Someone

Netbook power requirements: 10 Wh or less

Day:   16 h x 10 Wh x 0.06987 €/kWh = 0.0111792 €
Night:  8 h x 10 Wh x 0.04242 €/kWh = 0.0033936 €

Energy per day: 240 Wh
Energy per month: 7.2 kWh

Cost per day: 0.0145728 €
Cost per month: 0.437184 €