Q: How does the 0% VAT work, and am I eligible?

Good news: Most residential battery + solar installations now qualify for 0% VAT (down from 20%), saving you £2,000-4,000! Eligibility (as of 2026): ✅ You qualify if: • Installing solar panels + battery together (or battery added to existing solar) • Property is residential (your home, not a business) • Installation includes "energy-saving materials" (solar + battery qualify) • Installed by a VAT-registered company ✅ What's covered at 0% VAT: • Solar panels and mounting • Battery storage system • Inverters (solar and battery) • Installation labour • Electrical wiring and connections • Bird protection mesh, scaffolding (if part of installation) ❌ Not covered (still 20% VAT): • Standalone battery (without solar) • Commercial properties • DIY installations (you can't reclaim VAT on self-install) • Decorative or non-energy-saving work How it works: 1. The installer quotes you the gross price (including 0% VAT) 2. No VAT added at checkout (compared to the old 20% rate) 3. The installer handles VAT returns with HMRC 4. You don't need to do anything Example savings: • Old system (20% VAT): £15,000 + £3,000 VAT = £18,000 total • New system (0% VAT): £15,000 + £0 VAT = £15,000 total • Savings: £3,000 immediate discount! Deadline: Currently no end date for 0% VAT, but this could change with future budgets. Lock in now if considering installation. How to claim: • Your MCS installer automatically applies 0% VAT • Check your quote says "0% VAT (Energy Saving Materials)" • If installer charges 20% VAT, ask them to apply the energy materials exemption

Q: What grants/financing are available?

Available grants and financing (2024-2025): 0% VAT on Installation ✅ • Automatic £2,000-4,000 saving • No application needed - installer applies it Smart Export Guarantee (SEG) ✅ • 5p/kWh for exported solar (some suppliers pay up to 15p/kWh) • Typical earnings: £100-300/year • Requirement: MCS-certified installation • Top paying suppliers: Octopus Energy (15p/kWh variable), E.ON Next, OVO ECO4 Scheme (Low-income households) ✅ • Grants: £5,000-15,000 for solar + insulation • Eligibility: Benefits recipients (Universal Credit, Pension Credit, Child Tax Credits, etc.) • Income cap: <£31,000/year household income • Apply: Through ECO4-approved installer Home Upgrade Grant (Off-gas properties) ✅ • Grants: Up to £10,000-15,000 for solar + battery + heat pump • Eligibility: Homes without gas heating (oil, electric, LPG) • Income cap: <£36,000/year • Apply: Local authority (council-run scheme) 0% Finance Options ⚠️ • Many installers offer 0% APR loans (12-60 months) • Example: £15,000 system = £250/month for 5 years (0% interest) • Check: No hidden fees or early repayment penalties Green Mortgages ✅ • Some lenders (Nationwide, Barclays) offer cashback (£500-2,000) for green home improvements • Lower mortgage rates for energy-efficient homes Where to check eligibility: • ECO4: https://www.gov.uk/improve-energy-efficiency • Home Upgrade Grant: Contact your local council • SEG: Ask installer to register your system with a SEG-licensed supplier Action plan: 1. Check if you qualify for ECO4 or Home Upgrade Grant (could get £5,000-15,000 free!) 2. If not eligible, compare 0% finance offers from installers 3. Factor in SEG export payments (£100-300/year reduces effective cost) 4. Get 3+ quotes from MCS installers to compare prices

Question 1

How accurate are the savings estimates ?

Accepted Answer

Our optimizer uses real-world data, including:
 • PVGIS satellite-measured solar irradiance for your specific postcode
 • Actual UK energy tariff rates (updated regularly)
 • Manufacturer-verified battery specifications
 • Conservative degradation models (0.5%/year for batteries, accounting for warranty terms)
 • 
Accuracy: Savings estimates are conservative and assume typical usage patterns. Actual savings depend on:
 • Your chosen energy tariff (time-of-use tariffs like Octopus Go significantly increase savings)
 • Usage patterns (shifting consumption to off-peak hours)
 • Weather variations (solar generation fluctuates with actual sunshine)
 • Battery charging/discharging behaviour

We provide two savings scenarios:
 • Conservative (without export): Guaranteed savings from self-consumption only
 • Optimal (with export): Includes Smart Export Guarantee (SEG) payments at 5p/kWh

Most users experience savings closer to the conservative estimate in their first year, improving as they optimize usage patterns.

