By Nikki Henningsen
Revenue grade energy meters play a crucial role in the solar energy industry. Whether for calculating inverter efficiency, measuring net energy production, or monitoring an on-site energy storage system, revenue grade energy meters are vital to maximizing the value of solar energy generation. To understand their role within the solar system, think of a cardiac monitor used to measure a patient’s heart rate and rhythm; a revenue grade energy meter performs a similar task by precisely monitoring energy flowing through the solar system, detecting irregularities, and providing crucial insights into the overall health of the installation.
Available from a range of manufacturers, revenue grade energy meters were first developed as a way for building managers to the track energy consumption of individual systems within a facility. Imagine a manufacturing plant and its various energy loads. Specialized production tools, HVAC, lighting, office equipment, and other essentials all consume energy throughout the day. A monthly power bill cannot provide meaningful insight into energy waste, but a revenue grade energy meter can collect detailed energy consumption data for specific systems or equipment.
High-precision, revenue grade measurements are critically important, particularly in net metering applications, which require meters that comply with strict accuracy requirements. In fact, the term “revenue grade” specifically refers only to those energy meters that meet the accuracy benchmarks defined by the American National Standards Institute (ANSI), which outlines three accuracy classes in their C12.20-2015 standard: 0.1, 0.2, and 0.5. To be considered revenue grade, meter accuracy must be third party tested to conform to 0.5 percent or higher.
Solar systems may vary in size and energy output. Regardless of scale, they contain the same critical components for energy storage, including inverters, circuit breakers, and batteries. Each component requires careful and constant monitoring, making high-precision energy data from a revenue grade energy meter invaluable.
Here are a few ways the solar industry uses revenue grade energy meters.
Calculating Solar Inverter Efficiency
Solar inverters are integral to solar energy systems. These sophisticated devices are responsible for converting the direct current (DC) output from the solar array into the alternating current (AC) that is used throughout a facility. A small amount of energy may be lost during this conversion process. This amount can be identified by installing revenue grade energy submeters on both sides of the inverter to calculate efficiency. Not only does this data help identify upgrade opportunities, but the metered energy data can help highlight hardware issues that may go undetected without constant monitoring.
Measuring Net Energy Production
Net metering is an incentive program adopted by 34 states and several territories within the United States,1 and another important way that revenue grade energy meters are utilized within the solar industry. Net metering allows customers to send their surplus electricity back to the electrical grid in exchange for credit, which is applied to offset energy costs incurred during the month.
A revenue grade energy meter is required to monitor the flow of energy and confirm the exact amount of energy generated, which is then submitted to the utility for credit. Large-scale solar applications typically need multiple meters installed, while small installations may only require a single, bi-directional meter to monitor both energy consumption and generation. The precise solar production data directly benefits customers by helping to lower monthly energy bills.
Monitoring Energy Storage Systems (ESS)
Commercial and industrial customers rely on several strategies to limit their energy consumption during peak hours. In addition to facility upgrades, one technique that continues to gain traction is installation of an on-site energy storage system (ESS), which allows energy from the grid, or solar, to charge large batteries during off-peak times. Later, the stored energy supplements grid power during peak hours to lower demand, a strategy known as “peak shaving”.
Energy storage allows for the efficient distribution of energy resources. It can also increase grid resiliency by guaranteeing that power is always available, even during times of high demand or power outages. In addition, when the source of the stored energy is on-site solar, the ESS effectively compensates for periods of low solar production, smoothing out the available energy from a solar system throughout the day and reducing reliance on grid power.
Facilities that utilize on-site energy storage need more than just a large battery to effectively cap their demand. A sophisticated control system, powered by machine learning, interprets where and when energy is being used, and automatically compensates for peak consumption by engaging battery power at the right moment. Revenue grade power meters supply the control system with a constant stream of precise energy measurements. The granular data is used to make split-second decisions to mitigate power outages, reduce peak demand charges, and maximize the value of energy generation.
Increasing Need for Revenue Grade Energy Meters
The United States solar industry employs approximately 250,000 people, and is comprised of over 2.6 million solar energy systems2. As solar panels, inverters, and on-site energy storage systems continue to improve in efficiency and price, solar energy will be adopted at an accelerated pace. Whether it is a relatively small solar system or a sophisticated, commercial implementation, the need for revenue grade energy meters to provide accurate, timely energy measurements remains essential to evaluating system performance, maintaining peak efficiency, and obtaining maximum savings from incentive programs.
Nikki Henningsen is the Digital Marketing Specialist at Accuenergy, Inc., a manufacturer of power metering solutions, and has been in the power and energy metering industry for more than a decade. When not researching & creating content, Nikki enjoys exploring the mountains around her home in Bend, Oregon.
1 Pickerel, K. (2020, September 24). Which states offer net metering for certain utilities? Retrieved January 21, 2021, from https://http://www.solarpowerworldonline.com/2020/03/which-states-offer-net-metering/
2 “State-By-State Map.” SEIA, Solar Energy Industries Association, 2020, www.seia.org/states-map.