{ "method": "Steady-state hourly screening calculation; IAM=1, no collector heat capacity/start-up, no pipe or distribution losses; Tm=90 C Apr-Sep and 40 C Oct-Mar; coefficients on aperture area from Apricus ETC-30 2016 p9.", "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/seriescalc?lat=50.7753&lon=6.0839&startyear=2005&endyear=2023&raddatabase=PVGIS-SARAH3&angle=45&aspect=0&components=1&usehorizon=1&outputformat=json", "access_date": "2026-10-26", "input_sha256": "3ac758633868dd8c8bc3e536769e005eff3843ee9bc4553d9a0e13ed8fd6e521", "inputs": { "location": { "latitude": 50.7753, "longitude": 6.0839, "elevation": 173.0 }, "meteo_data": { "radiation_db": "PVGIS-SARAH3", "meteo_db": "ERA5", "year_min": 2005, "year_max": 2023, "use_horizon": true, "horizon_db": null, "horizon_data": "DEM-calculated" }, "mounting_system": { "fixed": { "slope": { "value": 45, "optimal": false }, "azimuth": { "value": 0, "optimal": false }, "type": "free-standing" } }, "pv_module": { "technology": null, "peak_power": null, "system_loss": null } }, "n_hours": 166536, "collector": { "eta0": 0.714, "a1_W_per_m2K": 1.243, "a2_W_per_m2K2": 0.009, "aperture_m2": 700, "Tm_summer_C": 90, "Tm_winter_C": 40, "IAM": 1 }, "seasonal": { "summer": { "G": 877.7731589473738, "q": 361.24503813147226, "hours": 83448, "eta": 0.41154714569385736, "Q_field_MWh": 252.87152669203056 }, "winter": { "G": 422.11345263157904, "q": 229.59074234392193, "hours": 83088, "eta": 0.5439076649004809, "Q_field_MWh": 160.71351964074535 } }, "monthly": { "1": { "G": 47.173266842105384, "q": 22.509678536720997 }, "2": { "G": 68.05160421052655, "q": 35.91198877217899 }, "3": { "G": 110.90479263157906, "q": 63.23043932524205 }, "4": { "G": 142.94758052631622, "q": 57.2695787440843 }, "5": { "G": 152.13180368421095, "q": 61.661513317457874 }, "6": { "G": 153.9175894736851, "q": 63.70240563134736 }, "7": { "G": 156.48868473684212, "q": 65.8426124837632 }, "8": { "G": 144.07639105263203, "q": 59.98065341618415 }, "9": { "G": 128.2111094736845, "q": 52.788274538636834 }, "10": { "G": 94.09671263157904, "q": 55.35927693655266 }, "11": { "G": 59.37282526315809, "q": 31.841009351347306 }, "12": { "G": 42.514251052631685, "q": 20.738349421878926 } }, "scenario": { "storage_ratio": 0.72, "storage_basis": "approximate graphical reading Hennaut et al. 2011 Fig7, 17.5m2 and 7500kg, Uccle climate; ratio reactor output to charging input, excludes low-grade source denominator. Transfer to Aachen is an assumption, not validation.", "Q_charge_MWh": 252.87152669203056, "Q_discharge_MWh": 182.067499218262, "Q_winter_MWh": 160.71351964074535, "Q_combined_MWh": 342.7810188590073, "ratio_to_160MWh": 2.1423813678687957 }, "sizing_scenarios": [ { "Q_target_MWh": 40, "V_reactor_m3": 666.6666666666666, "water_tonnes": 38.48961899109793, "V_water_min_m3": 38.48961899109793, "V_space_allowance_m3": 881.4453570722056, "depth_over_1000m2_m": 0.8814453570722056, "charge_MWh_at_eta072": 55.55555555555556, "ideal_evaporator_MWh": 26.468842729970326 }, { "Q_target_MWh": 80, "V_reactor_m3": 1333.3333333333333, "water_tonnes": 76.97923798219585, "V_water_min_m3": 76.97923798219585, "V_space_allowance_m3": 1762.8907141444113, "depth_over_1000m2_m": 1.7628907141444112, "charge_MWh_at_eta072": 111.11111111111111, "ideal_evaporator_MWh": 52.93768545994065 }, { "Q_target_MWh": 160, "V_reactor_m3": 2666.6666666666665, "water_tonnes": 153.9584759643917, "V_water_min_m3": 153.9584759643917, "V_space_allowance_m3": 3525.7814282888226, "depth_over_1000m2_m": 3.5257814282888225, "charge_MWh_at_eta072": 222.22222222222223, "ideal_evaporator_MWh": 105.8753709198813 } ], "volume_assumptions": { "heating_capacity_per_reactor_m3_kWh": 60, "reaction_enthalpy_kJ_per_mol_hydrated_salt": 337, "water_moles": 5, "water_density_kg_per_m3": 1000, "fraction_of_room_reserved_for_ancillaries_and_access": 0.2, "room_footprint_m2": 1000, "room_height_m": 3, "notes": "60 kWh/m3 is reactor-level full-reaction heating capacity of SOLUX reference, not whole installed useful density. Water is minimum liquid volume, excludes ullage and shell. 