406 North West Arctic Borough – Solar Awareness
Proposer: North West Arctic Borough
Benefit/Cost Ratio: Applicant 0.81 AEA .76 to 1.1 (average 0.92)
The Northwest Arctic Borough Proposes roughly $50,000 per school for the construction of two photovoltaic solar arrays in each of 11 district schools. Reconnaissance, feasibility, and design work has been completed. The grant is for purchase of equipment and construction.
Assembly of the arrays is proposed as a summer educational exercise for finishing high-school class students, with supervision by qualified maintenance personnel. Monitoring of performance is to be integrated into a developing curriculum in science-alternative energy.
A site project consists of two pedestals, each with an array of 10 panels mounted on a 2-axis tracking system. Every panel on an array has an in-line modular inverter. So rather than a central bus bar and larger wires, each panel is wired directly to the grid. This offers a more efficient conversion to AC power. Each inverter will report to a common web portal that can be viewed by anyone on the internet.
The district is budgeted for $561,887 total with in-kind contribution of 12,500 and grant funding of $549,387.Pedestal construction and connection to the grid is proposed to be done with KEA and AVEC “participation”. The budget shows $5,500 for integration of arrays.
Contribution to Lower the Cost of Energy:
The solar electric production offsets approximately 61,000 kWh of diesel generation annually. But Kotzebue is in a challenging area for solar and the economics are not bright.
There is not actually an existing off-the-shelf production unit of both dual axis tracker and the panels specified. In the AEA model the dual-axis trackers were eliminated and much less expensive single-axis trackers were substituted in their place. (Confirmed models and compatibility). Discounts for consolidation of orders and shipping were estimated. Solar maps based on satellite data were used along with PV-Watts.com calculator to compare performance by village. Noatak and Kivalina have estimated B/C just above 1 vs. Kotzebue <1. Kotzebue has about the lowest potential of the 11 schools.
ISER NS: I modified the spreadsheets to include a fuel cost premium equal to the average premium of the 11 communities over the price of fuel in Kotzebue. The economist’s analysis used Kotzebue’s price only.
Other than the application itself, the evidence of feasibility, design, and budget detail is lacking. The considerations during feasibility and design that resulted in this configuration are not clear.
The technology specified results in a number of constraints. Enphase inverters must match solar panels, which together must match the 2-axis tracking arrays. The combinations can produce systems in the range of 4kW, but there are significant differences in performance. Kotzebue may also require heavier framing for wind protection.
The performance gain from one-axis to two-axis tracking is small but the cost is large for this range of output. Capital costs for complete Enphase systems without tracking are about 4-5 cents per rated kWh. Adding on single-axis tracking yields more power, and at about the same cost.
But dual-axis tracking for this sized system may cost three times as much per kWh, and for that reason adding panels/pedestals makes better economic sense than 2-axis tracking. B/C ratio will improve without 2-axis tracking.
The co-ordination of construction with the educational goals is probably unrealistic as proposed. The schedule envisions both putting out bids for systems and delivering to schools in July of 2010. In August, summer student volunteers assemble the arrays. But at present, Enphase inverter orders are 2-3 months from manufacture after placement of order with 50% down. Conditions could change, but that puts the student summer project well into the fall semester at the least.
Pg 6 of the application speaks to the “ongoing Science-Alternate Energy Class” whereas p 8 refers to a “coming Alternate Energy Class at the High School and at Chuchi (sic) College.” (Confirmed by Superintendant letter). So the status appears to be a developing class at the Kotzebue high school and at Chukchi College.
The assembly resolution referred to just the Kotzebue school and some of the grant application language appears to be worded similarly. But the 11 locations are primarily village K-12 schools, some with very small senior classes so the planning distinction between Kotzebue and the other locations needs to be made clear.
So although the project proposes integration into high school curriculum as an integral component of the education, there are questions about the state of this development, the integration with construction as proposed, and implementation in Kotzebue vs other locations.
Letters from utilities were not in the application reviewed but were not considered critical.
These are off-the-shelf technology that can be added as modules as desired.
Solar is a maximum long-term sustainability.
Potential Public Benefits
The project is proposed as an educational vehicle and an offset to diesel generated power, for the benefit of the local resident electric users.
-- December 21, 2009