What is needed for a complete photovoltaic system?
A full PV system is a set of devices and protections that together convert solar energy into electricity used at home. The simplest on-grid installation consists of panels, inverter, structure, cables, protections, counter and documentation. A more extensive system may have energy storage, backup, smart meter, optimizers, EMS system and separate emergency circuits.
The modules produce DC electricity, and the structure holds them on the roof or ground at the right angle.
The inverter converts DC power from your panels into AC power for your home and grid.
They protect the installation against overvoltage, short circuit, insulation faults and fire risk.
List of elements of a complete photovoltaic installation
Below is a map of elements that are worth considering when planning a PV system. Not every home needs one all options, but each project should consciously decide whether a given element is needed.
| Element | Role in the system | Is it mandatory? | What to watch out for? |
|---|---|---|---|
| Photovoltaic panels | They produce DC current from solar radiation. | Not | Power Wp, efficiency, dimensions, weight, degradation, temperature coefficient. |
| Mounting structure | Attaches panels to the roof, ground, carport or facade. | Not | Roof covering type, wind/snow load, tightness and corrosion. |
| Inverter | Converts DC from panels to AC for your home and network. | Yes, unless microinverters are used. | MPPT range, string voltages, input currents, monitoring, warranty. |
| DC cabling | It connects the panels to the inverter on the DC side. | Not | Cross-section, UV resistance, connectors, cable routes, voltage drops. |
| AC wiring | Connects the inverter to the building's electrical switchboard. | Not | Cable cross-section, protection, route length, connection conditions. |
| DC protection | They protect the side of the panels and the inverter. | Depending on the project, protective elements are usually required. | DC disconnector, surge arresters, string fuses, polarization. |
| AC protection | They protect the network side of the installation. | Not | Overcurrent and residual current circuit breakers, SPD, protection selectivity. |
| Grounding and equipotential bonding | They reduce the risk of electric shock and the effects of overvoltages. | Yes, in accordance with the design and standards. | Continuity of connections, lightning protection, connection of structures. |
| Bidirectional counter | It measures energy taken from the grid and fed into the grid. | Yes for on-grid prosumer installations. | The procedure for reporting and replacing the meter depends on the operator. |
| Monitoring | Shows production, errors and inverter operation. | Technically not always, practically highly recommended. | Application access, Wi-Fi/LAN, data history, installer account. |
| Smart meter / energy meter | It measures energy flows in the home and allows you to control your self-consumption. | Optional, often needed for hybrid and stock. | Compatibility with the inverter and correct installation location. |
| Energy storage | It stores excess energy for use later. | Optional | Capacity, BMS, battery voltage, compatibility, warranty, safety. |
| Backup / EPS | Powers selected circuits during a network outage. | Optional | Not every hybrid inverter provides a full home backup. Circuits need to be separated. |
| Documentation | Confirms the parameters, diagram and compliance of the installation. | Not | Single-line diagram, catalog cards, certificates, measurement protocols. |
How does a complete photovoltaic system work?
In the simplest arrangement, panels produce DC current. The inverter converts it into AC alternating current, which can power receivers at home. Surplus energy goes to the grid or energy storage, if the system has a battery.
DC current
DC → AC
security
self-consumption
surplus
Three main variants of the system
The most common variant. Without energy storage and without proper backup, it does not work during a network failure.
The system can increase self-consumption and power selected emergency circuits, if designed this way.
It requires a larger battery, power reserve and a careful energy balance. It is not the same as typical on-grid.
1. Photovoltaic panels - energy source
PV panels are a visible element of the installation, but their selection must result from calculations. It is not only the power of Wp that counts, but also panel surface, efficiency, operating temperature, weight and electrical matching to the inverter.
What to check with PV panels?
- Power Wp – power under STC test conditions.
- Module efficiency – how much power will fit on a square meter of roof.
- Temperature coefficient Pmax – how much the panel loses in heat.
- Dimensions and weight – important for the roof and structure.
- Degradation – loss of power after years of operation.
- Voltage and current – must match the MPPT of the inverter.
More: types of photovoltaic panels and PV panel selection calculator.
