FAQs

How does REhnu convert sunshine into electrical energy?

REhnu’s technology, licensed from the University of Arizona, uses large mirrors to focus sunlight onto small but high-output triple-junction photovoltaic cells. These cells yield the highest efficiency conversion from solar to electrical energy of any method.

What makes REhnu’s generators unique?

REhnu’s generators build on three patented developments that take advantage of manufacturing methods already proven in very large scale mass production:

How big will a REhnu farm be?

At first, REhnu will build pilot farms producing just a few megawatts, but to achieve the lowest cost of energy, we envision farms each generating 1 gigawatt. The 70 foot long, 5 ton generators will be built on-site from containers packed with the component parts.

What is a gigawatt?

A gigawatt (1 GW) is a unit of electrical power equal to 1000 megawatts or one million kilowatts. For comparison, peak load in the U.S. (on the hottest summer afternoons) is 800 GW. The total energy produced annually by a 1 GW solar farm is about equal to that consumed by 200,000 U.S. homes.

What happens at night?

REhnu’s system produces electricity only during the day, as do all photovoltaic systems. At levels up to tens of gigawatts, this power can be used to help meet local daytime peak loads. In the longer term, hundreds of GW of daytime solar power can be combined with other renewable energy sources (such as wind, which is strongest at night) in an upgraded grid. With the aid of long-distance transmission lines and large-scale storage, such as pumped hydro, renewable energy can largely replace fossil fuel, 24/7, and on a continental scale.

Do REhnu’s large-scale solar farms consume water?

No. No water is used for cooling. The small amount of water needed to wash the reflectors will be obtained by collecting rainwater on the farm.

What will be the environmental impact of REhnu’s farms?

A 1 GW REhnu farm generates no CO2 and uses no water, while a 1 GW coal-fired plant emits 5 tons of CO2 every minute, while consuming 10,000 gallons of water. The carbon and energy used in manufacturing and installing a REhnu farm is paid back in less than 2 years. Every year after that, the farm spares the atmosphere 2 million metric tons of CO2. A thousand REhnu farms operated worldwide, (with a total area of 80 x 80 miles) would reduce total global CO2 emissions by 10%. Locally, the environmental impact of REhnu’s farms is small. Installation of the generators, which are set high above the ground, leaves most of the land undisturbed and largely unshaded. In operation, the solar trackers make almost no noise.

Where is REhnu in the development process?

REhnu is currently partnering with the University of Arizona, providing matching funds for the program to construct generator prototypes. Individual components have already been demonstrated, or are in the final testing phase. An end-to-end test, from reflector to triple-junction cell, has already been completed and demonstrated 27% conversion efficiency at 1000x concentration. A 16 kW prototype with eight reflectors and receivers is now being built at the University of Arizona. REhnu plans to start construction of a 30 kW prototype in 2010.

How long will it take for REhnu to build up to GW scale?

REhnu will build manufacturing facilities to start pilot production in 2012 at 2 megawatts per year, and will team with manufacturers to reach 20 MW/year in 2014 and gigawatt levels by 2020.

How much will a REhnu 1 GW solar farm cost?

The cost for manufacture, assembly, and installation is estimated to be $1 billion, including a $200 million contingency.

Is REhnu’s process dependent on government subsidies?

Not at gigawatt scale. REhnu’s process is inherently cost-efficient and is designed for high-volume production, lending itself to highly automated production and installation. The projected cost at gigawatt scale is fully competitive with electricity from fossil fuels. In the initial, smaller-scale phases, REhnu will benefit from Renewable Energy Credits (RECs) and solar investment tax incentives, but these are not used in REhnu’s long-term business model.