{"id":715,"date":"2012-09-06T11:15:35","date_gmt":"2012-09-06T10:15:35","guid":{"rendered":"http:\/\/lothianrenewables.co.uk\/?p=715"},"modified":"2024-10-31T09:52:39","modified_gmt":"2024-10-31T09:52:39","slug":"715","status":"publish","type":"post","link":"https:\/\/lothianrenewables.co.uk\/?p=715","title":{"rendered":"Are Solar Panels Green?"},"content":{"rendered":"

\"\"<\/a>Read this article today and found it\u00a0very interesting so have reproduced below. This is a conversation |I have had a lot with customers and academics alike and have heard views expressed of “energy payback (EYR)” of between 1 and 6\u00a0 so the conclusion of the author gives a fair average answer.<\/em><\/em><\/p>\n

Solar panels \u2013 are they really a clean energy technology?<\/a>
\nBy: Jonathan Hood<\/a><\/h2>\n

I bought a couple of solar photovoltaic cell (PVC) panels last year.\u00a0 They\u2019re generating electricity off-grid, so I\u2019m not eligible for the Feed-In-Tariff (FIT).\u00a0 Which is perhaps as well, since this article isn\u2019t about solar subsidy.\u00a0 Instead, it\u2019s about a question often raised when the subject of solar panels comes up: does manufacturing a solar panel use more energy than the panel produces over its lifetime?\u00a0<\/p>\n

It\u2019s an important question, because solar PVC is often referred to as a \u201cclean\u201d technology \u2013 one that generates electricity without producing environmentally-harmful greenhouse gas emissions.\u00a0 Solar panels do this at point of use of course, but they are complex pieces of kit with many components, and energy is required in their manufacture: mining the raw materials, processing, assembling etc.\u00a0 As the world\u2019s electricity system is still primarily fossil fuelled, the energy required to manufacture the panel will probably have come from burning fossil fuel, which means greenhouse gas emissions \u2013 the very thing a solar panel is supposed to avoid.<\/p>\n

The easiest way to determine whether there is a clean energy payback from solar PVC is to work out the \u201cEnergy Yield Ratio\u201d (EYR, the ratio of energy delivered over a panel\u2019s lifetime to the energy required to manufacture it).\u00a0 If the panel\u2019s EYR is greater than 1 (or \u201cunity\u201d, the break-even point), the panel will generate more energy than was required to manufacture it and is therefore an environmentally sustainable energy source.\u00a0 But if the EYR is less than unity, more energy was required to manufacture the panel than it will produce, and it cannot be labelled as a sustainable energy technology under current production methods.<\/p>\n

So what is the EYR of a typical solar PVC panel in the UK?\u00a0 To make this calculation, first you need to know how much energy was required to produce the panel.\u00a0 Then to calculate how much energy the panel itself will produce, you need to know the average sunlight intensity at the point of use and the conversion efficiency of the panel (how much of the light energy hitting the panel can be converted into electrical energy).\u00a0 You also need to know how many years the panel is expected to last for.\u00a0 Fortunately this information is readily available.\u00a0 The only thing to bear in mind is the units: energy is measured in Watts, and power (the rate at which energy is used or produced) in watt hours (Wh).\u00a0 Power levels upwards of 1000 Wh are expressed as kilowatt hours (kWh).\u00a0<\/p>\n

To treat each of the above points in turn:<\/p>\n