Sunsynk is a hardware manufacturer, not an installer. It makes hybrid solar inverters and lithium iron phosphate batteries, it sells them through installers and distributors rather than direct to homeowners, and its UK arm has been a registered British company since 2013. If the brand has appeared on your quote, nobody is trying to slip you something obscure. You are just looking at a supplier that sells to the trade and does very little consumer marketing.
That is also why there is so little independent writing about them. This page fills the gap. Every fact below was verified on 21 September 2026 against Sunsynk's own product pages, Companies House, the Energy Networks Association, MCS, HMRC VAT Notice 708/6 and the Energy Saving Trust.
Worth comparing it against two more before you commit, on the same inverter rating and the same battery capacity. Quotes come from MCS-certified installers covering your area.
Get a Quote →Who Sunsynk are, in plain terms
Sunsynk UK Ltd is a private limited company registered in England and Wales, company number 08778087, incorporated on 15 November 2013 and listed as active on Companies House. Its registered office is Unit 10 Edison Court, Ellice Way, Wrexham Technology Park, Wrexham LL13 7YT. The company's own site gives its UK operating address as Unit 8, Total Park, Bennetts Lane, Shell Green, Widnes WA8 0GW, and describes itself as part of Sunsynk Group Limited.
Sunsynk Group Limited is a separate and much newer entity: company number 15107233, incorporated on 31 August 2023, registered at the same Wrexham address. Both are worth knowing if you ever have to chase a warranty claim, because they are different legal persons and the one named on your paperwork is the one that owes you something.
The same check is worth running on Fox ESS, the other brand that turns up constantly on British hybrid quotes. The point of the exercise is not trivia. A twelve-year-old British-registered company with filed accounts is a different proposition from a brand that appeared last year and sells through a single importer. You can run the same check on any manufacturer named on a solar quote by searching Companies House, and it takes about a minute.
What Sunsynk actually makes
Two things matter for a UK home: hybrid inverters and LiFePO4 batteries. A hybrid inverter runs the solar panels and a battery from one box rather than two, which is why the brand shows up disproportionately on quotes that include storage.
On the domestic single-phase side, Sunsynk currently lists several families, and the naming is a mess because the families overlap:
- Lynks at 3.6kW, 6kW and 8kW.
- LP at 3.6kW and 6kW, plus IP65-rated outdoor units at 7.2kW, 8kW, 10kW and 12kW.
- Acure Ecco at 3.6kW, 5kW and 6kW, and Acure at 3.6kW, 5.0kW, 6kW, 7kW and 8kW.
- Ecco at 3.6kW, 5kW, 7kW and 8kW, and a Compact pair at 5kW and 8kW.
- Plain Hybrid Inverter units at 3.6kW, 5kW, 8kW, 10kW, 12kW and 16kW.
Three-phase and high-voltage commercial units run from 6kW up to 80kW, which is outside anything a normal house needs. If a three-phase unit has been quoted for a domestic property, ask why, because most UK homes are single-phase.
The battery range is broader still, and all of it is lithium iron phosphate. Sunsynk's low-voltage 48V families are L Series (3.0kWh, 5.12kWh, 5.32kWh), S Series (5.12kWh up to 16.07kWh), X Series (5.12kWh, 10.24kWh, 16.07kWh), W Series (5.32kWh, 10.24kWh, 10.64kWh) and Radia (5.12kWh, 10.49kWh, 16.07kWh). High-voltage options include the GM Series at 5.12kWh and the AR Series at 7.68kWh. Sunsynk states that every battery in the range is IP65-rated with an integrated battery management system.
For context on sizing rather than brand, the Energy Saving Trust puts a typical domestic array at around 4.5 kWp using roughly 12 panels over 20 to 30 square metres, and battery storage at around £5,000 to £8,000. Our guide to solar battery storage works through whether the battery earns that back, which is a separate question from which brand of battery it is.