2. Mounting structure - foundation of the PV installation
The mounting structure keeps the panels in place for several decades. It must be matched to the type of roof, coverage, wind and snow loads and cable routing.
| Mounting type | Application | Pros | Risks |
|---|---|---|---|
| Pitched roof | Most often, roof tiles, metal roof tiles, trapezoidal sheets. | Uses the existing roof, aesthetic installation. | Tightness, selection of hooks, roof unevenness, shading. |
| Flat roof | Ballasted or mechanically attached systems. | Possibility to set the angle and direction. | Ballast load, wind, row spacing. |
| Grunt | Plot with space for installation. | Good ventilation, easy service, bifacial option. | Cost of construction, location, shading, area protection. |
| Carport | Parking shelter with PV panels. | It combines the functions of roofing and energy production. | Cost of construction, permits, wind/snow resistance. |
3. Inverter – the center of the photovoltaic system
The inverter is responsible for converting DC power from the panels into AC power used in the home. It also controls the operation of the strings, monitors errors and communicates with the network. In more complex systems, it works with a battery or a smart meter and backup system.
Types of inverters
The panels are connected to form a string. A good solution for a simple roof without much shadow.
It can operate with a battery and often offers backup power functions, depending on the model and installation.
Useful for complex roofs, different directions and partial shading.
They are not an inverter, but they help manage the operation of panels in difficult conditions.
What to check with the inverter?
- number and scopes of MPPTs;
- maximum DC voltage;
- maximum input current per MPPT;
- permissible DC/AC oversizing;
- 1-phase or 3-phase system;
- monitoring, application and data export;
- warranty, service and documentation availability;
- compatibility with energy storage if you plan on having a battery.
More: how to choose panels for the inverter and replacing the inverter with a hybrid one.
4. DC and AC cabling – an invisible but critical element
Cables are often omitted in installation descriptions, but they have a real impact on safety and energy losses. The DC side operates with voltages from the panels, and the AC side connects the inverter to the building's switchgear.
| Element | Function | What to check? |
|---|---|---|
| DC solar cables | They connect the panels to each other and to the inverter. | UV resistance, operating temperature, cross-section, cable route. |
| MC4/compatible connectors | They connect wires and modules. | Do not mix random connectors from different manufacturers without confirming compatibility. |
| AC cables | They connect the inverter to the switchgear. | Cross-section, protection, voltage drop, route length. |
| Cable routes | They protect the cables mechanically and tidy up the installation. | Resistance to UV, water, temperature and mechanical damage. |
5. DC/AC protection, grounding and surge protection
Security is not an add-on. They are part of the system. Their task is to limit the effects of short circuits, overvoltages, insulation errors and failures. The selection of protection depends on the design, type of inverter, and building electrical installation and lightning protection.
Typical protection elements
- DC disconnector;
- DC surge arrester;
- string fuses if the project requires them;
- correct polarity and description of the wires.
- circuit breaker;
- residual current protection, if required;
- AC surge arrester;
- correct connection to the switchgear.
Grounding and equipotential bonding
The structure, module frames, surge arresters and switchboards must be properly connected according to the design. In a building with a lightning protection system, you need to pay special attention to the separation distances and the way the cables are routed.
6. Counter, smart meter and monitoring
Monitoring allows you to check whether the installation is working properly. The mere fact that the inverter is green is not enough. The application should show production, errors, work history, network status and possibly energy flows in the house.
| Element | What is it for? | When is it needed? |
|---|---|---|
| Bidirectional counter | It measures the energy consumed and fed into the grid. | For on-grid installation reported to the operator. |
| Inverter monitoring | Shows inverter production and errors. | It's almost always worth having. |
| Smart meter of the inverter manufacturer | Measures energy import/export in real time. | With energy storage, export restrictions, EMS and auto-consumption. |
| EMS / HEMS | Controls energy consumption at home. | With a heat pump, EV, energy storage and dynamic tariffs. |
7. Energy storage – when is it needed?
Energy storage is not mandatory, but it changes the nature of the installation. Without batteries, excess energy is usually given away to the network. With a battery, some of this energy can be used later, e.g. in the evening, at night or during a failure, if the system has a backup.
What does the battery part consist of?
- Battery modules – physical capacity of energy storage.
