davidwickh / solar_pv_and_battery_optimiser

Repo containing code for solar PV and battery optimisation

Solar PV and Battery Optimiser

Overview

An example diagram of the optimiser model can be seen in the image and the following equations below:

Energy Flow Constraints

$$Demand_{t} [kWh] ≤ Battery to house_{t} [kWh] + PV to House_{t} [kWh] \forall $$

$$Generation_{t} [kWh] ≥ PV to battery_{t} [kWh] + PV to House_{t} [kWh]$$

Battery State of Charge Constraints

$$State of Charge_{t=0} [kWh] = Initial State of Charge [kWh]$$

$$Battery Degradation_{t} [kWh] = State of Charge_{t} [kWh] ✕ Degradation Rate [Per]$$

$$State of Charge_{t} [kWh] = State of Charge_{t-1} [kWh] + PV to Battery_{t} [kWh] - Battery to House_{t} [kWh] - Battery Degradation_{t} [kWh]$$

$$State of Charge_{t} [kWh] ≤ Battery Capacity [kWh]$$

Solar Generation Constraints

$$Generation_{t} [kWh] = Solar Irradiance_{t} [W/m2] ✕ Solar PV Size [m2] ✕ Time Slice [h] ✕ Solar Eff [Per] ✕ 0.001 [kWh/Wh]$$

Objective Function

When minimising for battery capacity:

$$Min (Battery Capacity [kWh])$$

When minimising for total CAPEX:

$$Min ( Solar PV Size [m2] ✕ Solar PV CAPEX [£/m2] + Battery Capacity [kWh] ✕ Battery CAPEX [£/kWh] )$$

Installation

To install the optimiser, run the following commands:

1. clone the repo to your local machine
2. navigate to the repo directory
3. create and activate a virtual environment using the following commands:

python3 -m venv venv
source venv/bin/activate

4. install the requirements using the following command:

pip install -r requirements.txt

Usage

Inputs

The optimiser requires the following inputs:

1. Solar irradiance - the solar irradiance in W/m2. An example of this input can be seen below

• Energy demand profile - the energy demand profile in kWh. An example of this input can be seen below

Arguments

The optimiser takes the following arguments (these can be seen by running python run.py --help in the commandline):

• --solar_irradiance_path (required) - the path to the solar irradiance csv file
• --energy_demand_profile_path (required) - the path to the energy demand profile csv file
• --logging_level (default=INFO) - the logging level to use
• --output_path (required) - the path to save the optimisation results to
• --solar_array_size (required if minimising battery size) - the size of the solar array in m2
• --initial_battery_capacity (default=0.0) - the initial battery capacity in kWh
• --battery_degredation_rate (default=0.01) - the battery degradation rate in kWh of electricity per kWh of battery capacity
• --optimisation_objective (default="minimise_battery_cap") - the optimisation objective to use (either minimise_battery_cap or minimise_battery_and_solar_cost)
• --battery_capex (required if minimising total CAPEX) - the battery capex in £/kWh
• --solar_capex (required if minimising total CAPEX) - the solar capex in £/m2

Outputs

The optimiser outputs the following:

• Optimisation results - the optimisation results are saved as a CSV to the output_path specified in the arguments.
• Optimisation plots - the optimisation results are also plotted and saved to the output_path specified in the arguments.
• Commandline logs - a summary of some of the optimisation results are also logged to the commandline.

Running the optimiser

The optimiser can be run in two ways:

1. Minimise the battery capacity required to meet the energy demand profile. In this mode the battery and PV CAPEX are not considered.

python run.py --solar_irradiance_path <path_to_solar_irradiance_file> --energy_demand_profile_path <path_to_energy_demand_profile_file> --optimisation_objective "minimise_battery_cap" --output_path <path_to_save_results_to> --solar_array_size <solar_array_size> --initial_battery_capacity <initial_battery_capacity> --battery_degredation_rate <battery_degredation_rate>

2. Minimise the total CAPEX of the system (battery and PV). In this mode the PV size is no longer an input argument and is instead optimised.

python run.py --solar_irradiance_path <path_to_solar_irradiance_file> --energy_demand_profile_path <path_to_energy_demand_profile_file> --optimisation_objective "minimise_battery_and_solar_cost" --output_path <path_to_save_results_to> --initial_battery_capacity <initial_battery_capacity> --battery_degredation_rate <battery_degredation_rate> --battery_capex <battery_capex> --solar_capex <solar_capex>