The warranty position, including the gap
Sunsynk publishes a clear battery warranty and does not publish an inverter warranty period on its product pages, and that asymmetry is the single most useful thing on this page.
On the batteries, Sunsynk states that all of them "are IP65-rated, ship with an integrated BMS, communicate natively with Sunsynk inverters, and carry a 10-year product warranty as standard". It also claims "6,000+ charge cycles at 80% depth of discharge - over 16 years of daily use". Ten years as standard on storage is a competitive position and it is published in black and white.
The inverter is the gap. Sunsynk's inverter pages list an enormous model range and a "Product Warranty Available" badge, but no standard term. Its warranty page links to manufacturer terms and conditions documents rather than stating a period, and warranty registration is required: Sunsynk asks owners to register the product and warns that "incomplete or inaccurate information may lead to the rejection of a warranty claim".
That matters more than it sounds, because of what the Energy Saving Trust says about inverters generally. Panels "should last 25 years or more", but "if you have a solar inverter, you need to replace this after around 12 years". The Trust adds that "most inverters have warranties of five years as a minimum, which you can often extend by up to 15 years", and warns that "a 15-year warranty costs almost as much as a replacement inverter, so consider it carefully".
So on any Sunsynk quote, three things need writing down: the inverter warranty term in years, whether it is extendable and at what price, and who registers the product. If your installer registers it, get confirmation in writing that they have. If you register it, do it the week it is commissioned. Our guide to solar inverters covers why the inverter is the component that ends first regardless of who made it.
Why the inverter rating decides your grid paperwork
The number that decides whether your installer files the quick grid form or the slow one is the inverter's AC rating, which is why the choice between a 3.6kW and a 6kW Sunsynk unit is not purely about output.
The Energy Networks Association sets the national threshold: "A generator with a capacity less than 3.68kW/phase then EREC G98 applies" and "A generator with a capacity greater than 3.68kW/phase then EREC G99 applies." G98 is connect-and-notify. G99 means applying to your distribution network operator and waiting for approval before anything is connected.
Look back at the Sunsynk range with that in mind. The 3.6kW units in the Lynks, LP, Acure, Ecco and Hybrid families all sit under the 3.68kW line. Everything from 5kW upward does not. Sunsynk's own guidance says as much, carefully: "Suitable Sunsynk inverter models can be used in installations that meet UK grid connection and MCS requirements. Your installer should confirm the selected model's certification and follow the appropriate DNO application or notification process."
There is a second consequence specific to hybrid inverters and batteries, which is exactly what Sunsynk sells. MCS standard MIS 3002 states that the 16A per phase threshold is "the total aggregated AC output of all generators", counting solar and battery storage together, so a modest array plus a battery can cross the line when neither would alone. Our full guide to G98 and G99 covers both processes and the per-network differences, including Northern Ireland, where NIE Networks runs a separate G98/NI and G99/NI regime.
The register to check, and the one that will not help
You will not find a Sunsynk inverter in the MCS Product Directory, and that is not a warning sign. The MCS directory's technology filter covers solar photovoltaic modules, solar PV mounting, solar heating and solar heating mounting, biomass, micro CHP, wind turbines and the heat pump categories. Inverters are not a listed product category there, so their absence tells you nothing.
The register that does apply is the Energy Networks Association's LCT Register, which the ENA describes as "a repository ... where equipment manufacturers can submit information about their products and make their own declarations of compliance with EREC G98 or EREC G99". Entries the ENA has reviewed and found correct and complete are marked "compliant". You can search it yourself at connect-direct.energynetworks.org.
Here is the nuance that decides how much weight to put on it. For the smaller units, the register is compulsory. The ENA states that EREC G98, "which applies to generation equipment rated less than 3.68kW/phase, requires that manufacturers must always lodge their declarations of full compliance in the ENA LCT Register". Above that rating it is optional: the ENA notes it "is not mandatory for manufacturers of generation products with a capacity greater than 3.68kW/phase to use this register to declare compliance information about their generation products there".
