Medium-temperature collectors provide medium-to-high grade heat (greater than 110 degrees Fahrenheit, usually 140 to 180 degrees Fahrenheit), either through glazed flat-plate collectors using air or liquid as the heat transfer instrument or concentrator collectors that concentrate the heat of incident insolation to greater than “one sun,” and are mainly used for domestic hot water heating.[2] Evacuated-tube collectors are also included in this category.
High-temperature collectors are parabolic dish or trough collectors designed to operate at a temperature of 180 degrees Fahrenheit or higher and are primarily used by utilities and independent power producers to generate electricity for the grid.
The solar thermal collector performance rating is an analytically-derived set of numbers representing the characteristic all-day energy output of the solar thermal collector under standard rating conditions measures in Btu per square foot per day (Btu/ft2 day). In 2007, the average solar thermal performance rating for low-temperature collectors (metallic and nonmetallic) was 1,248 Btu/ft2 day, medium-temperature (air) was 918 Btu/ft2 day, medium-temperature (thermosiphon) was 926 Btu/ft2 day, medium-temperature (flat-plate) was 979 Btu/ft2 day, medium-temperature (evacuated-tube) was 851 Btu/ft2 day, medium-temperature (concentrator) was 2,150 Btu/ft2 day, and high-temperature (parabolic dish/trough) was 1,000 Btu/ft2 day (Table 2.14).
Solar Thermal Collector Shipments
Annual shipments of solar thermal collectors totaled 15.2 million square feet in 2007, more than a 27-percent decrease from the 2006 shipments of 20.7 million square feet, and lower than the 16.0 million square feet shipped in 2005 (Table 2.1).
In 2007, low-temperature collector shipments totaled 13.3 million square feet, which is 2.2 million square feet less than low-temperature collector shipments in 2006 (Figure 2.2 and Table 2.3). Approximately 99 percent of low-temperature collectors are used for residential solar thermal pool heating (Table 2.13). Several solar thermal pool heating manufacturers described the 2007 solar swimming pool heating market as flat, slow, or even declining due to the poor economy. While the effect of the economy and the housing slowdown on the low-temperature market is not yet clear, the future of residential solar thermal pool heating sales is a matter of concern for manufacturers.
Shipments of medium-temperature collectors totaled slightly less than 1.8 million square feet in 2007, a 34-percent increase from the 2006 shipments of 1.3 million square feet in 2006 (Figure 2.2 and Table 2.3). Approximately 80 percent of medium-temperature collectors are used for hot water heating (Table 2.13). The increase in medium-temperature collectors is believed to be mainly due to the Federal tax credits and state incentives. A typical residential solar water heater costs between $2,000 and $3,000. Taking advantage of the Federal tax credits and state incentives can reduce solar hot water heater capital costs by at least 30 percent.
In 2007, there was an enormous decline in high-temperature collectors shipments to 33 thousand square feet (Figure 2.2 and Table 2.3), highlighted by a substantial decline in parabolic dish/troughs used by electric utilities and independent power producers to generate electricity for the grid. Overall, shipments have declined by more than 99 percent compared with the 2006 level. The decrease was entirely caused by the completion of the Nevada Solar One project.
In contrast to the market during 2007 when no solar thermal power plants were started, a handful of commitments to build concentrating solar power (CSP) plants were announced during 2007.[3] The wave of announced plans to build new large solar power facilities throughout the United States seems to indicate that relatively large-scale systems could become more common. As of July 2008, the Federal Bureau of Land Management has processed 125 applications for future potential solar development on public lands and will continue to accept applications.[4]
Figure 2.2 Solar Thermal Collector Shipments by Type, 1998-2007
Total Revenue and Average Price
Sluggish shipments adversely affected revenue. The total revenue of solar thermal collector shipments was $ 59.8 million in 2007 (Table 2.12). This was an almost 51 percent decrease, compared with the revenue of total shipments in 2006, caused by the sharp drop in high-temperature collector shipments.
