United States Coast Guard Río Bayamón Housing Complex Photovoltaic System: Performance Review and Recommendations
Sponsoring organization: United States Coast Guard
Team members: Casey Arpin (Biomedical Engineering ’18), Charles DeWitt (Chemical Engineering ’18), Drew Gelinas (Management Information Systems ’18), Maryann O’Connell (Computer Science ’18)
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Executive Summary: “The average term of an ESPC task order is 17 years. The most common challenge during the post-acceptance performance period is personnel turnover, which leads to breaks in effective administration of the contract. Consistency in contract administration is required to keep the contract current.” (DOE, 2016b). This quote from the Department of Energy summarizes the exact problem that the Coast Guard has with their current photovoltaic (PV) system at the Río Bayamón Housing complex. Due to the frequent personnel changes, many individuals are unaware of the system specifics, how it’s performing compared to expectations, or even what the original expectations were. This gap of knowledge around the PV system has left the Coast Guard with unanswered questions regarding basic system specifications.
A result of the personnel disconnect is that the USCG has not been able to finish the pillar of their PV system contract, the net metering agreement. Based on limited consumption data, we know that the Coast Guard lost at least $380,000 for years one and two of the Energy
Savings Performance Contract (ESPC) for the Río Bayamón Housing (RBH) complex alone, as a result of not having a net metering agreement in place. This is due to the net metering agreement process being very long, and new personnel not knowing how much of a negative impact not having a net metering agreement has on the Coast Guard.
Another one of the Coast Guard’s concerns that we addressed, was whether or not the system had the potential to provide an energy backup system for the housing complex using the PV system, in the case of a power outage. This concern was brought forth as a result of the frequent power outages in Puerto Rico, which occur roughly once a week. The current system is a labor-intensive process, which still leaves individuals without power for outages lasting less than 4 hours. The possibility of the PV system providing a more reliable, renewable energy alternative was not looked into by the Coast Guard. This possibility was not further researched, as a result of individuals not knowing if it was a plausible idea based on the setup of the current system.
In order to address the Coast Guard’s overarching issues, we created two goals. Our first project goal was to gain an understanding of the Coast Guard’s PV system as well as the contract around it, in order to give a performance review and provide recommendations for possible system improvements. Our second, and final goal, was to look into the possibility of a reliable energy backup system powered by the PV system. Through accomplishing these goals, we provide information about the current contract and system the Coast Guard has in place. In addition to closing the gaps of knowledge created by the rapid personnel turnover, we provide insight into issues affecting current PV system performance, as well as contractual issues affecting potential Coast Guard savings.
Methodology
To accomplish the goal of evaluating and optimizing performance of the solar photovoltaic system at Río Bayamón Housing, we developed three primary objectives:
- Assess the performance of the photovoltaic (PV)
- Analyze the initial and ongoing costs associated with the PV
- Examine potential backup battery options to improve reliability of electricity at Río Bayamón
We used document and data collection and analysis in order to complete our three main objectives stated above. Each objective was broken down into smaller more detailed objectives in order to address all aspects contributing to our project goals. When completing the more
detailed objectives, key findings for our project were identified. A compressed list of the detailed objectives is listed below.
- Identified the Coast Guard’s expectations of the PV system performance and the system-level factors that affect the overall performance.
- Identified adjustment factors applied to annual PV production data at Río Bayamón
- Compared the expected, actual, and annual PV production of the system at Río Bayamón
- Identified the annual costs to the Coast Guard using the Puerto Rico ESPC Task
- Compared the post acceptance performance period expenses to the cost of terminating the
- Analyzed the RESA rates with respect to historical crude oil rates.
- Examined the benefits of a net metering
- Assessed the potential implementation of a backup battery source for use at the Río Bayamón Housing accounting for compatibility, safety risks, and potential environmental
- Analyzed the potential costs of purchasing, installing, and maintaining a compatible backup battery
Findings and Analysis
Finding #1. The photovoltaic system at Río Bayamón Housing produced less power annually than originally estimated.
