Solar technologies and economics

As renewable energy has become cheaper to produce and traditional hydrocarbon energy sources are getting more expensive, for the first time we are seeing that the future of energy in the US is renewable energy. I am especially excited about solar energy. Some solar technologies are already cheaper than natural gas fired utility grid pricing.

There are various way to delineate the current solar technologies:

Photovoltaic(PV) vs thermal (concentrated solar power - CSP)
Silicon based solar vs non-silicon based solar

I feel the silicon vs non-silicon is the best way to divide the solar technologies. Most all residential and commercial solar PV systems have been Si based. Si based technologies were born in the semiconductor age, and the material science about Si has flourished.

The main problem with using Si based solar for large scale power is that Processing silica (SiO₂) to produce silicon is a very high energy process - at current efficiencies, it takes over two years for a conventional solar cell to generate as much energy as was used to make the silicon it contains. Like all other energy sources - the concept of net energy is the crucial factor. You can also read my article on peak oil economics.

Besides full cycle cost, the other factor is efficiency. Basically this is the joules of energy that hit an area of the earth vs the joules of energy in electricity that solar can provide. Energy efficiencies have run from 5% to about 20% for most current practical solar technologies.

Si based solar has been more efficient PV than other materials, but now that gap has closed. Several thin film non Si solar systems have achieved 15% efficiencies, at full cycle costs that are over 80% cheaper than Si solar. So one can see it is the combo of efficiency and cost that determine if solar is cheaper than fossil fuels. This article about Heliovolt, A thin film spin-off technology from NREL demonstrates these factors. NREL just achieved 40% efficiency this year using new thin film technology. NREL will spin this technology out to the free markets if it shows economic progress. Many of the private solar thin film firms got their technology from NREL.

My economic research shows that thin film solar and concentrated solar power(CSP) are now cheaper then natural gas full cycle pricing. Concentrated solar firms are broken down by thermal solar(CSP) vs concentrated photovoltaic(CPV). A main difference between the CSP firms and thin film firms is that CSP firms have focused on efficiency. Here is a list of concentrated solar firms:

Thermal:
Ausra's
Abengoa Solar
Brightsource Energy
Solel
Esolar
SES

CPV:
SolFocus
CoolEarth
Greenvolts
Sunrgi
Skyline


That leaves us with thin film solar technologies. Read Nanosolars 3 generation of solar for a quick review of the history of thin film. Below are my recaps of the main thin film technologies:

CIGS: copper, indium, gallium, selenium. This thin film is getting a lot of press lately. This appears to be the technology that will be one of the solar winners.

Benefits: High absorptivity, low cost. Falling cost as in Moore's law will continue.
Negatives: relies on some rare materials - indium, gallium. Smelting of ores such as zinc require energy to extract. Would material cost rise if 20% of grid went solar?

CdTe: cadmium, telluride.
Benefits: High absorptivity, low cost.
Negative: Toxic cadmium. This is a toxic material and is the death sentence for CdTe being widely used IMHO. First Solar uses this thin film technology.

GaAs; Gallium arsenide.

Benefits: Insensitive to heat, low cost.
Negative: long term high cost of material if solar used 20% of grid.

Amorphous thin film silicon

Benefits: the bonding defects best for thin film. Much thinner mean less Si used.
Negatives: refining to 99.9999% purity is very energy intensive- High cost.

Here are just a few of the thin film solar firms that are well funded, and are currently ready to deliver economic solar solutions:

Nanosolar
Heliovolt
Solyndra

The solar industry is moving towards having customers use an implementation partner to install and maintain the solar systems. You would supply the land, and sign a power agreement, No upfront cost. Here are some of the implementors:

SunEdison
Phoenix Solar
AEE Solar
Akeena Solar
Solarcity

Another important discussion are the various market segments for solar, so we could have many "winners". An example would be the difference between residential roof top applications (need high efficiency), and large scale brownfield solar plants where land is cheap, used, with little other uses (low efficiency would be fine - if it's cheap per watt).... Here is a quick list of markets I see:

1)Residential roof top
2)Residential land
3)Commercial rooftop
4)Commercial land
5)Small town/rural solar municipal plants
6)Brownfield land - Right of way for US roads, and US power lines, and railroads.
7)Large scale greenfield power plants.
8)Specialty (Military, satellites remote locales, drilling, etc...)

Below are some articles that should interest city state, and county officials that are looking at solar. During the next five years we could see a revolution that changes the way we look at energy - and creates million of jobs in the process.

Marin county wants solar
Sunedison solutions
Tucson solar coming
Solar winery project
Tracy City Council wants to go solar
Cochise County Planning solar
Sutter Health system to install solar
Gainesville Regional Utilities plan
Solar grid pricing
Colorado hospital going solar
LA county orders solar rooftop
Farm gets 2mw solar
High real cost of pollution