What Does a Complete 65kWp Commercial Rooftop Solar System Include?
Commercial buildings across the Balkans and Southeast Europe are increasingly considering rooftop solar to reduce electricity costs, improve energy independence and make better use of available roof space. For businesses with daytime electricity consumption, a grid-connected photovoltaic (PV) system without battery storage can be a practical starting point.
However, purchasing a commercial solar system involves more than selecting solar panels and an inverter. A complete quotation should account for the mounting structure, DC and AC cables, connectors, grounding, electrical protection, monitoring and, where required, export control.
A typical project requirement might be around 65kWp of solar modules connected to one 50kW three-phase on-grid inverter, installed on a metal roof. The system does not include batteries, while a zero-export solution is quoted as a separate option.
This article explains how to approach this type of project, what equipment should be included in the quotation and which technical details should be confirmed before procurement.
1. Understanding a 65kWp PV System with a 50kW On-Grid Inverter
A 65kWp solar array refers to the combined rated DC capacity of the photovoltaic modules under standard test conditions. A 50kW three-phase on-grid inverter converts the DC electricity generated by the modules into AC electricity for the building and the grid.
The ratio between the PV array capacity and inverter rated AC output is:
65kWp ÷ 50kW = 1.30
This represents a DC-to-AC ratio of approximately 1.30. Such a configuration can be considered in commercial rooftop projects, but it is not automatically suitable for every site.
The final design must be checked against the inverter manufacturer's permitted DC input power, maximum DC voltage, MPPT voltage range, input current limits and number of MPPTs. The designer must also consider local solar irradiation, roof orientation, shading and the building's load profile.
A 65kWp array does not continuously produce 65kW of AC power. Actual output changes with irradiance, module temperature, orientation, shading, system losses and inverter operating conditions.
For this reason, the system should be designed around the building's energy consumption and the site's electrical conditions rather than relying on the nominal capacity alone.
2. What Equipment Should a Complete Commercial Solar Quotation Include?
A complete quotation should clearly separate the main generation equipment, mounting materials, electrical balance of system (BOS), monitoring and optional export-control equipment.
Solar PV Modules
The solar modules form the DC generation side of the system.
The quotation should specify:
Manufacturer and exact module model.
Rated power and total installed DC capacity.
Module quantity.
Datasheet and applicable product certificates.
Product dimensions and weight.
Product and performance warranty information.
The number of modules depends on the selected wattage. For example, a 65kWp array using 625W modules would require approximately 104 modules, subject to the final DC capacity and module availability.
The selected module must also be compatible with the inverter's voltage and current limits. The final string configuration should be calculated using the module's electrical data and the site's expected minimum and maximum temperatures.
Three-Phase On-Grid Inverter
The inverter converts the electricity generated by the PV array into usable AC power.
For a project using one 50kW three-phase inverter, the quotation should identify the exact model and include:
Rated AC output power.
Maximum DC input voltage.
MPPT operating voltage range.
Maximum input current per MPPT.
Number of MPPTs and string inputs.
Grid voltage and frequency compatibility.
Monitoring and communication options.
Applicable grid-compliance documentation.
The inverter should be selected according to the PV array configuration and the local grid requirements. A nominal 50kW rating alone is not enough to confirm compatibility.
Metal-Roof Mounting Structure
Metal roofs require a mounting solution that matches the specific roof profile and structural conditions.
The mounting quotation should identify the proposed system type, including whether it is designed for trapezoidal metal sheets, standing-seam roofs or another roof configuration.
Typical materials may include:
Roof brackets or clamps.
Mounting rails.
Module end and mid clamps.
Stainless-steel or compatible fasteners.
Splice connectors and bonding components.
Weatherproofing accessories where required.
Before installation, the roof structure and sheet condition should be assessed. Wind uplift, snow loads, roof age, corrosion, waterproofing and the allowable structural load must be considered.
The mounting method should not be selected from the phrase "metal roof" alone. The actual roof profile and fixing method determine which components are appropriate.
DC Cables and Connectors
The DC side connects the PV modules to the inverter.
A complete quotation should include solar DC cables, compatible connectors and the accessories required for the designed string layout.
Cable cross-section and insulation ratings should be selected according to current, voltage drop, cable length, installation method, ambient temperature and applicable electrical standards.
Connector compatibility is especially important. Connectors should be of the specified compatible type and assembled according to the manufacturer's instructions. Mixing visually similar but unverified connector products can create connection and safety risks.
AC Cables and Grid Connection Accessories
The AC side connects the inverter to the building's distribution board or designated grid connection point.
The quotation should specify the proposed AC cable type, cross-section, length allowance and relevant termination accessories. Final cable sizing depends on inverter output current, cable routing, installation conditions, voltage drop and local electrical regulations.
The connection point and any required modifications to the existing distribution board should be identified during the site assessment.
Grounding and Electrical Protection
Grounding and protection equipment are essential parts of a complete PV system, not optional accessories.
Depending on the system design and local regulations, the quotation may include:
DC isolators, where required by the inverter design and applicable standards.
DC surge protection devices.
AC circuit breakers or protective switching devices.
AC surge protection devices.
Protective earth conductors and bonding accessories.
Equipotential bonding components.
Relevant distribution enclosures and labels.
Protection device ratings and types must be determined by the electrical design, inverter instructions, installation environment and applicable standards. They should not be selected simply by copying a generic equipment list.
