PV Sells or PV cells, 1998

PV Sells – PV cells – or is UK advertising better than thinking

So, architects advocate photovoltaic cells as part of a green approach to their buildings. How many remember the early cells used for satellites made from Gallium arsenide ? Pretty nasty stuff. Nowadays, it is more common to find them made of second-grade chip silicon. Should we be surprised to find that the production of PV Si cells is near electronic chip factories? How many architects know how they work? -the freeing of electrons by photon energy. Or how long they last ? – at best 25 years.
Or what is the real pay-back period ? – 100 – 120 years when there is no subsidy, which someone is paying for anyway. Unfortunately, the PV cells died 75 years ago!
Installation costs on roofs, or land value for PV fields?
Or how efficient are they? – currently marketed amorphous Si modules achieve about 5% in use, 10% at very best, and theoretically only 27%.
(Vacuum tubes are 70% irradiation conversion efficient – only for heating water?)
Or how much they cost? – they say between £ 12 – 15/Wp, but some went up last year by 10%. Or how much energy is used in their fabrication? – the glass, the frame, the silicone, the wire, the protective packaging, the transport……Or how much do they cost to maintain/m2? – keeping the glass really clean to enable them to function near their capacity. Or how much energy is used to do this, and maintain the overall system? Or what do you do with the heat that they give off? – keeping them cool to enable them to function near their capacity, and, annoyingly, they tend to give off more heat in the summer (solar irradiation at its highest) when we don’t really want it. Most inconvenient for integrating into facades unless the facade has another skin and you ventilate the cavity and of course this all costs more money (energy) for the additional glass layer; and how inconvenient that they only last up to 25 years – which means either dismantling or throwing away the facade – depending how “well” they have been integrated into the facade – a bit of a waste of energy, no? In the UK, we receive a peak level of solar irradiation of only 600W/m2 – at a manufacturer’s stated of efficiency of 10%, gives 60Wp/m2 at £ 15/W = £ 900/m2, when really you only probably exploit half the energy because the protective glass is not kept clean, and/or they are not kept cool. So really, they probably cost the capital equivalent of nearer £ 1800/m2; or £ 30/W generated.
So, the architects’ argument goes like this: –