operation costs along with a competitive guaranteed-rate cost for future electricity. Solar has flexibility in both new and existing buildings, with rooftop, ground-mounted, and carport-mounted panels as viable alternatives.
Decades of effort to produce the lowest-cost electricity generation option globally and in the United States have resulted in the emergence of solar PV systems. Wind resources for very large-scale wind machines are cost-effective in some geographic areas, but these wind machines are too large for school districts to consider in most cases.
Because of the intermittent generation provided by solar and wind, BESSs are rapidly expanding to help fill the gaps when sufficient renewable energy is unavailable. They are being included in both utility-scale solar PV projects as well as on-site solar PV projects.
The advantage of an on-site BESS is its ability to provide emergency power and to support on-site solar power production if the utility grid goes down. Both solar PV systems and BESSs offer lower costs as manufacturing volumes increase and technology improves.
Previous solar projects at the NPSD schools used third-party investors at two schools and a special program offered by a local utility at the third school. The St. Germain PV/BESS project is funded by district-wide savings and by leveraging three grant programs:
> The Wisconsin Solar on Schools Program managed by the Midwest Renewable Energy Association
> The Wisconsin Focus on Energy Program
> The Energy Innovation Grant Program using Department of Energy funds and administered by the Public Service Commission of Wisconsin
The Clintonville project, which uses the same grant sources as the St. Germain project, will rely on third-party, green-minded investors to provide the up-front costs along with the grants and to leverage federal tax credits. The project will give the Clintonville Public School District a positive cash flow beginning in the first year, with no up-front funds required from the district. The Clintonville Municipal Utility is collaborating in this innovative effort.
School Design, Remodeling, and Construction for the Future
Tomorrow’s school design, remodeling, and construction won’t change unless leaders in education, building design and construction, student organizations, and communities take steps to implement new technologies like solar energy production and battery storage, which have shown themselves to make a profound difference.
For those who have already made these strides, it is important to share the message so that others understand the benefits and make changes as well.
Mark Hanson is director of sustainable services at Hoffman Planning, Design & Construction Inc., headquartered in Appleton, Wisconsin, and the author of The Inevitable Solar School: Building the Sustainable Schools of the Future, Today (Rowman & Littlefield, 2019). Email: firstname.lastname@example.org
Jody Andres is a senior project architect and the K-12 market leader at Hoffman Planning, Design & Construction Inc., and is a LEED AP, past president of the American Institute of Architects (AIA) Wisconsin. Email: email@example.com