In 2018, Loudoun County Public Schools (LCPS) contracted with 2RW to conduct a cost-benefit analysis of installing solar photovoltaic (PV) arrays at County elementary, middle, and high schools. The goals of the project were to determine the feasibility of generating renewable energy on-site and to better inform LCPS’s capital planning efforts.
2RW studied the 25-year cost implications of a variety of PV array configurations, sizes, financial options, and panel degradation schedules (see sidebar). Four building types were included in the study—the already-constructed Academies of Loudoun and the design prototypes for an elementary, middle, and high school. 2RW also analyzed the four facilities’ electrical systems to identify electrical infrastructure modifications that might be required to support PV connections.
Financial analyses revealed that installing solar PV arrays would consistently deliver long-term cost savings over the status quo regardless of array configuration. Roof-mounted paired with ground-mounted arrays that offset 100% of annual electricity usage are ideal when land is available; roof-only arrays that offset a portion of the building’s electricity demand are recommended where land is at a premium. PPA-financed systems that offset 100% of usage are expected to see the greatest cost savings over the 25-year life of the PV systems.
OWNER: Loudoun County Public Schools
TIMEFRAME: 2018 – 2019
SIZE: 855,000 SF
Elementary School Prototype Design
Middle School Prototype Design
High School Prototype Design
Academies of Loudoun (Constructed)
ARRAY CONFIGURATIONS ANALYZED
Largest possible roof array (no ground-mounted arrays)
Combination of roof- and ground-mounted arrays large enough to offset 100% of annual electricity usage
FINANCIAL Options Analyzed
Upfront purchase of PV array with net metering
Power purchase agreement (PPA)
Purchase of renewable energy credits (RECs) with no arrays
RATE STRUCTURES ANALYZED
Northern Virginia Electric Cooperative (NOVEC)
PANEL DEGRADATION SCHEDULES ANALYZED
Flat degradation as commonly observed by solar installers
0% degradation as commonly assumed in PPA calculations