When architect Michael Kracauer decided to design his carbon-neutral home, he knew it would include renewable energy. What he didn’t anticipate was what the PV system would reveal about his electricity use.
Kracauer’s PV installation also included Lightgauge, a real-time data monitoring system based on eGauge—one of several online data monitoring solutions that give real-time visibility into renewable energy system performance. Attached to the utility service entrance into the home and the inverter output (or other devices being monitored), Lightgauge measures electrical flow through household and system wiring via current transformers. The software simultaneously monitors the PV system’s production and the home’s electric consumption and presents the information through a user-friendly computer interface.
The data monitoring system takes readings every second to log real-time performance data, with a capacity of up to 30 years’ worth of information. Users access the information via the Web or a local area network. The Web page displays real-time PV system performance, the home’s actual consumption, total PV-generated energy, kWh purchased from the grid, pounds of carbon dioxide offset, and carbon-savings equivalencies presented in “miles not driven” and “trees planted.”
For Kracauer, the data monitoring system went beyond interesting—it also resulted in some lifestyle changes. “I was shocked by the load the electric dryer put on the system and the heat it added to the home,” he explains. “So I bought a clothesline to use instead—my solar-powered clothes dryer.”
This kind of reaction is exactly why data monitoring systems are gaining popularity with end users and installers alike, and why Lighthouse Solar now includes them with all the systems the company installs. Scott Franklin, president of Lighthouse Solar, explains, “By making the electricity consumed in your home or business visible in real-time, the abstract understanding of electrical usage becomes tangible—and manageable.”
System: Residential grid-direct PV
Installer: Lighthouse Solar, www.lighthousesolar.com
Date commissioned: September 2008
Location: Boulder, Colorado, 40.02°N
Solar resource: 5.5 average daily sun-hours
Array size: 7.2 kW STC
Average annual production: 10,434 kWh AC
Average annual utility bill offset: 100%
Modules: 36 Sanyo HIP-200BA3, 200 W STC
Inverter: Sunny Boy 7000
Array installation: Flush roof-mounted with UniRac SolarMount Standard Rail mounts to S5! clips to a standing seam metal roof oriented at 171° (west of south) at a 30° tilt