RATIOXA LEARN · Energy
Decision guides: Energy
Understand the variables, common mistakes and crossovers before you calculate. Evaluate investments through real cash flows, NPV, IRR and robust break-even points.
Solar payback, NPV and IRR
Why simple payback is insufficient and how cash flows make solar economics transparent.
Read article →Why self-consumption drives solar cash flow
Value avoided grid purchases separately from export revenue.
Read article →Heat pump versus gas: seasonal COP
How COP, heat demand, energy prices and investment combine into present value.
Read article →Battery storage economics
Translate usable cycles, price spread, efficiency and degradation into NPV.
Read article →Solar with or without battery storage?
Calculate the solar array and battery as two separate investment decisions.
Read article →What does solar payback time mean?
Understand when cumulative net cash flows cover the investment.
Read article →Use NPV, not only payback, to value solar
Why time value and all cash flows give a fuller picture than payback alone.
Read article →Heat pump in an older building: which numbers matter?
Test heat demand, temperatures, efficiency and investment instead of blanket suitability claims.
Read article →SCOP versus COP explained
Do not confuse point performance with seasonal heat-pump efficiency.
Read article →When does battery storage not pay?
A balanced test of price spread, cycles, sizing and degradation.
Read article →Think in scenarios instead of forecasts
Model uncertain energy prices and yields as ranges.
Read article →Heating subsidy from 21 July 2026
Separate basic subsidy, climate-speed bonus and individual eligibility.
Read article →Document subsidy as an assumption
Distinguish applied, approved and paid support in the investment model.
Read article →Value export and self-consumption separately
Do not equate avoided grid purchase with export revenue.
Read article →More battery capacity is not automatically better
Separate usable capacity, cycles and unused volume economically.
Read article →Battery degradation as cash flow
Carry declining usable capacity into later benefit years.
Read article →Electricity prices as scenarios, not forecasts
Apply price changes consistently to grid purchase, self-consumption and alternatives.
Read article →Combine seasonal COP and heat demand
Translate useful building heat into electricity through a realistic seasonal COP.
Read article →Gas efficiency in the cost comparison
Do not equate fuel input with useful heat.
Read article →Finance solar or pay cash
Put solar cash flow, debt interest and opportunity cost on the same period.
Read article →TOOLS
Related calculators
Does solar pay?Self-consumption, export, NPV, IRR and payback.→Heat pump or gas?Present-value comparison of investment, efficiency and energy.→Battery storageCycles, efficiency, degradation and net present value.→Energy costProject consumption, tariff and price changes.→GLOSSARY