300kW-class solar array can help a factory, warehouse, farm or other large Irish business reduce its daytime electricity purchases. The project’s suitability depends on more than the available roof. Electricity demand, roof structure, grid capacity and the amount of power used on site all shape the design and return.
In this guide, 300kW solar panel system means a panel array of about 300kWp DC. The inverter’s AC output rating may be lower, and the grid operator may approve a different export limit. We explain the panel count, estimated roof area, Irish generation, costs, grants and project process. All budget and return figures are estimates, not a quote or guaranteed result.
What is a 300kW commercial solar PV system?
Solar panels are rated in kilowatt-peak (kWp), which is their combined output under standard test conditions. A 300kWp array generates direct-current electricity when daylight reaches the modules. Inverters convert that electricity to alternating current for the building’s electrical system.
The array’s DC rating is not the same as its inverter’s AC rating. A design may pair 300kWp of panels with inverter capacity below 300kW, depending on equipment and the load profile. The approved export capacity may be lower again. A proposal should state the array capacity in kWp, inverter rating in kW or kVA and the permitted export capacity. Those distinctions matter for the system design, grant calculation and grid connection.
Electricity is used on site as it is generated. Any surplus may be exported or stored if the business adds a suitable battery. When generation is low or the building needs power after dark, electricity continues to come from the grid. The best system size is based on the building’s consumption pattern as well as its roof space.
300kW solar panel system: panel count by module wattage
The panel count depends on each module’s rated output. The comparison below rounds up to reach at least 300kWp. Dimensions are examples from individual module specifications; actual products vary by manufacturer and model.
•400W panels: 750 modules provide 300.00kWp. At approximately 1.722m × 1.134m per panel, the module-only footprint is about 1,465m².
•450W panels: 667 modules provide 300.15kWp. At approximately 1.762m × 1.134m per panel, the module-only footprint is about 1,333m².
•500W panels: 600 modules provide 300.00kWp. At approximately 2.094m × 1.134m per panel, the module-only footprint is about 1,425m².
•550W panels: 546 modules provide 300.30kWp. At approximately 2.278m × 1.134m per panel, the module-only footprint is about 1,411m².
For example, 300,000W divided by 450W per panel is 666.7, so the calculation rounds up to 667 modules. That array is 300.15kWp. The 550W option also rounds slightly above 300kWp. A designer may select another panel combination to suit the roof or meet a precise system capacity.
300kW solar roof space and access
The module-only footprint for these examples is about 1,330–1,465m². A real installation needs additional clear roof area for panel spacing, roof-edge clearances, walkways, access routes and maintenance. The layout must also work around skylights, vents, drainage, existing plant and fire-safety requirements. Flat roofs with tilted panel rows may need greater spacing to reduce inter-row shading.
As an early planning allowance, a 300kWp array may need approximately 1,700–2,050m² of usable roof area. This is an estimate based on the sample module footprints plus an allowance for access and spacing; it is not a statutory area requirement. A measured roof plan and installer layout are needed to confirm the true usable area. Orientation, roof shape, mounting method and local restrictions can all alter the result.
A structural survey should confirm that the roof can safely support the panels and mounting system under expected wind loads. It should also review roof age, waterproofing, warranty conditions and likely repair requirements. If major repairs are due, carrying them out before installation can avoid later disruption and removal costs.
300kW solar system output in Ireland
For an initial estimate, a 300kW solar panel system with a 300kWp array might generate around 240,000–270,000kWh per year (240–270MWh), using an illustrative yield of 800–900kWh per kWp annually. SEAI’s business guide gives an 870kWh/kWp example and estimates 900kWh/kWp for a well-designed, south-facing system inclined close to 35 degrees. These values are planning references, not a site-specific guarantee.
A project forecast should be modelled for the actual location and layout. The European Commission’s PVGIS tool estimates long-term PV production for a selected location and system configuration. Irish weather, roof direction, tilt angle, shading, panel temperature, inverter efficiency and electrical losses all affect the 300kW solar system output. South-facing panels can deliver strong annual production. East–west orientations may spread generation over more working hours. A low tilt can slightly reduce yield per kWp but may allow more panels on a flat roof.
Generation is seasonal rather than even throughout the year. Long summer days generally produce more electricity than winter days. Businesses should compare the hourly generation model with interval demand data. Factories, industrial facilities, cold stores and hotels with steady daytime loads may use a large share of their solar electricity on site. A property with a large weekend shutdown may export more power unless it can shift loads or install storage. SEAI recommends sizing commercial solar around electricity demand and self-consumption.
Commercial solar installation cost for a 300kW system
The 300kW solar installation Ireland cost depends on the equipment, roof and electrical works. Main cost components include the PV modules, inverters, mounting structures, cabling, isolators, switchgear and protection, metering and monitoring, design, labour, installation, testing and commissioning. Roof reinforcement, access equipment, distribution-board upgrades and network works can add to the investment.