20% is unverified geometric allowance, not literature performance." }, "economic_analysis": { "as_of": "2026-10-26", "basis": "Illustrative real-terms investment screening, not a quotation or demonstrated plant performance. All amounts gross of VAT, no grants or gas price escalation.", "tariff": { "provider": "STAWAG", "product": "Gas Extra", "document_version": "09/2026", "valid_from": "2026-01-01", "source_url": "https://www.stawag.de/fileadmin/stawag/content/Dokumente/Gas/26-09-09_PB_Gas_Extra-ENDF.pdf", "consumption_band": "12001 kWh/year and above", "variable_gas_price_EUR_kWh_Hs_including_19percent_VAT": 0.1138, "fixed_charge_EUR_year_including_VAT": 184.09, "fixed_charge_included_in_savings": false }, "assumptions": { "useful_space_heat_kWh_year": 160000, "gas_boiler_seasonal_efficiency_Hs": 0.9, "incremental_annual_operating_cost_EUR": 5000, "real_discount_rate": 0.03, "study_period_years": 20, "coverage_fractions_are_scenarios_not_predictions": true, "investment_scenarios_are_not_supplier_quotes": true, "salvage_value_EUR": 0, "gas_fixed_charge_saving_EUR": 0, "replacement_costs_must_be_included_in_capex_or_operating_allowance": true }, "baseline": { "gas_input_kWh_year": 177777.77777777778, "gas_variable_cost_EUR_year": 20231.11111111111, "gas_cost_with_fixed_charge_EUR_year": 20415.20111111111 }, "annuity_present_value_factor": 14.877474860455516, "coverage_scenarios": [ { "coverage_fraction": 0.5, "displaced_heat_kWh": 80000.0, "gas_displaced_kWh": 88888.88888888889, "gross_avoided_variable_gas_EUR_year": 10115.555555555555, "incremental_annual_operating_cost_EUR": 5000, "net_saving_EUR_year": 5115.555555555555, "max_incremental_capex_EUR_NPV0": 76106.54917504132 }, { "coverage_fraction": 0.8, "displaced_heat_kWh": 128000.0, "gas_displaced_kWh": 142222.22222222222, "gross_avoided_variable_gas_EUR_year": 16184.888888888889, "incremental_annual_operating_cost_EUR": 5000, "net_saving_EUR_year": 11184.888888888889, "max_incremental_capex_EUR_NPV0": 166402.90326143266 }, { "coverage_fraction": 1, "displaced_heat_kWh": 160000, "gas_displaced_kWh": 177777.77777777778, "gross_avoided_variable_gas_EUR_year": 20231.11111111111, "incremental_annual_operating_cost_EUR": 5000, "net_saving_EUR_year": 15231.11111111111, "max_incremental_capex_EUR_NPV0": 226600.47265236021 } ], "investment_scenarios": [ { "illustrative_incremental_capex_EUR": 300000, "simple_payback_years_at_full_coverage": 19.696527575138607, "NPV_20years_EUR": -73399.52734763979 }, { "illustrative_incremental_capex_EUR": 500000, "simple_payback_years_at_full_coverage": 32.82754595856434, "NPV_20years_EUR": -273399.5273476398 }, { "illustrative_incremental_capex_EUR": 1000000, "simple_payback_years_at_full_coverage": 65.65509191712869, "NPV_20years_EUR": -773399.5273476398 } ], "max_capex_if_incremental_operating_cost_zero_EUR": 300987.8469546378, "boiler_efficiency_sensitivity": [ { "efficiency_Hs": 0.85, "full_coverage_gross_saving_EUR_year": 21421.176470588238 }, { "efficiency_Hs": 0.9, "full_coverage_gross_saving_EUR_year": 20231.11111111111 }, { "efficiency_Hs": 0.95, "full_coverage_gross_saving_EUR_year": 19166.315789473687 } ], "gas_price_sensitivity": [ { "gas_price_EUR_kWh": 0.08, "full_coverage_gross_saving_EUR_year": 14222.222222222223 }, { "gas_price_EUR_kWh": 0.1138, "full_coverage_gross_saving_EUR_year": 20231.11111111111 }, { "gas_price_EUR_kWh": 0.15, "full_coverage_gross_saving_EUR_year": 26666.666666666668 } ], "heat_demand_sensitivity": [ { "specific_heat_demand_kWh_m2_year": 40, "annual_heat_MWh": 160, "potential_output_to_demand_ratio": 2.1423813678687957 }, { "specific_heat_demand_kWh_m2_year": 60, "annual_heat_MWh": 240, "potential_output_to_demand_ratio": 1.4282542452458638 }, { "specific_heat_demand_kWh_m2_year": 80, "annual_heat_MWh": 320, "potential_output_to_demand_ratio": 1.0711906839343979 } ], "technology_context_source": "https://www.iea-shc.org/article?NewsID=574" } }