Cheaper solar energy on the horizon

In the search for green energy, solar power is an attractive option, but the price tag is still too high

Finding a more cost-efficient solar technology is the aim of a research project on inverted photovoltalic solar cells at the National Research Council (NRC).

“Right now everyone knows that solar cells are very important for providing clean energy,” says project leader Dr. Ye Tao. “The real problem is the cost.”

Dr. Ye Tao is the leader of the organic materials and devices, NRC Photograph by: Michael Monette

Dr. Tao and his team work out of the organic materials and devices lab. Cast in an eerie yellow light, the lab houses devices used to develop and test solar cell models. The low-cost solar cells developed by the NRC are made of an organic polymer instead of the traditional silicon. This model has the potential to be produced on a mass scale, but it isn’t yet ready for the market.

“Efficiency of the polymer is so far from current solar power,” says Peter Glover, director of sales at Ottawa Solar Power. “It’s not viable now [and] it’s not commercially available.”

Ottawa Solar Power sells and installs solar panels for home and commercial use in Ottawa.

Glover says customers must make a significant investment to use solar power. Adopters can make back some of their investment through government incentives like the Feed in Tariff program in Ontario. Still, the high initial price restricts Glover’s market, he says.

Inverted Organic Photovoltaic Solar Cells
The team at the NRC has a plan to drive down the cost of solar power. With their inverted solar cell model, polymer solar panels will be much easier to manufacture; they can literally be printed.

“To print a solar panel like you print a newspaper, the only metal electrodes that can be produced at a high quality is silver,” says Dr. Tao.

Although silver is optimal for printing solar panels, it can’t act the same as the more efficient aluminum model. The metal in the aluminum model acts as a cathode, attracting a positive charge. Silver doesn’t make an effective cathode, so it must be used as the opposite of a cathode, an anode, which attracts a negative charge.

By changing the role of the metal component of the solar cell, the structure is inverted, allowing the complimentary material to act as a cathode.

“This model can be printed in a large press, and at a very high speed every second it can print 10 to 20-metre long solar cells,” says Dr. Tao. “Only by that fabrication process can you reduce the cost.”

Moving Toward a More Efficient Cell
Bridging the gap between polymer cells and commercial reality requires finding a more efficient model.

Recently, the NRC reached an efficiency of 7.1 per cent with their inverted polymer solar cell.

When the team began their work on organic solar cells, the cells operated at only three per cent efficiency. This meant that for every square meter of solar panel that receives 1000 watts of energy, only 30 watts would be converted into useable power.

The model’s efficiency depends on the structure of the polymer inside the solar cell. In solar cell technology different polymers are used to separate the positive and negative currents from sunlight’s energy. Only once these currents are separated can the power be harnessed.

Manipulating the polymers so they can keep the electron and electron whole pairs separate is a difficult task. The research group at the NRC has made the most progress in maximizing the efficiency of the polymer solar cells.

It’s this type of research that excites industry professionals like Glover.

“Things will change relatively quickly in the next ten years,” he says. “I’m really excited about all of the research that’s out there.”

As current research continues, the solar power industry can expect to eventually hit grid parody, Glover says. This means the cost of producing solar power energy will be equal to traditional forms of power administered by hydro companies.

“That is going to put a lot more people in a position where they will opt to get off the grid,” said Glover.

Story produced by Michael Monette

National Resource Council – Institute for Micro-structures
Ottawa Solar Power