 GenericStorage with investment in Oemof

hey everyone,

I want to model lead acid battery and Li-ion battery using Oemof. The capacities should be part of the optimization.

I’ve made some researches concerning for the technical parameter I have to enter into the GenericStorage.

• Question 1:
In the literature I find information about the C-rate which describes charging and discharging rates. In GenericStorage the C-rates for charging and discharging is described by the parameters:
invest_relation_input_capacity
invest_relation_output_capacity

I’m wondering wether it’s common to make the assumption that invest_relation_input_capacity= invest_relation_output_capacity, for instance for the lead acid and Li-ion batteries, as according literature reviews I used, there is no separate considerations for the discharge and charge c-rate values, is that always the same or there is storages where the discharge and charge rates have to be considered separately?

• Question 2:
the specific investment price for the battery can be given for example in USD/kWh as well as in USD/kW. Does it make sense, to optimise the power capacity and the energy capacity at same time based on ep_costs=USD/kW and ep_costs=USD/kW USD/kWh (see the example below)? according the constraints for storage in the documentation , the power P_(invest) ist determined by the optimised capacity E_invest and the C-rate and not based on the cost USD/kW. Does that mean that the optimization of the discharge/ charge power in GenericStorage with investment is irrelevant?  storage = solph.components.GenericStorage.
(label=“storage”,
inputs={bel: solph.Flow( investment=solph.Investment(ep_costs=epc_storage_USD/kW), variable_costs=0.0001)},
outputs={bel: solph.Flow()},
loss_rate=0.00,
initial_storage_level=0,
invest_relation_input_capacity=1 / 6,
invest_relation_output_capacity=1 / 6,
inflow_conversion_factor=1,
outflow_conversion_factor=0.8,
investment=solph.Investment(ep_costs=epc_storage_USD/kWh),)

I’m grateful for any help