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| | ==Explanation== | | ==Explanation== |
| − | This is another one of [[Randall|Randall's]] [[:Category:Tips|Tips]], this time a solar energy tip.
| + | {{incomplete|Created by an underpaid solar panel installer - Please change this comment when editing this page. Do NOT delete this tag too soon.}} |
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| − | {{w|Solar panels|Solar panels}} generally produce electrical power in proportion to the intensity of sunlight striking them. In order to maximize energy production, it's generally recommended that panels be mounted at an angle that will receive the most light intensity, on average, and avoiding anything that might shade the panels. The comic might be poking fun at how sometimes solar panel arrays are installed in unusual orientations to ensure a south-facing orientation and pushing it to its logical extreme by assuming a panel on the sun. | + | {{w|Solar panels|Solar panels}} are a relatively common method of supplying/augmenting power for uses from calculators to factories. They work by gathering solar energy reaching the Earth from the Sun and converting it to electricity. More specifically, they absorb vast amounts of photons from the solar rays and use them to knock electrons free. Those electrons produce the flow of electric current around the circuit and convey power onwards to where it is needed. |
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| − | Based on where the panel is located, the average amount of solar energy expected to strike it per day can be calculated (accounting for the angle of the sun, day and night cycles, and typical weather patterns). With this data, as well as the expected conversion efficiency and local cost of electricity, one can calculate the value of electricity the panel produces each year. In this case, [[Randall]] estimates the value of power produced by each square meter of solar cells at $58 per year.
| + | This comic proposes a solution to the issue of solar panels not generating enough power due to basic physical limitations. Solar panels on Earth have multiple things reducing their efficacy, such as their distance from the Sun reducing the intensity of light hitting them and the fact that for half of the time they can't generate any power because the Earth is blocking the Sun. Putting your solar panels in a close orbit above the Sun would eliminate most, if not all, of these issues (and is a partial implementation of the concept of a {{w|Dyson sphere}}, theorised by scientists and used in science fiction). However putting solar panels in this position introduces many new problems that can negatively impact their energy generating capacity, such as transmission losses and more undesirable effects from their proximity to the Sun. |
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| − | The strip then proposes a rather intense comparison: place the identical solar panel ''downwards'', on and towards the Sun, rather than ''upwards'' (upon a suitable equatorially-facing sloping roof), from the surface of the Earth. Due to the inverse-square law, this would result in ''much'' more solar energy striking the panel. If we assume that the solar cells could convert this energy to electricity at the same efficiency, then this would generate immense amounts of usable power, with the same calculation yielding $22 million per year as the value of a single panel in such a position. | + | The cost-effectiveness of solar panels is a complex topic, involving [https://www.energy.gov/eere/solar/solar-performance-and-efficiency efficiency], installation, and even costs of [https://cen.acs.org/environment/recycling/Solar-panels-face-recycling-challenge-photovoltaic-waste/100/i18 recycling at end-of-life]. The comic demonstrates a simplified calculation, where a solar panel of 1m^2 is estimated to return electricity eqyivalent to around $58/year, using 20% as the efficiency of conversion of sunlight to electricity for an otherwise optimally roof-installed solar panel unit. |
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| − | Of course, such setup would clearly be impossible, for the simple reason that the panels would melt and then vaporize long before they reached the surface of the sun. In point of fact, current photovoltaics operate less effectively at higher temperatures, so even bringing them mildly closer to the sun would impair their efficiency, and eventually cause them to stop working all together. This is in addition to the fact (acknowledged in the title text), that electricity produced at the sun's surface would be of little use to humans. The solution of "run[ning] transmission lines to earth" would obviously not be practical, even with millions of dollars at stake.
