Category: solar

Sooo..after roughly a year, here is a chart showing the solar output from my 2.1kwp ground mounted solar array outside my office window: (The left axis is kilowatt hours, so 1,000w for an hour, or one ‘unit’ of power in the UK).

No surprises really, the usual solar chart, but without all the randomness removed, and showing just how variable things are. I think the reporting screwed up for a few days in February where it suspiciously reports exactly 0 data. If I take a rough approximation from my energy bill, it looks like we use 5.7 units of power per day on average. That’s pretty low. It means we use 2,107kwh of power a year, which compares amazingly well with the data on this map:

http://www.guardian.co.uk/news/datablog/interactive/2012/apr/02/energy-use-map-electricity-gas

But it’s not all good news… if you adjust that graph to show 5.7 units as the base line you can see where we are exporting, and where we are importing power…

Yikes, that’s kinda scary, there are times even in summer where we couldn’t cover our power usage, and winter is just a disaster. Of course, this assumes a constant power consumption per day, because  we don’t have a ‘smart’ meter, and have no real idea, but it’s an interesting stat. Our power generation over those 365 days is 1,276 units, so it’s 60% of our power usage. The cost was about £9,000, which means buying enough home-grown capacity to make you zero-bill would cost about £14,800. That isn’t *that* bad when you consider it’s about 10 years electricity bills, and the panels last 25. but….. The cost of these panels has dropped like a brick, to about a third of what we paid. So in fact, the cost should be about £5k now, to be zero-bill over the year if you have low energy use like me. Also be aware we have an electric cooker. oh yes.

And actually…that’s WITHOUT the feed-in-tariff or any export payments. That’s purely looking at energy prices and installation costs. That’s also with an inefficient ground mounted array in a very shady garden in cloudy south UK.

Have I done my sums all wrong, or is this excellent value for money?

Sooo… One of my non-game ambitions is to run a renewable energy company. It’s my alternate plan if the game industry implodes or I fall out of love with it (unlikely for the foreseeable future). Anyway… I made one tiny step in that direction today by buying this:

Eat your heart out Brad Wardell!

Ok. Not all of it. I admit that. But I now officially own a tiny chunk of it. It’s the largest solar co-operative in the UK, near swindon. 30 acres of solar panels. Insert joke about it never being sunny in the UK here. If you have read my blog for ages, you will know I have some solar panels in my garden. I can see them from my desk! yay! The trouble is, that small scale solar isn’t as efficient as large scale due to the problems of occasional local shading, the economies of scale for inverters, and of course bulk buying discounts. I bet you get a decent discount on 30 acres of PV panels :D  (TBH, wind energy makes a lot more economic sense in the UK, but people like Donald Trump have some emotional hatred of wind energy that they funnel into campaigning against it, making the planning process for it more trouble than it’s worth. *sigh*)

Anyway, I feel very happy about it. I am going to GDC for the first time next year. I try to avoid flying when I can, because I’m a right eco-obsessive. I’ve never gone to a non-uk games event before, and I’m very skeptical that paying the odd twenty pounds to an ‘offset’ scheme really negates the environmental damage of long haul plane travel. My own tiny 10 panel array in the garden doesn’t even cover my own electricity needs, so I’m definitely in net deficit in terms of energy consumption. Until today! wootage.

Even forgetting the green-ness, I’m betting it’s a pretty good long term investment. Maintenance costs for the park are virtually zero, the fuel is free, and relatively predictable, and even the most anti-green government is unlikely to change feed-in-tariffs retrospectively. I’d rather do this than hand the money to some pension fund manager so he can invest half of it in landmines and pocket the other half as commission.

So it’s a year to the day since solar power got installed at positech towers. how much power has been generated?

1,331 kwh.

The panels are installed, not on the roof, but in the drive opposite my office, which is cool because I can just about see them from my desk, over the monitors. There has been a lot of talk about feed in tariffs etc, so I might as well do the math myself.

The install cost was £10,608 according to my old blog post

1,331 units at 43p/unit FIT is £572.33. assume 50% export at 3p/unit gives another £20. Also, I saved buying 1,331 units at 12.5p/unit from the power company, saving another £166. This gives total income of about £758

However, the FIT rose to 45p at some point along that, and the 3p/unit is rising too, so it’s a bit more than that. The FIT is locked for 25 years (index-linked) so the rate cuts don’t affect early adoptors.

At installation, the projected income was £1,029 for output of 1,845, so basically it didn’t generate the estimated power. why? Pretty simply, it’s a combination of shading in early mornings and early evenings through most of the off-peak, combined with amazingly poor sun in the last few weeks. June/July should be bumper months for solar, but the cloudy rainy days have been incredibly bad lately.

A combination of some tree pruning which has reduced (fairly recently) the shading, and presumably a more usual summer next year should mean for a much better return. I didn’t really do it for the money, I am a green-energy geek, but it’s good to know it makes some sort of economic sense. Energy prices are likely to recover their stratospheric climb after the current recession, which will also boost the economic case. Output would be much higher if the panels were roof mounted (and the installation cost would have been much lower).

Anyway, given that the energy my office consumes is certainly not 1,331 units a year, I’m pretty sure I could make a grand claim that positech is carbon-neutral, and do so with a straight face. Pity about the way everything else in modern life, travel especially, consumes so much energy. I gave up eating beef 3 years ago partly because of its appalling environmental footprint, so I’m claiming some extra points there too. (I don’t miss it at all, lamb rocks!).

Anyway, that’s enough tree hugging for one blog post. I intend to have a sudden outpouring of GSB related bloggage soon.

Ok, it’s been about a month, so lets look at some solar stats for the last 30 days. ( I have 10 solar panels outside my office window, for those new to the blog. I’m in the SouthWest UK)

Total power generated is 189 units. That’s 189 kwH, which at market prices is £23.62. Bad huh?

But wait a second… I earn 3p per exported unit (50% is assumed) and 43p Feed-in-tariff, regardless of usage, plus of course the 12.5p per unit the power would have cost me if I’d had to buy it. That means that really, each unit generated earns me 57p a unit, meaning I’ve generated £107.73. If we wanted to go mad, I’d claim 12 months of that is £1,292 :D

Obviously summer output is WAY higher than winter, but as a counter to that, we have had a shit 30 days in terms of sunshine (unusually so, the month before install was insanely bright).

Another reason to be cheerful in terms of future output, is that we have a big tree casting serious shade around 4PM. We knew about this, obviously, but didn’t realise the extent to which the late afternoon/early evening sun was going to be so bright here. Given that, we may well lop a few feet off the top (it’s BIG) and hopefully that should boost output a fair bit.

here is a chart showing the aggregated output over the time of day…

And a chart showing how massively it varies each day:

I’m sure I’ll be equally boring and geeky when we have lopped a bit of the tree and had a few days without it. Of course, then the sun will be lower overall…. Bah. comparing data is such a pain.