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S Georges' SPorts Centre, Scott Brown Rigg, Architects
April 7, 2021 In

St George’s College Iconic Solar Sports Hall

St George’s is an independent mixed Roman Catholic co-educational day school in Weybridge Surrey. The school have recently constructed a new Sports Hall for the school as their existing sports hall was only sized for 500 students (all boys).  The new sport hall now caters for over 1000 pupils (both boys and girls) over a wide range of sporting activities.

The new hall is a flagship architectural building, designed by Scott Brown Rigg Architects, with many unique design features that required careful integration of the solar PV.

The structure of the building is made from curved glulam columns and roof beams, which support a plywood deck.  Above the roof sites 150mm insulation, finished with a Sika Sarnafil single-ply roof membrane.  The roof is curved in two directions much like the Olympic Park velodrome, and also features diamond-shaped roof ventilation towers.

Careful Integration of Solar

As such, the design needed to account for the following sensitivities:

  1. As a high-end architectural project, aesthetics were paramount to the client.
  2. The installation mounting system needed to work with the curved surface of the roof.
  3. We needed to avoid shade from the ventilation towers.
  4. The chosen system needed to be lightweight so as not to compress the insulation, or led to puddling of water
  5. The system needed to be non-penetrative
  6. We needed to install sufficient solar PV to meet overall building CO2 targets.

The building carbon targets implied the building had a target of 32kWp of solar PV to generate 29,688kWh of electricity per year.  To meet this brief, we installed a system of 119 JA Solar 270W modules, connected to a single Solis 30kW inverter.

 

Sika SSM1 mounting system

Joju Solar are the solar energy partners of Sika Sarnafil who manufactured the roof membrane system.  Working closely with them and the main roofing contractors, Malone Roofing, we designed and delivered what we to believe to be a prime example of sensitive architectural integration of a commercial solar PV roof.

The chosen mounting system was the Sika Solar Mount SSM1, which offers several unique features, ideal for this project.  The mounting system consists of plastic triangular frames pitched at 15 degrees.  These frames use rubber fixing flaps, that sit over the frames which are then rubber-welded directly to the roof membrane.  Because the frames are bonded to the roof surface, the system is ballast-free, and therefore very lightweight.  This not only simplifies construction but helps from a structural engineering point of view, especially in case such as this where the span of the roof is large.  It also prevents compression of the insulation layer and puddling of water on the roof.

Uniquely, the mounting system and the roof membrane itself are covered under a single point warranty.  As Sam Rogan, Sika Sarnafil Technical Advisor explains: “The SikaSolar system offers a low profile panel with high output,  that is fully compatible with Sarnafil single ply roofing membranes”.  This avoids any potential conflict between the multiple contractors on-site, as there is a single holder of risk and responsibility.

Primarily designed for flat roofs, the SSM1 is limited to being installed on roofs of less than a 10-degree pitch.  We therefore restricted our array to those unshaded areas of the roof that met this design requirement.  The area chosen was such that optimisers were not required and the system could be strung on a single 30kW inverter.

As a further step to enhance the aesthetics of the installation, the DC cable routes were laid in channels cut into the insulation membrane, which were then covered with the main roofing membrane.  This removed the need for an unsightly cable tray running across the roof and preserved the clean aesthetics of the building.

 

(Images 1&3 courtesy of Scott Brown Rigg Architects)

Find Out More

  • Our PV design team is on hand to help you realise the solar part of any new build project, large or small
  • We have even integrated a bespoke solar PV array into the roof of Salisbury Cathedral
  • Solar schools like St George’s are a speciality of ours – find out more about the hundreds of solar schools we’ve already built
Oxford Brookes, Sunset, Solar PAnels, Salix Finance
February 2, 2021 In

A Hub of High Efficiency at Oxford Brookes University

Oxford Brookes is one of the UK’s leading modern universities with an international reputation for teaching innovation and excellence. They are also in the top tier of universities leading the way when it comes to limiting their effect on the environment*. Their 35% reduction in carbon emissions since 2005, already puts the university ahead of its 2025 target of a 34% reduction, but this hasn’t stopped Oxford Brookes wanting to push on and do more – to continue to reduce its environmental impact and create a student campus that truly supports sustainability, as well as inspiring students to significantly reduce wasted energy use and carbon emissions.

