Larger Surrey and SW London properties with multi-phase supplies, export limitation conditions or a grid-trading tariff such as Octopus Flux need solar, battery and grid integration handled as one connected system rather than three separate installs. If your site already needs, or is likely to need, a formal DNO application, this is the relevant page; the starting point is a feasibility enquiry to establish your available connection capacity. A well-integrated solar, battery and grid system does more than reduce energy bills - it manages the relationship between generation, storage and the grid intelligently. The hybrid inverter platform buys electricity from the grid during cheap off-peak periods, prioritises self-consumed solar during the day, and can export stored energy during higher-rate windows. G98 or G99 notifications are managed as part of the installation, and export limitation can be configured where the DNO requires it. The financial return from this type of system depends on battery capacity, solar array size, household consumption and the specific tariff structure in use. Battery performance depends on system design, tariff structure, usage profile and electrical infrastructure - we model these before specifying equipment. Grid interaction, such as export limitation and G98 or G99 notification, and backup behaviour during a power cut are separate design topics, so a system built for smart grid trading is not automatically configured for whole-home or essential-load backup unless specified for that purpose. For an overview of the full battery range, visit our battery storage hub. For solar and battery designed together, see solar and battery systems. For payment and finance routes, see smart financing options.
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Octopus Flux is a UK residential tariff designed for battery owners with solar. It offers a structured import rate overnight and a higher export rate during the late afternoon peak demand window. Your hybrid inverter connects to the Octopus API, receives half-hourly pricing data in advance, and executes charge and discharge cycles to align with these windows automatically. The financial value this generates depends on battery capacity, solar generation, household consumption, the prevailing Flux import and export rates, and how many full cycles the system achieves. These figures vary with tariff changes, seasonal generation and usage profile - we model the likely range at survey stage rather than quoting fixed annual returns.
Standard residential solar installations below 3.68kW per phase qualify for automatic G98 notification to the Distribution Network Operator. A luxury Surrey or SW London estate with a 12 to 20kWp solar array and 27 to 40kWh of battery storage will exceed this threshold on every phase - triggering the mandatory G99 application and DNO engineering approval process. This is a formal submission to UK Power Networks or SSEN requiring electrical load flow calculations, protection relay coordination data, and inverter technical compliance documentation. We manage the full G99 application on your behalf - from initial DNO feasibility enquiry through to grid connection approval. Our established G99 track record with both UK Power Networks and SSEN helps keep the process moving smoothly, though final approval timelines are set by the DNO and are outside our direct control.
Many affluent Surrey and SW London postcodes are served by overhead low-voltage distribution networks that were not designed for significant residential generation export. When the local grid has insufficient headroom to accept your full array export capacity, the DNO issues an export limitation condition as part of the G98 or G99 approval - restricting your permitted export to 0kW or a low fixed value per phase. Export limiting resolves this constraint without reducing your array size or your self-consumption potential. A smart current transformer installed on the grid connection point feeds real-time import and export data to your hybrid inverter, which modulates the battery charge and discharge rate to ensure that export does not exceed the DNO-permitted value at any point. A full-scale array can be installed for maximum self-consumption, while export remains within the approved limit at all times.
We assess your property's existing DNO connection, phase configuration, and local grid export headroom before any system is specified. For systems above 3.68kW per phase, we initiate the G99 DNO feasibility enquiry with UK Power Networks or SSEN to establish the approved export limit and identify any export limiting requirements from the outset.
We design the solar array, battery capacity, and grid connection architecture as a single integrated programme. String layout, phase balancing, inverter platform selection, CT sensor placement, and export limiting configuration are co-designed from day one to ensure DNO compliance and maximum system yield simultaneously.
We manage the full G99 application, compile all required technical documentation, and co-ordinate DNO approval before installation commences. Qualified engineers execute the full installation programme - solar array, hybrid inverter, battery, CT sensors, export limiting hardware and consumer unit integration - to BS 7671 standards throughout.
We configure Octopus Flux or Agile tariff scheduling, verify export limiting is operating correctly within DNO-approved parameters, complete SEG registration, and ensure all G99 compliance documentation is in order before engineers leave site. Your system is commissioned, verified and ready from day one.
The Octopus Flux tariff is structurally designed for battery owners with solar - with a defined low-rate import window overnight and a high-rate export window in the evening peak.
The import rate of 7 to 9p/kWh applies from 2am to 5am. The export rate of up to 15p/kWh applies from 4pm to 7pm. Your hybrid inverter connects to the Octopus API, receives the half-hourly price schedule 24 hours ahead, and executes the optimal charge and discharge cycle automatically. In summer, the battery fills on solar during the day and exports during the 4pm to 7pm peak. In winter, the overnight cheap import cycle fills the battery for daytime self-consumption and evening peak export.
Any system exceeding 3.68kW per phase triggers a mandatory G99 application to the Distribution Network Operator - a formal engineering submission requiring load flow calculations and inverter compliance documentation.
A luxury Surrey estate with a 12 to 20kWp solar array exceeds the G98 automatic notification threshold on every phase of a 3-phase supply. We manage the complete G99 application process: initial DNO feasibility enquiry, electrical load flow modelling, protection relay coordination data, inverter G99 compliance certificates, and all correspondence with UK Power Networks or SSEN from first submission to grid connection approval.
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A DNO export limitation condition does not mean a smaller array - it means smarter engineering. Export limiting allows a full-scale installation while the inverter is engineered to ensure the grid does not receive more than the approved export value at any instant.
Surrey and SW London suburban and rural overhead distribution networks frequently carry export limitation conditions of 0kW to 3.68kW per phase. A smart CT sensor on the grid connection point feeds real-time import and export data to the hybrid inverter, which adjusts battery charge and discharge rates in milliseconds to keep export within the approved limit - including during peak solar generation periods with low household consumption.
