Saturday, 11 January 2014

cloudy afternoon

Here’s today’s solar PV electricity generation, from sunrise (8:05 GMT) to sunset (16:09 GMT), with data points every 5 minutes.  We generated 25.1 kWh in total.

vertical scale: kW; green line: total energy generated; blue line: energy generated from top row of 15 panels; brown line: energy generated from bottom row of 12 panels

Despite the weather forecast being for clear skies all day, there were large clouds this afternoon for the sun to hide behind.  So we were right to run the washing machine this morning.

Maybe it was hiding because of its spots.

Today’s sun, with its enormous spots. Image from NASA’s current solar images page

Friday, 10 January 2014

PV chart II

Here’s today’s solar PV electricity generation, from sunrise (8:06 GMT) to sunset (16:07 GMT), with data points every 5 minutes.  We were getting nearly 6kW at one point!  We generated 19.8 kWh in total, twice as much as yesterday.

vertical scale: kW; green line: total energy generated; blue line: energy generated from top row of 15 panels; brown line: energy generated from bottom row of 12 panels

The scaffolding was removed during the morning, and hence isn’t shadowing the lower row of panels in the afternoon.  So the brown line is closer to the blue one then.  It was sunny all morning, and a little hazy all afternoon.  We have a very sensitive sunshine detector!

Tomorrow’s weather forecast is for sun all day, so I’ll post one more chart, but that will be enough, as I suspect that they are really of interest only to us.  (There will probably be some monthly and annual stats, of course.)

book review: Reamde

Neal Stephenson.
Reamde.
Atlantic. 2011

Richard Forthrast is an ex marijuana smuggler, and now millionaire owner of Corporation 9592 that markets the massively multiplayer online game T’Rain, a world with accurately depicted geology and a massively detailed backstory, designed to incorporate earnings from Chinese gold farmers. A member of his extended family, adopted niece Zula, is kidnapped when her boyfriend accidentally infects a Russian gangster’s computer with the REAMDE virus, T’Rain-based ransomware that has encrypted the wrong files this time. But when the Russian gangsters collide with Islamist jihadists while searching for the virus writers in China, being monitored by an MI6 covert ops agent, things rapidly spiral out of control into bloody violence.

Like Cryptonomicon, this 1000 page brick is a techno-thriller with an SF vibe (but a lot more gun-porn). It seems to simultaneously run at breakneck speed whilst the plot advances with glacial slowness, due to the typical Stephenson-esque crazy eye for detail. This detail is rendered with an SFnal style, describing all the “alien” cultures, from urban China, via Oxford colleges, to backwoods Idaho. Stephenson also manages to make several of the characters more sympathetic than you might at first believe possible.

And Stephenson has mastered endings. Unlike earlier offerings, this doesn’t merely stop; it has a conclusion. The conclusion isn’t totally satisfying – there seem to be copious loose ends left in T’Rain, and several small guns left hanging on real-world walls. But the overall story ends.

What is for me the best part is the way everyone’s “best laid plans” are thwarted by the others executing their own best laid plans. There is no easy linear progression of the hero: all the different arcs interact to scupper, or sometimes support, each character’s intentions. And most of the characters are competent – even the mad guys and the bad guys – which is so refreshing after the usual issues of plans not surviving scrutiny by a 4-year-old.

Definitely worth reading. And best use of a Love Actually DVD ever.

For all my book reviews, see my main website.


Thursday, 9 January 2014

time for a radical reform of the welfare state

Why we should give free money to everyone.
‘Poverty is fundamentally about a lack of cash. It's not about stupidity,’ author Joseph Hanlon remarks. ‘You can't pull yourself up by your bootstraps if you have no boots.’



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PV chart

We downloaded today’s data from the inverters this evening, and we can see the electricity we generated, from sunrise (8:06 GMT) to sunset (16:06 GMT), with data points every 5 minutes.

vertical scale: kW; green line: total energy generated; blue line: energy generated from top row of 15 panels; brown line: energy generated from bottom row of 12 panels

The top row of panels didn’t start generating until later, as they need a bigger voltage to kick their inverter into life.  It was cloudy and gloomy in the morning, but around midday, the low winter sun came out, and generation leapt to 4kW.  The afternoon stayed sunny, and the curve is essentially tracking the setting sun, with occasional cloud.

The brown line is somewhat less than 12/15 = 80% of the blue one, partly from shading from the scaffolding poles (due to be removed tomorrow), and partly from being lower on the roof.

That’s a total of 9.5 kWh generated on a winter’s day, when the sun was above the horizon for a total of 8 hours, and it was cloudy until noon.  So that’s about £1.30 due from the feed-in tariff.  Not bad.  Now we have to replan our electricity usage patterns to coincide with when the sun shines.

PV generating

Today was the first full day of PV solar generation.  We weren't particularly hopeful, as the forecaset this morning was quite gloomy

gloomy, but not as bad as the same forecast yesterday
It now being light, I had a chance to see the full installation.

all 27 solar panels installed
By noon, this lot was generating over 4kW, which is about 50% of total capacity.  That's not bad, given how low the sun is this time of year (which you can tell from the shadow of the soil stack in the middle of the roof), plus shadows being cast by the scaffolding.  Given our idling consumption seems to be around 1kW, we are now officially an energy exporter!

Also note the colour of the sky.  Blue, and clear.  At noon.  And it stayed blue and clear for the whole afternoon, until around sunset (4pm).  So much for weather forecasts.

Wednesday, 8 January 2014

magnets are cool

Here’s a small plastic bag, containing a really really small magnet, with a pair of pliers for scale.

the magnet is the tiny grey square in the bag

Here’s that same really really small magnet, easily supporting the entire weight of the pliers.