 

Funding and Fusion 21

When Oxford Brookes learned they could secure renawable energy project funding through Salix Finance (interest-free funding for the public sector to improve energy efficiency, reduce carbon emissions and lower energy bills), the university was keen to increase its existing solar PV capacity and looked into procurement routes to find the perfect solar PV partner.

They discovered Joju Solar through the Fusion 21 public sector procurement framework and after surveying the university site, we helped to identify five more suitable buildings for solar PV – designing and procuring the best possible system within Salix funding parameters. The project couldn’t cost more than £222 per tonne of carbon saved (over the lifetime of the project), with a project payback of 8 years.

 

A greater yield with SunPower

As Oxford Brookes University was committed to generating as much as possible in the available space, to “do more with less” and get the most value from existing building spaces, we used high efficiency SunPower modules on the Buckley Building, John Payne Building, Lloyd Building, Sinclair Building and the International Centre.

Although rare for a commercial solar panel installation project, these state-of-the-art panels gave Oxford Brookes greater output per square metre of roof space, adding just under 300kWp and doubling their solar PV capacity. From a cost perspective, this approach still worked within the Salix Finance funding model, so it was a winner all round!

Despite the installation being initially postponed due to Covid19, the 700 solar panels were installed in November 2020 and it was an absolute pleasure working with Oxford Brookes University to extend their visible commitment to a low carbon future by creating a high efficiency array – generating 224,912kWh per year, with a 57 tonnes CO2 saving.

 

Discover more

  • We love working in the education sector and Solar schools is one of our specialities.  We can deliver fully funded installations across your school or university estate, so do find out more about our solar for schools and education
  • Discover more about Solar PV and how we can help you.
  • SunPower modules are the state of the art – offering efficiencies of more than 23%.
Noah'sArk, Green roof, biosolar, aerial, BArnet
January 25, 2021 In

A Biosolar Roof for Noah’s Ark

Noah’s Ark Children’s Hospice make moments matter. They help seriously unwell babies, children and their families make the most of the special time they have together, providing clinical, emotional and practical support to over 300 families across North and Central London and Hertsmere.

 

The hospice wanted to support an increase in the scale and quality of their work and to do that, they needed a new building. ‘The Ark’, a highly sustainable ‘home-from-home’ and an inspiring space for palliative care, relaxation and adventure, launched in September 2019 and was constructed within their nature reserve in Barnet, becoming the first new hospice building in London for ten years.

 

The realisation of The Ark was a combination of an incredibly successful fundraising appeal which raised over £12million, architectural design by Squire & Partners and collaboration between a number of construction and sustainability professionals – all playing their part to create this iconic new build. At Joju Solar, we got involved when creating ‘a green roof with a difference’ became part of the plan.

 

A Green roof with added solar

Bridgman & Bridgman in partnership with Bauder Ltd began the construction of The Ark’s green roof and the idea was to create a living, wildflower meadow in the sky, to support native wildlife as part of the building’s strong connection with its natural setting.

 

It was also important to make The Ark as self-sufficient as possible from an energy perspective, which meant installing solar PV on the green roof. The solar was being funded by the community through Energy 4 All, which significantly reduced the overall capital expenditure of the project (saving over £84,000 in energy costs to the client over a 20-year period). We’ve worked closely with Energy 4 All on a number of community-owned, green energy projects and they invited us to be part of the team – to install 171 solar PV panels so that both green roof and solar worked together in harmony.

 

When installed correctly, that’s exactly what Biosolar roofs create. PV panels can work more efficiently on a green roof, as green roofs help to keep the temperature around the panels at the optimum 25 degrees celsius. A hotter micro climate can result in loss of panel efficiency, so green roof and solar is the perfect partnership from that perspective. Efficiency was critical in this very special new build, to make sure the hospice would receive as greater yield as possible.

 

Solar panels can also create shaded areas underneath them, which encourages a wider variety of vegetation to grow on a green roof. That means the combination can help different types of species to thrive and in a nature reserve setting, this worked beautifully.  Look how the wind protection allows taller species to grow near the panels!

 

The installation utilised Bauder BioSOLAR – an integrated mounting system made stable by green roof layering and vegetation, removing the need for penetrating the waterproofing to secure the mounting units to the roof. It was ready for us to install the solar panels on to, with the frame sitting around 300mm higher than the line of the roof. This allowed growing room for vegetation without blocking any light to the panels and also meant light and moisture could reach beneath them to support any vegetation or wildlife below.

