How solar panels make electricity
Photovoltaic (PV) cells turn light directly into electricity. The cells have no moving parts, while the illustrated tracker structures turn the modules to follow the Sun. Inverters connect their output to the grid.
In 60 seconds: how it works
Solar panels turn sunlight directly into electricity with no moving parts. An inverter then changes that power into the kind the grid uses.
- Sunlight hits the solar cells in each panel. Trackers can tilt the panels to follow the Sun.
- The cells turn light directly into direct current (DC) electricity.
- Cables collect the DC power from many panels wired together in strings.
- An inverter converts the DC power into alternating current (AC), the type the grid uses.
- A transformer raises the voltage and switchgear connects the plant to the grid.
Want the engineering detail? Explore the 3D model, then read the engineering notes and the types and variations.
By Power Stations Worldwide · Related reading updated · Preparation and review scope. Educational illustrations; no independent engineering peer review is claimed.
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Rotate equipment, follow energy flows and inspect each component. Read the steps below at any time.
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North–south single-axis PV trackers with a central inverter and AC collector/grid transformers. Nine rows contain eighteen 17-module strings. One enlarged module-layer inspection is educational, not an operating configuration. Manual Sun positioning, curve parameters, ratings and losses are illustrative; no shading/backtracking or structural design is solved. Motion is slowed for inspection. Coloured overlays reveal flow through enclosed equipment; gold pulses show net electrical energy transfer, not individual electrons.
How it works
- Sunlight
- Semiconductor cells
- DC collection
- Inverter produces AC
- Transformer and grid
A photovoltaic solar plant converts light into electricity inside semiconductor cells. Absorbed light gives charge carriers energy; the cell’s internal electric field separates charge so an external circuit can carry current. Metal contacts collect this output. Cells connect into protected modules, and modules connect into an array. The familiar panel is therefore an electrical generator, rather than a device that boils water. Its usable output depends on the light reaching the cells and their operating conditions.
Modules supply direct current, or DC. An inverter uses controlled semiconductor switches and filtering to deliver alternating current, or AC, suitable for the connected network. Electrical protection, cables and transformation complete the route to the grid. The illustrated tracker changes the panels’ orientation during the day; fixed arrays perform the same photovoltaic conversion without that movement. Solar generation and storage are separate functions: delivering electricity after sunlight has ended requires stored energy or another source of generation.
From photons to the grid
Selected stage: Whole-system overview
Read curve values as a table
| V (V) | I (A) | P (kW) |
|---|---|---|
| 0.00 | 161.94 | 0.000 |
| 102.77 | 161.94 | 16.642 |
| 205.53 | 161.94 | 33.284 |
| 308.30 | 161.94 | 49.927 |
| 411.07 | 161.94 | 66.568 |
| 513.83 | 161.90 | 83.187 |
| 616.60 | 161.24 | 99.423 |
| 709.46 | 153.76 | 109.089 |
| 809.28 | 46.72 | 37.812 |
| 822.13 | 0.00 | 0.000 |
| MPP: 709.46 V | 153.76 | 109.089 |
| OP: 709.46 V | 153.76 | 109.089 |
Simple explanation
Light gives carriers energy inside a semiconductor. Selective contacts allow an external circuit to collect electrical power. A module packages cells behind protective layers; it does not boil water or drive a heat engine. [S1]
Series modules add voltage; parallel strings add current. MPPT adjusts electrical loading to find useful power, whereas tracking changes the mechanical angle to the Sun. The inverter produces AC; the transformer changes AC voltage. They do different jobs. [S1] [S2] [S3]
Controlled semiconductor switching and filtering shape the inverter’s AC output for its grid interface. Our selected interface is 50 Hz; switching ripple, harmonics and grid-control transients are not calculated. [S4]
Engineering details
One PV equation, one bounded power stream
Module export current is I(V) = I_ph − I₀ expm1(V/a), with a = n Nₛ kT/q. I and I_ph are current and photocurrent (A), I₀ is saturation current (A), V is module voltage (V), n is assumed diode ideality, Nₛ is effective series-cell count, k is Boltzmann’s constant (J/K), q is elementary charge (C), and T is cell temperature (K). expm1(x) means exp(x) − 1. Series and shunt resistances are omitted. [S2]
