Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the total number of t (µm), when Technology is u c-si?

### Inputs:
table_name: table, columns: ['Technology', 'η (%)', 'V OC (V)', 'I SC (A)', 'W/m²', 't (µm)']

### Response:
SELECT COUNT t (µm) FROM table WHERE Technology = u c-si