- BMS – battery management system that controls voltage, current and temperature.
- Communication – most often CAN or RS485 between the battery and the inverter.
- Battery protection – depending on the type of warehouse and manufacturer.
- Smart meter – often needed to control charging and discharging.
How to choose battery capacity?
The capacity of the energy storage should result from the consumption profile, PV power, self-consumption, backup purpose and budget. For a single-family house, the range of several to a dozen or so kWh is often analyzed, but there is no single universal value.
8. Backup, EPS and emergency power supply
Backup is one of the most frequently misunderstood elements of a PV installation. A hybrid inverter alone does not automatically mean that the entire house will function during a network failure. You need to check what circuits are to be powered, what is the backup power, how switching works and whether the system operates in 1-phase or 3-phase mode.
What should you plan for a backup?
The most common units include a refrigerator, router, lighting, gate, circulation pump, automation and several sockets.
The system must safely separate the house from the grid so as not to apply voltage to the operator's line.
Some devices have a large starting current. The backup must be matched to real receivers.
You need to check which phases are powered and whether important loads are on the correct circuits.
9. Documentation, notification and acceptance of the installation
Good documentation protects the owner. It is needed when reporting installation, service, warranty, expansion, selling the house and possibly replacing the inverter or adding an energy storage facility.
What should be in the documentation?
- single-line installation diagram;
- data sheets for panels, inverter, protection and batteries;
- certificates and declarations of conformity;
- electrical measurement protocol;
- photos of switchboards and cable routes;
- description of strings and panel arrangement;
- login details and procedure for access to monitoring;
- warranty conditions and service details;
- confirmation of notification to the operator, if applicable.
10. How to design a PV system step by step?
- Check your energy consumption from invoices for 12 months.
- Assess the roof: area, direction, angle, shadow, load capacity, coverage.
- Select PV power based on consumption and available space.
- Select the type of panels: mono, TOPCon, HJT, glass-glass, bifacial depending on the conditions.
- Choose an inverter for strings, MPPT, currents and planned expansion.
- Check security DC/AC, grounding and switchboards.
- Consider energy storage, if you care about self-consumption or backup.
- Separate emergency circuits, if the system is to power the house during a failure.
- Prepare documentation and confirm the reporting procedure.
- Start monitoring and maintain administrative access to the system.
Checklist: what to check before purchasing a photovoltaic installation?
This list allows you to quickly assess whether the installer's offer is complete. If the offer includes only "panels + inverter", without protection, documentation and assembly details, requires clarification.
| Area | Review questions | Status |
|---|---|---|
| PV panels | What model, power, efficiency, dimensions, weight, warranty and degradation? | check the catalog card |
| Roof | How many panels will actually fit after taking into account obstacles and spacing? | required panel layout |
| Inverter | Does it match string voltages, MPPT currents and planned expansion? | check the project |
| Security | What DC/AC protection, SPD, disconnectors and equipotential bonding are offered? | do not skip |
| Monitoring | Does the owner have access to the application and error history? | recommended |
| Energy storage | Can the system be expanded with a battery? What communication and what limitations? | important when expanding |
| Backup | Does the backup power the entire house or only selected circuits? What power and switching time? | frequent misunderstanding |
| Documentation | Do you receive a diagram, protocols, data sheets and warranty data? | necessary |
FAQ
What does a complete photovoltaic system consist of?
From PV panels, mounting structure, inverter, DC/AC cabling, protection, grounding, meter, monitoring, documentation and optionally energy storage and backup system.
Will PV panels and an inverter be enough?
NO. Safe installation also requires structure, cables, protection, switchboards, grounding, documentation and correct reporting if the installation works with the network.
Does the PV installation work during a power outage?
A standard on-grid installation usually turns off when the grid goes out. It is needed for emergency operation appropriate backup system with battery and safe switching.
Is energy storage necessary?
It is not necessary, but it can increase self-consumption and enable emergency power supply. Battery selection should result from the consumption profile, PV power and system purpose.
What should you check before signing a contract with an installer?
Panel model, inverter model, panel arrangement on the roof, string diagram, security, documentation, warranty conditions, monitoring, notification procedure and the possibility of expansion with an energy storage facility.