Tag Archives: Solar energy

Just an innocent bystander?

The more I look into the story of the family that owned a Tesla powerwall (see previous four posts), the more I get the impression that there is more to the story than what meets the eye. In the article (and also the video that was linked to), it was the man of the family who did the talking. He was portrayed as a family man from Kermt (a tiny village with a population of 4.122) who installed a powerwall and this allowed him and his family to reduce their dependence on the power grid.

Yet, I was not really convinced. He looked indeed as an ordinary family man, but he sounded knowledgeable, the video was well made and only the advantages were highlighted, avoiding the disadvantages altogether. It seemed more like a slick sales pitch than an objective news item.

Later I learned that he signed in for the new model of the Tesla (the car). It is a hyped status symbol, not something that an ordinary family man would go for and he probably would have a higher than average salary.

There was also the puzzling tagline on his Facebook account:

Translation:

Here you find all details on the home battery of Tom Nijsen and his strive for an inter-dependent energy landscape.

His strive for an inter-dependent energy landscape?

These are not the words that I would expect from a simple family man.

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The powerwall and clear numbers: a difficult combination

A couple days ago, I read with increasing astonishing a new post on the kermtstroomt facebook account (the account of the family that owns the powerwall that was the subject of last three posts). The subject was the number of days that they didn’t need to draw power from the grid (translated from Dutch):

There are 219 days from September 1, 2016 until April 10, 2017, of which we have been able to bridge 75 days without grid because the sun produced more than we consumed! Thanks to the #Powerwall, which uses the surplus from one day on darker days afterwards, we can pull this up to 100 days. This means that we could do without grid in 100/219 = 45% of the darker half of the year!

Huuuuuuh?!?!

There is so much wrong in only three sentences.

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Easily through the night on a fully loaded powerwall

This is already the third post on the Tesla powerwall series and especially how it is (mis)presented in the mainstream media. This misinformation is not only limited to the mainstream media, it is also strong in social media. The subject of this post is a facebook post by the owners of the Tesla home battery mentioned in previous two posts.

It starts informative with a description of their powerwall (translated from Dutch):

Our home battery is a lithium ion battery with a usable capacity of 6.4 kWh (slightly less than our average daily consumption). We decided NOT to go for the #offgrid option, so when the grid voltage is lost, our battery will also not be able to power us. The battery can deliver 2 kW continuous power, with a peak power of 3.3 kW.

The capacity of their powerwall is indeed somewhat lower than their average consumption. I understood from a previous post that their annual consumption is around 3,200 kWh, meaning around 8.77 kW per day. On average of course, their consumption will be lower in summer (when production is high) and in higher in winter (when production is low).

Not sure whether all this 6.4 kWh is really usable and how long it stays that way (this battery is currently brand new, but lithium ion batteries degrade after a while). But that aside.

It becomes a bit trickier in the next sentence when it comes to the limitations of the powerwall (translated from Dutch):

With a load of 2 kW, the battery is depleted after 3 hours.

Followed by the justification that this is not much of a restriction for them (translated from Dutch, my emphasis):

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Break-even in thirty years (for something that probably will not last half that time)

The half-news show continues. The subject of previous post was the hurrah story from Belgian newspapers about a family that installed a Tesla powerwall. My impression was that things that didn’t fit the narrative were excluded, therefor coming to an overly positive success story. I wasn’t really sure whether this was caused by a wrong interpretation by the journalist or whether it originated from the interviewee.

I found out that the owner of this powerwall had a twitter account and recently started a facebook account in which he writes about his installation and (only) its advantages. Going through the posts, it seems likely that the one-sided positive narrative came from the owner and the journalist probably reported it uncritically.

Reading his tweets on the powerwall, I found a very small glimpse that it is not as positive as it was painted in the newspaper articles and the social media:

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Fully self reliant on solar power for 42 days (out of 210)

From the only-half-of-the-news-will-do department, this newspaper article titled Family from Limburg uses a home battery for one year already: “our house runs on its own power for weeks”. Not only this newspaper, all the other newspapers jumped on the story.

Screenshot article Het Nieuwsblad

Basically, a family from Kermt (a small village in the Belgian province Limburg) has solar panels on their roof and got themselves a Tesla powerwall (translated from Dutch):

For 42 days since the beginning of September, a family from Limburg has already been using the energy they generate themselves via the home battery. By storing the energy from the solar panels, it can be used when the owners see fit. “So our house runs on its own power,” says Tom Nijsen (39).

At first glance, it sounds really nice. A Tesla powerwall was installed, storing the energy produced by their solar panels and therefor making it possible to use that solar energy, even when the sun doesn’t shine. Reducing their dependence on the grid and for some periods even being self sufficient. What is not to like?

The reason why initially my attention was drawn to this article was because three statements in the title and summary were demonstrably false. You just had to read the article carefully to notice it.

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A future for solar energy in the Netherlands: fact check or wishful thinking?

The subject of previous posts was a statement in the second energy fact check of the “factchecker energie” from the Energy Agreement of the SER (Social Economic Council of the Netherlands). The question that get answered in this second fact check is whether solar energy has a future in the Netherlands. This post will focus on how this is answered.

Reading the fact check, it appeared overly optimistic. As with other communication on renewable energy, the author only highlights the positives and ignores the negatives.

This is how the fact check continued (translated from Dutch, my emphasis):

The central planning bureau (CPB) has recently published a report which concludes that solar energy will have a marginal role in the future European electricity supply and wind energy will play an important role. In the most optimistic scenario, solar power fills in up to 8% of the electricity demand. According to the analysis of the CPB, this is mainly because it is so difficult (expensive) to bridge the difference in summer and winter revenues.

Prof. Dr. Wim Sinke of ECN made several remarks on this CPB study. He points out that the CPB is too pessimistic about the cost of solar electricity and is still insufficiently sensitive to the rapid developments in the field of power-to-heat, power-to-gas and power-to-products. The CPB looks only to the electricity system, but not enough to what’s called system integration. By the way, the CPB points in his study also to its limitations, such as the fact that because of the followed methodology, electricity storage cannot properly be taken into account, and it indicates that follow-up study is needed.

If I understand that correctly, the CPB doesn’t believe that solar energy will have much of a future in the Netherlands, but the author of this fact check thinks otherwise. This because:

  1. the CPB is too pessimistic about the cost of solar power
  2. there are rapid developments in the field of solar energy
  3. electricity storage is not properly taking into account in the CPB report.

While that might all be true, it is only half of the story.

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Do wind and solar “complement” each other during winter?

The second fact check of the “factchecker energy” of SER is titled: Is there a future for solar energy in the Netherlands?. Although the author of this fact check admits that solar energy only has a very tiny share (0.1% of the energy consumption) and it needs to be balanced by other flexible energy sources, he is very optimistic about the future. His “fact” check seem to rely on future developments related to solar energy.

As a whole, it seems a quite bland and overly optimistic fact check, but there was one statement that caught my attention (translated from Dutch, my emphasis):

There is a factor of ten difference between summer and winter output of solar panels. What the share of solar power in the electricity mix will be, will depend to a large extent on the developments in electricity storage (for short and longer periods) and of the expansion of the electricity connections with other countries. Wind power and solar energy complement each other in that respect: the supply of wind power is higher in the winter when the supply of solar energy is lower.

That is an interesting statement. Apparently wind energy produces more power in winter and this compensates for the loss of output of solar cells during the same time. I decided to have a look at the data to find out to what extent “wind complements solar”, but also the significance of this phenomenon in a continuous working grid.

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