Based off of our findings, the PV system is not meeting the Coast Guard’s production expectations overall. The majority of these factors are out of the Coast Guard’s control.
Finding #2. The photovoltaic system at Río Bayamón Housing had the potential to produce more power Year 1 than originally estimated after adjustments were made. Years 2 and 3 did not have the potential to produce the estimated amount of power, even after adjustments were made.
When taking into account the PV production, as well as the adjustments for solar irradiance, the PV system did in-fact have the potential to exceed the Coast Guard’s expectations. Contract Years 2 and 3 were similar in the fact that they did not meet the Coast Guard’s expectations based on a raw data point of view. Adjustments were made as a result of lack of solar irradiance data based on clipping from high solar irradiance and pyranometer connection failure for Years 2 and 3.
Finding #3. A signed net metering agreement would make it possible for the Coast Guard to generate savings from the ESPC. Without a net metering agreement, no money is saved.
Without a net-metering agreement, the Coast Guard will continue to pay Schneider Electric for 100% of the electricity they produce and PREPA for 100% of the electricity they consume. If a net metering agreement were in place, the Coast Guard would pay the difference between their consumption and PV production.
Finding #4. The RESA rates have exceeded the PREPA rates for contract Year 2 through Year 4.
Schneider Electric’s use of the varied rates ended up benefiting the Coast Guard, which allowed them to receive a lower inflation rate then PREPAs average. The reasoning as to why the kWh rate the Coast Guard is paying for PV production is higher the PREPA rates is due to multiple annual drops in crude oil pricing.
Finding #5. Production and cost analyses for contract Year 1 through Year 4 did not provide sufficient evidence to support or oppose early contract termination through system buyout.
Savings are difficult to determine because the benefits of system buyout are highly dependent on multiple factors, including but not limited to changing PREPA rates and the status of a net metering agreement. We recommend reassessing this option periodically as more production and expense reports becomes available.
Finding #6. The most cost efficient battery to comprise the backup battery bank of is a 48V sealed lead acid battery.
Based on the information we gathered, and calculations we made, we found that the most cost effective option was to use 48V sealed lead acid batteries. Even though the 12V sealed lead acid batteries are slightly cheaper when used in the same scenario, there are four times as many batteries, creating more labor, causing a need for more wiring and based on the average energy densities it would also require a larger storage container.
Finding #7. A backup battery is not plausible based on the amount of batteries that would be needed to partially power RBH for four hours.
Based on the calculations of size, it would not be plausible to have battery banks of these size and weight installed in the Río Bayamón housing complex. It would not only take up a large amount of space, but the cost and potential environmental impact of having battery banks of that size would potentially do more harm than good.
Recommendations
Based on the factors discussed in our findings, the two major recommendations we have for the Coast Guard are:
Recommendation #1. The United States Coast Guard continues to use diesel generators in the case of a power outages, instead of implementing backup solar batteries.
The Coast Guard already has generators set up at the Río Bayamón housing complex, as already having an infrastructure in place for allowing them to easily obtain large amounts of fuel. Because of this, it would be incredibly inefficient from a cost perspective to implement a battery backup system. If the Coast Guard were to use the diesel generators already in place, as opposed to implementing the best possibly battery we analyzed, they would save roughly $255,000 over a 20 year span.
Recommendation #2. The United States Coast Guard should sign a net metering agreement with PREPA to reduce financial losses.
By not having a net metering contract the Coast Guard is losing a large amount of money that they would have gotten a credit for, had the contract been set up. This contract was put in motion many years ago, but is still awaiting final approval. We recommend signing the net metering agreement in order to not miss out on further energy savings. Due to lack of bills we were unable to calculate the exact losses of the Coast Guard as a result of not signing the net metering contract. Based on the bills we were able to estimate a loss of at least $380,000 for RBH in just Years 1 and 2, very confidently.