Monday 23 May 2016

In Praise of Small Things

Are we too Quick to Criticise Housebuilders for Small Solar Installations?

Those crazy housebuilding companies!   Imagine deciding to install solar on a new home, then only fitting a measly one or two panels!  It’s tick-box solar, a pointless waste of time.  What a shame!  What a missed opportunity!  Boooooo!  So goes the usual reaction from the solar industry.

For sure it is driven by ticking a box, achieving a target carbon emission level for the property and perhaps also achieving a site-wide planning target for renewable energy.  But so what if its small?  Is bigger always better?  Why is 4kWp the gold standard for a domestic solar installation?

I already feel that I’ve set myself quite a challenge, but I’m going to have a go at convincing you that there is something truly magnificent about these small-but-perfectly-formed solar installations.

Let’s start with self-consumption.  As I discovered while researching this topic for a talk at SEUK last year, (and wrote up in a blog here), even houses where people are at home during the daytime don’t use that much electricity when the solar is at a peak.  If it’s sunny at lunch time, people are sitting outside eating sandwiches, not arc-welding in the basement.  

Yes, you can shift some consumption, but there’s only so many clothes to wash.  Yes, you can dump your excess in a hot water tank, but you’re only saving the cost of gas heating in most cases.  Yes, you can charge an electric vehicle (unless you’ve driven it off to work).  And yes, of course you could put the excess in a battery for later.  But if you put a small system on a home it simply meets the base load.  In the homes I looked at data for, the base load was between 25 and 75 Wh/10 minute period.  Around 150 to 450W.  With a small system, everything you generate, you use.

And another thing.  Aesthetics.  Some roofs can take a 4kWp system, no trouble and still look great.  But it is a really quite big area to accommodate.  Other attempts to fit as much solar as possible on a roof are less successful.  Smaller homes, buildings with dormers or roof windows, these often look much better if a more compact and bijou solar system is installed.

The drive to 4kWp came from the Feed in Tariff banding, encouraging people to size for the greatest amount of subsidy they could get.  In this new low-FIT and soon-to-be post-FIT world we need to re-think what a solar installation has to be.  Small solar systems and lots of them can add up to a great deal of emissions reduction without stressing the grid.  Manor Solar is about to start installing Clearline fusion on new homes near Peterborough - it might only be 500Wp per house but there's 3,000 homes in the development - I make that 1.5MWp from one development.

Have I convinced you that small is beautiful?  Let me know what you think leave a comment below!

Fundamentally, if the solar industry wants house-builders and construction companies to use more solar, it should make the case for it, and do so in terms that are meaningful to the people we hope to convince.

Fortunately, solar has a great deal to offer the construction industry.  My next blog will look at this.