Comprehensive Design Services

Specialising in solar and renewable energy systems. From 3kW domestic installations to 1MW+ commercial projects. BS7671:2018 compliant designs with 24–96 hour turnaround.

Full-scope electrical design services.

Every deliverable is BS7671:2018 compliant, installation-ready, and produced by a designer with 20 years of hands-on industry experience.

☀️ PV Single-Line Diagrams

POC and PV SLDs in Armtech format. Clear, installation-ready drawings.

📐 Cable Sizing Calculations

Full BS7671 cable sizing with voltage drop analysis and correction factors.

📋 G100 Compliance Reports

G100 methodology reports for DNO applications and grid connection approval.

🔌 Coordination Reports

Coordination reports with CPD settings for protective device operation.

📊 DB/SB Arrangements

Distribution board and switchboard schedules with custom panel designs.

⚡ Earthing Diagrams

Earthing system design and safe isolation procedure documentation.

📝 Bill of Materials

Complete BOM with specified components, quantities, and references.

🔒 Shutdown Documentation

Shutdown and re-energisation documentation for safe working practices.

📑 Technical Reviews

Independent feasibility studies and compliance verification service.

Stop paying for empty chairs.

A full-time electrical designer costs far more than their salary. With ZESTEC, you only pay for designs you actually need.

Full-Time Designer
£74,300+
per year (true cost)
  • £50,000 base salary
  • £6,900 employer NI (13.8%)
  • £1,500 pension (3% minimum)
  • £5,400 holiday cover (28 days)
  • £2,000+ sick leave costs
  • £1,500+ training & development
  • £2,000+ equipment & software
  • £5,000+ recruitment costs
  • Still paying during quiet periods
VS
ZESTEC On-Demand
From £500
per month / or pay per project
  • Scale up for large projects instantly
  • Scale down during quiet periods — pay nothing
  • No recruitment delays or agency fees
  • Expert designer from day one
  • BS7671:2018 compliant designs guaranteed
  • No holiday pay, sick leave, or pension
  • No equipment or software costs
  • Cancel anytime — 30 days' notice
  • Transform fixed costs into variable savings

Flexible retainers for regular design support.

No long-term commitment. Hours scale with your workload. Cancel with 30 days' notice.

Starter

Light Support

£500/mo
Ideal for 2–4 domestic designs per month
  • Dedicated design hours each month
  • Priority turnaround (24–48 hours)
  • Direct access to your designer
  • Unused hours roll over (1 month)
  • Cancel with 30 days' notice
Request This Package →
Scale

Full Partnership

Custom
For high-volume or complex requirements
  • Custom hours tailored to your volume
  • Fastest turnaround available
  • Dedicated designer relationship
  • White-label delivery available
  • Volume pricing discounts
  • Monthly performance review
  • Flexible contract terms
Discuss Your Needs →

All prices exclude VAT. Terms and conditions apply.

Common questions about our packages.

What's included in the retainer hours?

All design work: SLDs, cable calculations, G100 reports, DB schedules, and any other design deliverables. Briefing calls, revisions, and basic queries don't count against your hours.

What if I need more hours in a busy month?

Additional hours beyond your retainer are available at a slightly higher rate. Growth and Scale tier clients receive a discounted overflow rate.

Do unused hours roll over?

Yes, unused hours roll over for one month. They don't roll further than that.

Can I cancel at any time?

Yes. All retainers can be cancelled with 30 days' written notice. No exit fees or penalties.

Do I have to use a retainer, or can I pay per project?

Both options are available. Retainers make sense when you need regular design support and want priority turnaround and better rates.

Ready to optimise your design costs?

Book a free call to discuss which option suits your workload, or send us a brief for your next project.