Answer :
The solar panels allow them to keep the energy that they don't use over time to keep for when they need it. Also, the price of fossil fuels are rising and the supply is dwindling. Therefore, the supply may completely be gone in that amount of time.
because solar panels are a one time investment, so even though they may be expensive, you need not pay any more costs for them besides maintenance costs. However, you must continually buy fossil fuels to continue heating your house.