Start with an equipment list
Write down the power in watts for every device and how many hours you expect to use it. Watts multiplied by hours gives a first estimate in watt-hours. Leave room for charging losses, changing use and equipment that may be added later.
Peak power is not the same as energy use
Some equipment needs more power for a short time when it starts. Look beyond average consumption and check the highest load when several devices run at the same time.
Make your enquiry practical
Tell us which equipment you use, the wattage, required hours and available charging source, such as grid power or solar. Also mention if a power interruption would be critical. That makes it easier to advise the right configuration.