Nov 01 2016

Tesla’s Solar Shingles

tesla-solar-shinglesI revealed recently on the SGU that I have had solar panels placed on my roof. This is something I have been thinking about for a while, but was putting off mainly because I was waiting for the next big solar breakthrough. I eventually came to accept the fact that improvements in solar efficiency and cost were continuous and incremental, and there would probably not be any significant game changer, so there was no reason to wait.

I decided to go with a company that assumes all the installation costs and then sells you the electricity for cheaper than what the power company is charging. This can be tricky, and you need to do some research before you commit to a contract. It may be more advantageous for you to buy or lease your solar panels, if you can afford the upfront costs or financing.

If you decide to go with a contract like I did you need to make sure your state has good net metering laws. This means you will get full credit for any electricity you put back into the grid. You also need to read the fine print, and make sure that your electricity prices won’t increase dramatically after an initial period.

I was pleasantly surprised that, living in Connecticut, my roof could hold more than enough solar panels to produce 100% of the electricity I consume averaged over a year. So, for no upfront cost I get cheaper electricity and a lowered carbon footprint.

Tesla Enters the Solar Industry

Elon Musk is as close as we come in real life to a comic book character – a billionaire looking to change the world through visionary technology. He definitely has a Tony Stark vibe.

His vision for colonizing Mars has been getting a lot of attention recently, but he has another vision that is more realistic, and definitely can be implemented in a shorter time frame.

His company, Tesla, is mostly known as a car company, making fully electric vehicles. The first models available were upmarket, but the Tesla Model 3 is meant to be an entry level car with a broad market. Pre-sales are apparently doing very well, and they will be available in 2017.

An affordable all-electric vehicle is only part of Tesla’s vision, however. If the electricity to recharge the car is produced by burning coal, the environmental benefit is minimal. That is where the other two parts of Musk’s vision comes in – solar panels and battery storage.

The Tesla Powerwalls, also available in 2017, are designed to be backup power for your entire home. With one unit installed for about $6,500 the company claims you can run a typical three bedroom home for one day. That would be a nice home feature for the occasional winter blackouts we have here. About once a year or two we lose power for a day or two. It would be nice to have seamless backup power, without needing to run a generator.

The real purpose of the Powerwall, however, is to enable solar power to be more functional and independent. One of the limiting factors in using solar to displace other energy sources is that the sun only shines during the day. Solar peak production misses peak energy use by about an hour or two, depending on time of year, and so solar alone would not have a dramatic effect on peak capacity on demand energy production.

Also, for early adopters, we can use the grid as our backup. We take energy from the grid when we need it and put energy into the grid when our solar panels are producing more energy than we need. However, once we get to about 30-40% penetration, we will exceed what the grid can take from distributed solar production.

This is a huge problem for further home solar installations. If you cannot essentially sell excess production back to the grid because it is already overwhelmed and doesn’t need it, then the cost-effectiveness of installing solar goes way down.

The obvious solution is that we need massive energy storage, which is where the Powerwall really fits in. If you have solar panels and a few Tesla batteries to store the excess energy, then you don’t need to rely as much on the grid. This can also displace your solar energy to peak demand, and actually reduce the need for peak capacity in the infrastructure.

Your Tesla car also serves this role. If you are charging your car from your solar panels, the car battery is another way to capture that power without putting it into the grid. Further, you are driving your car with clean solar power.

Musk’s vision, therefore, is to have solar panels on every roof, an all-electric car in every garage, and enough battery storage to make intermittent solar power available when needed. It’s a bold vision, but completely plausible. It also works incrementally. We don’t need to achieve complete solar independence before it is useful.

Latest News

The latest Tesla news in Musk’s drive to achieve this vision is his unveiling of solar panels made to look like roof tiles. The idea here is that you can have solar panels without the look of the bolt-on variety – they will look as good as a regular roof. They are also very resilient – stronger than slate or clay roofs. They will serve as both solar panels and a protective roof covering.

Solar roof shingles is nothing new. They have been around since 2005. They are starting to come down in price and improve in efficiency. Tesla claims his shingles are 98% as efficient as regular solar panels. Of course, efficiency will continue to slowly improve and prices will continue to come down.

The Tesla roof shingles are part of Tesla’s proposed acquisition of Solar City, a struggling solar company that Tesla has offered $2.6 billion to purchase (this still needs to be approved by Tesla’s board).


I admire Musk for his vision of three integrated technologies all designed to create a solar economy. He is correct that these three components – solar panels, battery backup, and electric cars – all work together.

Right now I think the weakest link in this chain in the battery backup. Solar panels are already crossing the line to being cost effective, depending on your local conditions, and this will improve a little bit each year. At some point in the next decade or so it will become silly not to have solar panels on your house.

For both the electric cars and the Powerwall, the battery technology is the big expense and the limiting factor. Battery technology is also improving incrementally, but I do think this link in Musk’s vision is lagging behind the other components.

The problem is that battery technology is very difficult, because in order to be useful a battery has to have many simultaneous beneficial features. It needs to have high energy density, fast charge and discharge rates, many discharge-recharge cycles, it needs to be stable (not burst into flames), and be made out of material that is abundant, cheap, and ideally non-toxic. Lacking any one of these features is a potential deal-killer.

The one thing that would go the longest way to making Musk’s overall vision a reality is a breakthrough in battery technology that gives us something like an order of magnitude more storage for the price/volume/weight. Suddenly electric cars are a no-brainer, as is home battery backup.

There is a lot of battery research going on, but there always seems to be a key ingredient missing. We may have to be content with incremental improvements. I think Musk’s vision is a good one, and I think we will see some version of it in the near future. If he wants to advance his vision the quickest, my sense is that he should invest heavily into battery research. He, of course, is. But perhaps this needs to be an even higher priority – higher than pretty solar panels.

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