Planning solar PV: roof, capacity and complete quotes
Photovoltaics generate electricity; solar thermal systems produce heat. Available space, building condition, demand and connection must work together. A good PV quote covers more than panel numbers: it specifies the necessary work and who will carry it out.
Complete system, expansion or installation only?
First clarify whether you need design and supply or already have equipment. An expansion must account for existing panels, the inverter and metering. A fitting-only quote is not comparable to a complete turnkey system.
Maintenance, repair and dismantling are separate tasks. For an operational system, electrical integration, necessary inspections and handover must also be clearly included or allocated.
Assess the site and building
Roof shape, orientation, shade and available area affect the panel layout. Pitched roofs, flat roofs and façades require different mounting approaches. Obstacles, existing equipment and maintenance access may reduce usable space.
A yield calculator does not replace site assessment. Have roof condition, fixing, load capacity and building-envelope interfaces checked professionally. Coordinate any planned roof work; customers should not be expected to certify that roofing material is harmless.
Separate capacity, generation and self-consumption
Panel rated capacity is usually expressed in kWp. Annual generation in kWh also depends on location, orientation and shading. Ask what assumptions underpin the yield forecast and whether it describes the complete proposed system.
Self-consumption is solar electricity used on site. Surplus may be exported to the grid. Annual generation is therefore different from power you can use at the same time. Usage times, heating, charging and optional storage influence the benefit.
Compare the fully installed price
Size and components are only part of the price. Access, scaffolding, cable routes, electrical changes and associated building work can significantly affect costs. A price per kWp is useful only when the included scope is comparable.
| Cost item | Specify what is included |
|---|---|
| Panels and inverter | Exact models, quantity, capacity and mounting |
| Roof and access | Fixing, scaffolding, protection and related work |
| Electrical work | Cables, connection, metering and modifications |
| Completion | Commissioning, inspections, records and tax |
Review options and warranties separately
Storage, EV charging and energy management may fit your needs but are not automatically required or included. A battery alone does not guarantee outage power. Ask for additional functions and associated wiring to be itemised.
| Comparison point | Decision basis |
|---|---|
| Yield forecast | Same area, orientation and shading assumptions |
| Storage option | Separate capacity, compatibility and added cost |
| Warranties | Distinguish equipment, output and installation work |
| Operation | Monitoring, support, upkeep and ongoing fees |
Plan checks and responsibilities
Depending on the property, notifications, permissions, grid connection and electrical inspections need coordination. Agree what the professionals handle and what coordination you provide. An enquiry does not require every specialist assessment to be completed already.
Funding, export payments and import prices affect the economics and may change. Calculations should state prices and assumptions. Funding is not automatically approved because it appears in an illustration.
From installation to a usable system
Panels on a roof do not mean the system is fully connected and inspected. Agree the path to commissioning and the necessary records, drawings and instructions. Electrical inspection responsibilities must be correctly assigned.
Ask how monitoring works and how to handle alerts. Identify contacts for faults and later work. Do not climb onto the roof or alter electrical equipment to obtain missing information for a quote.
Frequently asked questions
Is PV the same as solar thermal?
No. PV generates electricity; solar thermal supplies heat, for example for hot water. Design and connections differ.
Do I need to know the capacity already?
No. Known area or an idea of scale helps. The installer assesses the suitable layout and capacity for the property.
Can I have existing panels installed?
You can request installation-only work. State what you have; compatibility, missing parts, connection and warranty scope must be agreed.
Is a battery always necessary?
No. Storage is an additional option depending on usage and desired functions. Compare the system with and without storage separately.
Is scaffolding included in every quote?
Not automatically. Access and protective arrangements must fit the building. Check whether scaffolding and related work are included or charged separately.
How long does the project take?
Installation time differs from the overall timeline. Assessments, availability, connection and inspections affect timing. Ask for a project-specific schedule.
