High in the Chilean Andes, at the edge of a copper mine, a raft of solar panels sits on water the color of wet cement.<\/p>\n
The pond underneath is not a lake.<\/p>\n
It holds tailings, the ground up rock left behind after the copper is pulled out.<\/p>\n
The array on top is small enough to miss<\/strong>, and it makes about as much power as a handful of American houses burn through.<\/p>\n It was still worth building<\/strong>, for a reason the output figure never explains.<\/p>\n The installation went live in May 2019 at the Las Tortolas pond, part of the Los Bronces operation.<\/p>\n The array carries 256 panels rated at 330 watts each.<\/p>\n That works out to 86 kilowatts, roughly what a large gas station canopy might hold.<\/p>\n The floating solar panels ride on plastic pontoons, tethered so the array can rise and fall as the pond level shifts.<\/p>\n Across a year it produces about 150,000 kilowatt hours.<\/p>\n Its owner called it the first photovoltaic plant in the world built over mining tailings.<\/p>\n Nobody built it for the 150,000 kilowatt hours<\/strong>.<\/p>\n A mine the size of Los Bronces swallows that figure inside its rounding error<\/strong>.<\/p>\n Start with something every rooftop owner learns the hard way.<\/p>\n Solar panels lose efficiency as they heat up.<\/p>\n Heat is the standing tax on every solar installation on earth.<\/p>\n A cell baking at 150 degrees on a dark roof delivers noticeably less than the same cell kept mild.<\/p>\n Water is an excellent heat sink.<\/p>\n A panel floating a few inches above a pond sits in air the water holds steadily cooler<\/strong>.<\/p>\n Studies of paired installations generally find the floating array running ahead of an identical land array through the hottest hours.<\/p>\n That gain is real, and it is modest.<\/p>\n It is also not the reason<\/strong> this particular plant exists.<\/p>\n Water in an open pond leaves constantly.<\/p>\n In a dry, sunny, windy basin it leaves fast.<\/p>\n Across the American West, evaporation from open reservoirs is measured in feet of depth per year, not inches.<\/p>\n The loss does not pause at night, and it does not pause in winter.<\/p>\n For a farm or a city that loss is expensive.<\/p>\n For a copper mine in a water stressed country it is the whole game<\/strong>.<\/p>\n Los Bronces already recirculates most of its process water, between 70 and 80 percent of it.<\/p>\n Every gallon that escapes into the air has to be replaced from somewhere else.<\/p>\n In Chile, that somewhere else is increasingly contested<\/strong>.<\/p>\n Here is what the panels are actually for.<\/p>\n Where they cover the surface, they cut evaporation by about 80 percent, according to the operator<\/a>.<\/p>\n Shade keeps the sun off the water, and the floats break the wind that carries vapor away.<\/p>\n The electricity is a byproduct.<\/p>\n The saved water<\/strong> is the product.<\/p>\n Cover more of the surface and the saving scales along with it.<\/p>\n That inverts how most people picture a solar farm, and it is why the idea traveled.<\/p>\n A plant that pays for itself in water rather than in kilowatt hours can be justified in places where power alone would never cover the cost.<\/p>\n The same logic decides hardware everywhere in this industry, the way an offshore project<\/a> lives or dies on what its equipment can actually do.<\/p>\n It came with an honest limit, because the raft covered only a small fraction<\/strong> of the pond.<\/p>\n The United States holds an enormous amount of man made water.<\/p>\n Federal researchers put the floating solar potential on federally controlled reservoirs at between 861 and 1,042 gigawatts.<\/p>\n That is roughly half the solar the country would need to decarbonize its grid by 2050, as trade coverage<\/a> summarized the findings.<\/p>\n Texas alone holds about 16 percent of that total under a conservative scenario.<\/p>\n The median site would run near 123 megawatts, which is a real power plant rather than a demonstration raft.<\/p>\n Most of the largest opportunities sit across the sunbelt, where the water is already under the most pressure.<\/p>\n None of it is free.<\/p>\n Floating systems cost more per watt than ground mounted ones, permitting on federal water moves slowly, and the effects of shading a reservoir are still being studied, the way argument around a solar site<\/a> outlives the technical questions.<\/p>\n But the arithmetic that made a tiny raft worth building in Chile is the same arithmetic draining the Colorado River basin.<\/p>\n Land is scarce, water is scarcer, and a panel that protects both<\/strong> is worth more than its nameplate suggests.<\/p>\n The raft in the Andes was never really a power plant.<\/p>\n It was a proof of concept<\/strong> for something far larger.<\/p>\n","protected":false},"excerpt":{"rendered":" High in the Chilean Andes, at the edge of a copper mine, a raft of solar panels sits on water the color of wet cement. The pond underneath is not a lake. It holds tailings, the ground up rock left behind after the copper is pulled out. The array on top is small enough to miss, … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":2134,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-2133","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-solar-power"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/posts\/2133","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/comments?post=2133"}],"version-history":[{"count":1,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/posts\/2133\/revisions"}],"predecessor-version":[{"id":2135,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/posts\/2133\/revisions\/2135"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/media\/2134"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/media?parent=2133"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/categories?post=2133"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/uk\/wp-json\/wp\/v2\/tags?post=2133"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}The strange thing floating at Las Tortolas<\/h2>\n
Why a panel would rather be over water<\/h2>\n
What an open reservoir loses to the sky<\/h2>\n
The number that explains the whole raft<\/h2>\n
Why American reservoirs are suddenly interesting<\/h2>\n