 

The seeds were planted following our PV solar install and once the mains electricity install was complete, we returned to commission the 46.17kWp system.

 

Green roof and solar – a winning combination

The combination of green roof and solar on The Ark was a winning one. Not only did it encourage biodiversity and fulfil the goal of generating the building’s electricity, the project won the “Roof Gardens/ Living Wall Installations – Commercial Roof Garden or Podium Landscaping – Under £500k” award in the BALI National Landscape Awards 2020. It’s also the first time a community funded green roof with PV panels has been used in the UK.

 

As the Mayor of London, Sadiq Khan, said when the building opened:

“Noah’s Ark has been a beacon of light for the children and families it serves, so I’m delighted that they have a brand-new home,”

and we’re proud to have been able to play a small part in helping to make this peaceful sanctuary sustainable.

Discover more

 

Egni Coop, Graint Thomas Velodrome, Newport Councl, largest solar roof in Wales,
August 12, 2020 In

Egni Coop’s Welsh Community Solar Programme

Egni Coop and Joju Solar have developed and installed the most ambitious community solar scheme in Wales, including the largest single community solar rooftop at Newport’s Geraint Thomas velodrome. It’s quite a story – here’s how we did it.

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Salisbury Cathedral, solar, spire
July 29, 2020 In

The Salisbury Cathedral Solar Roof

How did a small local community energy group end up building one of the most iconic renewable energy projects in the UK?  Well, it turns out dedication, perseverance, and a little good fortune are all you need.

Salisbury Community Energy

Salisbury Community Energy is a relatively new community energy group.  They were formed in 2017 by a group of Salisbury residents who were trying to address climate change within their local area.  Director Caroline Lanyon explains “When we started we had a simple question: how can we get more renewable energy in Salisbury?”

From small beginnings …

In their early years, Salisbury Community Energy looked at a wide range of possible projects, and all possible renewable energy technologies.  They finally settled on developing a solar power portfolio, as potential hydropower schemes on rivers in the City looked complex due to Environment Agency concerns about the flood plain, and potential opposition from local anglers.

The group started scoping out a portfolio of solar PV projects in Salisbury, mainly on local schools, but with other large community buildings also considered.

Solar on Salisbury Cathedral?

Almost inevitably, someone suggested that the group should approach Salisbury Cathedral about the possibility of installing solar panels there.  However, the group didn’t expect much of a response.  “Local environmental groups had been pushing for the development of a solar array on the Cathedral since the 1990s”, said Caroline “But they’d always been refused”.

But as a new group, Salisbury Community Energy thought it was worth a shot, and they decided to try the door one last time.  To their surprise, it opened!

The Planning Process for Solar on churches

Canon Treasurer Robert Titley from Salisbury Cathedral was instrumental in making the scheme happen. As a local community group, Salisbury Community Energy found a receptive ear as Robert was already implementing a range of green initiatives across the Cathedral, including draft-proofing the medieval building, moving to a green tariff energy and installing LED lighting.  His faith and environmental vision went hand in hand.  “We are called to preach good news, and through this we are taking another small step toward being good news for God’s earth and not just part of the problem”.  Solar panels were an obvious next step, and the idea of a high-profile project appealed.  “It’s important to send a message to the rest of the city”, he added.

At around the same time, the Rt Rev Nicholas Holtam, Bishop of Salisbury was appointed the Church of England’s lead bishop for the environment.  He has recently signed a letter to the Government asking for the environment to be part of its post-COVID-19 plans.  He was naturally fully supportive of the idea of putting solar panels on the Cathedral.

However, before the project could happen, the proposal needed to pass through ecclesiastical planning.  Town planning rules cover development on most churches and local council planning departments adjudicate on them.  But as a Cathedral, especially a unique historical one, the proposals had to pass the scrutiny of church bodies instead.  As one might imagine, it is not an easy process to pass through the many internal committees.  They are very stringent, and rightly so – they do, after all, have a duty to protect these buildings of national importance.

