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Don't Guess. Engineer Your Energy Future
Independent electrical design, specification, and consultancy for self-builders. We create the roadmap; our approved partners build it.
Solar PV
MVHR
EV Charger
Heat Pump
Battery
Grid
Real-Time Energy Orchestration
This is not a static diagram. It shows the live control logic we design into every home on an Octopus Agile tariff. Solar charges the battery when prices are low. The heat pump runs when electricity is cheapest. The EV tops up from surplus solar. Every flow is logged, every decision is auditable. We call this Active Engineering — not passive monitoring. All systems are commissioned to Flexitest Ltd standards.
The Design-First Model
Independent consultancy, not sales. Technical rigour, not guesswork.
The Design Pack
We conduct heat loss calculations, solar modelling, airflow rates and electrical specification to create a 'Construction-Ready' technical pack. Fixed fee. No upselling.
The Tender
We hand your detailed specification to our MCS-Certified Partner Network for a guaranteed fixed-price quote. You approve before any work starts.
The Build
Installation is carried out by MCS & Part P - certified specialists, with oversight from your design consultant. No variations. No surprises.
Design Services
Transparent Engineering. Fixed Fees. 0% Commission on Hardware.
Independent consultancy you can trust
Feasibility Study
Desktop review & budget estimation
- Desktop review from plans
- Technology suitability (ASHP, PV, Battery)
- Compliance feasibility (Part L & Future Homes)
- 30-min video consultation with David Richards
Technical Design Pack
Complete specification for contractor tendering
- Room-by-room heat loss calculations
- PV array design & shading analysis
- Single-line electrical schematic (3-Phase optimised)
- DNO G99 application support
- Part L compliance documentation
Project Oversight
Site visits & performance validation
- On-site commissioning witness
- System performance validation testing
- Contractor technical queries & liaison
- Full client handover training & documentation
Installation by our MCS-Certified Partner Network, including KeySpark Electrical (NAPIT, MCS, ECS & TrustMark Certified)
View All Packages & PricingTechnical Capabilities
What's included in our design specifications
Every design pack covers the six systems below. We calculate exactly what your home needs — no guesswork, no oversizing. Solar and heat pump sizes are based on your actual floor plan and Part L targets. EV chargers, MVHR units, and smart controls are all specified to work together, not in isolation. SAP is the government energy rating your building control officer requires — we produce it as part of every full design.
Solar & Storage Design
We size your solar array and battery to meet the 2026 Part L rules. We handle the DNO application (the grid connection approval) and design the system for maximum export income.
Heat Pump Electrical Spec
We design the electrical supply for your heat pump (ASHP or GSHP). That includes cable sizing, circuit protection, and control wiring — all calculated to your actual heat loss figures.
EV Charging Infrastructure
We specify a charger that shares your available supply fairly across all loads. When solar is generating, the charger uses surplus power first — saving you money automatically.
MVHR & Ventilation
MVHR (Mechanical Ventilation with Heat Recovery) keeps air fresh without losing heat. We size the unit, specify the ductwork, and wire it into your smart home controls.
Smart Home Automation
We design Loxone and KNX systems that control heating, lighting, and energy use in one place. The system learns your patterns and cuts waste without any manual input.
SAP & Part L Compliance
SAP is the government's energy rating tool for new homes. We run the full calculation, produce the compliance report, and give you the evidence your Building Control officer needs.
Is Your Self-Build Ready for 2026?
Warm Homes Plan Compliance Verification
Mandatory Solar PV Installation
Minimum 1.5kWp per bedroom required for new builds from April 2026
Zero Carbon Heating System
Gas boiler ban in effect. Heat pump or equivalent low-carbon solution required
Smart Export Guarantee Registration
Export tariff integration for grid balancing and revenue generation
EV Ready Infrastructure
32A circuit provision for future EV charging capability
Building Regulations Part L Compliance
SAP calculation demonstrating target emission rate achievement
0% VAT Available
Eligible energy-saving installations qualify for zero-rated VAT
Trusted by Homeowners and Developers Across the UK
Over 2,000 completed projects. Independent advice. No commission. Every recommendation backed by engineering calculations.
2,000+
Completed projects
15+
Years engineering experience
14
Building Control partnerships
0%
Commission on hardware
"David produced a complete Technical Design Pack for our 4-bed new build in under two weeks. The SAP calculation passed Building Control first time. Excellent service."
James T.
New build, Gloucestershire
"We needed a DNO application and solar sizing for our self-build. David handled everything — the application was approved without any queries. Highly recommended."
Sarah & Mark W.
Self-build, Worcestershire
"Integravolt specified our heat pump, EV charger, and MVHR as one integrated system. Everything was installed without any revisions to the design. That rarely happens."
Phil B.
Eco retrofit, Bristol
Accreditations & Certifications
The Self-Builder's Guide to the £15bn Warm Homes Plan
Independent analysis of the 2026 requirements. How to secure 0% VAT and avoid the £10,000 cost of mis-specification. We calculate loads precisely so you don't overpay for oversized hardware. Technical guide with heat loss methodology, schematic examples, and compliance checklists.
Instant PDF delivery. No spam. Technical content only.
About Integravolt
Integravolt is the energy consultancy division of Flexitest Ltd (Company No. 07344798). We were founded by David Richards, a chartered electrical engineer with over 15 years' experience. We provide independent, fixed-fee energy design for self-builders and renovators across England and Wales.
We do not install anything and we do not earn commission on hardware. Every recommendation is based on technical merit alone. Our work follows BS 7671 (wiring regulations), BS EN 12831 (heat loss), SAP 10.2 (the government's energy rating tool), and Approved Document Part L (building energy compliance).
If you are building a new home, you can pay 0% VAT on qualifying energy technologies. This applies to solar panels, battery storage, heat pumps, EV chargers, and MVHR units. On a typical £50,000–£100,000 energy package, that saving is £10,000–£20,000. We produce the engineering documents your accountant needs to claim it.
From April 2026, new homes must install roughly 1.5 kWp of solar per bedroom to pass the Part L energy check. A four-bedroom home typically needs at least 6 kWp. If your roof faces east or west, you may need more. We calculate your exact figure based on your floor plan, heating system, and roof orientation.
About David Richards
Chartered Electrical Engineer · Founder, Integravolt / Flexitest Ltd
David Richards is a chartered electrical engineer with over 15 years' experience in energy strategy and electrical design. Through Flexitest Ltd, he has completed SAP calculations, DNO applications, and full energy design packs for residential and commercial projects across the UK — including new builds, deep retrofits, and off-grid developments.
David holds accreditations including NICEIC registration and MCS certification. Flexitest Ltd has Building Control partnerships with 14 UK local authorities and has delivered over 2,000 electrical safety inspections, solar PV commissioning tests, and ventilation certifications since 2010.