DIY power plant

Israelis have developed a home system for maximum exploitation of solar energy at low cost.

A solar-heated surface overlooks the rooftops of Ramat Aviv, across from the sea and the Reading power station. In the middle of surface is something that looks like a ramshackle robot, but dont let this description mislead you its an advanced-stage prototype of what is designed to be the next generation of more efficient solar energy systems.

The system is based on a parabolic mirror, which focuses solar energy on photovoltaic cells. The system produces both electricity and heat, and operates at higher efficiency than competing photovoltaic systems. Prof. Abraham Kribus of the School of Mechanical Engineering at Tel Aviv University and DiSP managing director Dr. Daniel Kaftori designed the system.

Ever since the 1970-1980 energy crisis 30 years ago, solar energy has been on the public agenda, Kribus said. However, the power station market is very competitive, and solar energy must be very cheap in order to win a place in it.

Conventional electricity costs $0.05 per kilowatt-hour (KWh), and the cost in Israel is even higher. In order for solar energy to significantly penetrate the market, it must be affordable to the consumer. The cost of solar energy is now double or triple the cost of conventional power, which means that solar electricity cant compete with power stations. Additional payments for electricity include the cost of transporting it and controlling the transportation process.

Thats why its better for consumers to produce their own electricity. Avoiding dependence on large power stations saves on related transportation and control costs, and ensures a supply of personal electricity. A solar device on the roof can save a lot. Electricity bills of consumers using their own private devices fall according to the amount of electricity they consume. Customers will pay only for what they consumer, not for transportation and other such costs. Thats the idea behind our development to set up a home power plant, or a system adapted to the building it can also be adapted to public buildings.

Kribus explains that DiSP does not compete directly with power plants; it makes it possible to produce electricity directly for the consumer. He adds that the companys system also provides optimal energy exploitation. He continues, In the existing solar energy system, only 15-20% of the energy becomes electricity. 80% of the energy absorbed and paid for is lost. Thats why solar energy is so expensive - inefficient conversion. 50-60% of the wasted energy is given off in the form of heat, and our system exploits this energy, instead of letting it go to waste.

In a large solar energy plant, its impossible to convert this energy into heat, because heat cant be transported for long distances. Optimal exploitation can be achieved only by a small system located near the consumer. DiSPs system achieves 60-70% exploitation of the energy produced, without incurring significant additional costs.

The system can use the large amount of heat produced for various applications, such as heating, production of steam for industrial uses, and cooling. There are air-conditioners that use heat instead of electricity. This energy is just the fuel they need. These air-conditioners are called absorption coolers.

"Globes": What youre talking about is a system designed to a great extent for the private consumer. How many such systems will a family with a 100-sq.m. apartment need? How much will it cost them?

Kribus: An apartment like that needs a maximum capacity of three kilowatts, and it therefore needs 25 one-meter units - 25 sq.m. -- on the roof. We can also put the units on angled rooftops, but the mirror has less freedom of movement there, so these units supply less energy.

Kribus and Kaftori assert that the cost of a heating system for a 100-sq.m. apartment will be $20,000. They estimate that the investment will pay for itself within 6-7 years, without government subsidies, and add that the cost of a photovoltaic system, which does not produce the same amount of energy and does not pay for itself, is similar.

Our ambition is to give the consumer the most energy that the home system can produce, and to sell the rest to the national grid. During the day, people are at work, not at home. They dont need the energy produced at these times, so it can be sold to the Israel Electric Corporation.

DiSP was founded eighteen months ago in the framework of the Yozmot Ha'Emek Ofek La'Oleh Technological Incubator in Migdal HaEmek. Italian company SHAP - Solar Heat And Power SpA was recruited as a strategic investor at the very beginning. They will install and distribute our systems when they are ready for commercial use, Kribus says. They are our entree into the market.

Yozmot HaEmek, the Ministries of National Infrastructures and Industry, Trade, and Labor, and SHAP have invested $750,000 in DiSP to date. Kribus and Kaftori are now looking for angels to invest in the company. They estimate that they need $1.5 million before they start making sales, which they expect to happen within eighteen months. The money is needed for continued development of their prototype, followed by marketing.

The global market for conventional energy products totals over $5 billion a year. Photovoltaic systems with an aggregate capacity of over 1,000 megawatts were sold in 2004. Its a huge market, Kribus says. If we take even a small market share, it will be respectable. My dream is for people to buy our system at a Home Center hardware store, and install them they way they now install air-conditioners. A technician will come, connect pipes, do a little welding, and the system will be installed.

Published by Globes [online] - - on October 16, 2005

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