Choice C is the best answer. In lines 10-17, the passage illustrates how the cost of solar energy has dropped in recent years: “A few years ago, silicon solar panels cost $4 per watt. . . . ‘Now it’s down to something like 50 cents a watt, and there’s talk of hitting 36 cents per watt.’” In lines 44-47, the passage describes some of the new technology that exists in the field: “Meanwhile, researchers at the National Renewable Energy Laboratory have made flexible solar cells on a new type of glass from Corning called Willow Glass, which is thin and can be rolled up.” Overall, the passage can be regarded as an objective overview of the solar panel industry delivered by a journalist covering the field.

Choices A and D are incorrect because the author does not present himself as either a consumer who plans to buy solar panels or a hobbyist with a personal interest in solar panel technology. Rather, the author focuses on developments in solar technology. Choice B is incorrect because the passage does not discuss research methods used in the solar panel field but rather the technologies that exist in the field.

Choice A is the best answer. In the context of describing the solar panel manufacturing industry as being “in the doldrums because supply far exceeds demand” (lines 2-3), saying it is currently a “poor” market implies it is a weak, or slow, market. Choices B, C, and D are incorrect because in the context of describing the solar panel manufacturing industry as being “in the doldrums,” saying it is a poor market implies it is a weak market, not a modest one (choice B), a pathetic one (choice C), or an outdated one (choice D).

Choice C is the best answer. It can reasonably be inferred that much of the solar panel industry believes current solar technology is too expensive and inefficient because the passage states that the industry has been working to improve those two things: “All parts of the silicon solar panel industry have been looking for ways to cut costs and improve the power output of solar panels, and that’s led to steady cost reductions” (lines 27-30).

Choice A is incorrect because the passage explains how solar panels work but never states or implies that consumers do not understand the technology. Choice B is incorrect because while the passage explains how two-sided solar cells can increase solar electric output, it does not suggest that they have any existing or possible weaknesses. Choice D is incorrect because the passage characterizes Willow Glass as entirely promising and doesn’t imply that it is not efficient enough to be marketed.

Choice D is the best answer. The previous question asks what can be inferred from the passage about beliefs in the solar panel industry, with the answer being that many in the industry believe current solar technology is too expensive and too inefficient. This is supported in lines 27-30: “All parts of the silicon solar panel industry have been looking for ways to cut costs and improve the power output of solar panels, and that’s led to steady cost reductions.”

Choices A, B, and C are incorrect because the lines cited do not support the answer to the previous question, which is that much of the solar panel industry believes current solar technology is too expensive and inefficient. Choice A highlights the industry’s current limited sales. Choice B addresses the high cost of solar panels but not their inefficiency. Choice C addresses a potential decrease in the cost of solar panels and does not mention efficiency.

Choice B is the best answer. The passage clearly states how two-sided solar panels will increase the efficiency of solar electricity units, explaining that they will be able to absorb excess reflected light, especially if those panels are built on sand: “That light reflects onto the back of the panels and could be harvested to increase the power output” (lines 61-62). Choices A, C, and D are incorrect because the passage explains only that two-sided solar panels can raise efficiency by harvesting reflected light, not that they can raise efficiency because they take little energy to operate (choice A), are cost-effective (choice C), or keep sunlight from reaching the ground (choice D).

Choice B is the best answer. The previous question asks how two-sided solar panels can raise the efficiency of solar electricity units, with the answer being they can increase solar power input by catching excess reflected light. This is supported in lines 61-62: “That light reflects onto the back of the panels and could be harvested to increase the power output.”

Choices A, C, and D are incorrect because the lines cited do not support the answer to the previous question about how two-sided solar panels can raise the efficiency of solar electricity units, instead highlighting that some sunlight is missed by current units (choice A), explaining why two-sided solar panels work well in sand (choice C), and projecting how much more effective those two-sided solar panels could be (choice D).

Choice D is the best answer. In lines 69-71, the passage states that “even longer-term, Green is betting on silicon, aiming to take advantage of the huge reductions in cost already seen with the technology.” In this context, the phrase “betting on” most nearly means “optimistic about,” as the sentence implies that Green has positive expectations for silicon use now and in the future. Choice A is incorrect because “dabbling in” a subject implies being only minimally involved with it, but in lines 69-71, Green is shown to be committed to silicon use. Choice B is incorrect because in this context the phrase “betting on” is figurative and implies believing in something, not actually being involved with games of chance. Choice C is incorrect because Green is said to want to “take advantage” of silicon use, meaning he does not intend to switch from it.

Choice B is the best answer. The passage concludes by stating that “the challenge is to produce good connections between these semiconductors, something made challenging by the arrangement of silicon atoms in crystalline silicon” (lines 81-84). As this last sentence identifies an issue the solar panel industry still faces, and describes it as a “challenging” one at that, it mainly serves to identify a problem or hurdle that must be dealt with by the industry.

Choices A, C, and D are incorrect because the main point of the passage’s last sentence is that there is a “challenge” or hurdle that the solar panel industry has to deal with; it doesn’t express concerns about what a material won’t be able to do (choice A), make predictions (choice C), or introduce a new idea for study (choice D).

Choice D is the best answer. Figure 2 shows that in 2009, the US average electricity cost per megawatthour (MWh) was $120. Of the projected 2017 energy costs for fuels listed in figure 1, the one closest to the 2009 US average electricity cost 120 dollars per megawatt-hour is the projected cost of advanced nuclear energy, estimated at just below 125 dollars per megawatt-hour.

Choices A, B, and C are incorrect because figure 1 shows the projected energy costs of natural gas, wind (onshore), and conventional coal as just below 75 dollars per megawatt-hour, 100 dollars per megawatt-hour, and approximately 105 dollars per megawatt-hour, respectively. None of these costs is as close to the 2009 US average electricity cost of 120 dollars per megawatt-hour as the projected 2017 cost of advanced nuclear energy, which is just below 125 dollars per megawatt-hour.

Choice B is the best answer. Figure 2 shows that the dropping cost of solar photovoltaic power per megawatt-hour is projected to intersect with the 2009 US average electricity cost of 120 dollars per megawatt-hour in the year 2020.

Choice A is incorrect because figure 2 projects that the solar photovoltaic cost per megawatt-hour in 2018 will be approximately $140, which is more than the 2009 US average electricity cost of 120 dollars per megawatt-hour. Choices C and D are incorrect because figure 2 projects that the solar photovoltaic cost per megawatt-hour will be around $90 in 2025 and $70 in 2027, both of which are less than the 2009 US average electricity cost of 120 dollars per megawatt-hour.