Eventually, the scheme was approved, subject to specific design criteria being met:

  • The panels must not be visible from the ground, or higher ground in the Salisbury area
  • There must be no drilling into the historic structure of the building
  • There must be no damage to the lead roof covering

But just as the project was gaining traction – a new hurdle appeared.  The Government planned to remove feed-in tariffs in April 2019, leaving just months to get this project, and other schools in the portfolio pre-accredited.

The Salisbury Cathedral solar design team

Salisbury Community Energy approached Energy4All’s Schools’ Energy Coop for advice.  They had years of experience in pre-accrediting community energy sites. They agreed to help with early project development stages, such as gaining EPC certificates.  They also managed the financial raise for the scheme when it went eventually ahead.

And this is where Joju Solar joined the team!  As the long-term installation partners for the Schools’ Energy Coop, we were asked to come up with a design that met the ecclesiastic planning committees stringent design requirements.

The project team chose the cloister area for the solar panels. The panels are not visible from the ground, and there is a parapet wall surrounding them.  This helps keep the panels hidden from view but does give local shading issues.  The church left some dummy panels on top of the cloister roof for several months before the build to see if these would be visible from the surrounding area.  It turns out they weren’t!

Because no direct fixings were possible, we decided to use panels mounted on a ballasted frame.  As a roofing material, lead is quite unique in that it is soft, and it moves around a lot as it expands and contracts in the sun.  Clamping on to the ‘broom handle seams’ is not a possibility as it would soon cause a hole around the fixing points.

Joju decided to work with solar mounting system specialists Sunfixings on this project.  Sunfixings have extensive experience in designing solar PV mounting systems for lead roofs and were an obvious technology partner for this project.  The roof has a stepped surface, and is generally a little uneven and not quite straight (it turns out our laser lines are more accurate than 800 years old craftsmanship).  The design team settled on a fully adjustable frame to ensure there was good contact at the right places over the surface of the roof.

It’s not just the panels; of course, there is also the wiring to consider.  The cables were collected under the array, then ran in a discretely positioned basket tray, on rubber feet, following the line of the roof.  The wires ran to the new café and gift shop section, which as a modern extension meant we could finally drill a hole to get the cables to the inverter and consumer unit inside.

Salisbury Cathedral’s Solar Roof

The solar array was finally built on the Cathedral in July 2020, as soon as we were able to come out of lockdown safely.  The system features 37kW of high-efficiency Sunpower 400W modules.

The system was formally opened by The Bishop of Salisbury.  His words, perhaps best sum up the scheme:  “The Church of England is working hard towards a Net Zero carbon footprint by 2030. I am delighted that Salisbury Cathedral is making a contribution that takes us towards this. With clear purpose and helpful partnerships even iconic buildings can make a difference towards sustainability. In these strange times the possibilities of living differently seem all the more important and this project even more significant.”

So, was this iconic project all just a stroke of good luck?  Did it only get built because the community group approached clergy who happened to be passionate about the environment? And then chanced to meet other partners to help with the financial raise, project development, design, and build?

Or maybe we all make our own luck, and the more we try to make our visions a reality, the more likely we are to find others who feel the same way. And then great things can happen. We like to think so, and we expect to see more historic buildings sensitively incorporating solar over the coming years.

 

All photos by the sublime Ash Mills.

Find out more

Rotherham, Metropolitan, Borough, Council, Wellgate, car park, solar PV
September 17, 2019 In

Rotherham Metropolitan Borough Council’s Full Set

Whilst we have seen residential customers installing the complete set of solar PV, battery storage, and electric vehicle chargepoints, it’s something of a rarity at a larger scale.  Rotherham Metropolitan Borough Council, however, have just completed a £600k scheme installing electric vehicle charge points across the borough, combining this with solar PV and battery storage at some of the sites.

Steve Brown, Transportation Officer, explains: “We’ve been very interested in the potential to replace our diesel/petrol fleet with electric vehicles to reduce carbon emissions and address air quality in the borough.  But we were very aware that doing so would increase our electricity consumption, and nationally there’d be a problem generating the electricity.  So we have looked to manage these knock-on effects ourselves by installing an equivalent amount of solar PV at the same time to offset this.”  And it’s not just the amount of new electricity that was a concern: “We wanted to use batteries to store this sustainable energy for us to use when we needed it, rather than when it was available”

Developing the Scheme

The flagship site in the programme is the Wellgate multi-storey car park, which features 5 dual Alfen Eve charge points, 87kW of solar PV and 3 Tesla Powerwall’s for storage.  The solar PV was hosted in a unique way, on the top deck of the multi-storey.  “It’s an odd feature of almost every multi-storey car park in the country that no-one parks on the top-deck”, says Steve.  “They’re massively underutilised assets, so we took the decision to close the top deck and use this space for generating solar electricity.”

