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.
Independent solar reporting
The numbers behind the panels on your roof
Solar Ledger explains photovoltaic technology, installation craft, system economics, storage and grid policy — in enough depth to make a decision, without the marketing gloss.
- 1,000 W/m²
- Peak irradiance at midday, clear sky
- 20–23%
- Typical module efficiency in 2026
- 0.4–0.55%
- Annual degradation of a good module
- 6–12 yrs
- Realistic residential payback range
Featured reporting
All articles
Technology11 min read
How a Solar Cell Turns Light Into Current
Silicon does something quietly strange when a photon hits it. Here is the full path from sunlight to the electricity in your kitchen, without hand-waving.
Installation10 min read
Roof Mounting Done Right: A Field Guide to Penetrations, Loads and Leaks
Most solar failures are not electrical. They are mechanical, and they start at the moment someone drills a hole in a roof.
Browse by section
Economics
Payback maths, tariffs, financing and the numbers that decide whether solar makes sense.
Installation
Mounting, wiring, commissioning and the practical craft of getting panels on a roof.
Policy & Grid
Regulation, grid connection rules, net metering and market design.
Storage
Batteries, hybrid inverters and shifting solar production into the evening.
Technology
Cell chemistries, module design, inverters and the hardware behind modern solar.
Latest articles
Technology11 min read
Anti-islanding detection methods for grid-tied inverters
A technical walkthrough of passive and active anti-islanding methods, why the non-detection zone matters, and how installers verify compliance during commissioning.
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.
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.
Policy & Grid11 min read
Export limitation and active power control for PV systems
How export limits are enforced technically, from simple fixed caps to dynamic zero-export control loops, and what to check when a limiter is not behaving as expected.
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.
Policy & Grid11 min read
Grid codes and inverter protection settings explained
How grid codes translate into the voltage, frequency and trip-time parameters programmed into a PV inverter, and why getting them wrong causes rejected commissioning.
Measured, not marketed
Every performance claim we publish is traced back to a datasheet, a standard test condition, or a measurement we can describe. Where a number depends on assumptions, we state the assumptions.
Written by practitioners
Our contributors have tested modules in accredited laboratories, commissioned utility-scale sites and modelled distributed energy investments. They write about what they have actually seen fail and succeed.
Corrections welcome
If a figure looks wrong, tell us. We correct articles in place and note what changed. Reach the desk through the contact page.
Common questions
How much roof space does a typical home system need?
A 400 W module occupies roughly two square metres. A 5 kW array is therefore about 13 modules and 26 square metres of unshaded roof, plus clearance for access and airflow.
Do panels still produce power on cloudy days?
Yes, but far less. Diffuse light on an overcast winter day can drop output to ten or twenty percent of the clear-sky value. Annual yield, not peak output, is the number that matters for payback.
Is a battery worth adding straight away?
It depends on your tariff. Where export payments are close to import prices, a battery adds little. Where export is worth a fraction of import, storage shifts self-consumption and can shorten payback.
How long do modules actually last?
Manufacturers typically warrant 80 to 87 percent of rated output at year 25. Field data suggests well-installed crystalline modules degrade around half a percent per year, so most outlive their warranty.