Glossary
Energy key figures
Specific yield
The estimated specific annual yield specifies how much energy the PV system can supply per installed kilowatt peak.
Self-consumption
The self-consumption specifies the amount of self-generated energy that is not fed into the grid but consumed by the customer. The energy can be consumed immediately or after being stored intermediately.
Self-consumption quota
The self-consumption quota describes which proportion of the energy generated is used by the customers themselves.
Self-sufficiency quota
The self-sufficiency quota indicates what proportion of the energy demand can be covered by self-generated energy.
Solar fraction (SF)
Solar fraction is the amount of energy provided by the solar technology divided by the total energy required.
Renewable energies share
With system components (e.g. heat pump): percentage of the renewable energy of the energy generation. At system level: percentage of renewable energy of the annual total energy consumption.
Generated renewable energy
Energy produced from power generating units of the energy system from renewable sources
Electrical energy generated
Electrical energy produced from the power generating units of the energy system
Heating energy generated
Thermal energy produced from the power generating units of the energy system per year
Electrical energy requirement of the load profiles
Sum of the electrical energy demand of all load profiles used in the project per year
Heating energy requirement
Thermal energy requirement for heating element
Hot water energy requirement
Thermal energy requirement for the hot water production
Total heating energy requirement
The annual thermal energy demand for heating and hot water production
Total energy requirement
The sum of the electrical energy demand from the load profiles used in the project and the thermal components per year
Energy consumption heating element
Thermal self-consumption of heating element
Energy consumption hot water
Thermal self-consumption for hot water production
Total energy consumption
The total annual consumption of electrical energy and energy from fuels
Total fuel energy consumption
The total annual energy consumption of fuels
Total electrical energy consumption
The total annual power consumption is calculated from the purchased electricity and the electric current generated, minus grid feed-in and the change in the energy quantity in the electrical storage between the start and the end of the calculation period.
Electricity and fuel consumption
The total annual consumption of electrical energy and energy from fuels
Total purchased energy
The total electrical energy drawn from the grid and energy from fuels
Grid supply
Electrical energy drawn from the utility grid
Max. purchased electricity power
The maximum value of the electrical power drawn from the grid during the period under review
Grid feed-in
Electrical energy fed into the utility grid
Energy consumption saving percentage
Percentage change of the total energy consumption: (before - after)/before x 100. Positive values represent savings.
Percentage of purchased energy savings
Percentage change of the total purchased energy from electric current and fuels: (before - after)/before x 100. Positive values represent savings.
Reduction of the purchased power peak
Change of the maximum value of the electrical power drawn from the grid during the analysis period of profitability: maximum value before - maximum value after. Positive values represent a reduction.
Purchased electricity savings
Percentage change of the purchased electricity (before - after)/before x 100. Positive values represent savings.
Fuel savings
Percentage change of the purchased fuel: (before - after)/before x 100. Positive values represent savings.
CO₂ emissions
Annual carbon dioxide (CO₂) emission due to using fossil fuels
CO₂ reduction
Percentage change of the annual CO₂ emission: (before - after)/before x 100. Positive values represent a reduction.
Electrical energy withdrawn
The electrical energy drawn from the battery system per year
Annual nominal energy throughputs of the battery
The annual nominal energy throughputs of the battery are calculated from the total electrical energy stored intermediately per year, divided by the battery's nominal energy.
Intermediately stored electrical energy
The intermediately stored electrical energy in the battery system per year
Operating time
The operating time is calculated from the ratios of the total energy demand of electric current during a twelve-month period and the highest load within this period.
Annual performance factor
The annual performance factor is a measure for the efficiency of a heat pump. It states how much thermal energy is generated by the heat pump in relation to the current used in the course of a year.
Economic key figures
Energy cost savings
The absolute energy saving costs versus the previous energy costs (user input) or versus an alternative interpretation.
Relative energy cost savings
The energy savings costs as a percentage versus the previous energy costs (user input) or versus an alternative interpretation.
Electricity purchase costs avoided
The difference in the electricity purchase costs (costs before - costs after)
Avoided fuel costs
The difference in the fuel purchase costs (costs before - costs after), taking into account the specified inflation rates
Heating cost savings
The absolute heating cost savings versus the previous heating costs (user input) or versus an alternative interpretation.
Relative heating cost savings
The heating cost savings as a percentage versus the previous heating costs (user input) or versus an alternative interpretation.
Total savings
The total savings over the period under consideration is made up of the total energy cost savings and the feed-in tariffs. The investment costs, the financing costs and the operating costs incl. replacement investments are deducted from this. Here, the inflation rate is included in the operating expenditure and the electricity price increase rate is included in the electricity purchase costs. Furthermore, the degradation of the PV modules is taken into consideration in the feed-in remuneration.
