Mark Group has gone into administration —
here's what to do next
Mark Group Limited of Leicester entered administration in October 2015 with 939 job losses. They installed thousands of solar PV systems across Yorkshire and the UK through government energy efficiency schemes — many using Fronius inverters that are now over a decade old and reaching end of life. If your system was installed by Mark Group, here's what you need to know.
We're an independent solar support company based in Yorkshire. Mark Group systems are among the most common we see — particularly the Fronius inverter installs from government energy efficiency schemes. We handle fault diagnosis, inverter replacement, monitoring setup, and ongoing maintenance. We cover Barnsley, Wakefield, Leeds, Sheffield, Rotherham, Bradford, and across Yorkshire.
System Recovery Service → Book a call to discuss →Independent — not affiliated with any installer, manufacturer, or trade body.
What happened to Mark Group
Mark Group Limited was founded in 1974 as Mark Insulations — a family-run insulation business based in Leicestershire. Over four decades they grew into one of the UK's largest energy efficiency installers, operating 13 branches, employing over 1,100 staff, and installing cavity wall insulation, loft insulation, solid wall insulation, solar PV, solar thermal, and air source heat pumps. They installed thousands of solar PV systems across Yorkshire and the UK through government-backed energy efficiency programmes including CERT, CESP, and the Green Deal.
Companies House filings — Company no. 01304470
US energy giant SunEdison purchased Mark Group as part of their UK expansion strategy.
SunEdison exited the UK market citing "uneconomic" conditions from proposed changes to the government's Feed-in Tariff. Chris Farrington, Matt Cowlishaw, and William Dawson of Deloitte LLP appointed as Joint Administrators. 939 staff made redundant immediately, with a further 226 at risk.
The insulation side of the business was purchased by the management team. The solar PV installation and support operations ceased entirely.
Over a decade on — the hardware issue is now the priority. Mark Group's administration was in 2015, so most consumer protection time limits have long passed. The practical concern now is that Fronius inverters from this era are 10–14 years old and many are failing. If your system is underperforming or has stopped generating, an inverter fault is the most likely cause. A diagnostic will confirm.
What Mark Group's closure means for your solar system in 2026
Mark Group closed over ten years ago. The consumer protection picture is different from a recent closure — but your system is still generating (or should be).
Installer workmanship warranty — void since October 2015. If your installation included an insurance-backed guarantee (IBG), the typical 2, 5, or 10-year terms will also have expired by now. Any workmanship issues at this stage need an independent engineer.
Aftercare and support — gone for over a decade. No one to call for system queries, inverter faults, or configuration issues.
Standard manufacturer warranties — most will have expired. Standard Fronius inverter warranties are 5 years, panel warranties are typically 10–12 years for product defects. However, if you purchased extended warranties at the time of installation, some may still be active.
Monitoring access — if Mark Group set up monitoring under a company account (common with Fronius Solar.web), the account is long gone. Your data can be recovered.
Extended manufacturer warranties — if you or Mark Group purchased an extended Fronius warranty (10 or 20 years) at the time of installation, this is held directly with Fronius and survives the installer's closure. Contact Fronius UK with your serial number to check.
Panel performance warranties — solar panels typically carry a 25-year performance guarantee promising at least 80% output. This is separate from the product warranty and still valid. If your panels are underperforming beyond the guaranteed degradation rate, you may have a claim with the manufacturer.
Your generation data — Fronius Solar.web retains historical data. If you can locate your system's serial number, you can set up a new homeowner account and access your full generation history.
MCS registration — permanent. If Mark Group registered your installation with MCS, that record is independent and searchable at mcscertified.com.
Feed-in Tariff (FiT) — if your system was registered for the Feed-in Tariff before the March 2019 closure, your FiT payments continue for the full 20-year term regardless of the installer's status.
The Fronius inverter problem
Mark Group commonly installed Fronius inverters — particularly the Fronius IG, IG Plus, and Galvo series. These units are now 10–14 years old. A standard Fronius warranty is 5 years (extendable to 10 or 20 at the time of purchase), so many of these inverters are out of warranty and approaching or past their expected lifespan.
Red or orange fault lights on the inverter. System generating less than it used to. Inverter display showing error codes or going blank. Complete shutdown — system producing nothing. Tripping your consumer unit. If you're seeing any of these on a Mark Group Fronius inverter, the unit likely needs replacing rather than repairing.
For Fronius inverters of this age, repair is rarely cost-effective. Modern inverters are significantly more efficient, more reliable, and offer better monitoring. Replacement is straightforward — the new inverter connects to your existing panels and wiring. This is also the ideal time to consider adding battery storage, which wasn't widely available when Mark Group were installing.
Before paying for a replacement, check whether Mark Group or you purchased an extended Fronius warranty at installation. These are held directly with Fronius and survive the installer's closure. Contact Fronius UK with your inverter serial number (on the label on the unit) to check your warranty status. If it's still within warranty, Fronius will arrange a replacement unit — you just need an installer to fit it.
Five steps to recover your Mark Group system
Mark Group systems are over a decade old, so the priority is establishing the current condition of the hardware and getting the system back to full performance.
A remote diagnostic (£75) gives you a structured assessment: is the inverter working, are the panels generating, what's the monitoring status, and what needs attention. For systems this old, this is the essential first step — it tells you what to spend money on and what to leave alone.
Contact Fronius UK with your inverter serial number to check whether an extended warranty was purchased at installation. If it's still active, Fronius will supply a replacement unit at no cost — you only need to pay for the installation labour. This single check could save you hundreds of pounds.