Lightning protection and coordination with an existing building lightning protection system should also be assessed where relevant.
3. Monitoring: Included as Standard or Quoted Separately?
Monitoring allows building owners and system operators to check PV generation and identify abnormal operating conditions.
A monitoring package may include the inverter's communication interface, data logger or gateway, internet connection accessories and access to the manufacturer's monitoring platform.
Before ordering, confirm:
Whether monitoring hardware is included with the inverter.
Whether Wi-Fi, Ethernet or another communication method is required.
Whether a separate data logger or meter is needed.
Whether monitoring is available at inverter level or through a complete plant-monitoring interface.
Whether the customer needs remote access for multiple users.
Monitoring and export control are related to system operation, but they are not the same function. A monitoring platform displays operating information; it does not necessarily prevent electricity from being exported to the grid.
4. Zero-Export Control: Why Should It Be Quoted Separately?
Some commercial buildings are allowed to connect rooftop PV systems to the grid but are not permitted to export surplus electricity. Others may have a limited export allowance under their grid-connection agreement.
In these cases, a zero-export or export-limitation function may be required.
A typical export-control arrangement uses a compatible meter or current transformer (CT) at the designated grid connection point. It measures the direction and amount of power flowing between the building and the grid. The control system then communicates with the inverter to limit PV output when necessary.
However, not every inverter supports the same export-control configuration. The required meter, CT, communication cable, controller and firmware compatibility should be checked against the selected inverter model.
The quotation should therefore show zero-export equipment as a separate option, including:
Compatible smart meter or CT.
Export-control device or controller, if required.
Communication accessories.
Required installation and commissioning scope.
The customer should also confirm whether the local utility requires a certified export-limitation arrangement or additional grid approval. A zero-export device does not replace the grid-connection approval process.
5. Why a Battery Is Not Always Necessary
A grid-connected PV system can operate without battery storage.
During daylight hours, solar energy is used by the building's electrical loads. If PV generation is lower than consumption, the grid supplies the difference. If generation exceeds consumption, surplus electricity may be exported where permitted or curtailed through an export-limitation system.
For commercial buildings with substantial daytime electricity demand, a PV-only system can be a reasonable first investment.
A battery may become relevant when the customer wants to store surplus energy for evening consumption, manage peak demand, provide backup power or improve energy use under a specific tariff structure. These objectives require additional analysis of load profiles, battery capacity, inverter architecture and operating strategy.
For a project that explicitly requests an on-grid system without batteries, the quotation should not add battery equipment by default. It should clearly state that storage is excluded and can be evaluated separately if the customer's requirements change.
6. Information Required Before Finalizing the System Design
A preliminary equipment list can be prepared from the target capacity, but a reliable final quotation requires more project information.
The buyer or installer should provide:
Roof details: Metal roof profile, available roof area, roof drawings or photographs.
Location: Project city and country, to assess climate and grid requirements.
Electricity supply: Three-phase grid voltage and frequency.
Consumption profile: Daytime load and, ideally, electricity bills or interval data.
PV capacity: Target DC capacity and any restrictions from the utility.
Export policy: Whether export is permitted, limited or prohibited.
Installation scope: Whether the purchase covers equipment supply only or also installation and commissioning.
Delivery requirements: Destination, preferred Incoterm and target delivery schedule.
These details help determine whether the proposed 65kWp PV array and 50kW inverter are appropriate, whether zero-export equipment is needed and which mounting and protection components should be included.
7. A Practical Procurement Checklist for Commercial Rooftop PV
When comparing quotations from different suppliers, check whether each offer includes the same scope.
Equipment or Service | What to Confirm |
|---|---|
Solar modules | Brand, exact model, wattage and quantity |
On-grid inverter | Model, 50kW three-phase output and grid compatibility |
Mounting structure | Compatibility with the actual metal roof |
DC materials | Solar cables, connectors and string accessories |
AC materials | AC cables, terminations and distribution accessories |
Grounding | Protective earth and bonding materials |
Protection | DC/AC isolators, breakers and surge protection as required |
Monitoring | Data logger, meter, communication and platform access |
Zero-export option | Compatible meter/CT and control equipment, quoted separately |
Documentation | Datasheets, certificates, manuals and warranty information |
Logistics | Packaging, shipment, delivery terms and lead time |
A line-item quotation makes it easier to identify missing equipment, compare suppliers and understand the real project cost.
8. Commercial Solar System Supply from MoregoSolar
MoregoSolar supports international customers sourcing solar modules, inverters and related system components for commercial rooftop and other PV applications.
For a project in the Balkans or Southeast Europe, the equipment selection should begin with the building's roof conditions, electrical supply, energy consumption and grid-export requirements.
Based on the project information, MoregoSolar can help prepare an itemized equipment proposal covering PV modules, a suitable three-phase on-grid inverter, metal-roof mounting materials, DC and AC accessories, grounding and electrical protection. Monitoring and zero-export equipment can be identified separately according to the selected inverter and project requirements.
The purpose of an itemized proposal is to make the equipment scope clear before the buyer commits to procurement. It also helps installers and project owners identify which components still require site verification or local engineering approval.
Planning a commercial rooftop solar project? Share your target PV capacity, roof type, inverter preference and destination with MoregoSolar to request an itemized equipment quotation.
