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.
Editorial
Solar Ledger Editorial
Editorial and technical review desk
Solar Ledger is written and reviewed by a small editorial desk that works from primary engineering sources rather than vendor marketing. Every guide is built from published standards, peer-reviewed literature and public datasets, and is checked against those sources before publication.
Technical basis
Guides are grounded in IEC 60364-7-712, IEC 62446, IEC 61730, IEC 61215, EN 1991-1-3/1-4, IEEE 1547 and the relevant national wiring rules, together with public research from NREL, Fraunhofer ISE and IEA PVPS Task reports.
Review process
Each guide is drafted against primary sources, checked for numerical consistency by re-deriving every worked example, reviewed for standards accuracy, then re-checked on a rolling schedule. The last-reviewed date on each page reflects the most recent check, and material changes are listed in the update history.
Guides by Solar Ledger Editorial
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.
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.
Technology9 min read
Reactive power and voltage support from PV inverters
How modern PV inverters use reactive power and power factor control to support grid voltage, with worked examples of cos-phi and Q(U) droop behaviour.
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.
Installation13 min read
Array layout and row spacing: the shading-density trade-off
A worked-trigonometry guide to inter-row shading geometry, solar altitude at the design hour, and how ground coverage ratio trades off against annual shading loss.
Installation13 min read
Ground-mount vs roof-mount PV systems: the real trade-offs
A technical comparison of ground-mount and roof-mount PV covering yield, tilt freedom, foundations, cost per kWp, cabling, permitting, and O&M access.
Technology12 min read
Potential-induced degradation: mechanisms and prevention in PV
PID can cut PV yield by 10-30% within seasons. This guide covers its mechanisms, field detection, prevention, and IEC TS 62804 testing.
Technology12 min read
Anti-reflective coatings and module glass: transmission and durability
How AR coatings and glass texturing raise light transmission into PV cells, what durability trade-offs they carry, and how soiling interacts with coating choice over a module's service life.
Installation13 min read
Wind and snow loads on PV structures under Eurocode
How EN 1991-1-3 and 1991-1-4 govern PV mounting design, from terrain factors and edge zones to uplift arithmetic and roof capacity checks.
Installation13 min read
Lightning and surge protection for PV installations
How to assess lightning risk and size, place, and coordinate SPDs on DC and AC sides of PV systems under IEC 62305 and IEC 61643-32.
Storage13 min read
Backup power and islanding: grid-forming, switching, and sizing
A practical guide to grid-forming versus grid-following inverters, automatic transfer switching, and correctly sizing loads for solar backup power.
Storage13 min read
Battery safety and fire risk in residential storage systems
A technical look at thermal runaway mechanisms, chemistry differences, siting rules, ventilation, and the IEC/EN standards governing home battery safety.
Installation8 min read
Troubleshooting an underperforming PV array: a diagnostic workflow
A structured symptom-cause-fix approach to diagnosing PV yield shortfalls, from weather-corrected baselines through I-V curve tracing and thermal imaging.
Technology8 min read
TOPCon vs HJT vs PERC: cell architectures compared
A practical comparison of three dominant crystalline silicon cell architectures across efficiency, temperature behaviour, bifaciality, degradation and manufacturing cost.
Technology8 min read
Temperature coefficients and real-world PV yield
How NOCT, cell temperature models, and performance ratio explain the gap between STC nameplate ratings and what a system actually delivers.
Technology9 min read
String inverters vs microinverters vs optimisers, compared
A practical comparison of the three PV inverter architectures across shading tolerance, monitoring, cost, and failure modes to inform design choice.
Installation9 min read
Solar panel orientation and tilt: optimising for yield
How azimuth and tilt shape annual PV yield, when east-west arrays make sense, and how to weigh seasonal tradeoffs with worked yield calculations.
Technology9 min read
Solar module degradation and warranties, decoded
How LID, LeTID and PID actually degrade a module, and how to read a product versus performance warranty against the IEC test sequences that support it.
Installation10 min read
Shading analysis and mitigation in PV arrays
Why partial shading costs more output than the shaded area suggests, and how sun-path analysis, bypass diodes, and module-level electronics address it.
Installation9 min read
Building a PV maintenance schedule that actually catches faults
A structured annual and quarterly maintenance plan for PV arrays, covering inspection intervals, test methods, and the records that keep warranty claims valid.
Installation10 min read
PV commissioning checklist: testing and documentation
A full walk-through of PV commissioning per IEC 62446, from visual inspection and insulation resistance to IV curve tracing and handover documentation.
Installation9 min read
Off-grid vs hybrid solar systems: architecture and sizing compared
How off-grid and grid-tied hybrid solar systems differ in architecture, autonomy sizing, generator backup, and what actually happens during a blackout.
Technology8 min read
MPPT explained: how inverters find the maximum power point
A technical walkthrough of IV curves, MPPT algorithms, and how string design choices interact with tracking behaviour in real installations.
Storage8 min read
LFP vs NMC batteries: chemistry, safety, and cost compared
A technical comparison of lithium iron phosphate and nickel manganese cobalt battery chemistries covering energy density, cycle life, safety, and cost.
