Step 1: Solar energy can be collected and stored in different forms.
Step 2: A solar pond is a body of water designed to collect solar radiation and store it as heat.
Step 3: It works by reducing heat loss due to convection, often using salinity gradients.
Step 4: A solar cell converts solar energy into electrical energy, while a solar still is used for water distillation.
Step 5: Therefore, the correct answer is:
\[
\boxed{\text{Solar pond}}
\]