The parameters are the user-defined numerical inputs to the model. While usually the structure of a model, therefore the sets, remains fixed across scenarios, it is common practice to change the values of some parameters when running different scenarios and/or sensitivity analyses. As will be clear in the following, each parameter is a function of the elements in one or more sets. For instance, CapitalCost[r, t, and y] indicates that the capital cost is a function of the region (r), the technology (t) and the year (y). A list and brief description of the parameters declared in the master version of OSeMOSYS is given in the below table [3].
| Parameter Name | Description |
| YearSplit[l,y] | Duration of a modelled time slice, expressed as a fraction of the year. The sum of each entry over one modelled year should equal 1. |
| DiscountRateTech[r,t] | Technology specific value for the discount rate, expressed in decimals (e.g. 0.05). |
| DiscountRateSto[r,t] | Storage specific value for the discount rate, expressed in decimals (e.g. 0.05). |
| DaySplit[lh,y] | Length of one DailyTimeBracket in one specific day as a fraction of the year (e.g., when distinguishing between days and night: 12h/(24h*365d)). |
| Conversionls[l,ls] | Binary parameter linking one TimeSlice to a certain Season. It has value 0 if the TimeSlice does not pertain to the specific season, 1 if it does. |
| Conversionld[ld,l] | Binary parameter linking one TimeSlice to a certain DayType. It has value 0 if the TimeSlice does not pertain to the specific DayType, 1 if it does. |
| Conversionlh[lh,l] | Binary parameter linking one TimeSlice to a certain DaylyTimeBracket. It has value 0 if the TimeSlice does not pertain to the specific DaylyTimeBracket, 1 if it does. |
| DaysInDayType[ls,ld,y] | Number of days for each day type, within one week (natural number, ranging from 1 to 7) |
| TradeRoute[r,rr,f,y] | Binary parameter defining the links between region r and region rr, to enable or disable trading of a specific commodity. It has value 1 when two regions are linked, 0 otherwise |
| DepreciationMethod[r] | Binary parameter defining the type of depreciation to be applied. It has value 1 for sinking fund depreciation, value 2 for straight-line depreciation. |
| Demands | |
| SpecifiedAnnualDemand[r,f,y] | Total specified demand for the year, linked to a specific 'time of use' during the year. |
| SpecifiedDemandProfile[r,f,l,y] | Annual fraction of energy-service or commodity demand that is required in each time slice. For each year, all the defined SpecifiedDemandProfile input values should sum up to 1. |
| AccumulatedAnnualDemand[r,f,y] | Accumulated Demand for a certain commodity in one specific year. It cannot be defined for a commodity if its SpecifiedAnnualDemand for the same year is already defined and vice versa. |
| Performance | |
| CapacityToActivityUnit[r,t] | Conversion factor relating the energy that would be produced when one unit of capacity is fully used in one year. |
| AvailabilityFactor[r,t,y] | Capacity available eachTimeSlice expressed as a fraction of the total installed capacity, with values ranging from 0 to 1. It gives the possibility to account for forced outages. |
| OperationalLife[r,t] | Maximum time a technology can run in the whole year, as a fraction of the year ranging from 0 to 1. It gives the possibility to account for planned outages. |
| ResidualCapacity[r,t,y] | Useful lifetime of a technology, expressed in years. |
| InputActivityRatio[r,t,f,m,y] | Capacity available from before the modelling period. |
| OutputActivityRatio[r,t,f,m,y] | Rate of use of a commodity by a technology, as a ratio of the rate of activity. |
| Technology costs | |
| OuputModeofOpeartion[r,t,m,y], | Binary parameter indicating the mode of operation in which a technology has an output activity ratio |
| CapitalCost[r,t,y] | Capital investment cost of a technology, per unit of capacity. |
| VariableCost[r,t,m,y] | Cost of a technology for a given mode of operation (Variable O&M cost), per unit of activity. |
| FixedCost[r,t,y] | Fixed O&M cost of a technology, per unit of capacity. |
| Storage | |
| TechnologyToStorage[r,t,s,m] | Binary parameter linking a technology to the storage facility it charges. It has value 1 if the technology and the storage facility are linked, 0 otherwise. |
| TechnologyFromStorage[r,t,s,m] | Binary parameter linking a storage facility to the technology it feeds. It has value 1 if the technology and the storage facility are linked, 0 otherwise. |
| StorageLevelStart[r,s] | Level of storage at the beginning of first modelled year, in units of activity. |
| StorageMaxChargeRate[r,s] | Maximum charging rate for the storage, in units of activity per year. |
| StorageMaxDischargeRate[r,s] | Maximum discharging rate for the storage, in units of activity per year. |
| MinStorageCharge[r,s,y] | It sets a lower bound to the amount of energy stored, as a fraction of the maximum, with a number reanging between 0 and 1. The storage facility cannot be emptied below this level. |