LVP Renewables publishes a broad commercial solar guide of €850–€2,000 per kWp installed. Applied to 300kWp, that gives a rough range of €255,000–€600,000 before grant support. It is a broad budgetary indicator, not a project quotation or an independent market benchmark. The public price guide does not define the scope or VAT treatment of every project. Ask for a written quotation that identifies whether VAT, roof repairs, grid reinforcement, export-limiting equipment, monitoring and other works are included. Battery storage should be priced separately.
Larger arrays can benefit from economies of scale, but site complexity can outweigh that effect. A roof with good access and spare electrical capacity will differ from a site needing structural reinforcement, new switchgear or network upgrades. The final commercial solar installation cost should be based on a roof survey, electricity-use data, grid assessment and a clear equipment specification.
Commercial solar grants Ireland: current SEAI support
The principal SEAI support for eligible non-domestic solar PV is the Non-Domestic Microgen Grant (NDMG). Eligible applicants include businesses, farms, public bodies, schools, community centres and non-profit organisations. The scheme supports systems up to 1,000kWp for self-consumption, subject to its conditions.
As of 14 October 2026, the enhanced support applies to new applications made from 6 October 2026 to 6 July 2027. SEAI’s current grant guide lists €115,200 as the size-based value for an exact 300kWp system. This is subject to the rule that the amount paid is the lower of the application-summary grant and 45% of eligible invoiced costs. The grant is not automatic, and the invoice-cost cap or eligibility conditions can reduce the payment.
For example, if eligible installation costs were €255,000, 45% would be €114,750, so the grant could not exceed that figure. On a €300,000 eligible invoice, 45% would be €135,000, but the 300kWp size-based value of €115,200 would be the lower limit. The scheme guide gives applicants eight months from the grant offer to complete the work and submit the required evidence.
Key conditions include:
•The premises must have been built and occupied on or before 31 December 2024. Grant support is limited to once per MPRN.
•The system must serve a site with electricity demand for self-consumption. NDMG is not for export-only generation.
•The applicant must use a company and installer registered for the SEAI non-domestic scheme. Electrical work must be completed by a Safe Electric-registered electrician.
•SEAI grant approval must be received before purchasing materials or starting work. An application is not the same as an approved grant offer.
•Other State funding can affect the amount because the 45% aid-intensity cap applies cumulatively. Battery and supplementary equipment are not eligible costs under the standard PV grant.
The usual application sequence is to choose a registered installer, agree the project scope, submit the grant application and wait for the offer. The installer then progresses the grid-connection application, completes the approved installation and provides the required completion records. Check the grant rules before work begins, and do not assume an older offer will receive the October 2026 uplift.
Self-consumption support or export tariff?
A business planning to use solar power on site may apply for the NDMG if it meets the eligibility requirements. A separate SRESS export-tariff route is intended for projects that export all electricity produced. The Department’s currently published SME solar rate for projects over 50kW and up to 1MW is €130/MWh, with 15-year support terms. The Department says the tariff review is under way and the published rates remain in effect until changed. An export-only project cannot combine that route with the self-consumer grant and is not eligible for the Clean Export Guarantee.
For self-consumer projects, surplus power may have value, but the applicable export price and connection conditions depend on the system classification, metering and supplier arrangements. Do not assume a household export rate applies to a 300kWp commercial project. Confirm the actual arrangement in writing before including export income in a forecast.
Savings, export payments and payback example
The following is an illustrative calculation, not a promise of savings. Assume a 300kWp DC array, an installed cost of €360,000 before grant, annual generation of 255,000kWh (850kWh per kWp), and on-site consumption of 75% of generation. Value self-consumed power at an assumed avoided import price of €0.20/kWh and exported electricity at an assumed €0.10/kWh.
On these assumptions, the business uses 191,250kWh on site, worth €38,250. It exports 63,750kWh, worth €6,375. Together, the estimated annual energy value is €44,625. If the project receives the full size-based NDMG value of €115,200, subject to eligibility and the invoice cap, the example net investment is €244,800. Dividing by the annual energy value gives a simple payback of about 5.5 years.
The model excludes finance costs, maintenance, inverter replacement, VAT, tax, standing charges, degradation, downtime and future changes in energy prices. It assumes the business can use 75% of generation at the stated import price and receive the assumed export value. Actual savings depend on the load profile and contract. SEAI advises calculating savings from electricity used on site rather than total solar generation.
Installation, grid connection and electrical safety
A commercial installation generally moves through site assessment, roof and structural survey, load analysis, system design, grant and planning checks, grid application, equipment procurement, installation, testing and commissioning. The installer should document the design, protection arrangements and responsibilities for network approval. At commissioning, monitoring should be configured so the business can compare real output with the forecast.