Question 2

Why does the report recommend adding solar panels if I already have some ?

Accepted Answer

If the report suggests adding panels when you already have solar, this usually means:

1. Frontend didn't capture existing solar: Make sure you selected "Yes - [system size]" in the "Existing Solar" question, not "No solar panels"
2. Your existing system is undersized for your battery: A 10kWh battery typically needs 4-6kW of solar to charge fully. If you have a 2kW system, the optimizer may suggest adding 2-3kW more panels to maximise battery utilisation.
3. EV charging increases demand: If you have an EV, your annual usage increases by ~2,000 kWh/year. The optimiser may recommend increasing solar capacity to cover this additional load.

To prevent unnecessary recommendations:
 • Always fill in the "Existing Solar System" field accurately
 • Include system age (older systems are less efficient)
 • If you're happy with your current setup, choose "Balanced" or "Lowest Cost" scenarios, which minimise solar additions

Question 3

What's the difference between the 4 optimization scenarios ?

Accepted Answer

Each scenario optimizes for different priorities:
Scenario 1: Lowest Upfront Cost
 • Minimizes initial investment (typically £8,000-£12,000)
 • Chooses cheapest battery that meets minimum requirements
 • Minimal solar (just enough to be useful)
 • Best for: Budget-conscious buyers, renters, testing before full commitment
 • Payback: 8-12 years

Scenario 2: Most Environmentally Friendly
 • Maximizes carbon reduction (up to 4+ tonnes CO₂/year saved)
 • Larger solar array to reduce grid reliance
 • High-efficiency batteries
 • Best for: Eco-conscious buyers, those with green energy goals
 • Payback: 10-15 years (but highest carbon savings)

Scenario 4: Balanced Optimization (Most Popular)
 • Balances cost, savings, and carbon reduction
 • Typically 5-8kW solar + 10-15kWh battery
 • Best for: Most homeowners, families, typical usage
 • Payback: 7-10 years

Scenario 5: High Self-Consumption
 • Maximizes grid independence (60-80% self-sufficiency)
 • Large battery + optimal solar sizing
 • Best for: High energy users, those planning to go off-grid eventually
 • Payback: 9-13 years

Question 4

Do I need to change my energy tariff?

Accepted Answer

Short answer: Not required, but highly recommended for maximum savings.
 
Current tariff assumptions:
 • Standard variable: 24-28p/kWh      (flat rate, 24/7)
 • This is what most people have      by default
With a battery, switching to a time-of-use (TOU) tariff can DOUBLE your savings:

How it works:
1. Battery  charges overnight at 7p/kWh (Octopus Go)
2. Discharges during peak hours   instead of buying at 27p/kWh
3. Saves 20p per kWh stored =    £2-3/day extra savings

Question 5

What permits and approvals do I need?

Accepted Answer

Most systems require:
DNO (Distribution Network Operator)  Notification
 • G98: Solar under 3.68kW per phase (simple notification, installer handles)
 • G99: Solar over 3.68kW (requires approval, 2-4 weeks, installer handles)
 • Cost: Typically £50-200, included in installer quote

MCS Certification (Microgeneration Certification  Scheme)
 • Required for: Smart Export Guarantee (SEG) payments
 • Who needs it: Your installer must be MCS-certified,       not you
 • Why it matters: Without MCS, you can't claim SEG export payments (5p/kWh)

Planning Permission (rare, but check if):
 • You live in a conservation area
 • Your property is listed  (Grade I/II)
 • Panels exceed the roof line or face a main road
 • Check with local council  (most residential solar is "permitted development")

Building Regulations
 • Electrical work must comply with Part P
 • MCS installers automatically  meet this
 • You'll receive a Building Control certificate after installation

Who handles this: Your MCS installer manages all permits and notifications. Costs are usually included in the installation quote.
 
