Daily energy budget? It is NOT based on a homes sq. ft. It is NOT based on how many people are living in the house. It is based on the equipment or appliances you want to run and how long each day you typically run them. It does not get more individual than that. The amount of energy you and your family consumes each day will vary among individuals habits and personal choices.
To begin the process of sizing your solar system you first need to pull your most recent 12 months utility bills and record the kWh from each month. Then take the total of the 12 months kWh then ÷ by 365 to get your daily average usage. This number is critical to begin the process for a grid-tie system. Don't have 12 months worth of history? Then average what you do have or if you are moving into a different house use the bills from your current home to get an idea of your energy usage.
You can usually find the kWh near the top of the first page of you utility bills. An alternative method would be to go on line and down load the information or call your local utility company to find out your most recent 12 months total.
One thing to note is that at some locations around the country you are charged extra for using electricity during a specific time of the day, usually in the afternoon hours of the summertime. It may be important to understand that peak period of higher charges because that information may help you down the road when you decide on your budget for your project and how best to maximize your return on investment. A smaller solar kit positioned to harvest and create the most energy during these peak tier rate times may be where you want to start.