An additional five sites incorporated both solar PV and electric vehicle charge points.  Hellaby Depot, Rawmarsh Library, Riverside House, Rother Valley Country Park, and Thrybergh Country Park host 17 dual charge points and 141 kW of solar PV.

Aston Health Centre, Drummond Street car park, Walker Street car park and Wath Library are also home to dual chargepoints, increasing the coverage of the public EV charging network in the Rotherham Metropolitan area.

If we build it, they will come

“The main difficulty we had was whether the scheme would work at all”, said Steve.  “There’s a certain amount of ‘If we build it, they will come’ when developing a chargepoint scheme.  But Rotherham does not have the same level of per capita income as parts of southeastern England, and we didn’t know how quickly the community here will take up EVs, as they are still more expensive than petrol or diesel vehicles.”

Funding from the Government’s Clean Air Fund early measures programme provided the initiative to get the scheme off the ground, and Rotherham Metropolitan Borough Council instructed Joju Solar to install the project, following a mini-tender through the ESPO Framework.  Joju Solar are uniquely well placed to deliver schemes like this as we are one of the largest installers of Public Sector EV charge point programmes, as well as having decades of experience installing solar PV and battery storage.

“Our fears have been unfounded – the chargepoints are being widely used, and people are prepared to use charge points at outlying council offices and country parks.  From our point of view, it’s worked extremely well”.  The Council are seeing the solar PV generation being used on their own sites, reducing bills, and the battery storage is covering lighting requirements overnight.

A Holistic Public Sector Approach to EV Charge Points

Rotherham’s approach appears to be paying dividends, and there’s an appetite for more.  “The whole system has been really well thought out – there’s chargers in the basement for staff and outside for public use.  We’d like to do more of the same – perhaps in innovative locations like schools and colleges as well”.

Rotherham Metropolitan Borough Council’s pioneering scheme is a strong example to other councils, particularly in the way that they have looked at the larger energy picture.   Electrifying transport will inherently increase demand for electricity, and it shows a truly holistic approach to sustainability to consider how this will be provided as part of one installation programme.

Find Out More

  • We’ve developed the Joju Charging Portal – an information hub for public sector bodies looking to install electric vehicle charge point programmes
  • The Rotherham Metropolitan Council scheme was procured through the ESPO framework
  • See how the complete set of solar PV, battery storage and electric car charge points can help in the home
University of Reading, solar panels, Edith Morley, sunshine, blue sky
November 23, 2018 In

Subsidy Free Solar at University of Reading

Reading University have just completed the installation of 168 kW of solar PV across their main campus, and due to a peculiarity of the site, have installed this subsidy free – that is to say without the use of any feed-in tariff support.  Extensions to solar PV systems do not qualify for feed-in tariffs, and with the whole of the campus on one supply, any new PV systems do not qualify for support due to the presence of an existing array on site.  That left Reading University with a choice – install PV without subsidy, or not to install at all.

Reading University did indeed install, as the economic case for them was still strong.  As such, this project forms an exemplar for future commercial solar installations once the feed-in tariff is removed in April 2019.

Opportunities from re-roofing

The scheme focussed on 2 building on the main campus.  The Edith Morley building is the largest building on site, and centrally located.  At 124 kW, this gave good economics due to its scale, and also acted as a very public statement of the University’s drive towards a low carbon campus.

The second building – the Wager building – offered a different opportunity.  The roof was being replaced, and so it made sense to install 44 kW solar PV at the same time as these other roof-works.  With scaffolding typically making up 10% of the cost of a commercial solar installation, there is an immediate cost saving for running the 2 works concurrently.  Again, this is a good guide for those considering solar PV projects in a subsidy free environment– cost savings from sharing scaffolding like this can offset the lack of feed-in tariff income.

