Quick answer: Solar thermal energy storage stores heat in a medium such as molten salt, concrete, rock or water. Dehumidification has nothing to do with the storage process itself; that is the job of the process design. Moisture control matters for the auxiliary equipment around it: control cabinets, motor-control centres, junction boxes, instrument panels, pump rooms and electrical buildings. These see condensation when they cool at sunset and during shutdowns, especially in desert sites with big day–night swings. Fix water ingress first, then protect each enclosure or room with heaters, sealed enclosures or dehumidifiers, sized from its own moisture load.
Quick answer
- Process (salt, tanks, piping) ≠ ambient equipment environment.
- Risk windows: sunset, night and shutdown, when equipment cools.
- Fix ingress first; then cabinet or room moisture control.
Two boundaries
| Boundary | Includes | Controlled by |
|---|---|---|
| Process system | Storage medium, tanks, piping, pumps, heat exchangers | Process design (temperature, chemistry, freezing, corrosion) |
| Ambient equipment environment | Control cabinets, MCCs, junction boxes, instrument panels, pump rooms, electrical buildings | Enclosure design, HVAC, heaters, dehumidification |
The US DOE describes thermal storage media and heat-transfer research for concentrating solar power (US DOE, Solar thermal energy storage and heat transfer media); NREL studies corrosion and durability of CSP materials (NREL).
Where moisture matters
| Location | Risk |
|---|---|
| Outdoor control cabinets and junction boxes | Night condensation, dust plus moisture → corrosion |
| MCCs and electrical buildings | Humid air during shutdowns; HVAC off |
| Pump and valve areas | Cold surfaces after shutdown; washdown |
| Insulation jackets | Water entering and soaking insulation; corrosion under insulation |
| Instrument panels | Sensor drift, connector corrosion |
High-risk windows
- Sunset and night: enclosures cool fast in clear, dry climates; humid air drawn in by day condenses.
- Shutdown and maintenance: equipment heat stops; see seasonal shutdown condensation.
- Rare humid or rainy spells in desert sites.
Order of actions
- Fix water ingress and drainage (seals, cable entries, roofs, insulation jackets).
- Control dust and salt (filters, sealed enclosures).
- Choose a method per zone: anti-condensation heater, sealed enclosure, or dehumidifier; see heater vs ventilation vs dehumidifier.
- Coordinate with process and safety functions (interlocks, alarms).
- Commission: trend dew point vs surface temperature over several nights.
Our electrical cabinet dehumidifiers protect control and instrument enclosures.
FAQ
Frequently asked questions
Does molten salt storage need dehumidification?
The salt system doesn't; its control cabinets and electrical rooms may.
When is condensation most likely at a solar thermal plant?
At sunset, overnight and during shutdowns, when equipment cools.
How do I protect outdoor control cabinets at a CSP plant?
Seal against dust and water, then use heaters or cabinet dehumidifiers on dew-point control.
Sources
- US DOE, Solar thermal energy storage and heat transfer media.
- NREL, CSP corrosion and durability.
- ASHRAE Handbook—Fundamentals, Psychrometrics.