Our empirical calibration uses ΔT = T − 298.15 K; reference-irradiance targets I_ref = 12 + 0.0048ΔT A and V_ref = 49 − 0.15ΔT V; I₀ = I_ref/expm1(V_ref/a), I_ph = I_ref G/1000. The temperature targets follow the book’s linear form; these coefficients and the derived I₀ law are illustrative, not a fitted real semiconductor model. n = 1.2; Nₛ = 72. [S2]
G = G_front + 0.70G_rear (W/m²), with front = direct-normal irradiance × max(0, module normal · Sun vector) during daylight. Rear irradiance is independently entered, not inferred from the Sun or ground. Both contributions are zero at/below the horizon. Bounded tracker tilt maximises direct-beam incidence about the north–south axis; ±55° travel is assumed. No backtracking or row shading is solved. [S2] [S6] [S7]
Maximise module VI to obtain MPP. String V = 17 × module V; array I = 18 × string I. P_available is their MPP product. P_DC = min(P_available, 130000/0.97) W; P_AC = 0.97P_DC; P_grid = 0.98P_AC. Inverter heat = 0.03P_DC; downstream heat = 0.02P_AC; unharvested clipping = P_available − P_DC. Actual clipped voltage/current solve the same curve’s high-voltage branch. [S2] [S5]
Illustrative assumptions and checked example
At standard test conditions (STC: reference irradiance 1000 W/m², cell temperature 25°C, specified reference spectrum), this constructed curve gives 0.483 kW per module and 147.734 kWdc total. The 130 kWac inverter, 97% inverter efficiency, 98% transformer/collector efficiency and all curve parameters are invented teaching assumptions. Spectrum, wiring loss, standby import, thermal balance, mismatch, bypass diodes, inverter voltage windows/startup thresholds, grid disturbances and harmonics are not computed. [S1]
The reset scenario uses direct-normal irradiance 800 W/m², 25°C cells, elevation 42°, azimuth 118° and rear 0 W/m². Tracker -44.439° gives front irradiance 749.732 W/m². Array MPP 709.459 V × 153.763 A = 109.089 kWdc → 105.816 kWac → 103.700 kW export. Checked balance: 109.089 = 103.700 + 3.273 + 2.116 kW; no clipping. Rounded display values may differ at the last decimal.
Mechanics, heat and common misconceptions
Piers, bearing housings and foundations stay still; torque tubes, rails and modules turn. Flexible cable loops connect moving and fixed terminals. The model checks rigid geometry, not wind loading, fatigue or certified cable bend radius. A selected module opens into enlarged layers and reassembles when you leave it; this is an inspection view, not an operating arrangement. [S2]
- Cell temperature is not ambient temperature. Higher temperature reduces voltage in this model; temperature is imposed, not thermally simulated.
- Clipping is electrical potential not harvested, not extra inverter heat.
- MPPT is not mechanical tracking or a mandatory separate DC/DC stage.
- Night ambient lighting is for inspection, not modelled solar irradiance. Pulses are energy teaching aids, not photon/electron speeds.
- Scale is approximately 2 m per unit. Travel limits, compressed station spacing, expanded cutaway layers and simplified conductors do not establish engineering compliance.
Download the editable Blender scene. Reproducible scripts, equations, source map and validation scope are supplied with the website source.
Main book references
- [S1] Antonio Luque and Steven Hegedus (eds.), Handbook of Photovoltaic Science and Engineering, 2nd ed., Wiley, 2011. ISBN 9780470721698; DOI 10.1002/9780470974704. Checked Chapter 1 §§1.2–1.2.1, printed pp. 4–7 in the lawful publisher excerpt.
- [S2] Klaus Jäger, Olindo Isabella, Arno H. M. Smets, René A. C. M. M. van Swaaij and Miro Zeman, Solar Energy: Fundamentals, Technology, and Systems, TU Delft course-book manuscript, 2014. Checked §§9.1–9.3 (pp. 102–111), §16.4 (pp. 241–242), §17.1 (pp. 251–259), §§17.2–17.3 (pp. 264–275), §§18.3.5–18.3.6 (pp. 322–324), §18.4.1 (pp. 327–328), including temperature equations (18.24)–(18.25). Lawful university-course PDF. These are 2014 manuscript pages, not the 2016 published edition’s pagination.
- [S3] Robert W. Erickson and Dragan Maksimović, Fundamentals of Power Electronics, 3rd ed., Springer, 2020. ISBN 9783030438791; DOI 10.1007/978-3-030-43881-4. Only the public introductory abstract was checked for power processing/control. Detailed circuit and PWM chapters are unverified further reading; accessible S2 supports the PV-system derivations.
Supplementary technical sources
- [S4] US DOE, Inverters and grid services: switching, filtering and grid interface.
- [S5] pvlib, PVWatts inverter model: AC cap and measurement boundaries. Our assumed fixed efficiency is not its load-dependent curve.
- [S6] pvlib, Single-axis tracking: limits and the distinct backtracking option.
- [S7] NREL bifacial_radiance, Effective front plus weighted rear irradiance. No ray-traced bifacial model is run here.
Passages checked . No independent engineering peer review, structural certification, protection study or real equipment calibration is claimed. The books support principles; they do not certify this geometry or numerical implementation.
