Take the 17 family in Fuyang City, Zhejiang, China who use solar roof tiles as an example.

As the country's first residential test plot for photovoltaic power generation, 17 farmers tried high-tech and tested the self-sufficient electricity model.

From a distance, the tiles of the 17 houses are black, and the roofs are not much different from ordinary tiled houses, but when you look closer, in the center of each tile, there are sometimes thick white lines and thin yellow lines in the black material, electric energy, It flows in these lines. These tiles are photovoltaic tiles that uniquely turn solar energy into electrical energy.

Each tile can generate electricity, and the more special tiles used on the roof, the more electricity the roof can generate per minute under the sunlight. Before installation, after investigation, the main electrical equipment of 17 households includes refrigerators, TVs, electric lights, electric fans, etc., with an average of more than 50 kilowatt-hours of electricity per household per month.

According to the monthly electricity consumption of more than 50 kWh, an average of 98 tiles that can generate electricity are installed on the roof of each household, and the remaining tiles are ordinary tiles with similar appearance. According to estimates, each household generates an average of about 57 kWh per month, and the annual power output of 686 kWh is roughly the same as the total electricity consumption of residents.

What about rainy days and nights?

The State Grid launched a new policy, and small solar power generation equipment below 6000 kilowatts can be connected to the State Grid.

In other words, during the day with little cloud, every house is a power plant, and in rainy days and at night, it becomes a consumer of electricity. For example, if a house generates 1,000 kWh a year, all power generation is not wasted, and it is sent to the grid for everyone to use. If the total power consumption of this house a year also happens to be 1,000 kWh, it will not be supplied to hydropower stations, thermal power stations, Public power generation institutions such as nuclear power plants increase the burden of power generation, which is equivalent to self-sufficiency, while the huge power supply network of the State Grid is equivalent to the battery of rooftop power stations.

A tile that can't be smashed by hail

This kind of tile has undergone an endurance experiment. An egg-sized steel ball was smashed from a height of 1 meter, and it was hit 25 times without leaving any scars. There is no hail heavier than an egg-sized steel ball in the world. This means that it can withstand the most violent impact test in nature.

Generally, tiles absorb about 5% of water after a heavy rain. The water absorption rate of such tiles is only 1/10 of that of ordinary tiles. Too much water absorption will affect the life of the tiles. Although I am willing to accept the sun’s scorching, it can turn sunlight into electricity, but in the midsummer when electricity is generated, the temperature of the roof is actually lower than that of ordinary roofs, between 50-60 degrees Celsius. This is not difficult to understand. On ordinary tiles, it is heat energy. Photovoltaic tiles convert about 20% of the light energy into electricity, which is 20% less heat. Solar tile houses are much cooler than ordinary houses in summer.

Can residents even sell electricity to make money?

In the homes of 17 farmers, each household has installed two electric meters. One electric meter is connected to the roof. The tiles capture the electric energy generated by solar energy. Bit by bit will pass through this electric meter and flow to the large power grid. It faithfully records each one. How much electricity does this household generate each month and each year? There is also an electric meter, like an ordinary residential house, with one end connected to the power supply line of the home and the other connected to the large power grid. It records how much electricity the family uses every month.

With these two meters, households that can generate electricity can calculate the electricity bill clearly with the power supply bureau. For example, if the electricity generation is 100 kWh this month and the electricity consumption is 120 kWh, then this family only needs to pay the electricity bill for 20 kWh. So, what if more electricity is generated than the electricity supplied to the grid? Residents can sell electricity to make money.

Electricity bill and environmental protection account of a farmer

Self-sufficiency in electricity consumption sounds beautiful, but if the power generation tiles sell for sky-high prices, the installation and maintenance costs are also high, which is not cost-effective, and the new technology is difficult to promote no matter how good it is.

The power generation of a tile is 8 watts. On average, 98 tiles are installed on the roof of each villager. The power generation power of the rooftop power station is 784 watts. How much electricity can a small power station of 784 watts generate in a year? This calculation is a difficult problem, because each province, each county, and even the shaded and sunny sides of the hillside receive sunlight for a different amount of time each year. It is estimated that in the suburbs of Fuyang City, the average annual solar photovoltaic power generation is 0.87 kWh per watt. Then, considering the fluctuation of the annual sunshine time, the annual power generation of a household is around 686 kWh.

According to the design life, these solar tiles can be used for 25 years. The 17 households in Fuyang can generate 11,637 kilowatt-hours of electricity a year, and about 290,000 kilowatt-hours can be generated in 25 years, saving about $ 27,000 in electricity costs, and an average of about $ 1500 per household. The construction cost of the roof of each household is about $2300 on average. In this way, the cost of building the roof is higher than the total electricity bill. But don’t forget, these roofs are not only generators, they are also roofs. Even if solar roofs are not used, the cost of building a common roof is around $1500.

In addition to the consideration of the economic account, the environmental account is a pure income. Thermal power plants can generate 290,000 kilowatt-hours less, save 134 tons of coal, use 1,339 tons of water, and reduce 333 tons of carbon dioxide and 91 tons of dust in the air.

As for how much electricity your house can generate in a year, in Zhejiang, the average power of solar tiles per watt can generate 1 kWh per year. There are 450 tiles on a 50 square meter roof, with a total power of 3,600 watts, which roughly generates electricity a year. 3600 degrees is enough to meet the electricity needs of most households in Zhejiang.

If the solar tile house is installed in Yunnan, where the sun is more intense, the electricity generated by the same power tile is 1.5 times that of Zhejiang.