Free Online Solar Panel & PV System Simulator
Build and test complete photovoltaic circuits with PVAlign's free online solar panel simulator. Connect panels, batteries, controllers, inverters, protection, wiring, meters, grid power, and loads.
PVAlign Simulator
Interactive photovoltaic circuit workbench
Build and test connected solar power systems in a browser. Add panels, storage, conversion equipment, protection, measurement, distribution, and realistic loads; wire their terminals; enter equipment ratings; and inspect the calculated operating point.
PVAlign is currently intended for educational and preliminary planning use. Professional-grade capabilities and validation are under development. Until validated, results should not be used as the sole basis for final design, permitting, procurement, or installation.
Read the complete PVAlign simulator guide · Review the simulation methodology
How to build a circuit
Add equipment
Click a part in the component sidebar to place it, or drag it onto the canvas.
Connect terminals
Click one terminal and then another compatible terminal to create a conductor. To make a branch, connect a terminal to an existing wire. Wires that merely cross remain electrically separate.
Configure ratings
Select equipment or a wire to open its inspector. Enter datasheet ratings, operating limits, conductor length and material, load behavior, and other available settings.
Read the results
Observe simulated voltage, current, real and apparent power, energy, state of charge, loss, temperature, frequency, operating state, warnings, and protection outcomes where supported.
Change one variable
Compare configurations by changing a connection, rating, environmental input, or load and observing how the complete connected system responds.
33 interactive equipment nodes
The current workbench includes the following user-addable hardware and measurement models.
Generation
Solar Panel
Models monocrystalline, polycrystalline, and thin-film environmental profiles alongside datasheet ratings, I-V behavior, shading, cell temperature, cold-design Voc, and series-parallel arrays.
Power control
MPPT Controller
Finds the calculated PV maximum-power point and converts array power for battery charging and a controlled DC load output.
Power control
PWM Controller
Models PWM operation near battery voltage, charge stages, current limits, night detection, and switchable load output behavior.
Energy storage
Battery
Tracks voltage, state of charge, stored energy, temperature, current limits, chemistry, and series or parallel bank behavior.
Conversion
Battery Inverter
Converts battery DC into selectable pure or modified sine-wave AC with efficiency, standby demand, DC limits, continuous output, startup surge protection, and load compatibility warnings.
Conversion
Hybrid Inverter
Coordinates PV, battery, AC loads, and the utility grid while applying MPPT, conversion, charge, discharge, surge, and voltage limits.
AC source
Utility Grid
Supplies compatible AC circuits and estimates import demand, exported power, accumulated energy, and simple energy cost.
Grid-tied conversion
Microinverter
Converts panel-level PV to grid-synchronized AC with MPPT, input and power limits, efficiency, 50/60 Hz selection, export accounting, and anti-islanding shutdown.
AC source transfer
Automatic Transfer Switch
Models a two-source, two-pole, break-before-make ATS with normal and emergency source qualification, automatic or manual operation, live transfer countdowns, return and transition delays, contact ratings, and separate load-side output pairs.
Protection
Power Breaker
Choose AC/DC MCBs for branch circuits, AC/DC MCCBs for higher-current feeders, or AC RCBOs with residual-current protection. MCBs and MCCBs support one- or two-pole switching. Models thermal overload and instantaneous overcurrent trips, circuit-type and voltage-rating checks, and a clickable RCBO test button with latched trip and reset behavior.
Surge protection
Surge Protective Device
Models surge clamping, let-through voltage, cartridge wear, and diversion to protective earth during an educational surge test.
Grounding
Ground / Earth
Provides the modeled protective-earth reference, with separate electrode resistance and surge bonding impedance.
PV distribution
MC4 Branch Connector
Combines two, three, or four PV leads of one polarity, sums branch currents, and models contact losses and rating warnings. Positive and negative connectors remain separate; this connector contains no fuse or automatic disconnect.
PV protection
MC4 Fuse Connector
Models a compact single-conductor gPV fuse with PV-only terminals, current accumulation, a latched blown state, and a configurable DC voltage rating.