Inside the engineering
Follow the machinery, the working fluids and the electrical connection.
Mechanical
Steel posts support a torque tube and module rails. The tracker turns the row about one axis to change its orientation to the Sun; module frames and foundations resist wind loads.
Thermal & chemical
Light absorbed in semiconductor cells produces charge carriers; the cell junction separates them. This is photovoltaic conversion, without a steam cycle. Temperature affects cell voltage and performance.
Electrical
Seventeen modules add series voltage and eighteen parallel strings add current. Paired DC collection feeds the central inverter, whose maximum-power-point tracking is not a separate DC/DC stage in this architecture. Three-phase 50 Hz AC passes through station transformation/switchgear and collector/grid equipment. A transformer cannot convert DC into AC. One steady-state model distinguishes available DC, harvested DC, AC clipping and heat losses.
Main types and variations
The model illustrates tracking photovoltaic panels. Mounting, cell material and inverter arrangement are independent design choices that can be combined. Concentrating solar-thermal power uses a different conversion process entirely.
Fixed-tilt photovoltaics
Modules remain at a chosen angle and orientation on a permanent mounting structure. The structure must support the array and withstand environmental loads. The Sun’s angle changes across the day and seasons, while the cells continue producing DC whenever sufficient sunlight reaches them; no tracking drive is required.
What changes in practice
This provides a straightforward mounting arrangement for roofs and ground arrays. Orientation and shading still matter, even though there are no tracking mechanisms to operate.
Single-axis and dual-axis tracking
A tracking structure rotates modules to change their orientation to the Sun. Single-axis tracking, as illustrated, turns an array around one axis; dual-axis tracking adjusts around two. The panels still generate through the photovoltaic effect: the mechanism changes how sunlight reaches them, rather than changing the cell’s conversion process.
What changes in practice
Tracking can increase captured sunlight, but adds moving structures and controls. The choice depends on site conditions, mounting constraints and the value of the additional energy.
Crystalline-silicon and thin-film cells
Crystalline-silicon cells use silicon wafers, whereas thin-film technologies deposit semiconductor layers onto a supporting surface. Cadmium telluride and copper indium gallium diselenide are examples of thin-film materials. Both create electrical charge from absorbed light; different materials and structures absorb and convert the solar spectrum differently.
What changes in practice
Cell chemistry affects manufacturing and module performance. Material choice is independent of whether panels are fixed or tracked and of the inverter architecture downstream.
String and central inverters
A string inverter converts DC from connected groups of modules into AC. A central-inverter arrangement collects output from a larger part of an array before conversion. Both use power electronics rather than a rotating generator; their distinction is how the solar field is divided and electrically collected.
What changes in practice
Grouping determines which panels share conversion equipment. Shading, maintenance and a converter outage can affect different portions of the plant depending on the electrical layout.
Microinverters and module-level control
A microinverter converts output at an individual panel instead of feeding a common DC string inverter. Panels can therefore operate more independently when their conditions differ. A DC optimiser is a different device: it controls a module’s DC output but still needs an inverter elsewhere to produce AC.
What changes in practice
Module-level equipment can help with uneven shading or roof orientations. It also distributes more electronics across the array, changing installation, monitoring and maintenance considerations.
Concentrating solar-thermal power (CSP)
Mirrors concentrate sunlight onto a receiver, producing high-temperature heat. A working-fluid system then supplies an engine or turbine-generator. Tower systems use mirrors aimed at an elevated receiver; linear systems focus along receiver tubes. This is a heat-engine power plant, distinct from the photovoltaic panels shown in the model.
What changes in practice
CSP can incorporate thermal storage before electricity generation. Its receivers, heat-transfer circuits and power block make it mechanically and thermally different from a PV-and-inverter plant.
Worth knowing
- Solar plants produce nothing at night, so their average output is well below rated capacity.
- Panel makers and inverter suppliers are rarely published in open plant registers.
- Rooftop systems work the same way at a much smaller scale.
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Textbook references
Suggested technical background for this topic. These books are further reading, not proof that every explanation was checked against every edition. See the full bibliography and review scope.
- Handbook of Photovoltaic Science and EngineeringSemiconductor physics of solar cells, module technologies and system design.
- Renewable and Efficient Electric Power SystemsPV system sizing, inverters and the difference between DC and AC ratings.
Sources
- EIA: Photovoltaics and electricity ↗
- US DOE: Photovoltaic cells, modules and systems ↗
- SMA: Utility-scale inverter, transformer and switchgear arrangement ↗
Cutaways reveal enclosed equipment. Layouts, dimensions, materials and animation speeds are illustrative; this is an educational model, not a plant design or a thermodynamic simulation.