Badger Blog Alliance

Sic Semper Tyrannis

Sunday, June 08, 2008

Re: Thin Film Photovoltaic Efficiency Bleg


Photo - light
Voltaic - electricity
Photovoltaic - producing electricity from light.

The stereotypical electricity from light generation material is heavy & cumbersome. Generally, being a silicon material under a sheet of glass. If one wants to put the stuff on their house they generally have to make sure the surface bearing that load CAN bear the load. Meaning, a sturdier, and of course, more expensive roof.

The new generation of photovoltaic material is thin, pliable, and lightweight. One can roll it up and unroll it, and no special roof reinforcement is required (however, some materials require metal pan roofing). One product I see you can just unroll onto your roof and it even mimics the look of a traditional shingle roof.

I have studied the payback period of such material in our region and I am convinced it is very close to bursting out from early adopters and going mainstream. Certainly, in sunny regions it is very likely the material will make rooftop solar cheap enough to go mainstream. Still, it will lessen the need for traditional electrical generation not supplant it.

However, in my calculations I have to make certain assumptions. The one product I am looking at says it can generate a maximum of (for instance) 150 watts. I am guessing but not certain about what that means.

Data I retrieved from NASA indicates during June the sun delivers an average of about 6 kW-hours of energy per square meter per day in my area which translates into 250 watts per square meter over the entire day (of course, at night the level will be nil and during the day it will be higher). My concern is will my 150 watt material deliver 150 watts or (assuming a 15% conversion rate) more like 37.5 watts? I am assuming it is the later rather than the former. Efficiency numbers (the rate at which light energy is converted to electricity) have been hard to come by.

My calculations show this translates (if the installation is eligible for WE Energies green energy plan) into about $100 per year of electricity being generated. This means the material is paid for in about 7 years (I am as of now neglecting the cost of the grid-tie in hardware, the metal roofing required, labor, and the cost of money).