It is possible to melt semi-sweet chocolate chips in a bowl using a microwave. It's recommended to melt no more than 2 1/2 cups of unmelted semi-sweet chocolate chips at a time.
Chocolate chips are thick and they don't melt in to a flowing solution. If a thinner chocolate sauce is wanted, it is recommended to add 1/4 cup of coconut oil, cocoa butter or vegetable shortening for every cup of chips. Place the bowl in microwave on medium heat for 40 seconds. Remove the bowl and stir. Then repeat this at 10-20 second intervals until the semi-sweet chocolate is melted to the desired consistency.