Timeline: Add 2-4 weeks for DNO G99 approval (G98 is faster).

Question 6

How long do batteries and solar panels last?

Accepted Answer

Solar Panels:
 • Lifespan: 25-30 years (some last      40+ years)
 • Warranty: Typically 25 years      product + 25-30 years performance warranty
 • Degradation: ~0.5%/year (after 25      years, still produces 85-90% of original output)
 • Maintenance: Minimal - rain usually      cleans panels; check for debris yearly

Batteries:
 • Lifespan: 10-15 years (varies by  chemistry and usage)
    • LiFePO4   (LFP): 12-15  years, 6,000-8,000 cycles (safest, longest-lasting)
    • NMC (Tesla,  most brands): 10-12  years, 3,000-5,000 cycles
 • Warranty: Typically 10 years or  70-80% capacity retention (whichever comes first)
 • Degradation: ~0.5-1%/year capacity loss
 • Replacement: Budget £3,000-6,000 for battery replacement at year 10-12

Inverters:
 • Lifespan: 10-12 years (most      likely component to fail first)
 • Warranty: 5-10 years manufacturer  warranty
 • Replacement Cost: £800-1,500  (budgeted in our 20-year analysis at year 12)

Our 20-year analysis includes:
 • Battery degradation (reduced capacity over time)
 • Inverter replacement at year  1 2
 • Panel efficiency decline
 • This gives you a realistic, conservative financial projection

Question 7

Can I install the system myself to save money?

Accepted Answer

Short answer: Legally possible, but not recommended for several critical reasons:
 
Why DIY is a bad idea:
You lose SEG export payments  (5p/kWh)
 • SEG requires MCS  certification
 • Only MCS-certified installers can provide this
 • Loss: ~£100-300/year over 20       years = £2,000-6,000 total
Safety risks
 • High-voltage DC (solar panels produce 300-600V)
 • Lithium battery fire risk if  improperly installed
 • Roof work hazards (falls,  structural damage)
 • Grid connection errors can damage home electrics or cause fires
No warranties
 • Manufacturer warranties require professional installation
 • Home insurance may be voided
 • No legal recourse if  something goes wrong
DNO rejection
 • G98/G99 applications require installer certification
 • DNO can refuse connection if not professionally installed
Building regulations
 • Part P electrical work must be certified
 • DIY requires separate Building Control approval (costs £300-500)
 • 
What you CAN do:
 • Get multiple quotes (3+ MCS installers) to compare prices
 • Negotiate on labour costs (installation is ~30% of the total cost)
 • Buy components yourself, hire an MCS installer for labour (some will do this)
 • Do prep work (clearing loft space, running cables to the meter) to reduce labour hours

Bottom line: Hiring an MCS installer costs £1,500-3,000 more than DIY, but you gain:
 • £2,000-6,000 in SEG payments  over 20 years
 • Full warranties and insurance  coverage
 • Safe, compliant installation
 • Legal grid connection

Question 8

What happens during a power cut?

Accepted Answer

Standard grid-tied systems: The battery does not work during power cuts

Why?
 • Anti-islanding  protection: UK law (G98/G99) requires systems to shut down during grid outages to protect utility workers repairing lines
 • If your solar/battery kept      running, it could electrocute engineers working on "dead" power      lines
Options for backup power:
Hybrid inverter with islanding  capability (£1,500-3,000 extra)
 • Detects grid failure and  automatically switches to "island mode"
 • Power essential circuits  (fridge, lights, heating) from the battery
 • Examples: SolarEdge Energy Hub,  GivEnergy AIO, Tesla Powerwall (has this built-in)
 • Limitation: Only powers circuits  wired to the backup panel (not the whole house)
Separate backup battery with UPS functionality
 • Dedicated battery for power  cut protection
 • Instant switchover (<20ms, doesn't even turn off computers)
 • Cost: £800-2,000 (5kWh backup battery)
Generator integration
 • Some hybrid inverters can work with generators
 • The diesel generator kicks in when the battery runs low
 • Cost: £500-2,000 (generator) + installation

What's included in standard systems:
 • ❌ No power cut protection by default
 • ✅ Battery charges from solar   and cheap overnight grid power
 • ✅ Discharges during expensive peak hours

Recommendation:
 • If you live in an area with frequent power cuts, Add islanding/backup capability
 • If power cuts are rare (most of UK): Standard system is fine, save £2,000-3,000

Question 9

How does the 0% VAT work, and am I eligible?