| + | To solve this, Randall here proposes a rather more direct solution: place the identical solar panel ''downwards'', towards the Sun, rather than ''upwards'' (upon a suitable equitorially-facing sloping roof), from the surface of the Earth. This gives access to substantially more light energy and would (through naïve upscaling of the power flux available, ignoring a number of technical issues) produce greatly increased amounts of energy for the owner. |
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| − | The assertion that the solar panel would pay for itself in no time seems flawed. For example the Helios 1 probe cost 260 million dollars in 1975 (approximately 1.5 billion dollars in 2023 money) and the Parker Solar Probe, which will fly 6.2 million km from the surface of the sun, also cost 1.5 billion dollars. The Parker Solar probe mass is 50kg, which is the same order of magnitude as a 1m² solar panel. | + | The title text acknowledges ''some'' difficulties, but hand-waves them away as being surmountable and entirely worthwhile given the theoretical income generated. This may or may not be true, but is atually extremely unlikely at the end of the economies of scale whereby an individual is expected to make their own best use of a single solar panel. |
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| − | There are conceptual proposals, for {{w|Space-based_solar_power|siting solar arrays in space}}, but in orbit around earth, rather than than on the sun. This would allow for somewhat more solar intensity, and provide more consistent power, but the obstacles of launching the arrays into space and then transmitting the power remain serious pragmatic difficulties.
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| − | ;Calculations
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| − | The formula Randall uses in this comic is electricity price × solar irradiance × panel area × panel efficiency = savings.
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| − | Electricity price is measured in dollars per kilowatt-hour, a unit commonly used by electric utility companies. In both cases, it is assumed to be $0.20 per kilowatt-hour, which is a [https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a reasonable estimate] for domestic, retail electric rates in [[Randall]]'s home of Massachusetts.
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| − | {{w|Solar irradiance}}, a special case of {{w|irradiance}}, is the total amount of power delivered to a surface by the Sun per unit area. This measurement varies substantially by geography, and must account for hours of daylight, angle of the sun, and weather patterns (all three of which vary by season). This number is expressed in kilowatt-hours per square meter per day, though this number is typically averaged for the whole year. Randall assumes a value of 4 kWh/m<sup>2</sup>/day, which is also [https://www.nrel.gov/gis/solar-resource-maps.html reasonable for Massachusetts]. He also calculates the value for the surface of the Sun as its total luminosity (electromagnetic power, ≈3.83×10<sup>26</sup> W) divided by its total area (≈6.07×10<sup>18</sup> m<sup>2</sup>), which comes out to around 6.31×10<sup>7</sup> W/m<sup>2</sup> or 1.51×10<sup>6</sup> kWh/m<sup>2</sup>/day.
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| − | Solar panel area is measured in square meters.
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| − | Solar panel efficiency, a dimensionless quantity, is the fraction of solar power that a panel can effectively convert into electricity. Here, both panels are assumed to be 20% efficient, which is a [https://www.forbes.com/home-improvement/solar/best-solar-panels/ reasonable estimate] for commercially available photovoltaic cells operated near room temperature (300K).
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| − | Multiplying these quantities together yields a unit of money per unit time, per area (dollars per day per square meter with these specific units). For the parameters for the Earth-bound example, the formula yields $0.16 per day in effective earnings, which can be multiplied by 365 to get approximately $58 per year. For the parameters on the Sun, it instead yields $60,400 per day in earnings, or approximately $22 million per year.
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| − | It should be noted that these values are for each square meter of solar panel. Solar systems almost always consist of multiple panels. With the same assumptions, a 30-square-meter system (which is a relatively small, home system) would be worth $1,740 per year.
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| | ==Transcript== | | ==Transcript== |
| | {{incomplete transcript|Do NOT delete this tag too soon.}} | | {{incomplete transcript|Do NOT delete this tag too soon.}} |
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| − | :[Heading:] Option A:
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| − | :[A stereotypical house with a single solar panel upon its roof and an arrow from a label:] 1 m<sup>2</sup> (south-facing)
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| − | :[Formula:] ($0.20/kWh)×(4 kWh/m<sup>2</sup>/day)×(1 m<sup>2</sup>)×20% = <big>$58/year</big>
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| − | :[Heading:] Option B:
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| − | :[A short width of the Sun's undulating 'surface', with two solar prominances/flares and at their height (but above a different part of the surface) a solar panel with some attachment upon its upper surface, depicted horizontally aligned to the Sun and with an arrow from a label:] 1 m<sup>2</sup> (downward)
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| − | :[Formula:] ($0.20/kWh)×(sun luminosity/sun area)×(1 m<sup>2</sup>)×20% = <big>$22 million/year</big>
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| − | :[Caption below the panel:]
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| − | :Solar energy tip: To maximize sun exposure, always orient your panels downward and install them on the surface of the sun.
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| | {{comic discussion}} | | {{comic discussion}} |
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| − | [[Category:Tips]]
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