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

EV Charging Time for Mr Wolff

EV Charging Time for Mr Wolff

What time is it Mr Wolff? Electric Vehicle Charging time of course! Joju residential customer Dick Wolff explains his reasons for having Electric Vehicle (EV) charging installed when he hasn’t even got an electric vehicle yet.

Oxford councillor and Green Group’s Shadow member for Transport, culture and communities Dick Wolff became one of our newest Joju solar PV customers this month. He also became one of our newest EV charging point customers too. A 7.98kWp SolarWorld system on SolarEdge optimisers and metering was fitted at Dick’s Oxford home alongside a 7.2kW eOLEV home charger supplied by EO charging.

The EO home charger describes itself as “the most easy-to-use, reliable and affordable charger on the market.” There is no software required so you can just plug in and instantly get a charge. EO is, therefore, great for customers who want a quick and easy solution. All you need to do is decide the power you want.

Power Miles of charge p/h Charge time Perfect for
3.7kW 15 7hrs Overnight parking

 

7kW 30 3.5hrs At work parking

 

11kW 50 2hrs Parking whilst you shop

 

22kW 100 1hr Quick stop parking

We spoke to Dick about why he had chosen to have solar PV and EV charging installed at his home. Here’s what he said.

What were your reasons for installing Solar PV?

“It’s two-fold really. The first reason is about energy security for our future. We have bought this house for our retirement. It’s a new build and we wanted to take a long term look to our future. We wanted to be less dependent on the grid as energy prices are certain to rise and rising energy costs will be a challenge when we have less income in retirement.

The second reason is to lower our impact on the environment. I have been a member of the Green Party and I am a councillor in Oxford and reducing our carbon footprint and helping to do our bit to fight climate change is important. Together these two reasons make a strong case for why solar PV was a logical choice for us.”

Why did you install EV charging as well?

“We wanted the house to do as much as it could. We haven’t even got an electric vehicle yet but this gives us the opportunity for the future. I know that our next vehicle will be electric so it was the smart thing to do. We have smart metering throughout the house and we replaced the entire gas heating system with an underfloor ground heat pump. Like I said this house is about our future retirement so it made sense to make it a house for the future too.”

Why did you choose Joju?

“Joju had come to us highly recommended. But I was also very aware of them from my work as a councillor in Oxford. I had seen the work they had done in areas of Oxford like Rose Hill and knew they offered high quality products and great service. We weren’t disappointed. Joju have been brilliant. The whole process worked really well. The only delay in the whole process came from the Government and waiting for approval. Joju did everything in their power to ensure a smooth process.”

If you are interested in EV Charging

If you would like EV charging installed then Joju can definitely help. We are authorised to install electric vehicle charging points under the Government’s Electric Vehicle Homecharge Scheme (EVHS), which means that for approved systems, customers like yourselves can now receive grants. For more information on EV charging, approved systems, and how to obtain a grant, please do not hesitate to get in touch.