Revenue of low-temperature collector shipments was $26.3 million, a decrease of 13 percent, compared with the revenue in 2006. This was the lowest revenue received for low-temperature solar thermal collectors since 2003. The revenue from medium- and high-temperature collector shipments was $33.5 million, a 63-percent decrease compared to $90.8 million in 2006.
The average price for low-temperature collectors was $1.97 per square foot in 2007, virtually unchanged from $1.95 in 2006. The average price for medium- and high-temperature collectors increased from $17.47 to $18.33 per square foot. However, the overall average price for total shipments decreased more than 32 percent, from $5.84 per square foot in 2006 to $3.95 per square foot in 2007 (Figure 2.3 and Table 2.12). The cause of the fluctuation was heavily influenced by custom-made collectors, which are high-temperature collectors. These collectors are designed for limited, specialized applications, and their average prices are much higher than the conventional collectors.
Figure 2.3 Solar Thermal Collector Average Price, 1998-2007
Domestic Shipments
Corresponding to the decrease in total shipments, domestic shipments of solar thermal collectors plunged more than 29 percent to 13.8 million square year during 2007 (Table 2.2). On the whole, total and domestic shipments of solar thermal collectors fell back to the 2004 level.
The residential sector is the largest domestic market in the United States for solar thermal collectors. Solar thermal collectors shipped to the residential sector in 2007 totaled 12.8 million square feet, approximately 93 percent of total domestic shipments (Table 2.13). This market sector primarily involves the use of low-temperature solar collectors for pool heating and medium-temperature solar collectors for water heating. The second largest domestic market for solar thermal collectors in 2007 was the commercial sector, which accounted for 7 percent of total domestic shipments.
The largest end use for solar thermal collectors shipped in 2007 was for swimming pool heating. Pool heating accounted for 88 percent of the total domestic shipments. The second-largest end use in 2007 was for domestic hot water heating, which accounted for 10 percent of the total domestic shipments (Table 2.13).
More than half (56 percent) of the total domestic shipments in 2007 were sent to the wholesale market, 33 percent to retail distribution, 3 percent to exporters, 6 percent to installers, and about 2 percent directly to end-users (Table 2.11).
Complete Systems
Of the 60 active companies, 34 companies accounted for shipments of 59,914 complete solar thermal systems. These systems accounted for 3.8 million square feet, or 25 percent of total solar thermal collectors shipped in 2007. The revenue value from these solar thermal system shipments was reported as $30 million (Table 2.15).
Origin of Shipments
Imports of solar thermal collectors totaled 3.9 million square feet in 2007 (Table 2.7). Almost 90 percent of all imports were low-temperature collectors (3.5 million square feet). These imports originated in seven foreign countries, and about 3.7 million square feet of the solar thermal collectors were imported from Israel (Table 2.7 and Table 2.8).
In 2007, 72 percent (10.9 million square feet) of all solar thermal collectors were manufactured in five states: California, New Jersey, Florida, Pennsylvania, and Connecticut, with 62 percent (9.4 million square feet) of the total shipped from California and New Jersey (Table 2.4 and Table 2.6).
Destination of Shipments
Export shipments totaled 1.4 million square feet in 2007. More than 1.3 million square feet, or 97 percent of total exports, were low-temperature solar thermal collectors (Table 2.9). The export market accounted for 9 percent of total shipments and was dominated by sales to Canada (37 percent of exports), Mexico (20 percent), and Brazil (18 percent) (Table 2.10).
In 2007, 13.8 million square feet of domestic solar thermal shipments went to all 50 States within the U.S., together with the District of Columbia, the Virgin Islands, Guam, and Puerto Rico (Table 2.6). Over two-thirds were shipped to the top five destinations (states): California, Florida, Arizona, Oregon, and Illinois. California and Florida received nearly 54 percent of total shipments (Table 2.4 and Table 2.6). Notably, there was a dramatic decrease in shipments to several states in 2007, including Alabama, California, Florida, Nevada, New York, and North Carolina. This mainly was caused by the sharp decrease in demand as reported by a number of companies.
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