Economics9 min read
Inverter replacement and lifecycle costs
Realistic timing and budgeting for inverter replacement, the largest single lifecycle cost after installation, with a worked cost comparison.
Economics
Payback maths, tariffs, financing and the numbers that decide whether solar makes sense.
What a system is worth, argued from cash flows rather than from headline payback figures. Every number here is derivable: yield assumptions, tariff structure, degradation, replacement costs and the discount rate you choose to apply.
What this hub answers
- How is payback period actually calculated?
- What does levelised cost of electricity include and exclude?
- When does self-consumption beat export compensation?
- How should inverter replacement be budgeted?
- Does a battery improve or worsen the return?
Start here
Economics9 min read
Electricity tariff structures and time of use
How flat, time-of-use and dynamic tariffs change the value of self-consumed and exported solar electricity, with a worked comparison.
Economics9 min read
Financing solar: loans versus cash purchase
How to compare a cash purchase against a solar loan on a like-for-like basis, including the effect of interest rates on payback and NPV.
Calculators
Field checklists
Terminology
- Capacity factor
- Levelised cost of electricity
- Payback period
- Self-consumption ratio
All guides in Economics
Economics9 min read
Solar insurance and warranty claims
What PV insurance typically covers, how manufacturer warranties differ from performance guarantees, and how to actually make a claim.
Economics10 min read
Discount rates and NPV for solar projects
How to choose a discount rate and build a defensible net present value model for a rooftop or ground-mount PV investment.
Economics13 min read
Building the business case for commercial rooftop solar
How to model a C&I rooftop solar investment using load profiles, demand charges, and depreciation, with a worked payback calculation.
Economics14 min read
Levelised Cost of Electricity for Solar, Calculated Properly
LCOE is the only figure that lets you compare a rooftop array with a grid tariff or a gas plant on equal terms. It is also routinely computed wrong.
Economics13 min read
Net Metering, Net Billing and Feed-in Tariffs: How Export Compensation Actually Works
The scheme that governs your exported kilowatt-hours changes the value of an array more than any hardware decision. Here is how the three main models differ, and what to check before signing.
Economics13 min read
Solar PPAs, leases, and EPC purchase compared
A technical comparison of power purchase agreements, leases, and direct purchase for solar projects, covering contract terms, risk allocation, and total cost of ownership.
Economics13 min read
Self-Consumption and Load Shifting: The Number That Decides Your Solar Economics
Two identical arrays on two identical roofs can differ by half in annual savings. The variable is not the hardware, it is what fraction of the generation is used on site.
Economics12 min read
The Honest Payback Calculation for Rooftop Solar
Sales quotes flatter solar. Discount rates, degradation and self-consumption ratios do not. Here is how to build the number yourself.