In practice: if a 3.6kW Sunsynk unit is quoted, the declaration should be on the register and you can check it in a browser. If a 5kW or 8kW unit is quoted, absence from the register proves nothing, and the right move is to ask the installer for the manufacturer's declaration of compliance for that specific model. The ENA is blunt about where the duty ultimately sits: "Compliance is the responsibility of the customer who is quite often, but not always, the owner of the generation."
MCS, export payments and what the brand does not buy you
No inverter or battery brand makes your installation MCS certified. The installer does. This is the most common misreading of a hardware brand on a quote.
MCS sets out the Smart Export Guarantee eligibility test directly: you need solar panels, wind or micro CHP, "a smart meter that records your exported electricity", and a system "installed by an MCS certified installer using certified products", adding that a supplier signing you up "might ask for your MCS certificate to confirm this". SEG covers England, Scotland and Wales only. Sunsynk's own wording agrees that "eligibility for Smart Export Guarantee payments depends on the complete installation meeting the relevant certification, metering and export supplier requirements, rather than the inverter alone".
One thing no hardware brand can change: the Feed-in Tariff closed in March 2019 and to new applicants from 1 April 2019, so no new install earns FiT whatever hardware is on it. Our guide to Smart Export Guarantee rates covers what suppliers actually pay, and the Energy Saving Trust's rough benchmark is around 12p for each unit you export rather than use.
What it costs, and the VAT rule that applies to all of it
No UK primary source publishes what a Sunsynk inverter or battery costs, and retail listings move week to week, so we are not going to print a figure we cannot stand behind. What is fixed is the tax treatment, and it is worth understanding because it can swing the total.
HMRC's VAT Notice 708/6 applies a zero rate to the installation of specified energy-saving materials in residential accommodation, and the current notice covers supplies up to 31 March 2027. Section 2.11 defines qualifying solar panels to include "photovoltaic (PV) panels with cabling, control panel and AC/DC inverter", so a Sunsynk hybrid inverter supplied and fitted as part of the job carries no VAT. Batteries are covered too: since 1 February 2024 the zero rate extends to "electrical storage batteries installed in residential accommodation", explicitly including retrofitting a battery to an existing microgeneration system.
That retrofit point is the practically useful one for this brand, because adding a hybrid inverter and battery to an existing array is a common Sunsynk job. Done as a supply-and-install by a VAT-registered installer, it is zero-rated today.
The clock is running. HMRC states that "From 1 April 2027 onwards, supplies of installations of energy-saving materials will revert to the reduced rate of VAT of 5%". That is 5%, not 20%, a distinction a lot of sites get wrong. Our guide to VAT on solar panels works through the supply-only trap and what the 2027 change means for a replacement inverter.
For the whole-system picture, the Energy Saving Trust benchmarks a typical 4.5 kWp domestic install at around £7,600, with payback of about 9 years in London, 10 to 11 in Manchester, 9 to 10 in Aberystwyth and 11 to 12 in Stirling on July 2026 fuel prices. Our full breakdown of solar panel costs shows what sits inside that number.
What to check on a quote that specifies Sunsynk
Five questions, all answerable in writing before you sign.
- Which exact model, and what is its AC rating? "A Sunsynk 5kW" is not a model. There are at least four different 5kW single-phase families. Get the full name on the quote.
- Does that rating keep us inside G98? Under 3.68kW per phase means connect-and-notify. Over it means a G99 application first, so ask for the expected timeline before you agree a fitting date.
- What is the inverter warranty term, in years, and is it extendable? Sunsynk publishes 10 years as standard on its batteries and no standard period on its inverters. Get the number written down.
- Who registers the warranty, and when? Sunsynk requires registration and warns that inaccurate details can lead to a claim being rejected.
- Is the battery capacity quoted usable or nominal? Sunsynk lists nominal figures such as 5.12kWh and 10.24kWh. Usable capacity is the number that decides how many evenings it covers.
