Smart Home Battery Storage Integration: SolarEdge, GivEnergy and Tesla Powerwall — App Control and Tariff Shifting

Summary

Battery storage installation has moved from a niche solar add-on to a mainstream electrical trade in under five years. With domestic electricity prices regularly hitting 30–35p/kWh at peak and cheap-rate tariffs (Octopus Go, Agile) available at 7–12p/kWh, a 10 kWh battery with tariff shifting can deliver payback in 7–10 years even without solar. When combined with solar PV, payback tightens to 5–8 years for most UK properties.

For smart home integrators, battery storage creates both an opportunity and a technical challenge. The opportunity is that all three major battery platforms — GivEnergy, SolarEdge, and Tesla Powerwall — expose APIs and smart home integrations that allow the battery to be controlled alongside heating, EV charging, and other loads as part of a whole-home energy strategy. The challenge is that the DNO registration process, G98/G99 compliance, and the electrical installation itself require a qualified installer registered with a Competent Person Scheme (typically NAPIT or NICEIC Solar and Battery Storage registration).

This article covers the smart integration layer — app control, API access, tariff-shifting configuration, and interoperability with home automation platforms — alongside the installation compliance requirements.

Key Facts

• G98 notification — required for inverters up to 3.68 kW (16 A per phase); notify DNO within 28 days of connection; no prior approval needed
• G99 application — required for inverters over 3.68 kW; prior DNO approval required before energising; process can take 11 weeks for larger systems
• Export limitation — many DNOs impose a 3.68 kW export limit per phase even on larger systems; compliance is verified by the DNO during G99 assessment
• Smart Export Guarantee (SEG) — licensed export tariff available to any system with an MCS-certified inverter and smart (half-hourly) export meter; rates currently 3–20p/kWh depending on tariff
• GivEnergy — UK-designed hybrid inverter system; 2.6 kWh to 19.2 kWh modular battery; local API via local modbus and GivTCP docker container; integrates natively with Home Assistant
• SolarEdge StorEdge — DC-coupled with SolarEdge HD-Wave inverter; monitoring via SolarEdge cloud API (OAuth2); no local-only API without third-party tools; battery 10 kWh DC units
• Tesla Powerwall — AC-coupled; integrates with any inverter; monitoring via Tesla app; local API available via undocumented Gateway access; supports VPP (Virtual Power Plant) programmes
• Powerwall VPP — Tesla operates VPP programmes where enrolled Powerwall owners receive bill credits in exchange for allowing Tesla to dispatch their battery during grid stress events; currently available via select UK energy suppliers
• Tariff shifting schedules — all three platforms allow charge/discharge schedules aligned to cheap-rate grid windows; GivEnergy and Powerwall support dynamic tariff integration via Octopus API
• Octopus Intelligent integration — Octopus Agile and Intelligent Octopus tariffs publish half-hourly prices via API; GivTCP and Tesla can pull these prices and auto-schedule accordingly
• CT clamp positioning — whole-home consumption monitoring requires a clip-on CT clamp on the import/export tails; position and calibration is critical for accurate self-consumption calculations
• Backup power — Powerwall and some GivEnergy units support whole-home backup (islanding) on loss of grid; requires ATS (automatic transfer switch) and compliant islanding protection per G98/G99
• Battery degradation — lithium iron phosphate (LFP) cells used in GivEnergy and Powerwall retain 70–80% capacity after 3,000–4,000 cycles; roughly 8–12 years daily cycling

Quick Reference Table

Detailed Guidance

DNO Registration and Pre-Installation Compliance

Before any battery storage system is energised, the installer must confirm the registration pathway. This is not optional — energising a battery system without G98 notification or prior G99 approval is a breach of the Distribution Connection and Use of System Agreement (DCUSA) and potentially an Electrical Safety Standards in the Private Rented Sector obligation.

G98 pathway (≤3.68 kW per phase):

1. Install the system
2. Submit G98 notification to DNO within 28 days of commissioning
3. DNO confirms registration; system may operate immediately

G99 pathway (>3.68 kW per phase, or systems exceeding other thresholds):

1. Submit G99 application to DNO before installation (forms available from each DNO's website)
2. DNO assessment — up to 11 weeks for complex applications
3. DNO issues conditional approval (possibly with export limitation)
4. Install and commission per approved specification
5. Submit commissioning notification to DNO

For residential solar plus storage systems where the solar inverter was already G98-registered, adding a battery may trigger G99 if the combined inverter rating exceeds 3.68 kW. Check the existing DNO registration before specifying battery capacity.

MCS certification: Battery storage systems installed alongside solar PV and claiming Smart Export Guarantee must use MCS-certified components. MCS certification is held by the manufacturer; the installer must be MCS-registered (or sub-contract to an MCS-registered installer) for the certificate to be valid.

