Technical deep dive: How SolShare works

This world-first technology allows a single solar PV and battery system to be shared among multiple flats, delivering increased SAP points, simplified wiring, regulations compliance and seamless grid integration.

Become a certified installer

Tier 1: kWp allocation & the SAP "Magic wand"

At the point of commissioning, each flat is allocated a specific proportion of the solar PV system, measured in kWp. This allows the system to be tailored to the exact needs of every flat in the building, creating true energy equity.

Typically, top and ground-floor flats suffer from worse SAP scores and EPC ratings than mid-floor flats due to exposed walls and roofs. SolShare acts as a "magic wand" for developers: a higher proportion of the solar array can be allocated to these lower-performing flats so they can "catch up" with the rest of the building. For example, a 2-bed top-floor flat might receive a 1.5 kWp allocation to jump from an EPC Band C to a B, while a 2-bed mid-floor flat only requires a 1.0 kWp allocation to achieve the same Band B rating.

Tier 2: Dynamic demand-based delivery (The 200ms rule)

Once the kWp allocation is set, SolShare continually monitors the real-time demand of every connected flat. It dynamically directs the available solar energy to the flats that actively have a load, switching delivery every 200ms. This high-speed routing maximises on-site consumption and drastically reduces solar spill into the grid, resulting in greater bill savings for every household.

Tier 3: monthly balancing & rollover

Over the course of each month, SolShare meticulously tracks the exact kWh of solar delivered to each flat. If the system identifies that a flat is receiving disproportionately too much or too little energy compared to its commissioned kWp allocation, it will begin to prioritise solar delivery to the underserved flats. If the allocation cannot be perfectly satisfied within the month, any deficit is automatically rolled over into the next month so the flat can catch up.

New build apartment buildings with rooftop solar

Maximising SAP scores & EPC ratings

Because SolShare guarantees that a set proportion of solar energy will be delivered to each flat based on its kWp allocation, the system is classified under SAP 10.2 as a "PV array serving one dwelling".

Even though it is a shared system, this direct connection classification is imperative as it yields the maximum possible SAP score uplift available for solar energy. Following installation, each flat receives its own individual MCS certificate specifying its exact kWp value, which is then inputted directly into the SAP assessment.

Simplified electrical architecture

When compared to multiple, individual solar PV systems for each flat, SolShare fundamentally streamlines the building's electrical design, reclaiming valuable riser space, reducing cabling complexity, and eases fire safety concerns.

Key wiring & installation specifications:

Single live cable: Only a single live cable is required to connect from the SolShare to each flat's solar point of connection.
No neutral to flats: There is no neutral paired with the live cable to the flat; instead, a single neutral and earth is connected from the SolShare to the main Multi-Service Distribution Board (MSDB) or DNO cutout. Note: Because there is no neutral, Steel Wire Armoured (SWA) cable is not suitable due to eddy currents; non-ferrous cable must be used.
CT placement: SolShare comes with 15 Current Transformers (CTs), each with 10m tails. These can be extended up to 100 metres using 24 AWG shielded and twisted pair cable, providing excellent flexibility for riser installations.
Capacity: A single SolShare 35 unit handles a maximum input capacity of 35 amps per phase (typically paired with a 10kW to 20kW inverter) and connects up to 15 single-phase flats (or 5 three-phase flats).

Get a technical CPD

Fire safety and maintenance isolation

When a multi-residential building utilises traditional individual PV systems, emergency responders are faced with multiple points of isolation scattered across the roof or building.

SolShare's safety advantage:

Single Point of Generation Isolation: Because SolShare centralises the PV array, only a single AC isolator is required between the inverter and the SolShare, acting as a single point of isolation for the entire solar system.
Dedicated Maintenance Isolation: For safe maintenance, SolShare requires dedicated isolation from each flat. A lockable consumer unit (with no bus bar) containing a single pole MCB for each flat is installed locally. The MCBs must be rated to carry the maximum current of a single phase of the inverter, as SolShare can direct all available power on one phase to a single connection.

Grid compliance and credibility

SolShare is built to the highest regulatory standards and is fully accepted for installation in the UK, offering specifiers and installers complete peace of mind.

Pioneering G99 Standards: Allume Energy’s technology helped author the rulebook. SolShare was used as the basis for the entirely new Section 7.8: Power Generating Module Sharing System in the ENA's Engineering Recommendation G99 Issue 2.
Ofgem Reviewed: The system has successfully undergone a stringent technical review by Ofgem.
DNO & IDNO Acceptance: Officially accepted for installation on all major DNOs and IDNO networks following a rigorous assessment by an ENA working group, which included a technical deep dive, comprehensive documentation review, and live witness tests.

UK CA Marked & IP65 Rated: Fully certified with the UK CA mark and IP65 rated for indoor and outdoor installation.
TrustMark: Meets TrustMark Framework Operating Requirements V2.6, most notably Section 15: Product Suitability.
MCS certification: Each flat receives an individual MCS certificate based on its associated kWp following commissioning.
10-year warranty: SolShare is supplied with a 10-year parts a labour warranty.

SolShare and community batteries

SolShare integrates seamlessly with communal DC-coupled battery systems, allowing stored renewable energy to be shared across multiple flats without installing battery equipment inside individual homes.

We’re here to help assess technical suitability and ensure the solshare system is designed to deliver the best possible results for your project.

Reach out to our technical team if you have a battery storage project in the works.

Contact our engineering team

Monitor every SolShare system with SolCentre

SolCentre gives asset owners complete visibility across every SolShare installation.

Monitor generation and consumption
Track resident savings flat by flat
Automate reporting
Detect faults remotely
Manage portfolios from one dashboard

Explore SolCentre

Allume SolCentre software dashboard displaying real-time solar energy usage data, financial savings, and carbon reduction metrics for apartment flats.

General specifications Electrical specifications Standards and compliance

Parameter	Value
Dimensions	880mm x 480mm x 235mm (h x w x d)
Weight	41 kg
Max Number of connections per unit	15 single-phase or 5 three-phase(or a combination)
Degree of protection	IP65 (suitable for indoor and outdoor installation)
Operating temperature range	-40 to +50°C

Parameter	Value
Max. current per phase	50.9 A
Voltage range (line to neutral)	216 – 253 VAC
Voltage drop (at nominal current at 25°C)	2.3 V
Frequency range	47-53 Hz

Description	Certification
CE Mark	Certified
Electromagnetic Compatibility (EMC)	EN IEC 61326-1:2021, ETSI EN 301 489-1 V2.2.3, ETSI EN 301 489-17 V3.2.4

Icon representing a solar calculator for SAP 10 calculations to help M&E consultants and developers improve EPC ratings for apartments.

How the SolShare system works

Why social housing providers choose Allume

Become a certified SolShare installer

Resources for apartment solar projects

Technical deep dive: How SolShare works