Solar PV as part of a carbon reduction strategy

Reading University have an ambitious carbon reduction programme of 45% by 2021, and are already ahead of target.  However, the simpler measures, typically energy efficiency, have already been carried out.  By addressing the ‘low-hanging fruit’ in early years, solar PV now makes increasing sense as one of the next set of measures.  It’s a very good technology for a 2nd wave of energy retrofits, as deep carbon reductions require moving beyond energy efficiency and looking at generation technologies as well.

The Edith Morley Building, for example, gave rates of return on investment of 12% even without feed-in tariffs, which equates to an eight year payback.  Reading University considered this a financially attractive option for meeting their carbon targets.

Complexity in project management

The most complex aspect of the project was coordinating the works on site.  All roof works had to be completed in the summer holidays, and the PV had to follow after the re-roofing works were complete.  This required careful and flexible project management in order to take advantage of the opportunity.  Reading University have indicated that when they are reroofing other buildings they will look to incorporate solar at the same time.

This approach of sharing scaffolding costs across 2 pieces of roof work is something Joju Solar are very experienced at, and one we commonly use in our work on solar schools.

A subsidy free solar future

The Reading University project is an exemplar for solar PV projects operating without any form of subsidy – and where the benefits of the PV come solely from reducing the bills on site.  The project provides pointers to what makes a successful solar project, namely:

  • All electricity is used on site – commercial buildings with high on-site usage give the best economics
  • There is a clear carbon reduction strategy in place across the institution
  • Solar PV has clear role in that strategy, becoming increasingly important once ‘low hanging fruit’ energy efficiency measures have been carried out
  • There are opportunities re-roofing to improve economic case
  • Public space, where a clear statement about green activities can be projected.

Further Reading

Sunpower, Tesla, Powerwall2, installation
June 15, 2017 In

Robert Llewellyn’s Home of the Future

Comic actor, TV presenter and creator of Fully Charged, Robert Llewellyn, is a passionate proponent of new energy technologies. Fully Charged, started as a YouTube channel looking not just at electric vehicles, but also at the way electricity is generated from renewable sources. It’s now a global phenomenon, with live shows across the world. If you’re not following Fully Charged, we thoroughly recommend you do – it really is the best source of news about new energy technologies out there, and puts mainstream media to shame!

Why choose solar and storage?

Robert Llewellyn has had solar PV on the roof of his house in the Cotswolds for some years, but has increasingly felt he could do more.  “I’ve had solar since 2011 and as soon as you have it, you want a battery. In theory, it makes so much sense and for once in life the practice proves the point”.

The design challenge

Robert is, of course, also passionate about his electric vehicles which also need charging at home.  Our brief was to therefore boost his solar generation, utilise a greater percentage of the solar electricity on site, and use any excess to charge his cars.

The home of the future

We upgraded Robert’s existing solar PV system of 2.5kW conventional modules to 16 high efficiency Sunpower 327 modules, totalling 5.23kW.  These high efficiency modules (over 21%) have doubled the generation from his roof space.

In order to use more electricity onsite, we installed one of the first Powerwall2 battery systems in the country.  This Tesla solar battery unit is much larger than conventional battery units, holding an impressive 13.4kWh of energy.  This greater battery capacity matches to the larger PV system – anything smaller would fill up too quickly.

The system works by using excess solar electricity to charge the Powerwall2 during the day.  It discharges in the evening to loads in the house, but by midnight we don’t expect the battery to be empty.  It’s at this point that the Powerwall2 discharges into Robert’s car batteries.  The car batteries then fill any remainder with cheaper night-time tariff electricity.

This approach is perfect, as the battery is completely empty the next morning ready to capture the maximum possible solar energy throughout the day.

It is slightly unconventional to charge a battery (Powerwall2) and then discharge it into another battery (vehicles), and thermodynamically this might not seem sensible.  It is, however, the best thing to do economically.  Robert uses his free solar electricity first, then cheap night-time electricity, with any remaining (on poor days in winter) coming at standard day rates.

Early results were very promising. As Robert said:

“I’ve had the system running for 2 days and my mains electricity usage has reduced by 95%.  Okay, it’s summer, it’s sunny, and over the year I’m sure it won’t manage that, but it’s obvious it will reduce our overall demand on the grid by a substantial amount and utilise far more of the power the panels produce.”

We think this is a perfect example of integrating solar generation, storage technologies and electric vehicle charging.  It’s complex, from an engineering standpoint, as we have to balance PV capacity, battery storage capacity, loads in the house and electric vehicle loads, but we’ve found an optimal solution.  The home of the future is increasingly going to incorporate all these technologies operating in combination.