| OperationalLifeStorage[r,s] | Useful lifetime of the storage facility. |
| CapitalCostStorage[r,s,y] | Binary parameter linking a technology to the storage facility it charges. It has value 0 if the technology and the storage facility are not linked, 1 if they are. |
| ResidualStorageCapacity[r,s,y] | Binary parameter linking a storage facility to the technology it feeds. It has value 0 if the technology and the storage facility are not linked, 1 if they are. |
| Capacity constraints | |
| CapacityOfOneTechnologyUnit[r,t,y] | Capacity of one new unit of a technology. In case the user sets this parameter, the related technology will be installed only in batches of the specified capacity and the problem will turn into a Mixed Integer Linear Problem. |
| TotalAnnualMaxCapacity[r,t,y] | Total maximum existing (residual plus cumulatively installed) capacity allowed for a technology in a specified year. |
| TotalAnnualMinCapacity[r,t,y] | Total minimum existing (residual plus cumulatively installed) capacity allowed for a technology in a specified year. |
| Investment constraints | |
| TotalAnnualMaxCapacityInvestment[r,t,y] | Maximum capacity of a technology, expressed in power units. |
| TotalAnnualMinCapacityInvestment[r,t,y] | Minimum capacity of a technology, expressed in power units. |
| Activity constraints | |
| TotalTechnologyAnnualActivityUpperLimit[r,t,y] | Total maximum level of activity allowed for a technology in one year. |
| TotalTechnologyAnnualActivityLowerLimit[r,t,y] | Total minimum level of activity allowed for a technology in one year. |
| TotalTechnologyModelPeriodActivityUpperLimit[r,t] | Total maximum level of activity allowed for a technology in the entire modelled period. |
| TotalTechnologyModelPeriodActivityLowerLimit[r,t] | Total minimum level of activity allowed for a technology in the entire modelled period. |
| Reserve margin | |
| ReserveMarginTagTechnology[r,t,y] | Binary parameter tagging the technologies that are allowed to contribute to the reserve margin. It has value 1 for the technologies allowed, 0 otherwise. |
| ReserveMarginTagFuel[r,f,y] | Binary parameter tagging the fuels to which the reserve margin applies. It has value 1 if the reserve margin applies to the fuel, 0 otherwise. |
| ReserveMargin[r,y] | Minimum level of the reserve margin required to be provided for all the tagged commodities, by the tagged technologies. If no reserve margin is required, the parameter will have value 1; if, for instance, 20% reserve margin is required, the parameter will have value 1.2. |
| RE Generation target | |
| RETagTechnology[r,t,y] | Binary parameter tagging the renewable technologies that must contribute to reaching the indicated minimum renewable production target. It has value 1 for thetechnologies contributing, 0 otherwise. |
| RETagFuel[r,f,y] | Binary parameter tagging the fuels to which the renewable target applies to. It has value 1 if the target applies, 0 otherwise. |
| REMinProductionTarget[r,y] | Minimum ratio of all renewable commodities tagged in the RETagCommodity parameter, to be produced by the technologies tagged with the RETechnology parameter. |
| Emissions | |
| EmissionActivityRatio[r,t,e,m,y] | Emission factor of a technology per unit of activity, per mode of operation. |
| EmissionsPenalty[r,e,y] | Penalty per unit of emission. |
| AnnualExogenousEmission[r,e,y] | It allows the user to account for additional annual emissions, on top of those computed endogenously by the model (e.g. emissions generated outside the region). |
| AnnualEmissionLimit[r,e,y] | Annual upper limit for a specific emission generated in the whole modelled region. |
| ModelPeriodExogenousEmission[r,e] | It allows the user to account for additional emissions over the entire modelled period, on top of those computed endogenously by the model (e.g. generated outside the region). |
| ModelPeriodEmissionLimit[r,e] | Annual upper limit for a specific emission generated in the whole modelled region, over the entire modelled period. |
| StorageUvalue[r,s] | Heat transfer co-efficient of the thermal energy storage tank. |
| StorageFlowTemperature[r,s] | The temperature of water inflow into thermal energy storage. |
| StorageReturnTemperature[r,s] | The return water temperature in the heating grid where the thermal energy storage is connected. |
| StorageAmbientTemperature[r,s] | The ambient temperature of the locations where the thermal energy storage is located. |
| StorageL2D[r,s] | Binary parameter which indicates the length to diameter ratio of the thermal energy storage tank. Value is 0 if the L2D is 2 and is 1 if the L2D is 4. |
| Storagetagheating[r,s] | Binary parameter indicating whether the thermal energy storage is connected to the district heating network. 1 if it is connected and 0 is if is not. |
| Storagetagcooling[r,s] | Binary parameter indicating whether the thermal energy storage is connected to the district cooling network. 1 if it is connected and 0 is if is not. |