Two more habits are worth keeping regardless of brand. Get three quotes, and check each installer is MCS certified, which the Energy Saving Trust recommends for exactly the reason above. And compare like with like: two quotes with the same panel count can differ by thousands on inverter and battery choice alone. Our guide to choosing a solar installer covers the checks that matter more than the hardware badge.
Sunsynk inverters and batteries: frequently asked questions
Sunsynk UK Ltd is a private limited company registered in England and Wales under company number 08778087, incorporated on 15 November 2013 and listed as active on Companies House, with its registered office at Unit 10 Edison Court, Ellice Way, Wrexham Technology Park, Wrexham LL13 7YT. Its site gives a UK operating address in Widnes, Cheshire, and describes the business as part of Sunsynk Group Limited, a separate company registered on 31 August 2023 under number 15107233. Manufacturing is international; the UK entity is the one on British paperwork.
Ten years as standard. Sunsynk states that all of its batteries "are IP65-rated, ship with an integrated BMS, communicate natively with Sunsynk inverters, and carry a 10-year product warranty as standard", and claims "6,000+ charge cycles at 80% depth of discharge". The company requires owners to register the product for warranty and warns that incomplete or inaccurate registration details may lead to a claim being rejected, so register it the week the system is commissioned and keep the confirmation.
Sunsynk does not publish a standard inverter warranty period on its UK product pages, unlike its batteries, which carry a stated 10 years. Its warranty page links to manufacturer terms and conditions documents rather than naming a term. Ask your installer to write the inverter warranty term into the quote in years, along with whether it is extendable and at what cost. For context, the Energy Saving Trust says most inverters carry a minimum five-year warranty, often extendable up to 15 years, and cautions that a 15-year extension "costs almost as much as a replacement inverter".
Inverters are not a product category in the MCS Product Directory, whose technology filter covers solar photovoltaic modules, PV mounting, solar heating and mounting, biomass, micro CHP, wind turbines and heat pumps. So the absence of any inverter brand from that directory means nothing. The relevant register for an inverter is the Energy Networks Association's LCT Register of manufacturers' declarations against EREC G98 or G99. What makes your installation MCS certified is the installer, not the hardware brand.
The hardware brand is not what decides it. MCS sets the test as solar panels, wind or micro CHP, a smart meter that records your exported electricity, and a system installed by an MCS certified installer using certified products, with the supplier likely to ask for your MCS certificate. SEG applies in England, Scotland and Wales only. Sunsynk's own guidance agrees that eligibility depends on the complete installation meeting certification, metering and supplier requirements "rather than the inverter alone".
The 3.6kW single-phase units, which sit under the national threshold. The Energy Networks Association states that "a generator with a capacity less than 3.68kW/phase then EREC G98 applies" and that above 3.68kW per phase EREC G99 applies instead, meaning an application to your distribution network operator and approval before connection. Every Sunsynk single-phase unit from 5kW upward is therefore a G99 job. With a hybrid inverter the threshold is counted across solar and battery output together, so ask your installer which route your specific configuration takes.
Not when it is supplied and installed in a home as part of a qualifying job before 31 March 2027. HMRC's VAT Notice 708/6 zero-rates the installation of energy-saving materials, defines qualifying solar panels to include "photovoltaic (PV) panels with cabling, control panel and AC/DC inverter", and since 1 February 2024 extends the zero rate to electrical storage batteries installed in residential accommodation, including retrofitting a battery to an existing solar system. From 1 April 2027 installations revert to the reduced rate of 5%, not to 20%.
Often yes, and it is a common reason the brand appears on a quote. Sunsynk says a hybrid unit can be added alongside an existing string inverter using AC coupling, or the existing inverter can be replaced outright, and that an MCS installer should assess your existing array voltage, string configuration and switchgear first. Two things to settle before agreeing: the retrofit changes your total aggregated AC output, so check which grid process now applies, and confirm the VAT treatment, since the zero rate covers retrofitting a battery to an existing microgeneration system when supplied and installed.