What is my home's "Sleep" (vampire standby) bill and how is it calculated?

Your standby load is the continuous baseline electricity consumed while the household is asleep (filtered between 01:00 and 05:30). It captures always-on appliances like broadband routers, fridge/freezer compressors, ventilation units, and devices in standby mode. WattMatrix calculates the 20th percentile (P₂₀) of your overnight demand combined with Hampel outlier filtering, strictly removing EV charging and heating spikes, and computes what this continuous draw costs across an entire year.

Why does electricity used during the 5pm–7pm "Dinner Rush" cost significantly more?

Under Irish smart Time-of-Use tariffs, electricity consumed between 17:00 and 19:00 on weekdays is billed at a premium peak rate (often 36c–44c/kWh inc-VAT). Standard Day rates are typically 25c–34c/kWh. Running high-consumption wet appliances (washing machines, dryers, dishwashers) during these two hours incurs a direct peak surcharge penalty. Shifting those runs to overnight timer windows saves substantial amounts annually.

Should I install a solar hot water diverter (e.g. Eddi) or export excess solar to the grid for CEG?

It depends on your backup fuel. If your home heats water using kerosene or natural gas, thermal heat costs only 11c–14c/kWh. In contrast, Irish energy suppliers pay 18.5c–21c/kWh in guaranteed, tax-free cash under the Clean Export Guarantee (CEG) up to €400/yr (Section 216D TCA 1997). Diverting solar electricity to heat water instead of exporting it causes a net cash loss of 6c–9c per kWh. However, if your alternative is direct electric immersion (34c–42c/kWh), a diverter delivers strong savings and fast payback.

How long does a home battery take to pay for itself in Ireland?

Battery payback depends on your overnight-to-peak tariff price spread, your household evening consumption, net capital expenditure after the €600 SEAI grant, and realistic 2%/yr capacity degradation. Homes with high evening consumption (heat pumps, large families) can achieve payback in 6 to 9 years, whereas homes with low evening consumption or flat tariffs may see payback horizons exceeding 12 to 15 years.

Is my ESB smart meter file uploaded to a remote server or saved?

No. WattMatrix processes your ESB Networks HDF interval file 100% client-side in local browser memory. All MPRN identifiers, meter serial numbers, and raw timestamps are processed locally and discarded upon closing the tab. Zero telemetry or personal data is transmitted over the internet.

PLAIN-ENGLISH HOMEOWNER DECISION ENGINE

Household Energy Intelligence & What-If Simulator

Translates raw half-hour smart meter readings into plain-English financial decisions, vampire standby load disaggregation, and lifestyle scenario simulations.

100% Client-Side Privacy GuaranteedCRU & §216D TCA 1997 Statutory Compliant

Smart Meter Dataset & Active ProfileSample 1-Year Dataset Active

Upload your official ESB Networks HDF interval CSV, or explore with verified Irish household profiles.

Upload ESB CSV(s)

Active Electricity Plan:

Grid Profile:

County / Solar Irradiance:

Hot Water Backup Fuel:

WHAT-IF LIFE-EVENT SANDBOX

Simulate Life Changes On Your Meter Data

Inject synthetic high-draw appliances or work-from-home shifts in memory. Calculations update in real-time.

Add Electric VehicleDisabled

Annual Driving Distance:15,000 km/yr

10,000 km20,000 km30,000 km

Annual EV Energy:2,700 kWh/yr

Wallbox Power:7.2 kW (32A)

Boost Slot Capture:100% in Super-Off-Peak

Work From Home (WFH)Disabled

Remote Workdays / Week:2 days (Tue & Thu)

0d (Office)2d–3d (Hybrid)5d (Full Remote)

Continuous Daytime Load:250 W

150 W (Laptop)250 W (Monitors)600 W (+Heating)

Added Daytime Import:+208 kWh/yr

Solar Self-Absorbed:0 kWh/yr

Battery Sizing OverrideAuto-Sized

Test specific lithium iron phosphate (LFP) module sizes against your household's peak and evening demand:

Usable Sizing:7.5 kWh

Net CapEx (€600 Grant Deducted):€4,400

Degraded Payback:6.8 years

Current Plan Financial Ledger (Annualized Basis)

Bord Gáis Energy — Smart EV Drive

€1,485net ongoing annual cost (inc-VAT)

Metered Duration365 daysFull-Year Basis

Annual Import4,520 kWhAcross 48 slots

Standing Charge€240.00Urban DG1

9% Domestic VAT€122.60Statutory Irish VAT

Section 216D CEG-€0.00Untaxed Microgen

Year 1 Net Bill€1,485Excl. Cashback

CORE AREA 1

The "Sleep" Bill (Vampire Standby Load)

24/7 Idle Draw

Annual Idle Standby Cost:

€318/yr(21.4% of total electricity bill)

Always-On Baseload

120 W(1,051 kWh/yr)

Continuous 120 W Baseload Detected (Above 80 W Target)

Your home maintains a continuous standby draw of 120 W while everyone is sleeping. This uses 1,051 kWh annually, costing approximately €318 per year (21.4% of your total bill).

Night / Sleeping Idle:€98/yr (31%)

Daytime Idle Standby:€220/yr (69%)

Rule of thumb: Each 50 W cut permanently saves ~€132/year.01:00–05:30 Sleep Floor

CORE AREA 2

The "Dinner Rush" Peak Penalty (17:00–19:00)

Weekend Surcharge Waived

Annual Peak Timing Penalty:

+€74/yrextra peak surcharge

Dinner Rush Energy Share

(+1.9% vs national avg)

High Peak Concentration: 18.4% Consumed in 2h Window

Your evening dinner rush accounts for 18.4% of your daily electricity (vs. 16.5% national benchmark). Running power during peak adds +€74/year in premium surcharges.

