Write down all the electronic equipment that you have in your house and need to run smoothly. Check the internet for the amount of power required for different types of electronics. For example, air conditioner consumes 1kW of power. Calculate the total. If the total is around 8kW, double it to 16kW.
Purchase a generator which has a power outage of at least 16kW. Don’t go for house generators that huge power output because it won’t be of much use. It will use a lot of fuel, which will become an expensive affair. Before buying the generator, visit a local repair shop and ask them for the best brand that you should buy.