Cost of energy

REhnu’s goal is cost parity with fossil fuel by 2020, to encourage wholesale adoption of solar electricity and significant reduction in carbon emissions worldwide. REhnu has set its target for gigawatt-scale production at $0.05/kW-hr, and an installed capital cost of $1/watt.

The three main cost elements for the farm are the generator components, assembly and installation, and operations and maintenance. The same choices that lead to good environmental stewardship also lead to low cost for all three elements.

Cost of generator manufacture and installation

Estimated component costs, at GW level

Components Mass kg/kW Cost $/kg Cost /watt
Steel struts, weldments 100 1.0 $ 0.10
Silvered glass dishes 42 1.0 $ 0.04
Triple-junction cells 0.004 40,000 $ 0.16
Silica ball lens 1 40 $ 0.04
Remainder of receiver 1 90 $ 0.09
Aluminum heat exchanger 10 2.0 $ 0.02
Copper wiring 5 6.0 $ 0.03
Pumps, drives 1 50 $ 0.05
Inverters, controls - - $ 0.15
Total 160 $ 0.68

The cost of generators has been minimized by separating and optimizing the manufacturing processes for the different components, and by use of inexpensive materials in lightweight structures. REhnu estimates that the cost of components made in very high volume and delivered to the farm assembly facility will total $0.68/watt, as shown in the table.

Assembly and installation of generators will be at 1 per hour, 24/7. For the 1 GW farm, which takes 4 years to build at this rate, the total labor cost is estimated at around $120 million, or $0.12/watt. The total cost for manufacture and installation is thus $0.80/watt, giving a $0.20/watt margin.

Price of REhnu generators compared to pickup trucks

Could REhnu sell installed generators at gigawatt scale at $1/watt? A comparison with the price of pickup trucks provides an independent check. Generators will be mass-produced in a volume comparable to that of pickups and by similar methods, thus we can expect similar economies of scale. A pickup truck weighing 2.5 tons and delivered to the dealer retails for around $25,000, or $10/kg. An installed 30 kW generator weighs 4.8 tons, and, if it were sold also at $10/kg, the price would be $48,000, or $1.60/watt. However, we can expect the price on a per-kilogram basis to be considerably less, because a generator incorporates a larger fraction of low-cost materials and is simpler both to manufacture and to bring to market. Thus, a selling price of $1/watt does seem realistic.

Economics in the Southwestern desert

On the basis of the NREL map at the top of the page, the annual energy yield is 2.3—2.6 billion kW-hr for a 1 GW farm located in the red or orange regions across most of Arizona and southern California. Sold for $0.05/kW-hr, this will bring an income of $115 million or more annually. REhnu projects a farm lifetime > 20 years. For the glass reflectors, this is based on long-term solar trough experience. For triple-junction photovoltaic systems there is no long-term experience, but by minimizing thermal cycling and avoiding completely any polymers in the high-concentration light path, REhnu projects a similarly long life for its receivers. Farm maintenance, including periodically washing the reflectors in dry, dusty weather, and servicing the moving parts of the drives and cooling systems, has a projected total cost of $20 million/year. The remaining income will be more than sufficient to amortize the cost of the solar farm.