Earth Area Required for a Solar Economy

Intro

Below, we motivate the solar economy transition on first principles, and propose a million PV entrepreneurs worldwide to transition the world to a solar economy by distributed PV panel production.

This would require other, simpler means to producing silicon. There is ongoing research into alternate routes for silicon production, see review [1]. But, silicon can also be produced with traditional means, in a bootstrapping approach, even if energy payback times are 2 years. But the article points out that the cost would be 7x higher if Chinese solar-grade silicon subsidies did not exist? And mentions billion dollar costs of solar grade silicon refining operations? Perfect place for open source zone refining. This article is a useful starting point for exploring the true cost economics of solar grade silicon refining.

Metallurgical grade silicon costs only 14-16kWhr/kg - [2]. This energy requirement is much less electrolytic hydrogen, see Hydrogen Production. For comparison, Solar Concrete is only about 1 kWhr/kg.

For perspective - note that 1 kg of silicon (when transformed to PV cells) - can produce the equivalent energy of 100 tons of oil [3] (fact check this by doing the calculation).

Metallurgical grade silicon can be used to make solar cells - [4]. This appears to be 2008.

How is solar grade silicon made? Leaching with acid gets to 99.9% pure - [5].

Monocrystalline is 25% efficient and 38 cents per watt - [6]. It is made from a single crystal, sliced. [7]. Produced by Czochralski process [8], but requires semiconductor grade silicon. How is semiconductor grade silicon made? Requires the silanes and CVD of the Siemens Process.

One way to solar grade is quasi-mono silicon. [9]. Cost is down to 11 cents/watt. [10]

Another way to solar grade silicon is upgrading metallurgical grade. Upgraded metallurgical-grade silicon (UMG-Si) - use induction heating to melt silicon [11]. Cast it.

More

• http://landartgenerator.org/pdf/PosterSolar.pdf
• Cost would be $3-5 trillion, or a fraction of global GDP. [12]
• Then to summarize, WTF is this not happening by next year?
• Only 150 GW of panels are produced per year [13]
• Average consumption is 350W per person for 8 billion people. [14]. This means 3 TW needed. But need to multiply by 4 as sun shines 6 hours on average on any place, World. So say it's about 10TW need for installed PV.
• This means one decade gets us 1.5TW - need a few decades. But this is accelerating.
• OSE proposal - entrepreneurs get involved in PV module production en masse.
• Startup cost of PV manufacturing facility - about $1/W so $5M for a 5MW/year facility. But costs underneath are already 2/3 of finished panel cost, see NREL presentation slide 45 reference below. So highest open source advantage comes from vertical integration, which can arguably perform at lower capital cost than PV panel gigafactories.
• Startup plant for PV manufacturing - See [15] - full breakdown. Initial capitalizatin appears to be spread out over an undefined period. Looks like facility would be somewhere around $2M in equipment? See example of laminator and facility. [16]. 5MW per year is typical, for about 40kW actual power use on laminator. 5MW = 250W*(20,000). 20k panels - or enough for 100 facilities of 50kW each. In this model, the cost is 43 cents per watt, sale price is 64 cents per watt. This is in 2014, so it's a generation ago. Price of solar cells has been dropping - down to around 20 cents per watt for solar cells only [17]. Note that the actual silicon material is a small fraction of the PV module cost - processing is most of the cost.
• Cost breakdown - wafer is 1/3, cell is 1/3, module is 1/3. Each has a 20% margin or such. See p 45 of [18]. But, this is 2011 - so it's about 2 generations ago in PV time.
• Therefore, if we have a bunch of vertically integrated, open source startup entrepreneurs - how much capital would be needed? At a dollar a watt, it's $3T for the transition. Note that the simple calculation of $1/W of PV panels agrees with the Borntoengineer,com article above - which mentions 3-5 tees for the transition. However, we need to multiply this 4x because the sun shines a quarter of the day.
• For roughly 10 trillion (10E12), we need a number of 5MW (5E6)production plants. Or we need 2M entrepreneurs, to do it in a year. The limiting factor is solar cells - which now matches the PV panel production, assuming the cells are used up every year.
• If there are 8B people - one person in 4,000 would have a job as a PV panel entrepreneur. And in a multipurpose facility - this can produce the panels and then reconfigure to derivative functions such as solar steel, hydrogen, or concrete production.