PV distribution and protection
PV Combiner Box
Combines two to eight parallel solar strings, models an isolating switch and independently latched 1–32 A gPV string fuses, and checks summed output-current and design-voltage ratings.
DC protection
Low Voltage Disconnect
Protects battery-powered DC circuits with chemistry-aware thresholds, hysteresis, and latched current- or maximum-input-voltage rating faults.
Control
SPDT Relay
Uses an electrically isolated AC or DC coil to move COM between NC and NO, with pickup/dropout hysteresis, coil consumption, voltage warnings, and contact-current limits.
AC control
Wall Switch
Models one to four independent two-way rockers with connectable COM, L1, and L2 terminals and editable contact-current and voltage ratings.
High-current control
DC Contactor
Uses an isolated DC coil to close a normally-open positive contact, with realistic pickup/dropout hysteresis, coil consumption, switching-voltage limits, and contact-current warnings.
Distribution
Extension Socket
Distributes one AC or DC source across two to eight outlet pairs and reports combined load, current, use, and overload state.
Electrical load
Appliance
Represents AC or DC constant-power, resistive, constant-current, motor, and compressor loads with startup and duty-cycle behavior.
Lighting load
LED Light Bulb
Models an AC electronic lamp with voltage and frequency limits, glowing yellow while valid power is delivered.
Compressor load
Refrigerator
Models a dedicated AC refrigerator with power factor, compressor startup surge, thermostat duty cycling, voltage limits, runtime, energy use, and independent width and height controls.
Resistive heating load
Rice Cooker
Models a fixed-AC rice cooker as a resistive heating load with voltage-dependent power, operating-voltage protection, live readings, runtime, and accumulated energy.
Motor load
Washing Machine
Models a fixed-AC washing machine with motor power factor, startup surge, intermittent agitation duty cycling, voltage limits, runtime, and energy use.
Electronic load
Television
Models a fixed-AC television as a constant-power electronic load with power factor, brief startup demand, voltage protection, and energy tracking.
Resistive heating load
Electric Kettle
Models a fixed-AC 1,500 W kettle whose heating power and current respond to the delivered voltage, with live state and accumulated energy.
Electronic load
Laptop
Models a laptop and its fixed-AC power adapter as a constant-power load with power factor, brief startup demand, voltage limits, runtime, and energy use.
Motor load
Fan
Models a three-speed AC or DC fan with editable watts, RPM, startup demand, operating-voltage range, and runtime.
Measurement
Multimeter
Measures simulated AC/DC voltage, current, watts, VA, power factor, frequency, available power, and flow direction.
Inline AC measurement
AC Watt Meter
Measures one single-phase AC branch through line and neutral IN/OUT terminals, with watts, RMS volts and amps, frequency, power factor, apparent power, and resettable import/export kWh counters.
Inline DC measurement
DC Watt Meter
Measures PV, battery, controller, or DC load branches through positive and negative IN/OUT terminals, with watts, volts, signed amps, and separate forward/reverse kWh and Ah counters.
Measurement
PV Analyzer
Tests an isolated panel or array for Voc, Isc, Vmp, Imp, Pmax, and a simulated 41-point current-voltage curve.
Wire junctions are created on existing conductors when a branch is added. Junctions are electrically meaningful; simple visual crossings do not join circuits.
Reference circuit presets
Use a preset as a working example, then change its ratings or topology to explore the result. The current build contains 5 presets:
- Grid-tie
- Off-grid
- PWM - Solar Charge Controller
- Solar panel series
- wall switch
What the simulation models
The engine resolves physics-informed steady-state operating points and selected forward time effects using equipment settings, conductor properties, graph-based connection topology, environmental inputs, limits, and protection rules.
