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Residential Solar Hot Water Performance Monitoring Interim Report
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| Division: Renewable Energy Generation | ||
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| Type: Reports | ||
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In July, 2012, BEAM Engineering produced a Solar Hot Water Performance Monitoring Interim Report. The executive summary is below; the full report can be downloaded as a PDF here.
In February 2011, the Massachusetts Clean Energy Center (“MassCEC”) launched the Commonwealth Solar Hot Water Program, a pilot program providing rebates through a non-competitive application process for the installation of solar hot water projects by professional installers at residential and multi-family (1-4 unit) homes.
As part of the Massachusetts Clean Energy Center's (MassCEC) investment in solar heating technologies under the Commonwealth Solar Hot Water Program, a performance monitoring program was established to understand and quantify the performance of solar thermal systems deployed in Massachusetts. Forty residential systems were accepted for monitoring. There are currently 30 of the target 40 residential solar hot water projects online. With 30% of the target amount of data (12-months each project) having been collected, preliminary comparisons have been made between modeled performance, monitored performance, and SRCC OG-100 performance benchmarks. Additionally, field issues related to performance monitoring installations have been identified.
Overview: One of the primary goals of the pilot program was to meter a subset of solar hot water systems to gather and analyze performance data to help develop subsequent program design. MassCEC offered additional funding to system owners who volunteered to install performance monitoring equipment. MassCEC funds the equipment and installation cost in full, up to $1,000 for a 'single' BTU calculation (four data points) and $1,500 for a 'double' BTU calculation (eight data points).
Premise - By understanding the actual, real-time performance of solar hot water systems incentivized under the Commonwealth Solar Hot Water Pilot Program, best-practices can be encouraged in future iterations of the program. Not fully understanding real-life performance of solar hot water systems has hindered market growth, as financing, sources of system risk, proper design, or the longevity of system performance. The design of the MassCEC Performance Monitoring program seeks to address and understand these concerns, with the intention of alleviating these issues, and paving the way for sustained, understandable growth in the solar hot water industry.
Innovation - The approach is innovative in the sense that for the first time in the country, a statistically significant set of projects have been monitored to better understand solar hot water technologies. Other programs have pursued a non-funded, "opt-in" approach to monitoring, which has had poor customer participation results, and subsequently extremely high administrative costs. The decision of the MassCEC to allocate funds to project monitoring costs directly has been well received by the contractor base and customers alike, with robust customer participation and delivery coming in substantially under comparable programs.
Participation - A total of forty (40) customers had monitoring systems installed by nineteen (19) different contractors. Five (5) monitoring technologies were deployed, with the majority (35) being the SunReports system. These systems are monitoring twenty-seven (27) glazed flat plate collector projects, eleven (11) evacuated tube collectors projects, (1) combined flat plate and evacuated tube project, and one (1) parabolic concentrating collector project; the collector-types include seventeen (17) manufacturers. These systems will displace fuel costs related to fifteen (15) oil systems, twelve (12) natural gas, eight (8) electric, four (4) propane, and one (1) wood.
Costs - Due to increasingly streamlined system integration, costs for monitoring systems have been dramatically reduced over the past few years. Average system cost for the residential performance monitoring program was $1,138 per project. Typical equipment costs are $400 - $1,000; install labor costs $200 (assuming 2-3 additional hours of installation time). Additionally, data services may add cost if internet is not already present. MassCEC capped 'single' BTU calculation (four monitored data points) systems at $1,000 / project and 'double' BTU calculation (eight monitored points) systems at $1,500 per project.
Progress to Date: The program has compiled approximately 30% of the required 480 months of data (40 projects times 12 months each = 480 data-months). Thirty (30) projects are now online and accessible by the MassCEC. The remaining ten are expected to come online within the next few months.
Performance - Energy generated from all 40 systems is modeled to be 4,931 therms annually (144,446 kWh equivalent). Actual system performance has measured 393.3 therms for the customers that are online. Expected monthly monitored energy production has varied from 26.7% to 134.6% of expected. Projects known to have other issues, as well as intermittent internet availability has skewed results, and this must be corrected for the full analysis of the data.
Preliminary Findings - When reporting correctly, the performance monitoring system has the ability to track expected production quite closely to modeled energy production. Actual production appears to be within 80%-110% of the expected generation indicated by energy modeling. The statistical signification of these findings and influencers has yet to be determined.
As we reviewed the data from the monitored sites, we recognized that drastic variations in performance are often due to inconsistent installation practices. The improper placement of sensors or erroneous configuration entries will adversely affect the results displayed in the performance monitoring system. The only way to establish valid and accurate information is to develop consistent installation practices and and verification procedures that can be implemented for every new installation. A detailed installation checklist, including pictures, could be created emphasizing the criticality of proper placement and verification.
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