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Category Archives: Personal

Via Russel Coker of Debian fame, the Boston Globe reports that 55 percent of the world’s installed photovoltaic power is in: Germany. Yay! With my solar roof contributing, if even only the tiniest amount…

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Guess it’s about time to post some update to my photovoltaic roof thingy. The generator is now running for 6 months, without any downtime, and produced ~700 kWh during that period. Right now, that’s about 10 percent below the estimated yield (based on a simulation, which in turn is based on the mean from 20 years of local weather recordings), and has saved the athmosphere around 88 kg of CO2 exhaust (well, not really. First of all, the generator has to earn the energy it has used up for producing and mounting it. This might take some years).

Currently, with the May providing a cloudless sky one day after the other, we’re reaping 20 to 25 kWh per day (could be even more, if it wasn’t so damn hot for the season – thermal effects in the panels now cancel even more of the electrons).

All in all: feels really good.

Operational, and in the sun

Coherent with all the CoolThreads and Eco computing fuzz, this amazing pun occurred to me today: The Sun powers my Sun running Sun Solaris – cute, ain’t it? And even more so, as both that old box and the new T1000 will probably be content with the ~100 Watts my solar generator was producing today (yeah, t’was a rather darkish winter day here in Hamburg) – the Niagara chip is purported to sip only ~70 Watts.

Had my datalogging facility from the solar step-up converter finished & connected today – unfortunately, the data aquisition software comes only for Windows. D’oh. But on the plus side of things is this: Fronius, the converter manufacturer, actually publish the protocol specs!

So, time for some low-level RS232 hacking! This has to work on my brave SparcStation10, being my home comms hub & usually up 24/7.

And on a related note: this is why I’m so in favor of Open Standards.

After some delays (a few parts for my switching cabinet were missing, and took quite some time to order – I’m always surprised how fast things are ‘discontinued’ from manufacturing), we’re now online with my photovoltaic generator!

Notwithstanding low sun and part of the solar modules in shadow, the generator produced an impressing ~1000 watts today at noon. Admittedly, it was a bright, sunny winter day in Hamburg, though.

So, things are mostly done there, with basically only the data logging facility missing (for which I’m really longing for – as it offers oh so many ways to script and analyze data).

Today, the last solar modules were mounted, and we started with the wiring. There’s a total of 20 solar modules, divided up into 5 groups – i.e. four modules are connected in a row, and form a ‘string’, which are two cables individually connected to the DC/AC step-up converter. That’s a lot of wires, which had to be squeezed beneath roofing tiles, glass wool, and other obstacles.

Solar panels mounted

Anybody knew that electricity generated by photovoltaic cells (aka “solar cells”) can be passed into the power grid in Germany? In fact, the local grid company must accept it (and yes, even pay you for it, just the same as it pays the nuclear power plant next door).

Which is a nice thing indeed, as I’ve some square meters of my southwards roof to spend, plus some boxes sucking electricity 24/7 and gnawing at my conscience.

So I went for it, and construction started just yesterday – laying the grounds for a total of 3.1 kilowatts peak solar power.

Preparing roof mounts