Tesla, powerwall, ev charging, electric vehicle

Chris’s Complete Set

Chris Savage has jumped straight into the smart electric future; he purchased the complete set of technologies offered by Joju Solar in one go.  His home now features a solar PV roof, Tesla Powerwall 2 battery storage, an electric vehicle charging point, and an Immersun device to divert any excess solar electricity into hot water heating.

Driven by his electric car

Chris’s reasons for getting solar and battery storage shows how complementary these technologies are.  Whilst we have seen people with PV roofs going on to get and electric car, for Chris it was the other way round.  “I’m fundamentally green, but it was getting an electric car that pushed me into finally doing this.  I’d been thinking about solar for some years, but it was the idea that it could help charge my car that was most appealing.”  Seeing an episode of Fully Charged about the Tesla Powerwall also prompted Chris to incorporate storage into his home energy upgrade.

The design challenge

Integrating so many components can be complex, so ensuring all aspects work well together is critical.  The system is designed so that the solar produces electricity in the day, which is used or stored in the battery.  The battery discharges in the evening and night-time into lights and appliances in the house, and trickle charges the car.  Chris has a plug-in hybrid Mercedes, which has a comparatively small battery capacity of 6.5kWh, so it’s not a drain on the battery.  Chris has got involved too: “I fiddled with the charging profile on the electric car, so it doesn’t exceed the output capacity of Powerwall”.  On the best days in summer, Chris’s PV system will generate more electricity than even the Powerwall 2 can take, so here any excess electricity is diverted into the hot water tank, using the Immersun, rather than being fed back to the grid.

Turning carbon into a game

It does give you a fuzzy glow to know you are producing your own electricity. It’s very interesting and I’ve been rather obsessive about it! We’ve managed self-powered up in the high 90%’s.  It’s almost a game trying to minimise grid electricity – a bit like driving the car, when we sort of consider it a failure to use fossil fuels

Further Reading

 

Sunpower, Tesla, Powerwall2, installation

Robert Llewellyn’s Home of the Future

Comic actor and TV presenter Robert Llewellyn is a passionate proponent of new energy technologies.  He runs a Youtube channel, called Fully Charged, looking not just at electric vehicles, but also the way in which that electricity is generated from renewable sources.  If you’re not following it, 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 did you chose solar and storage

Robert Llewellyn has had solar PV on the roof of his house in the Cotswold 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, therefore was to 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 Roberts 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 do not expect the battery to be empty.  It is 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 through the day.

It is slightly unconventional to do 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 seem very promising: “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 exemplar of integrating solar generation, storage technologies and electric vehicle charging.  It is 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 look to have 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

 

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

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
fully charged, robert llewellyn

Glenn gets Fully Charged

Glenn Tweedie’s decision to get a Tesla Powerwall and solar PV has led to both energy savings and TV fame!

Background

When Glenn Tweedie decided to have a solar PV array and a Tesla Powerwall installed on his family home in St Albans he probably hoped and expected that it would lead to energy savings for him and his family. What Glenn didn’t plan for was that the installation would lead to internet stardom and a starring role in Robert Llewelyn’s internet show Fully Charged. 

The episode of the show which featured Glenn and his family was filmed a few weeks after Joju installed the system, which included our first ever Tesla Powerwall installation in May 2016.

The Solution

In the Fully Charged episode Glenn talks to Robert Llewellyn about the benefits the Tesla Powerwall has brought to his family and just how much it has lowered their energy consumption from the grid. Indeed, on the day of filming 97% of Glenn’s Family’s energy had come from energy stored in the battery and produced by the solar PV. With only 3% being drawn from the grid thanks to both the 4.5kWp solar array and the Tesla Powerwall working in perfect harmony. Thanks to the SolarEdge PV monitoring platform Glenn and his family can monitor their energy usage via a smart app on their phones and laptops, which has enabled him to show his two sons just how much energy they are wasting when they forget to turn off lights and Playstations.

Getting Fully Charged

The video demonstrates perfectly the benefits of when a solar PV array is installed in sync with a home battery storage solution. The energy savings, the improved family education on energy usage, and even the status that come with having such a complete home energy solution are all highlighted and discussed in depth in the episode.

Watch the film Fully Charged Episode here

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Further Reading

  • Inspired by Glenn’s story, Robert Llewellyn went and got himself the new model Tesla Powerwall2 and an upgraded solar PV system for his Home of the Future
  • We blogged the installation of the Powerwall2 unit live
  • Find out more about our battery offering, and how we work with households

Project ERIC

Social Housing tenants in Rose Hill reduce energy bills through the installation of solar PV.

Project ERIC (Energy Resources for Integrated Communities) is a collaborative research project part funded by the UK government (Innovate UK) to investigate how using innovative energy storage technology can help a community to save energy. Working in collaboration with  Oxford City Council, GreenSquare, Bioregional and Moixa Technology. Joju were chosen as the Solar PV provider for the project. Project ERIC represents a £1.2 million investment in Rose Hill over two years.

Project ERIC’s main aims were to help reduce the energy bills of low income residential tenants in the community while at the same time help generate long-term savings for the council and reduce the carbon footprint of the city. Project ERIC aims to demonstrate that 100% of Solar PV energy generated in Rose Hill can be used by the community.

Joju were proud to be a part of such an innovative and important research project that promoted community energy. We were selected as a partner and collaborator for the Project through the Buy for Good procurement framework, which recognised Joju as the highest ranked provider in the area. The City Council were also keen to select local suppliers to work on the Project.

Joju Solar led the installs of solar PV in Rose Hill alongside the council working to a very ambitious schedule in order to achieve the best possible Feed-in-Tariff. Joju were also supportive in helping the ERIC team support tenants and maximise the learnings within the project.