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The complete integrated hardware stack - solar, battery, inverter, and grid connection infrastructure - may qualify for 0% VAT when installed as a single concurrent programme, subject to current HMRC rules and confirmation at quotation.
On a grid-integrated system of this scale, a zero-rated VAT position can represent a meaningful capital saving applied at invoice where eligible - the exact figure depends on the scope of the project. Every installation is executed by our qualified engineers, with certification handled by appropriately qualified professionals where required, and all DC and AC cabling concealed through building fabric, powder-coated steel trunking where surface routing is unavoidable, and plant room equipment positioned and mounted to data-centre layout standards.
"We have a 3-phase supply and a 16kWp array that required a G99 application. The team managed the full DNO submission to UK Power Networks and kept us informed throughout the approval timeline. The Octopus Flux configuration was set up on commissioning day. In the first monitored quarter, the combined self-consumption saving, Flux export income, and overnight arbitrage return came to just over 1,100 GBP - ahead of the pre-commitment model projection."
"Our property is in an area with a strict 0kW export limitation on the local network. We were told by another installer that this meant we could only install a small system. The electricalworks team engineered a full 12kWp array with 27kWh of storage and an export limiting solution. The grid sees zero export at all times. Our self-consumption is running at 91 percent. The installation aesthetics in the plant room are exceptional - every cable concealed and every component mounted exactly as the pre-installation render showed."
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G98 is the automatic self-notification route for single-phase systems up to 3.68kW and 3-phase systems up to 11.04kW total. Above these thresholds, a formal G99 application to your Distribution Network Operator is mandatory before any installation can proceed. Most luxury Surrey estates with arrays above 8kWp on a single-phase supply, or 12kWp on a 3-phase supply, will require G99 approval. We identify the correct route during the initial feasibility assessment and manage the entire DNO process on your behalf at no additional engineering charge.
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Octopus Agile offers variable half-hourly import rates that can drop to 1p/kWh or below during overnight low-demand periods - useful for maximising overnight charging on highly variable pricing. Octopus Flux offers a structured and predictable import rate of 7 to 9p/kWh overnight combined with a published export rate of up to 15p/kWh during the 4pm to 7pm peak window, subject to change by the tariff provider. For estate owners with large battery capacity who need to model a reliable annual export income, Flux's predictable two-rate structure delivers a more consistent financial model. We configure and review the optimal tariff for your specific battery capacity and consumption profile annually.
A common and costly misconception: a DNO export limitation condition of 0kW or 3.68kW per phase does not restrict your array size. It restricts what you can send back to the grid. With export limiting hardware and a correctly sized battery, a 16kWp array can be installed on a 0kW export-limited connection - capturing the full generation for self-consumption and battery storage, with the CT-sensor-controlled inverter engineered to maintain zero export at every instant. Homeowners who accept a scaled-down array in response to a DNO export limitation have not been given the correct engineering advice.
A G99 application is required when the total installed generation capacity exceeds 3.68kW per phase on a single-phase supply, or when the combined system capacity on any phase of a 3-phase supply exceeds 3.68kW. For a typical luxury Surrey estate with a 10 to 20kWp solar array, a G99 application to your Distribution Network Operator - either UK Power Networks or SSEN depending on your postcode - is almost certain to be required. G99 approval must be received before installation commences. We initiate the feasibility enquiry as the first step of every large system project and manage the full application on your behalf.
An export limitation condition is a restriction issued by the DNO as part of your G98 or G99 approval, specifying the maximum amount of power you are permitted to export to the grid. Common limits are 0kW, 3.68kW per phase, or a fixed value per phase. Export limiting does not restrict how much solar you can generate or store for self-consumption - it only restricts what you send back to the grid. A CT sensor on the grid connection point monitors real-time export, and the hybrid inverter modulates battery charge and discharge so that the DNO limit is not exceeded. We engineer export limiting solutions as a standard capability for all Surrey and SW London estate installations.
For a Surrey estate with a 12 to 16kWp solar array and 27kWh of battery storage on Octopus Flux, the total annual financial return combines three streams: solar self-consumption savings of approximately 1,400 to 2,200 GBP (replacing 25 to 35p grid imports with self-generated solar power), peak export income of approximately 600 to 900 GBP from battery discharge at up to 15p/kWh during the 4pm to 7pm window, and overnight import arbitrage of approximately 400 to 600 GBP from charging at 7 to 9p/kWh overnight. Total combined indicative return: approximately 2,400 to 3,700 GBP per year from a single 3-phase grid-integrated system. These figures are illustrative; we model your specific property with your actual consumption data and provide a tailored forecast before any commitment is made.
Some residential solar, battery storage and qualifying energy-saving installations may be eligible for 0% VAT, subject to current HMRC rules and confirmation at quotation. Where solar panels, battery storage, and all associated grid integration hardware are installed as a single concurrent programme and the project qualifies, HMRC can classify the entire installation as a qualifying energy-saving installation, applying the zero rate to the full hardware stack: solar modules, hybrid inverter, battery modules, mounting system, CT sensors, export limiting hardware, consumer unit amendments, and installation labour. For example, on a Surrey grid-integrated system investment of 25,000 to 45,000 GBP, this could save in the region of 5,000 to 9,000 GBP at invoice where eligible. We confirm the correct VAT treatment and exact saving in writing at quotation stage before any commitment is made.
Maximize your investment. Without a battery, you likely export 50-70% of your solar energy back to the grid for pennies.
With a properly sized battery system:
"A battery transforms your home from a passive energy consumer into an active energy hub."