One happy customer

“Joju Solar have been patient and supportive throughout the install of my new solar array and Powerwall 2 battery system. They needed to be patient due to my constant faltering, budget anxiety and ridiculous schedule.  They fitted the battery in a day, wired it up, stayed longer than expected to make sure it was all working, left the place spotlessly tidy and did a very fine job.” – Robert Llewellyn

And there’s more!

We’ve since been back to Robert’s home for a further install. Watch this space for details.

 

Further reading

  • We’ve developed a free guide to Tesla’s Powerwall2, so you can understand if it is the right option for you.
  • You can see the installation process for Robert’s Powerwall2 in this technical blog
  • The high efficiency Sunpower solar modules are essential to make this system work. Here’s our guide to the most efficient modules on the market
commercial battery storage, sonnen, repower balcombe, sussex, Eco8
May 3, 2017 In

Commercial Battery Storage at Turners Hill School

Good things come in threes for this commercial battery storage system

Background

Repower Balcombe is a community energy group founded as a positive response to threats of fracking in the area.  The group have funded solar PV on 4 schools in the area, including this one at Turners Hill Primary which was installed by Joju in 2015.  With their community benefit fund from existing sites bearing fruit, they decided to set up a battery storage project to understand this new technology better.

Commercial Battery Storage

The challenge for Joju Solar was to design and specify a battery storage system that maximises the benefits to the host school.

The school is typical of a small commercial battery storage system, which has very different characterisitcs to domestic battery systems.  The electricity supply to the school is 3-phase, so we needed to install storage across all three phases.  With 3-phase batteries of this scale not available in the UK as present, we installed 3 separate battery systems, each dealing with the load and generation on that phase.  You can see the three individual storage units, manufactured by Sonnen, in the photos.  Technically the greatest challenge related to the battery’s monitoring – it needs to monitor the extent of import and export from the school and the generation from the solar PV.  The PV system was some 20 meters from the battery installation so we needed to run long monitoring cables as part of the works.

The system operates under a regime where excess solar generation is captured during the day, and used to run the school in the evenings and through the night.  We gathered half-hourly electricity demand data from the school, and undertook a comprehensive modelling exercise to determine the optimal battery size.  In order to meet the evening and night-time demand, we settled on a storage capacity of 4kWh per phase.

The graph (left) shows that we have sized the system almost perfectly. The purple line shows the energy stored in the battery.  The solar charges it up to full capacity in the morning, where it remains until early evening.  Once demand is no longer met by solar, the battery discharges to meet demand on site.  It’s empty again just a matter of minutes before the sun comes up and starts charging it again!  Electricity imported from the grid, shown in pale blue is virtually non-existent; the school is running on its own solar generated electricity.

The installation and the stats

The installation took place at Turners Hill School in Turners Hill village in Sussex.  Joju Solar installed 3 x Sonnen Eco 8 4kWh batteries in just 2 days at the site.

The system is meeting the school’s needs for electricity in the spring/summer/autumn months.  However, it should be noted that in winter there will not be sufficient surplus electricity to charge up the batteries and the system will remain dormant at this time.

For this reason, paybacks for this battery system are long, and in excess of the battery lifetime.  Repower Balcombe were able to fund this project as they already had surplus funds generated for good causes such as this (i.e. saving the school money)

However, do not despair!  Our modelling shows that there are other ways of operating commercial battery storage systems in commercial premises that does give paybacks shorter than the battery lifetime, especially with the good economics of the Tesla Powerwall2 battery.  If you’d like to see how this could work for you, then do get in touch with our batteries and smart grids team.

Further Reading

  • Read how we pioneered storage in the community by installing batteries for social housing tenants in Oxford
  • For larger sites than Turners Hill, the Powerwall 2 looks to be an excellent option, and installs very easily
  • Find our more about our work with community energy groups across the country
January 25, 2017 In

On the grounds of Chilworth Manor

In Autumn 2011 Joju installed a 196 panel ground mounted solar system in the grounds of grade II listed Chilworth Manor, Surrey.

Background

Chilworth Manor is a historic country house located in Surrey. The manor, itself, is grade II listed by English Heritage. In 2011 Joju were commissioned to install a ground mounted solar array.

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