Liquid vs. air cooling — differences in practice
| Parameter | Liquid | Air |
|---|---|---|
| Cell temperature spread | < 3 K | 8–12 K |
| Derating at 0.5C in heat | none | frequent |
| Parasitic load | 1.5–2.5% | 3–5% |
| 20ft container capacity | 5.0–6.9 MWh | 3.4–4.2 MWh |
| Servicing | coolant change every 3–5 years | filter cleaning 2×/year |
Impact on cell degradation and system lifetime
Pack degradation is determined by the weakest cell. With a 10 K spread, the hottest cells can age up to twice as fast, reducing the usable capacity of the entire string. Temperature uniformity translates directly into meeting the 70% SOH warranty after 10 years.
Parasitic load and round-trip efficiency
The parasitic load of a liquid cooling system is 1.5–2.5% of throughput energy, versus 3–5% for air-cooled systems. At 300 cycles per year in a 20 MWh installation, the difference reaches 150–250 MWh of energy annually.
Operation in heat and frost — Polish conditions
A system with a heating function keeps cell temperature in the 15–35°C window even at -25°C outside, a prerequisite for charging without lithium-plating risk. Above 35°C, no derating means full availability during peak-price hours.
Servicing the cooling system
- Leak-tightness and pressure checks at every scheduled inspection
- Coolant replacement every 3–5 years
- Cleaning heat exchangers and inspecting circulation pumps
- EMS monitoring of cell temperatures with threshold alarming