My garden and solar panels

My garden is at its best in May, so I thought I’d post a recent photo of the pond. The pond was built at the end of 2007 and mostly planted in 2008. It’s home to tadpoles, dragonflies, snails and water beetles.

garden pondThis made me think about other changes we have made to the house since we moved here in 2003 – and how our solar panels are doing.

The house was built in 1976 and has gas central heating. The main modifications we’ve made have been to make the house warmer and more energy-efficient – they have included fitting a condensing boiler, solar thermal panel, cavity wall and roof insulation (2007), double glazing (2008), a back porch and an energy-efficient fridge (2009), and solar PV panels (2010).

Has this made a difference?

We have utility bills back to Sept 2006 for gas and electricity consumption, and since 2009 have been taking weekly readings of gas, electricity, solar thermal and solar PV panel activity.

From the annual readings, we used 42% less gas and 44% less electricity in Sept 2011-Sept 2012 compared to Sept 2006-Sept 2007 (the last full year before we made major changes).

Annual Gas Consumption (updated May 2015)

Annual Gas Consumption (updated May 2015)

[A note on the measurement of solar hours pumped: when the ethylene glycol in the solar panel gets hot enough, it is pumped around the system and heats the water in the cylinder. The time that the pump runs is recorded. The panel does not heat our central heating, just the hot water (Jonathan has just patiently explained to me again exactly why that is the case).]

The changes that affected gas consumption all took place in 2007 and probably the condensing boiler and insulation made more difference than the solar thermal panel, as it was only properly working by April 2008, and so did not contribute so much in that year.

Annual electricity to 2014 (updated May 2015)

Annual electricity to 2014 (updated May 2015)

It’s more difficult to attribute reasons for changes in electricity consumption, as we made modifications to the house or appliances in most years. Replacing two old fridges with one (large) energy efficient one made an immediate and significant saving. Since 2010 the only change has been to install solar panels. Comparing Sept 2011-Sept 2012 to Sept 2009-Sept 2010, we see a 23% fall in electricity consumption.

Since we (our son, in fact) has been collecting weekly readings since 2009, we can look at this in a much more fine-grained manner.

Weekly gas consumption to 2014 (updated May 2015)

Weekly gas consumption to 2014 (updated May 2015)

The solar thermal panel has made us nearly self-sufficient in hot water in the summer. In 2007 we used 360 m3 of gas between April and September, now we use about 80 m3.

Weekly electricity to 2014 (updated May 2015)

Weekly electricity to 2014 (updated May 2015)

The solar PV panels also appear to have an effect, reducing the electricity that we draw from the grid each summer. We are clearly not using our generated electricity very efficiently (otherwise our summer consumption would be much lower). That could be improved by using appliances more during the day and less during the evening in summer (something we try to do, but have not made huge efforts in that direction). Or of course if we could store the electricity somehow.

Was it worth it?

I’m not even going to attempt a cost/benefit analysis! The improved insulation and draught-proofing (not to mention the pond) have made our home much more pleasant to live in, and the condensing boiler is far more efficient than the old one. I’m less persuaded by the solar panels, which contribute most during daytime in the summer when we are using least energy. But the panels are working at least as well as we hoped they would, the FITs, of course, reduce our electricity bill, and the whole process has made us rather more aware of how we use energy in our home.

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7 thoughts on “My garden and solar panels

  1. Love the pond!

    I had fish in mine until recently when the local cats had a few carryouts. So now I’m going to leave it as a wildlife pond. I already have a satisfying number of creepie crawlies, but nothing more exotic as yet.

    Any tips?

    • Thank you! We decided not to add fish, and just see what turns up. I was hoping for newts, but have not seen any. My only tip is benign neglect! I add a bundle of barley straw each spring when the blanket weed starts to get out of hand – though I don’t know if it works – I have to scoop the weed out as well).

    • The thermal panel got so hot on Friday that the system shut itself down for self preservation; I have never seen that before! It recovered nicely with the cooler (actually, what really matters is less sunny) weather over the weekend and is now working as normal again.

  2. At last this blog lives up to its name and we get to see the pond! Ours is about 10 years old and has newts and frogs of various sizes. This year the cold spring was a bit of a disaster on the tadpole front. The main problem with it is that the plants grow at such a rate that it would revert to a muddy swamp without frequent intervention. Definitely the most interesting part of the garden though (closely followed by the compost heap).

  3. You’ve done an excellent job with the pond – are you using a pond pump with it? There’s many solar pumps you can get to work with your pond – that way you’ll save energy and maintain a clean environment for any animals.

  4. As Paul Matthews says, it’s nice to see the pond of your Blog title.
    I made a small scruffy wildlife pond out of our children’s old sandpit. It attracted loads of frogs, which spawned in Spring. But that’s all but stopped now we have newts. I guess they eat the frogs spawn. Personally I prefer frogs. At least you can see them hopping around the garden.

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