Technology8 min read
Inverter efficiency explained: weighted efficiency and clipping
How European weighted efficiency, CEC efficiency, and MPPT efficiency differ, and how DC/AC ratio and clipping shape real annual energy yield.
Technology10 min read
How solar panels work, from photon to breaker panel
A systems-level walk through the physics, materials and electronics that turn sunlight into usable household electricity, from the silicon lattice to the consumer unit.
Storage9 min read
Home battery storage explained: architecture, sizing, economics
How residential battery systems work, the practical differences between AC and DC coupling, a sizing method with worked numbers, and what storage really saves.
Installation8 min read
Cleaning solar panels: when it pays and when it does not
Soiling loss ranges by climate, cleaning methods and water quality considerations, safety practice, and the arithmetic that decides whether a cleaning contract is worth it.
Installation10 min read
Cable sizing and voltage drop in PV systems
A practical guide to sizing DC and AC PV cables, covering ampacity derating and voltage drop calculations with worked numeric examples and IEC references.
Technology8 min read
Bifacial solar modules: how much extra energy do they really add?
How bifaciality factor, ground albedo and mounting height combine to determine the rear-side energy gain of bifacial modules, with a worked gain calculation.
Storage8 min read
Battery degradation and cycle life: what actually shortens lifespan
How calendar ageing and cycle ageing combine to degrade home batteries, how depth of discharge and temperature affect lifespan, and how to read warranty terms.
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.
Policy & Grid12 min read
Community and shared solar: models and EU policy
How energy communities and shared solar schemes work under EU RED II/III, including allocation models, legal structures, and typical member economics.
Policy & Grid12 min read
Curtailment and negative electricity prices explained
Why wholesale electricity prices turn negative at midday in high-solar grids, how curtailment is dispatched, and what it means for new PV systems.
Installation13 min read
DC arc faults and rapid shutdown: physics, detection, and safety
How DC arc faults form, why AFCI detection differs from AC, and how module-level rapid shutdown architectures protect firefighters and equipment.
Policy & Grid14 min read
Solar Permitting in the EU: Deadlines, Exemptions and How to Avoid Losing Six Months
Since the revised Renewable Energy Directive, most rooftop installations sit under binding permitting deadlines and many are exempt altogether. Knowing which applies is worth more than any hardware choice.
Technology12 min read
EV charging with solar: surplus charging and load management
How to size, control, and integrate EV charging with a home PV system, covering surplus-only charging, charger types, and tariff interaction.
Installation12 min read
Flat-roof ballasted PV systems: ballast, uplift and membrane care
Ballasted racking avoids roof penetrations but trades that for weight, wind uplift risk and membrane wear that must be engineered, not guessed.
Technology13 min read
IV curve tracing in the field: equipment and interpretation
A practical guide to portable IV curve tracers, how to read curve shapes against a healthy reference, and the fault signatures they reveal in PV strings.
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.
Installation12 min read
PV earthing and bonding: protective, functional, and equipotential
A technical guide to PV earthing and bonding practice, covering protective earthing, functional earthing, equipotential bonding, and IEC 60364-7-712 requirements.
Technology13 min read
PV module construction and materials: glass to junction box
A layer-by-layer look at how crystalline silicon modules are built, the bill of materials involved, and the failure modes each component is prone to over a 25-year service life.
Technology13 min read
PV monitoring and performance ratio: definitions and practice
How performance ratio is defined and measured under IEC 61724, what data acquisition architecture it requires, and how to set alarms that catch faults without noise.
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.
Technology12 min read
Sodium-ion and emerging battery chemistries: an honest status check
Where sodium-ion, LTO, flow, and solid-state batteries actually stand today on energy density, cost, and cycle life for solar storage applications.
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.
Installation13 min read
Solar carports and agrivoltaics: structure, clearance and yield
Elevated PV over parking or farmland recovers land value but costs more per kWp in steel and yield; the case only closes when land use is priced in.
Technology14 min read
Solar irradiance and resource data: sources and uncertainty
How GHI, DNI, and DHI are measured and modeled, which TMY datasets and databases to trust, and how P50/P90 uncertainty bands should shape yield assessments.
Technology12 min read
Solar panel efficiency explained: STC, real-world yield and area
Module efficiency is a lab metric under standard test conditions. This explains what it measures, why real-world yield differs, and when area matters more than the percentage on the datasheet.
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.
Technology13 min read
Thermal imaging of PV arrays: method and fault interpretation
How infrared inspection of PV arrays works in practice, the hotspot patterns that identify specific fault types, and drone-based workflows aligned with IEC TS 62446-3.
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.
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.
Storage10 min read
Sizing a Home Battery Without Guessing
Battery capacity is usually chosen by round numbers and salesmanship. Your own consumption data gives a better answer in about twenty minutes.
Policy & Grid9 min read
Grid Connection and Export Rules, Explained
Why your inverter throttles at noon, what a G99 or VDE-AR-N 4105 application actually reviews, and how export limits are enforced.