{"id":2621,"date":"2015-10-31T18:25:35","date_gmt":"2015-10-31T23:25:35","guid":{"rendered":"http:\/\/huewhite.com\/umb\/?p=2621"},"modified":"2015-10-31T18:25:35","modified_gmt":"2015-10-31T23:25:35","slug":"another-approach-to-solar-ctd-2","status":"publish","type":"post","link":"https:\/\/huewhite.com\/umb\/2015\/10\/31\/another-approach-to-solar-ctd-2\/","title":{"rendered":"Another Approach to Solar, Ctd"},"content":{"rendered":"

A reader asks about those new solar panels<\/a>:<\/p>\n

Is it possible to predict where this will work, i.e. in areas with lots of sunlight. Everywhere in the world? It depends?<\/span><\/span><\/span><\/span><\/p><\/blockquote>\n

It depends.<\/p>\n

Let’s start with the ultraviolet side of things.\u00a0 UV<\/strong> consists of two bands, UVA<\/strong> (wavelength of 315\u2013400 nm) and UVB<\/strong> (280\u2013315), courtesy Wikipedia<\/strong><\/em><\/a>.\u00a0 This division is important because UVA is not absorbed by the ozone layer<\/em><\/a>, while UVB is mildly to mostly absorbed by the ozone layer (there’s also a UVC layer, which is completely absorbed and also carries some energy).\u00a0 From the Windows to the Universe<\/a><\/strong><\/em> solar emission chart,<\/p>\n

\"Solar<\/p><\/blockquote>\n

we can see that UVA, which is closer to the visible spectrum than UVB, also carries more energy than does UVB.\u00a0 Since UVA isn’t absorbed by the ozone layer, the depth of the ozone layer at the location of interest (or the altitude of the site, for that matter) isn’t as important as it might be.\u00a0 It’s not irrelevant, since UVB is carrying some of the energy we’re interested in harvesting, but it’s not paramount.\u00a0 My quick research suggests the ozone layer becomes thinner at altitude (thus pilots’ concerns about cataracts caused by solar rays and sunburn) as well as at the higher latitudes, i.e., near the poles.\u00a0 So at higher altitudes and latitudes you may receive a little more harvestable energy.<\/p>\n

What about infrared?\u00a0 Turns out it, too, has problems reaching the Earth’s surface.\u00a0 Windows to the World<\/strong><\/em> has another handy chart<\/a>:<\/p>\n

\"Solar<\/p><\/blockquote>\n

What is absorbing the radiation?\u00a0 According to the Climate Science Investigations<\/strong><\/em><\/a> site, CO2<\/sub> is highly absorbent:<\/p>\n

Carbon dioxide (CO2)<\/strong> is also an important greenhouse gas. It has a long lifetime in Earth’s atmosphere. Carbon dioxide strongly absorbs energy with a wavelength of 15 \u03bcm (micrometers). This makes carbon dioxide a good absorber of wavelengths falling in the infrared radiation region of the spectrum.<\/p><\/blockquote>\n

This explains why CO2<\/sub> is classed as a climate change gas – by absorption, the gas warms.\u00a0 And there’s lots of CO2<\/sub>.\u00a0 More or less evenly distributed, so siting your installation based on infrared considerations doesn’t appear to be an effective strategy, insofar as this amateur (me!) can tell.<\/p>\n

There are other factors as well.\u00a0 The tilt of the Earth relative to its orbital plane (the source of our seasons, basically) means differing levels of solar radiation reaching a given location on Earth varies with the season.\u00a0 The location itself defines the angle of incidence, as moderated by the season.\u00a0 Yet, interestingly enough, a location directly on the equator may not be as effective as a location at 20 degrees latitude, because wet tropical forests will screen out the rays, while at 20 degrees there are a number of dry deserts.<\/p>\n

So, yeah, it depends.\u00a0 Having gone through all this, I have to wonder if these are going to be a gimmick, or part of a larger array where the visible spectrum is also harvested.\u00a0 The diagram from Windows to the World certainly\u00a0 clarifies just how much radiation the Earth’s atmosphere (and magnetic belts) screen out, and what is the best part of the spectrum to harvest – the visible spectrum.<\/p>\n","protected":false},"excerpt":{"rendered":"

A reader asks about those new solar panels: Is it possible to predict where this will work, i.e. in areas with lots of sunlight. Everywhere in the world? It depends? It depends. Let’s start with the ultraviolet side of things.\u00a0 UV consists of two bands, UVA (wavelength of 315\u2013400 nm) \u2026 Continue reading → <\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2621","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/posts\/2621","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/comments?post=2621"}],"version-history":[{"count":8,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/posts\/2621\/revisions"}],"predecessor-version":[{"id":2629,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/posts\/2621\/revisions\/2629"}],"wp:attachment":[{"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/media?parent=2621"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/categories?post=2621"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/huewhite.com\/umb\/wp-json\/wp\/v2\/tags?post=2621"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}