Planning permission is not required for every rooftop installation, but exemptions have conditions. Within a Solar Safeguarding Zone, rooftop solar is limited to 300m² per roof unless the business obtains planning permission for a larger proposal. Outside those zones, there is no equivalent roof-area limit, but roof-edge conditions and restrictions for protected structures or Architectural Conservation Areas may still apply. A 300kWp array will normally cover well over 300m² of panel surface, so check the site against the official map and ask the local planning authority before relying on an exemption.
The correct grid-connection process depends on the inverter’s AC capacity and the existing connection. ESB Networks’ small-scale generator route covers inverter-connected capacity above about 50kVA and up to 200kVA, subject to the site’s Maximum Import Capacity. Government guidance directs generators above 200kW to the Enduring Connection Policy process. A 300kWp panel array is not necessarily a 300kW AC generator, so the installer should confirm the route with ESB Networks before finalising the design.
ESB Networks currently reports an average of 8–10 weeks for a small-scale connection offer after the application fee is paid. Complex applications may take longer. This is only the connection-offer assessment, not the overall project timeline. A 300kW project can involve separate time for surveys, grant approval, planning confirmation, procurement, electrical work and any network upgrades. There is no single reliable installation duration for every site; allow for a multi-stage programme and start grid checks early. The grant offer is valid for eight months, so align installation scheduling with that deadline. Do not energise equipment until the connection conditions, protection and required testing are complete.
Electrical design and installation should be completed by appropriately qualified professionals. Depending on the project, the system may include grid-interface protection, isolators, surge and overcurrent protection, export limiting, upgraded distribution equipment and metering. ESB Networks’ connection offer determines the technical requirements for the connection.
Warranties, maintenance and long-term performance
Review module, inverter, mounting, workmanship and performance-guarantee terms separately. A product warranty covers specified faults; a performance warranty sets out a minimum output or degradation schedule over time. Neither by itself guarantees a certain reduction in electricity bills. Ask who handles a claim, how performance is measured and what exclusions apply.
Once the system is operational, monitor generation and respond to inverter alerts or unexplained output drops. Maintenance commonly includes periodic visual checks, inspection of cables and protection equipment, and keeping drains and access paths clear. Cleaning should be based on site conditions and installer advice. Businesses should also understand the expected service life and warranty arrangements for inverters, since their replacement cycle may differ from that of the modules.
LVP Renewables says it offers a commercial performance guarantee against its professional forecast. Ask for the guarantee’s written terms, measurement method, exclusions and remedy as part of the quotation.
Which properties suit large-scale commercial solar PV?
A large-scale commercial solar PV array of around 300kWp may suit factories, warehouses, industrial facilities, farms, hotels and other large business premises. The strongest candidates tend to have substantial unshaded roof space and consistent daytime electricity demand. Refrigeration, manufacturing equipment, pumps, ventilation and lighting can use solar power as it is generated. Sites with evening-heavy consumption or weekend closures should model expected exports before fixing the system size.
LVP Renewables states that its commercial PV systems range from 2kW to 400kW and that it designs systems for membrane, bitumen and metal roofs. Its website lists schools, creches, farms, offices and food outlets among its commercial experience areas. Suitability still depends on the individual roof, load profile and connection approval.
How LVP Renewables can help
LVP Renewables can help Irish businesses assess roof space, panel count, electricity bills and grid requirements before choosing a system. The company says an initial quote can be based on the previous year’s ESB bills, the Eircode and a short conversation. A tailored commercial assessment should confirm the array rating, inverter capacity, likely generation, self-consumption, grant route, planning position, connection requirements and project scope.
When comparing a 300kW solar panel system, check that each proposal clearly distinguishes panel-array kWp from inverter kW or kVA. Ask for the assumptions behind the 300kW solar panel count, usable roof area, output estimate, grant value and savings calculation. A detailed proposal helps facilities managers compare options and avoid relying on headline payback claims.
For a tailored commercial solar assessment and quotation, contact LVP Renewables through its website or visit its commercial PV page.
Frequently asked questions
How many solar panels are required for a 300kW solar system?
Approximately 750 panels at 400W, 667 at 450W, 600 at 500W or 546 at 550W. The 450W and 550W configurations round slightly above 300kWp. Confirm the exact array rating in the final design.
How much roof space is needed for a 300kW solar panel installation?
The sample module footprints are about 1,330–1,465m². Allowing for spacing and access gives a preliminary usable-roof estimate of roughly 1,700–2,050m². A measured layout and structural survey are needed to confirm the requirement.
How much electricity can a 300kW solar PV system generate annually in Ireland?
A first-pass estimate of 800–900kWh per kWp gives around 240,000–270,000kWh a year from a 300kWp array. Local modelling is needed because orientation, tilt, shading and system losses affect production.
How long does it take to install a 300kW commercial solar system?
There is no standard duration that applies to every project. The programme includes surveys, grant and planning checks, grid approval, equipment procurement, installation and commissioning. ESB Networks currently reports an average of 8–10 weeks for a small-scale connection offer after the application fee, but complex cases may take longer.
