class pv_config:
    def __init__(self, capacity, cost_per_kW, pv_lifetime):
        self.capacity = capacity
        self.cost_per_kW = cost_per_kW
        self.pv_lifetime = pv_lifetime
class ess_config:
    def __init__(self, capacity, cost_per_kW, pv_lifetime):
        self.capacity = capacity
        self.cost_per_kW = cost_per_kW
        self.pv_lifetime = pv_lifetime