What Size Solar System Do You Need for a 3‑Bed Irish Home?

For most 3‑bedroom homes in Ireland, a 4–4.5 kWp solar PV system (about 10–12 panels) is ideal. Balancing roof space, household energy needs, SEAI grants, and optimal ROI.

This guide explores the specifics of sizing a solar system for 3-bed Irish homes, explaining why We often recommend 4–4.5 kWp and how it stacks up in Dublin, Cork, and beyond.

1. Quick Sizing Rule Yourself

Start by understanding your annual electricity use:

• Typical 3-bed homes consume 4,000–4,500 kWh/year
• A rule of thumb: 1 kWp ≈ 1,000 kWh output/year in Ireland

So, a 4.5 kWp system suits homes with ~4,500 kWh/year usage, making 10–12 panels a sweet spot for most Irish semi-detached homes.

2. Real‑World Examples in Cork & Dublin

For a 4.4 kWp system (approx. 10 panels, ~21 m²):

• Annual output ≈ 3,894 kWh 
• For a 4.5 kWp setup (10–11 high‑watt panels):
• Output ≈ 4,060 kWh/year

These systems match or slightly exceed a typical 3-bed home’s usage, significantly reducing reliance on grid electricity and with SEAI grants, that’s powerful savings.

3. Roof Space & Orientation

• 10 panels (≈ 435 W each) need 20–22 m²
• Ideal placement: south-facing, 30–40° pitch
• East/west-facing roofs may see ~5–20% less output

WattCharger conducts remote and on-site roof evaluations to confirm your layout, shade, pitch, and orientation before any installation.

4. Cost, Grants & Payback

• Typical costs for a 4–4.5 kWp installed system:
• Before SEAI grant: €7,000–€8,500
• After grants (~€1,800–€2,100): €5,000–€6,500 
• Annual generation: 3,900–4,100 kWh
• At current rates (~€0.34/kWh), that’s €1,300+ annual savings 
• Payback period: 4–6 years, often quicker with export returns or solar batteries
  
  

5. Thinking Ahead: Batteries & EVs

If you’re considering an EV or solar battery down the line:

• Bigger systems (4.5 kWp and modular) give you headroom
• Battery-ready inverters help future-proof your install
• Home EV charging can significantly boost self-consumption, leveraging that extra solar energy
  
  

6. Why Choose WhattCharger

Our process ensures you get:

• Accurate sizing based on real usage and future needs
• Professional SEAI grant support for smooth approval
• Premium equipment & installation with industry-leading warranties
• Scalable system design, ready for storage or EV adds

Final Takeaway

For most 3-bedroom homes in Ireland, 4–4.5 kWp solar systems (10–12 panels) offer the best balance of performance, cost, and future flexibility.

Want to go deeper into sizing analytics or compare systems? Check our full guide: How Much Solar Power Do You Really Need in Ireland. Contact us today using the form below for a free, personalised quote.