Purpose of storage in solar desalination
Storage smooths the intermittency of solar energy, enabling desalination systems to provide water beyond peak sunlight hours and improving system reliability.
Batteries (electrical storage):
- Store PV-generated electricity to run pumps, control systems, and membranes during cloudy periods or at night.
- Enable consistent operation of PV-RO systems and reduce the need for oversized PV arrays.
- Add cost and maintenance but greatly increase service continuity.
Thermal storage:
- Stores heat collected by solar thermal collectors, allowing thermal desalination (e.g., MED, HDH) to continue after sunset.
- Options include sensible heat storage (water, molten salts), latent heat storage (phase-change materials), or storage in insulated tanks.
- Thermal storage can be more cost-effective for thermal-driven systems than batteries for long-duration storage.
Hybrid approaches and sizing:
- Combining batteries and thermal storage can optimize overall system performance—use PV for pumps and electrical controls, thermal storage for continuous heat-driven evaporation.
- Storage sizing depends on desired autonomy (hours/days without sun), water demand patterns, and the cost trade-off between storage and oversized generation capacity.
Careful planning of storage options increases reliability and user confidence in solar desalination systems, making them practical for household and community needs.