Energy purchase costs
The energy purchase costs are composed of the electricity purchase costs and the fuel purchase costs.
Electricity purchase costs
The costs calculated from the energy drawn from the utility grid according to the selected purchase cost tariff and the tariff components defined therein (e.g. fixed costs or demand rate). The annual rate of electricity price increases is taken into account.
Specific electricity purchase costs
The costs calculated from the energy drawn from the utility grid per kWh according to the selected purchase cost tariff and the tariff components defined therein (e.g. fixed costs or demand rate). The annual rate of electricity price increases is taken into account.
Fuel costs
The calculated fuel purchase costs according to the selected purchase cost tariff and the tariff components defined therein (e.g. fixed costs). The annual rate of price increases is taken into account.
Heating costs
The absolute heating costs are composed of the purchase and generation costs.
Specific heating costs
The specific heating costs are composed of purchase costs and generation costs per kWh.
Total energy supply costs
The total energy supply costs includes, in addition to the costs for the purchased energy carriers (more specifically, the energy costs) all costs for the internal energy conversion, distribution, storage and disposal. They also include the capital costs, the replacement investments and the operating expenditure. The impacts of the inflation rate and the energy price increase are taken into account throughout the analysis period of profitability. The total energy supply costs of the operational energy supply are also referred to as input energy costs.
Energy production costs
The energy production costs determine the costs for the generation of 1 kWh energy. When calculating the energy production costs, the LCOE calculation method is used. The running costs of the year under review are calculated and added up throughout the observation period. They are then discounted to the reference date using the imputed rate of interest and the one-time costs are added. The discounted costs are divided by the energy amount discounted to the reference date. LCOE is a customary calculation method for power generation costs which is used here to calculate the production costs of all energy types.
Operating costs
The operating costs (operating expenditure) of the system component throughout the analysis period of profitability. These are composed of the annual fixed costs taking into account the inflation rate and the costs for replacement investments due to limited technical service life. This is the sum of operating costs of all system components for the overall system.
Investment costs
One-time investment costs (CAPEX) for the system component (turnkey PV system) At the overall system level, it is the sum of the investment costs (CAPEX) of all system components
Specific investment costs
One-time investment costs for the system component per activity unit or capacity, depending on the component under review.
Debt capital
The credit costs (borrowing costs) specify the interest charges for a loan at nominal terms. They are independent from the inflation. The total interest charges depend on the type of loan.
Residual value
The residual value of the system component or of the system at the end of the period under review with linear depreciation and amortization. The service life, the system components and the replacement investments are taken into account in the calculation.
Grant amount
The subsidy amount stated with the system component or the sum of the subsidy amounts of all system components for the overall system.
Feed-in tariff
The feed-in tariff of the electrical energy fed in and possibly self-consumed as well as the sales after expiry of the feed-in tariff according to the selected feed-in tariff. The degradation of the PV modules is taken into account in the calculation for the PV system.
Return on assets (IRR)
The calculation of return is based on the return on assets. The return on assets refers to the total capital employed (capital expenditure) and puts this in relation to the profit (feed-in tariff + savings in purchasing costs + self-consumption tariff – self-consumption apportionment – operating costs). The financing costs through debt capital are not included in the return on assets. Long-term influences on the rate of return due to inflation, module degradation and the electricity price increase rate are also taken into account. For energy system projects, this also includes replacement investments and residual values. The rate on return is therefore calculated dynamically using the IRR method over the entire period under review (internal interest rate, internal rate of return). It indicates the average mean annual return on the investment and corresponds to the interest at which the discounted returns represent the capital employed.
Annual return
The return is calculated as an internal interest rate (internal rate of return). This effective rate of return reflects the economic advantageousness of the investment as the mathematically calculated return of all payment flows of the investment during the selected period under review compared to the before-after values or an alternative interpretation.
Net present value
The net present value method is used to add up all income and expenses of a planned system within the selected period under review and with the interest rate adjusted. The income takes into account the feed-in tariffs, energy procurement costs savings, subsidy amounts and credits compared to the before values or to an alternative. The payments in the individual years are discounted to the current point in time with the selected imputed rate of interest. From this, the so-called present values of the payments result. The net present value (or present value) is a possible way of expressing the economic advantageousness of an investment.
Amortization time
The amortization time is the period in years within which the capital tied up in an investment is returned or from which the effective savings become positive.
Amortization time (discounted)
The discounted amortization period is the time period in years after which the discounted savings become positive.