Accepted Answer

Good news: Most residential battery + solar installations now qualify for 0% VAT (down from 20%), saving you £2,000-4,000!
 
Eligibility (as of 2026):

✅ You qualify if:
 • Installing solar panels + battery together (or battery added to existing solar)
 • Property is residential (your  home, not a business)
 • Installation includes  "energy-saving materials" (solar + battery qualify)
 • Installed by a VAT-registered  company

✅ What's covered at 0% VAT:
 • Solar panels and mounting
 • Battery storage system
 • Inverters (solar and battery)
 • Installation labour
 • Electrical wiring and  connections
 • Bird protection mesh, scaffolding (if part of installation)

❌ Not covered (still 20% VAT):
 • Standalone battery (without      solar)
 • Commercial properties
 • DIY installations (you can't  reclaim VAT on self-install)
 • Decorative or  non-energy-saving work

How it works:
1. The installer quotes you the gross price (including 0% VAT)
2. No VAT added at checkout  (compared to the old 20% rate)
3. The installer handles VAT returns with HMRC
4. You don't need to do anything

Example savings:
 • Old system  (20% VAT): £15,000  + £3,000 VAT = £18,000 total
 • New system  (0% VAT): £15,000   + £0 VAT = £15,000 total
 • Savings: £3,000 immediate discount!
Deadline: Currently no end date for 0% VAT, but this could change with future budgets. Lock in now if considering installation.
 
How to claim:
 • Your MCS installer      automatically applies 0% VAT
 • Check your quote says      "0% VAT (Energy Saving Materials)"
 • If installer charges 20% VAT,      ask them to apply the energy materials exemption

Question 10

What grants/financing are available?

Accepted Answer

Available grants and financing (2024-2025):
0% VAT on Installation ✅
 • Automatic £2,000-4,000  saving
 • No application needed -  installer applies it

Smart Export Guarantee (SEG) ✅
 • 5p/kWh for exported solar (some suppliers pay up to 15p/kWh)
 • Typical earnings:  £100-300/year
 • Requirement: MCS-certified  installation
 • Top paying suppliers: Octopus Energy (15p/kWh variable), E.ON Next, OVO

ECO4 Scheme (Low-income households) ✅
 • Grants: £5,000-15,000 for solar + insulation
 • Eligibility: Benefits recipients  (Universal Credit, Pension Credit, Child Tax Credits, etc.)
 • Income cap: <£31,000/year household income
 • Apply: Through ECO4-approved  installer

Home Upgrade Grant (Off-gas properties) ✅
 • Grants: Up to £10,000-15,000  for solar + battery + heat pump
 • Eligibility: Homes without gas heating (oil, electric, LPG)
 • Income cap: <£36,000/year
 • Apply: Local authority  (council-run scheme)

0% Finance Options ⚠️
 • Many installers offer 0% APR  loans (12-60 months)
 • Example: £15,000 system =  £250/month for 5 years (0% interest)
 • Check: No hidden fees or  early repayment penalties

Green Mortgages ✅
 • Some lenders (Nationwide,  Barclays) offer cashback (£500-2,000) for green home improvements
 • Lower mortgage rates for  energy-efficient homes

Where to check eligibility:
 • ECO4:  https://www.gov.uk/improve-energy-efficiency
 • Home Upgrade Grant: Contact  your local council
 • SEG: Ask installer to register your system with a SEG-licensed supplier

Action plan:
1. Check  if you qualify for ECO4 or Home Upgrade Grant (could get £5,000-15,000   free!)
2. If not eligible, compare 0%  finance offers from installers
3. Factor in SEG export payments  (£100-300/year reduces effective cost)
4. Get 3+ quotes from MCS   installers to compare prices