With a financing plan in hand, the next challenge was net metering. The co-op would only receive credit for PV electricity that offset the annual usage of one utility meter, and we had 30 separate meters. We needed to find a way to combine the meters into fewer separate utility connections.
New York State has well-established procedures to allow the conversion of individual meters to master meters in multifamily dwellings. By following the procedures, we were able within a few months to get our local utility to agree to the conversion. We reduced from 30 separate meters to four—one for each quadrant of the neighborhood.
Moving to master metering meant that the co-op would be responsible for metering and billing of residents, which required installing new submetering equipment. Our initial equipment survey was disappointing—most products we found were expensive and lacked key features. We wanted “smart meters” that would interface with our internal Internet-connected network that allows either wide or local-only access as we see fit. So far, we have chosen to make display data available only internally, but we could make it accessible to the outside world if residents feel comfortable about making their usage info public.
Most products with these capabilities work only with proprietary software and required significant monthly fees. Other smart meters are more suited to individual homeowners and not designed to be centrally installed and managed. Luckily, we found EKM Metering of Santa Cruz, California, which approached smart meters more like a computer startup company and less like a utility, creating inexpensive products that act as flexible building blocks to be “mashed-up” in various ways, rather than creating rigid systems that lock a customer into using only the capabilities provided by one vendor.
We were able to create a cost-effective smart-metering system with no monthly fees. Besides the basic meter reading, we developed software for graphical display of real-time power usage for individual homes as well as aggregate displays of use, PV generation, and purchased energy for each group of townhouses and the whole neighborhood. We are considering making this available for free as open-source software.
With the overall plan in place, we now had to get official approval from our 30 households to commit to the project. In our neighborhood, this happens through monthly meetings open to all residents, with decisions made by consensus after lots of discussion. Our group was challenged to explain the details of a complex project and answer many probing questions.
By the end, it was clear that some aspects of the project, such as exact design requirements and pricing from the utility for master meter installations, utility tariffs, and extraneous permits, could only be confirmed as the project moved through the process. We were frank with residents about these uncertainties. The project was approved unanimously in April 2011.
With approval in hand, the focus switched to Tony Henderson and his crew at Hayes Electric to get things rolling. Tony worked with us to obtain approvals for a zoning variance, building and electrical permits, and our application for PV rebates from NYSERDA (New York’s state agency that manages RE rebates). By the end of June, we were ready to break ground.
The system consists of four subarrays of 56 Trina 230-watt modules. Each subarray is connected to a pair of Sunny Boy SB6000US grid-tied inverters. The array, about 200 feet from the nearest building, required trenching across backyards of the residences for more than 500 feet. We located the inverters at the residence-end of the trenches rather than near the array, sending the higher-voltage DC over the long conductors to reduce voltage drop.
We experienced a few big delays, particularly related to the foundation holes, rocks, and a couple of passing hurricanes, but were still able to meet our end-of-year deadline. The system came online on December 29, 2011.