GivEnergy Integration and App Control

GivEnergy is built around a modular battery stack connected to a hybrid inverter (the Gen 3 All-in-One integrates inverter and battery in a single unit). The GivEnergy cloud portal provides real-time monitoring, charging/discharging scheduling, and tariff-shifting configuration.

Local API (GivTCP):

GivEnergy inverters expose a modbus TCP interface on the local network. The GivTCP open-source project (available on GitHub) runs as a Docker container or Home Assistant add-on, polling the inverter every 20 seconds and publishing data to MQTT. This enables full local control without cloud dependency.

Home Assistant integration via GivTCP provides:

• Real-world grid import/export power (W)
• Battery state of charge (%)
• Solar generation (W)
• Inverter charge/discharge rate control
• Schedule management (charge window 1 and 2, discharge window)
• Force charge/discharge commands

Tariff-shifting with Octopus:

GivEnergy inverters support Intelligent Octopus (scheduled EV charging) integration via their cloud portal. For more advanced tariff shifting — particularly on Agile Octopus with half-hourly variable rates — GivTCP combined with a Home Assistant automation can:

1. Pull the next day's Agile prices from the Octopus API each evening
2. Calculate the cheapest six-hour window overnight
3. Programme the inverter charge schedule to match

This requires Home Assistant, GivTCP, and the Octopus Energy Home Assistant integration (available via HACS).

Tesla Powerwall Integration

Powerwall 3 (released 2024) integrates the solar inverter with the battery in a single unit, replacing the separate Gateway previously required. The Tesla app provides real-time monitoring, storm watch mode (fills battery to 100% before forecast storms), backup reserve settings, and Time-Based Control for tariff shifting.

Local Gateway API:

Tesla Powerwall exposes a local REST API via the Gateway device (or the built-in gateway in Powerwall 3) on the local network at https://[gateway-ip]/api/. This API is undocumented but stable; it provides real-time power flow data and allows mode changes. Home Assistant's Powerwall integration uses this local API.

Time-Based Control:

Powerwall's Time-Based Control mode allows custom charge/discharge schedules aligned to peak and off-peak tariff periods. The Tesla app supports manual schedule configuration, but for dynamic tariff integration (Agile Octopus), a third-party automation layer is needed. The Tesla Fleet API (released 2023 for commercial developers) provides a documented OAuth2 endpoint for energy products.

VPP enrolment:

Tesla's Virtual Power Plant programme in the UK is operated in partnership with Octopus Energy. Enrolled Powerwall owners receive a one-off payment and bill credits in exchange for allowing Tesla to discharge their battery during grid frequency response events. Enrolment is via the Tesla app; no additional hardware is required. The system retains the owner-configured backup reserve and only dispatches above that level.

SolarEdge StorEdge Integration

SolarEdge StorEdge uses a DC-coupled architecture — the battery connects to the DC bus of the SolarEdge HD-Wave inverter, which manages charge/discharge via the inverter's StorEdge interface card. This architecture is efficient (no DC-AC-DC conversion losses) but limits battery expansion to SolarEdge-compatible units.

mySolarEdge App and Cloud API:

SolarEdge provides a monitoring portal and mobile app with real-time generation, consumption, and battery data. A cloud REST API is available for third-party integrations (OAuth2 authentication required, rate-limited). Home Assistant integration uses this cloud API, meaning local control is not available without third-party reverse-engineering tools — a notable limitation compared to GivEnergy.

StorEdge Charge/Discharge Scheduling:

StorEdge charge scheduling is configured via the SolarEdge Monitoring Portal (not the app). The portal allows setting a storage profile:

• Maximize Self Consumption — default mode; charges from solar first, supplements from grid if needed
• Time of Use (TOU) — charge from grid during defined cheap-rate windows; discharge during expensive peaks
• Backup Only — holds battery at configured reserve; does not participate in normal tariff shifting

TOU mode requires manual configuration of cheap-rate windows; SolarEdge does not dynamically integrate with Octopus API pricing. For dynamic tariff optimisation, a third-party controller (e.g. Solar Assistant running on a Raspberry Pi with Modbus) is required.

Whole-Home Energy Management

The most sophisticated installations combine battery storage with EV charging, heat pump control, and smart metering into a whole-home energy management system. The commercial platforms (Loxone Energy, Salia, Mixergy) provide integrated management, but for Home Assistant-based systems the following architecture is common:

1. GivEnergy (battery) → GivTCP → MQTT → Home Assistant
2. Ohme or Hypervolt EVSE → OCPP or cloud API → Home Assistant
3. Mitsubishi Ecodan or Vaillant Arotherm (heat pump) → MELCloud or sensoCONNECT → Home Assistant
4. Octopus Energy → Octopus Energy HA integration (HACS) → Home Assistant
5. Home Assistant Energy Dashboard — aggregates all data; automation rules optimise charge/discharge/EV charging against tariff prices

This architecture allows a single automation to decide in real time whether cheap grid electricity should charge the battery, charge the car, run the hot water cylinder, or some combination — a materially better outcome than each device operating independently.

