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Sea Lion Rocks in Solar Powered Socks!

After 15 years of diesel generators, the remote Sea Lion Rocks Tea Rooms on the Isle of Man has been able to transition to solar power, thanks to the help of our amazing off-grid team, and a generous grant from the Manx Lottery Trust.


Above: Sea Lion Rocks Tea Rooms

The isolated cafe, perched on a clifftop at the end of the historic Groudle Glen narrow railway, is a popular destination for families throughout the summer. After a ride on one of the steam trains that run along the line, you can enjoy a nice Steam Tea or a refreshing ice cream overlooking the sea.

But with no grid connection available, up until recently, enjoying a cup of tea or an ice cream relied on power generated by a loud and costly diesel generator. Thanks to a £8500 grant from the Manx Lottery Trust in 2023, this was all about to change. A new volunteer at the railway had experience with renewable energy, and researched the possibility of powering the cafe using solar power. 

Due to the lack of a grid connection, the PV system would have to be entirely off-grid. But designing an off-grid PV system is quite complex, requiring more technical considerations than with a standard grid-connected system, and so, in early 2023, the Sea Lion Rocks Tea Room contacted our specialist off-grid team.

Left: Steam train "Sea Lion" approaching the tea rooms. The Groudle Glen Railway is run and operated entirely by volunteers

But will the toaster toast?

The calculation and design stages for an off-grid system are pretty important… With no grid connection to back you up, if you haven't calculated the size of the array, inverter or storage quite right, then you might find yourself unable to use the kettle at the same time as the toaster - less than ideal in a busy cafe. 

And so, the wonderful Ollie in our off-grid team, set about calculating the size and design of the off-grid system required. To do this, you need to think about things such as:

  • How much solar is needed to cover the typical daily energy consumption? 

  • What is the maximum amount of power required at any one time? E.g. kettle + freezer + toaster = how much power? (this will decide what size inverter required)
  • How much backup power is needed? For those cloudy days, how much energy do you need to have stored up in your batteries?

For the tea room, their energy demands were rather modest, with the cafe only opening on Sundays and Wednesdays during the summer months while the train operates. They required enough power for an internet connection to run the card machine, as well as running the fridge-freezer and CCTV 24/7.

Ollie designed a system to suit these requirements, as well as a wiring diagram to show how each of the components should be connected. The system included x8 Longi 405W panels, a Victron Multi-Plus II 48/5000 (the inverter-charger), a Victron SmartSolar MPPT 250/85 (the MPPT controller), a Victron Cerbo GX (the “brains” of the system), with x2 Pylontech US5000 batteries (providing over 9000Wh of usable capacity), all of which was supplied by Midsummer.

Solar-powered steam teas! 

After some weather-related delays to the installation, the off-grid system is now up and running, and the cafe is using renewable energy to cover all of their energy needs. 

As well as reducing the cafe’s carbon footprint and energy bills, it means that the cafe staff will no longer have to ferry ice creams back and forth on the train, thanks to the freezer now running on solar power 24/7!

If you fancy a trip along the Groudle Glen Railway and a “Steam Tea” in the Sea Lion Rocks Tea Rooms, check out their 2024 timetable here, including various special events throughout the year.

Above: the newly installed panels, catching the last rays of the day

Have a potential off-grid project you need designing or supplying? 

Contact our specialised off-grid team at sales@midsummerenergy.co.uk with the details, or ring us on 01223 858414. We have a separate off-grid website, where you can explore our full range of off-grid products and information pages.