For questions 9-16, read the text below and think of the word which best fits each space. Use only one word in each space.
Renewable Green Energy Power
Calculators powered by solar cells – devices that never need batteries, have been used since the early 1970s. A similar concept has been put (9)… by various energy companies which introduced solar panels. (10)… panels turn energy from the sun’s rays directly into useful energy used in homes and businesses. There are two main panels’ types: solar thermal and photovoltaic, or PV. The first collects the sun’s energy to heat water (11)… PV panels use the photovoltaic effect to turn the sun’s energy directly into electricity, which might supplement or replace a building’s supply.
Solar panels are usually mounted (12)… the roof and angled to face the sun, (13)… allows a large number of resident owners to reduce their monthly electricity bills that will lessen the need of electricity provided by utility companies and also result in extra savings. (14)… fossil fuel based technologies, which are scattered and finite, solar power does not lead to any harmful emissions during operation, (15)… addition, it is available nearly everywhere. It has (16)… estimated that by 2050 27% of global electricity will be generated by solar panels.