Choosing a small solar system size and capacity that suits your needs requires considering the following factors:

Energy demand: Firstly, you need to understand your energy demand, which is how much electricity you need every month or day. This can be determined by reviewing past electricity bills or recording the power and usage time of household appliances. Identifying energy needs can help you determine the capacity of the solar system you need.

Solar radiation: The amount of solar radiation in your area is another important factor in considering the capacity of solar systems. The higher the amount of solar radiation, the greater the power generation capacity of the system. You can obtain local solar radiation data from the meteorological bureau or solar system supplier.

Installation space: Determining the installation space of the system is also an important factor. You need to consider the available area of roofs, courtyards, or other outdoor spaces to determine what size of solar panels you can install.

Budget: Finally, you need to consider your budget. The price of solar systems usually increases with the increase of capacity. Choose the appropriate system capacity based on your budget.

Generally speaking, you can find a professional solar system supplier or consulting expert who can help you choose a suitable size and capacity of small solar systems based on your needs and conditions.