Revision as of 21:40, 8 December 2024

Working Doc

See this reference for more detail [1]
And this discusses poly si vs mono si [2]
embodied energy of 165-375 kWhr/kg [3]
- Good news - 65% of all energy goes into the wafers, as opposed to everything else (glass + All + EVA) according to same link
- Similar for amorphous silicon [4]
Compare to steel at 20 MJ/kg [5], and 200MJ/kg more than this for aluminum [6]
How many grams of silicon are needed for 1kW of PV panels? 2 kg [7], based on 2g/W.
5% of weight of PV is silicon [8]. 76% is glass, 10% is aluminum, and 10% is EVA.
Embodied energy of EVA is about 80 mega joules per kilogram [9]

600 kWhr for 2 kg of silicon
3kWhr per kg for glass, or 90 kWhr for 30 kg glass. [10]
About 40 kWhr per my of EVA/aluminum x 8 kg = 320 kwhr
Total 1010 kWhr
- if the low estimate of 165 kilowatt hours above is true and this is 65% of the energy required then we have around 300 kilowatt hours of energy for wafers, and total around 500 kWhr for 1 kW of new PV panels - meaning energy payback of around 1/4 year!
The case here would be easy for open sector PV production
365*6kWhr~2100 kWhr/yr
Payback is thus 1/2 yr with only the above.
This matches results from Fraunhofer 2021, close enough - .7-1.4 year payback time. [11]

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 =PV Panel Embodied Energy=
 *{{Check}}See this reference for more detail [https://greenchemuoft.wordpress.com/2017/12/12/embodied-energy-and-solar-cells/]