If the inverter is out of warranty and faulty, inverter replacement is the next step. Modern inverters are more efficient and include built-in monitoring. This is also the time to consider adding a battery — your existing panels can charge it and you can store energy for evening use. From £249 for on-site repair work.
Many Mark Group systems were installed with Fronius Solar.web monitoring that may have lapsed or been lost when the company closed. If you're getting a new inverter, monitoring comes built in. If the original inverter is still working, we can help set up monitoring under your own account. Our monitoring recovery guide covers the process.
A system this age benefits from a proper health check — panel condition, wiring, mounting brackets, earthing, and generation performance. An annual maintenance visit catches degradation and minor faults before they become expensive. From £195 per year.
Services for former Mark Group customers
We're based in Yorkshire and see Mark Group systems regularly — particularly Fronius inverter installs from the 2012–2015 government scheme era. These are the services most relevant to your situation.
Fronius IG, IG Plus, or Galvo failed? We replace with a modern inverter — more efficient, better monitoring, and battery-ready. Same-day diagnosis where possible.
Inverter replacement →Mark Group systems need a thorough assessment after a decade without professional support. We check the Fronius inverter, inspect panel condition, rebuild missing documentation, and produce a written report on the full system state.
System Recovery →Is your Mark Group system still generating? A 30–45 minute engineer call checks whether the Fronius inverter is working, whether output has degraded, and what needs attention. Written action plan included. £75.
Remote diagnostic →If Mark Group purchased a 10 or 20-year extended Fronius warranty on your behalf, we verify the cover and manage the claim — evidence gathering, Fronius liaison, and replacement coordination.
Warranty support →Full on-site inspection of the installation quality — wiring, mounting, earthing, panel condition. Particularly valuable for government scheme installs where quality was sometimes variable.
Independent inspection →Yearly system health check — generation performance, inverter condition, panel inspection, wiring review. Essential for systems over 10 years old. From £195.
Annual maintenance →We cover the areas Mark Group served across Yorkshire
Mark Group installed across the UK from their 13 branches, with a particularly large presence in Yorkshire through government energy efficiency scheme work. We're based in Yorkshire and provide on-site solar support across all of these areas. Remote diagnostics are available nationwide.
Guides for customers of installers that have closed
Step-by-step process for claiming an orphaned monitoring account from a defunct installer. Covers Fronius Solar.web and all major UK brands.
Monitoring recovery guide →How to claim directly with the manufacturer when your installer has ceased trading. Includes Fronius extended warranty process.
Warranty claim guide →Mark Group installations from the government scheme era often have gaps in paperwork. Here's how to recover MCS certificates, DNO notifications, and missing warranty documents.
Documentation guide →A Port Talbot installer that entered administration in 2020. Combined solar, battery, and EV charger systems with HIES-backed guarantees — a similar era to Mark Group installs.
Solar Plants guide →Common questions from Mark Group customers
Mark Group entered administration in October 2015, so their installer workmanship warranty has been void for over a decade. However, if your installation came with an insurance-backed guarantee (IBG), that cover was designed to survive installer closure — though given the time elapsed, most IBGs (typically 2, 5, or 10 years) will have expired by now. Your manufacturer warranties on individual components may also have expired depending on the product. Fronius inverters, which Mark Group commonly installed, typically carry a 5-year standard warranty (extendable to 10 or 20 years if purchased at install). If you purchased an extended warranty, check whether it is still active by contacting Fronius directly with your serial number. Warranty claim guide →
Mark Group installed thousands of solar PV systems across the UK through government energy efficiency programmes including CERT, CESP, and the Green Deal. These scheme installations were subject to regulatory standards at the time, but the specific consumer protection frameworks varied by programme. If your system was installed under a government scheme and you are experiencing problems with installation quality, the practical route now — over a decade later — is to have an independent inspection carried out to assess the current condition. Any workmanship faults found can then be addressed by an independent engineer.
Fronius inverters installed by Mark Group in the 2012–2015 period are now 10–14 years old and many are reaching end of life. Common failures include the Fronius IG, IG Plus, and Galvo series. If the inverter is within an extended warranty period, contact Fronius UK directly with the serial number — the warranty is with the manufacturer, not the installer. If the warranty has expired, replacement is usually the most cost-effective option. Modern inverters are more efficient, and this is also an opportunity to add battery storage. Inverter replacement service →
Check any paperwork you received at installation — the MCS certificate, warranty pack, or commissioning documents should show the installer company name. You can also search the MCS database at mcscertified.com using your postcode and approximate installation date. Mark Group traded from 70 Boston Road, Beaumont Leys, Leicester LE4 1AW and operated 13 branches across the UK. They commonly installed Fronius inverters alongside panels from brands like Sharp, Sanyo, and Canadian Solar.
Yes. We support solar PV systems regardless of who installed them or how old they are. Mark Group systems are among the most common we see in Yorkshire — particularly on properties that had solar installed through government energy efficiency schemes in the 2012–2015 period. Our System Recovery service covers fault diagnosis, documentation rebuild, monitoring setup, and a written condition report. For ongoing support, our Annual Maintenance service provides a yearly health check and priority access to repairs. We are based in Yorkshire and cover all the areas Mark Group served.
Tell us what you're dealing with
Let us know what you have — whether it's a Fronius inverter playing up, a system you haven't checked in years, or just wanting to know if everything is still working properly. We'll come back with a clear plan — usually same day.