Inputs and Outputs

Data Inputs

Solar Parameters

  • Solar Profile

    • According to the location chosen by the user, the hourly solar power output (in W/kWp) for 24 hourly values per day is being obtained from the Global Solar Atlas. The typical values should be between 0 and 1000. The retrieved profiles from the Global Solar Atlas are the average hourly profiles for one day per month, retrieved from the Global Solar Atlas. The values assume a ground-mounted large-scale system, with optimum tilt.

    • For uploaded profiles using a CSV file, the solar data (hourly solar output in W/kWp) should be one CSV column, with a multiple of 24 rows.

  • Solar Cost

    • The price of the solar portion of the plant, including inverters and other supporting infrastructure.

  • Solar Asset Life

    • The economic lifetime of the solar portion of the plant, which is generally around 25-30 years, considering the energy production reduction over time.

  • Nominal Solar PV Size

    • Used for Smoothing solutions. The desired nominal size of the PV plant inserted by the user. This is a specific requirement for the solver -- it will return a solution with the exact sizing of the battery storage for the solar plant.

  • Solar Capacity Limit

    • Used for the Shifting solutions. This is the maximum size of the PV plant considered by the solver for the optimization process. The plant will be optimally sized up to this value to serve the load described by the demand profile which is inserted by the user.

Smoothing Parameters

  • Smoothing Period
    • The requested time period in hours for the total system output to be flattened to the average solar input over that time.

Shifting Parameters

  • Peak Demand

    • The power level corresponding to a factor of 1.0 on the Demand Profile (MW).

  • Demand Profile

    • The relative demand for power from the system over the course of a day. This expects hourly values in the range of [0, 1]. The peak value of 1.0 corresponds to the value given in for Peak Demand.

    • The default demand profile has an evening demand peak after the solar production peak at midday.

    • The graph shows the currently selected solar profile in the background. This profile is updated when the user updates the solar profile.

  • Unserved Energy Cost Profile

    • Unserved energy cost is the economic value to the cost of electricity interruptions to electricity consumers and the economy as a whole. The profile is the relative cost of unserved energy over the course of the day with hourly values in the range of [0, 2]. The user can adjust the cost profile to have periods with higher unserved energy costs such as during the peak hour periods. A value of 1.0 corresponds to the value inserted by the user for Unserved Energy Cost which can range from $0.5-10/kWh in the developing countries depending on the country.

    • The default Unserved Energy Cost profile has a higher value in the evening hours.

Battery Parameters

  • Battery Technology

    • There are 5 choices for battery technology that preset appropriate values for the individual battery inputs which can then be adjusted by the user.

  • Cost of Battery

    • The cost of the energy storage component of the plant, excluding inverters and other costs.

  • Cost of Battery Inverter

    • The cost of the battery inverter and balance of plant separate from the cost of the battery itself.

  • Energy Capacity Limit

    • The maximum size allowed for the battery portion of the plant which can be adjusted by the user. This limits the total energy storage of the system that is considered within the solver.

  • Power Capacity Limit

    • The maximum size of the battery inverter. This limits the peak power delivery and charging rate for the energy storage system. The solver will be limited by this value.

  • Minimum State of Charge

    • The amount of energy (in percentage) that must remain in the battery system at all times. This reduces the nominal battery capacity to the usable capacity.

  • Round Trip Efficiency

    • Accounts for the losses from the inverters, charging/discharging of the battery system.

  • Battery Asset Life

    • The Economic lifetime of the battery portion of the plant. This can be set separately from the lifetime of the solar portion of the plant.

Economic Parameters

  • Unserved Energy Cost

    • Unserved energy cost is the economic value to the cost of electricity interruptions to electricity consumers and the economy as a whole.

  • Discount Rate

    • The cost of funds to finance the system.

Data Outputs

The solution presents the optimal sizing of the solar and battery storage systems for the two different applications of “Solar energy output smoothing” and “Solar energy output shifting to meet a given demand profile”.

The summary of each output parameter is explained below:

Summary

  • Solar Capacity. For smoothing, this is the specified Nominal PV Size. For shifting, this is a component of the least cost solution. An asterisk appears in the results if this component is limited by the input in case of the solar energy output shifting application.

  • BESS Energy Capacity. An asterisk appears in the results if this component is limited by the input.

  • BESS Power Capacity. An asterisk appears in the results if this component is limited by the input.

  • LCOE Levelized Cost of Energy, here calculated as the total solution cost excluding the unserved cost, divided by the energy generated by the solution.

  • Solar Plant Cost, calculated as the Solar Capacity * Solar Cost.

  • BESS Energy Cost, calculated as the BESS Energy Capacity * Cost of Battery.

  • BESS Power Cost, calculated as the BESS Power Capacity * Cost of Battery Inverter.

  • Total Capex is the sum of Solar Plant Cost, BESS Energy Cost, and BESS Power Cost.

  • Unserved Energy Cost is the total cost of the unserved energy, including the unserved energy cost profile if running the solar energy output shifting solution.

Time Series

  • Load Served from Solar (Green area, top graph). The load served directly from the solar PV plant.

  • Load served from BESS (Blue area, top graph). The load served from the BESS system.

  • Unserved Energy (Red Area). The energy that was uneconomic to serve with this solution. This is shown in context in the top graph and highlighted in the bottom graph.

  • Solar Output (Yellow Area). The output from the Solar portion of the system. This output is divided between load served directly and the charging of the BESS system.

  • Served Energy (Black Dotted Line). The total output of this solution. The sum of the served energy and the unserved energy is the demand profile.

  • BESS Discharge per hour (Blue Area, middle graph). The output from the BESS system, corresponding to the Load Served from BESS.

  • BESS Charge per hour (Green Area, middle graph). The input to the BESS system from the solar component.

  • BESS Stored Energy (Light Blue line). The overall state of charge of the BESS energy component.