Shiftable 250-Cycle Appliance Savings:

🍽️ Dishwasher (1.5 kWh)Save €68/yr

Shift from 18:00 to 23:00 Night or EV Boost

🧺 Washing Machine (2.2 kWh)Save €100/yr

Shift from 17:30 to off-peak / EV timer

Total appliance shift arbitrage: up to €168/year250 Cycles Basis

CORE AREA 3

Rooftop Solar & Cylinders "Spilled"

Export For CEG (Oil Home)

Annual Combined Solar Value:

€892/yrcombined bill offset + CEG cash

Surplus Hot Water Equivalent

78cylinders / yr

Arbitrage Verdict: Exporting Earns +€48/yr More Than Diverter

A 4.0 kWp array in Dublin generates 3,900 kWh/yr. You would self-consume 46% and export 54%—enough surplus energy to heat 78 domestic 150L hot water cylinders from 15°C to 60°C.

Self-Consumed Bill Offset:€562/yr

Exported CEG Credit:€330/yr

Diverter vs. CEG Arbitrage Verdict:Exporting Earns +€48/yr More

At €1.05/L kerosene, oil heating costs 12.1c/kWh. Exporting untaxed under Section 216D earns 19.5c/kWh. Selling surplus to the grid yields 7.4c/kWh more than diverting into hot water!

150L cylinder sensible heat: 7.845 kWhSEAI Grant: €1,800

CORE AREA 4

Home Battery Storage Payback Horizon

Strong / Viable (< 7 yrs)

Year 1 Arbitrage Savings:

€650/yrannual peak-shaving benefit

Degraded Payback Horizon

6.8 yrsamortization

Recommended: 7.5 kWh Usable Capacity (6.8-Year Amortization)

Pre-charging a 7.5 kWh battery at 8.7c/kWh overnight to displace 45.8c/kWh peak and 32.7c/kWh shoulder demand saves €1.78/day (€650 in Year 1). After the €600 SEAI grant, net cost is €4,400 with a 6.8-year degraded payback.

Peak Arbitrage Spread:+36.1c/kWh (RTE 88%)

10-Yr Cashflow (2%/yr Fade):€5,915 saved

Net CapEx: €4,400SEAI €600 Grant Included

FIRST-PRINCIPLES CONSUMER FINANCIAL ENGINES

Statutory Capital Optimization & Market Risk Audits

Mathematical models for optimal solar sizing, CRU dynamic wholesale volatility, Section 216D €400 tax cliff, and 10-year degraded battery amortization.

CRU • SEMOpx • Revenue Part 07-01-44

Rooftop Solar Sweet-Spot Sizing (2.0–6.0 kWp)

4.0 kWp (9 panels)

Net Outlay (0% VAT):€5,200

Fastest Payback:5.4 yrs

Self-Consumption:64%

10-Yr Net Profit:+€3,480

Based on your daytime usage, a 4.0 kWp system offers the fastest payback knee.

⚠️ Diminishing Returns Above 4.0 kWp:The SEAI grant maxes out at €1,800 at 4.0 kWp (€0 marginal grant above 4 kWp).

SEAI €1,800 Grant • 0% VAT Supply-and-InstallJensen-Corrected

CRU Dynamic Wholesale Tariff Risk (SEMOpx)

LOW RISK

Expected Delta vs TOU:Save €65/yr

17:00–19:00 Peak Share:3.1%

SEMOpx Capture Factor:0.74

Worst-Case Winter Delta:+€22/yr

Low risk: Your usage concentrates in cheap overnight hours, insulating you from calm-winter peak spikes.

🛡️ CRU Retail Safeguard:Wholesale pass-through capped at 50c/kWh ex-VAT. All-in scarcity spikes bounded at ~75.8c/kWh incl. VAT.

Single Electricity Market Operator (SEMOpx)1-in-20 Cold Winter Stress Test

Section 216D TCA 1997 €400 Microgen Tax Cliff

Tax-Free Exemption Active

Gross Export Cash:€495/yr

Tax-Free Allowance:€400/yr

Case IV Tax Due (52.2%):€50/yr

Net Post-Tax Yield:€445/yr

Export earnings above €400 trigger Schedule D Case IV income tax, USC, and PRSI.

💡 Revenue Compliance Tip:Put two names on your electricity bill to double your tax-free allowance to €800/year (Revenue Part 07-01-44).

Schedule D Case IV • Form 12 / Form 11 ExemptionTCA 1997 §216D

True 8–10 Year LFP Battery Amortization

Unviable (> 10.0 yrs)

Net CapEx (0% VAT):€2,800

Year 1 Savings:€125/yr

8-Yr Return (2% Fade):€933

10-Yr Deficit / Gain:-€1,657

Factoring in 88% RTE and 2%/yr cell fade, low evening demand extends payback beyond the 10-year warranty.

⚡ Export Cannibalization Paradox:Charging overnight at ~8.7c while exporting daytime solar at 19.5c earns 3x more than storing solar at 88% efficiency!

88% RTE • 2%/yr Linear Cell DegradationWarrantied Life Model

DECISION LEDGER

Optimal Smart Tariff Comparison (Simulated With Your Data)

Ranked strictly by lowest ongoing net annual bill