Read the section titled "solar power." what are some of the benefits of using solar energy? (site 1)

The energy is heat and light that gets generated from the sun. Therefore, solar heat is converted into electricity, which is renewable in nature.  

The benefits of using solar power are as follows:

Using solar energy helps in reducing pollution as it do not require the burning of any fossil fuels.  It reduces the operational costs as the cost of establishing and maintaining the solar pannels are less expensive. Solar energy is renewable which makes it usable for many years. It is useful for reducing the dependence of the economy on energy or resources that are non-renewable in nature.  

Learn more about solar power here:

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Following are a few benefits of using Solar energy:

The use of Solar energy does not create pollution. Using Solar energy helps in cutting operational costs. Using Solar energy helps in ceasing the depletion of other non-renewable energy resources. The use of Solar energy reduces the dependence on conventional sources of energy. Explanation:Solar energy exists in abundance and is freely accessible. The operations that are fuelled by Solar energy cause negligible or no pollution at all. If the Solar energy is looked at as a reliable alternative to fossil fuels, the fear of running out of fossil fuels would no more exist.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.