| System area | Implementation | Current scope |
|---|---|---|
| PV generation | I-V curve, temperature, irradiance, shading, bypass behavior | Steady-state module and reducible array model |
| PV array topology | Series, parallel, and series-parallel networks | Shared-current and shared-voltage operating points |
| Charge controllers | Separate MPPT and PWM behavior | Limits, losses, charging stages, load output, and faults |
| Battery storage | Lead-acid, LiFePO₄, and lithium-ion | SOC, energy, current limits, charge acceptance, and bank safety |
| Power conversion | Battery, microinverter, and hybrid inverter models | Efficiency, standby, surge, MPPT/DC limits, grid synchronization, anti-islanding, and AC demand |
| Automatic source transfer | Two-source, two-pole open-transition ATS | Normal and emergency voltage/frequency qualification, preferred-source logic, manual modes, transfer and return timers, break-before-make delay, and contact-load checks |
| Loads | Configurable loads, six dedicated household appliances, and three-speed fans | Fixed AC compatibility where required, constant-power and resistive behavior, motor or compressor startup, duty cycles, voltage windows, runtime, and energy |
| Conductors | Copper or aluminum cable model | Resistance, voltage drop, I²R loss, ampacity, and temperature |
| Protection and control | AC/DC MCBs and MCCBs, AC RCBOs, MC4 branch connectors, MC4 gPV fuses, PV combiner boxes, low-voltage disconnects, SPDT relays, and DC contactors | One- or two-pole MCB/MCCB switching, thermal overload and instant overcurrent trips, RCBO residual-current testing and latched reset, fuse opening, parallel-string combining, connector rating checks, battery-aware LVD thresholds, and isolated coil switching |
| 2D circuit canvas | Mouse, touch, minimap, recentering, and saved display preferences | User-defined 10%–500% zoom limits, grid and map visibility, terminal-selection sizing, and current, loss, or temperature wire labels |
| 3D workspace | Equipment models, routed cables, Walk mode, and scene rendering | Spatial placement, terminal wiring, component and wire readings, separate 3D project files, and PNG exports |
| Measurement | Separate AC/DC watt meters, multimeter, and PV I-V analyzer | Branch watts and current, directional kWh and DC Ah counters, adjustable meter ratings, live port readings, and isolated array testing |
| Environment | Time, weather, irradiance, ambient temperature, and wind | Shared conditions with forward battery and energy progression |
Environment and time controls
The optional Environment panel can apply time, irradiance, ambient temperature, wind, and clear, partly cloudy, cloudy, rain, or manual weather conditions. Supported solar panels use these inputs to estimate cell temperature and available production. Forward time progression can update battery energy, load runtime and energy, conductor temperature, and grid import or export totals.
Educational safety and compatibility checks
PVAlign checks many supported conditions, including terminal polarity, AC/DC compatibility, voltage class and frequency, battery chemistry and bank matching, PV cold-voltage limits, shorts, reversed connections, invalid loops, array mismatch, conductor loading, breaker circuit type and trips, MC4 gPV fuse current and voltage ratings, low-voltage disconnect thresholds and ratings, relay coil and contact limits, DC contactor switching limits, inverter input and output constraints, and incompatible load supplies.
Warnings describe modeled problems, but they are not a safety certification, code-compliance review, permit, or substitute for physical protective devices and qualified electrical work.
Workspace controls and circuit files
- Export and import: save or load circuit data as JSON.
- Print: create a circuit image preview and download it as PNG.
- Save and unsave: retain or remove the current circuit in browser storage.
- Undo and redo: move backward or forward through supported editor changes.
- Presets: load a reference circuit from the current preset library.
- Settings: control the grid, minimap, toolbar and navigation buttons, wire current, loss and temperature labels, environment panel, default wire properties, label size, and notification timing.
- Clear: remove the current circuit from the canvas.
Important model limitations
Simulator outputs are calculated estimates, not laboratory measurements. Displayed decimal places improve readability and do not claim matching measurement accuracy.
A general educational model cannot reproduce every manufacturer control algorithm, transient event, inrush waveform, fault energy, protection curve, thermal installation detail, aging effect, shading geometry, local weather condition, workmanship issue, utility rule, or electrical-code requirement.
Before buying, wiring, permitting, connecting to a utility, or energizing real equipment, verify current manufacturer documentation, ratings, site conditions, applicable electrical codes, and qualified professional calculations. Use PVAlign to learn, compare, ask better questions, and perform preliminary exploration.
Learn before you energize
Continue with the complete simulator guide, browse the solar learning library, or read the editorial policy and simulation methodology.