Frequently Asked Questions

Do I need to be MCS-registered to install battery storage without solar?

For standalone battery storage (no solar), MCS certification is not required. The installation must still comply with BS 7671, G98/G99 requirements, and Building Regulations Part P, but MCS certification only applies to installations claiming the Smart Export Guarantee. If the client wants SEG eligibility in the future (i.e. they may add solar), use MCS-certified battery hardware from the outset.

What export tariff is available for a battery without solar?

Battery-only systems cannot claim Smart Export Guarantee — SEG is only for installations that generate electricity. However, some Virtual Power Plant programmes (Tesla VPP, Octopus Powerloop) pay for battery dispatch without requiring solar. Octopus Powerloop is specifically designed for battery-only homes.

The client has Economy 7 — can they still do tariff shifting?

Yes. Economy 7 provides 7 hours of cheap rate overnight (typically midnight–7 AM, but time-of-use varies by meter and region). Configure the battery charge window to match the Economy 7 cheap period. Economy 7 rates are currently around 13–17p/kWh cheap, 25–35p/kWh peak — a smaller differential than Octopus Agile, so payback on tariff shifting alone is longer. Switching to Octopus Agile or Intelligent Octopus (if eligible) will improve tariff shifting economics significantly.

How does backup power work during a grid outage?

Whole-home backup (islanding) requires the battery system to form its own micro-grid — an inverter mode that is separate from normal grid-tied operation. Powerwall 3 supports whole-home backup natively; GivEnergy supports it on specific models with ATS (automatic transfer switch) fitted. When grid power fails, the battery disconnects from the grid, forms an island, and powers selected circuits (or the whole home depending on installation scope). The G98/G99 approval must include islanding mode; DNOs require proof that the anti-islanding protection disconnects within 0.5 seconds of grid loss per BS EN 62116.

Can the smart home turn off the battery if it's below 20% to protect battery life?

All three platforms support configurable backup reserve — a minimum state of charge below which the battery will not discharge. GivEnergy allows this in GivTCP as a numerical parameter; Powerwall has a "backup reserve" slider in the app; SolarEdge allows minimum reserve in the StorEdge settings. Set this at 10–20% to preserve cycle life and retain emergency backup capacity.

Regulations & Standards

• G98 (Engineering Recommendation G98) — Engineering Recommendation for connection of generating plant to the 230 V low voltage distribution network; covers systems up to 3.68 kW per phase

• G99 (Engineering Recommendation G99) — connection of generating plant over 3.68 kW; requires prior DNO application and approval

• BS 7671:2018+A2:2022 (IET Wiring Regulations 18th Edition) — all domestic electrical installation work including battery inverter circuits

• BS EN 62116 — utility interconnection safety requirements for grid-connected inverters; anti-islanding test procedure

• MCS 012 — MCS standard for battery storage systems installed alongside solar PV

• Building Regulations Part P — notifiable electrical work; all 230 V aspects of battery storage installation

• Smart Export Guarantee (SEG) Order 2020 — statutory instrument establishing the SEG; requires MCS certification and smart export meter

• UK GDPR / DPA 2018 — applies to any VPP programme data sharing with third parties (e.g. Tesla/Octopus VPP enrolment)

• Ofgem Smart Export Guarantee Guidance — eligibility and licensing requirements for SEG

• Engineering Recommendation G98 Issue 1 Amendment 6 — Energy Networks Association G98 specification

• GivTCP GitHub Repository — open-source GivEnergy modbus integration for Home Assistant

• Tesla Powerwall Fleet API Documentation — documented Tesla API for energy products (commercial access)

• MCS 012 Battery Storage Standard — MCS standard for certified battery storage installations

• [G99 registration](/wiki/solar-pv/solar-pv-installation-overview|solar PV installation and G98/G99 registration)

• [ev charger installation guide|EV charger installation and smart charging integration](/wiki/ev-charging/ev-charger-installation-guide|EV charger installation and smart charging integration)

• [smart heating controls|smart heating controls and heat pump integration](/wiki/smart-home/smart-heating-controls|smart heating controls and heat pump integration)

• [home networking for av|home networking infrastructure for smart home systems](/wiki/smart-home/home-networking-for-av|home networking infrastructure for smart home systems)