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San Diego Gas &Electric Signs for 300MW to 900MW of Solar Power

A Stirling Solar Dish system.

San Diego Gas & Electric (SDG&E) has contracted to buy 300MW of solar power for 20 years, with the potential to grow to 900 MW within 10 years, from Arizona-based Stirling Energy Systems (SES).

SDG&E will buy the electrical energy produced from the 300MW SES Solar Two plant, an array of 12,000 Stirling solar dishes on approximately three square miles in the Imperial Valley of Southern California. SDG&E has options on two future phases that could add up to 600MW of additional renewable energy and capacity to SDG&E’s resource mix.

SDG&E has committed to delivering 20% of its electricity from renewable sources by 2010. The utility also announced the purchase of approximately 4MW of energy and capacity from a local biogas landfill project.

The contract marks the second major deal recently for SES. In early August, SES announced a contract with Southern California Edison that will result in the development of a 500MW solar project in the Mojave Desert northeast of Los Angeles, with an option to expand the project to 850 MW. The first 500 MW phase, consisting of a 20,000-dish array, is to be constructed during a four-year period.

The Stirling Solar Engine

The SES dish technology converts solar thermal energy to electricity by using a mirror array to concentrate the sun’s rays on the receiver end of a Stirling engine. (This type of approach to solar generation is termed Concentrating Solar Power (CSP), as opposed to photovoltaic (PV).

The internal side of the receiver then heats hydrogen gas, which expands. The pressure created by the expanding gas drives a piston, crank shaft, and drive shaft assembly much like those found in internal combustion engines but without igniting the gas. The drive shaft is connected to a small electricity generator.

The entire energy conversion process takes place within a canister the size of an oil barrel. The process requires no water and the engine is emission-free.




Any idea about how much for each of these things cost?

Seth Murphy

My math could be way off on this, as I have no access to actual company information, but I've read that the goal is to get the cost down to $25,000 to $30,000 per concentrator with a decent profit margin when selling at six to eight cents per Kw. Each concentrator should generate 25 Kw per hour for an average of six hours per day. I have no clue regarding the yearly maintenance costs, but my calculations show a 20 year return (in today's dollars) of $65,000 to $87,000. I don't know the price per acre, price of transmission lines, etc.., but I am absolutely fascinated with this technology. The idea of mass production, a distributed clean system, and returns that banks or investors can see is a break through. I may need to buy a ticket and fly down to see some of the inital systems.

Harvey D

A very interesting solution. Delivering clean intermittent (during sunlight hours) power to the electrical grid at 6 to 8 cents a Kwh would be more than acceptable, specially where the solar units could be paired with other primary power sources that could easily be turned on and off. The same applies to wind farms with much longer cycles. Both systems could reduce reliance on coal/gaz/fuel power generating units and reduce air pollution while producing the extra clean power required to recharge the plug-in hybrids.


I thought the SES engines used a wobble plate instead of a crank shaft.


According to Seth, you get 10~14% of returns per annual. Which is a good investment! Plus you do not need to worry about any oil or market problems.


SES pricing info and much more -



me interesa el tema por favor si pueden les agradesco dicha informacion
gracias sdo.atte arnold

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