Solar Power, like coffee, is performance enhancing; but you have to know when too much is no longer having an effect. And by this I mean, it won't have the carbon reducing effect we all want it to.
This week came the news that almost certainly all new homes built in the state of California, will have to have solar photovoltaic (electricity generating) panels on their roofs after 2020. Given the state is famous for it’s sunshine and electricity shortages, this would seem to be a no-brainer decision. And in many ways, it is. Electricity use in the U.S.A. tends to go up in summer when the sun is out, because of the use of air-conditioning to cool homes. That means solar power and power use at home are sympathetic, and home-owners will save energy and money, even when you consider the higher mortgage cost to fund buying the panels.
The UK however is not California. When the sun is out in the UK, the electricity grid demand is typically at its lowest, as people turn-off their heating and lights, and go outside. There is nothing better than a British summer, as the saying goes. As in California and elsewhere in the World, many new UK house builds are coming with solar power panels on the roof as a means to pass Government energy regulations, that themselves are set to reduce carbon dioxide emissions and halt climate change. But if the UK home-owner isn’t indoors to use that electricity then who is using it? Well the answer is that the grid is using that energy, and very grateful they are for that energy, to power factories, offices and shops. With home-owners over a year only using around 35% of the electricity they produce from their solar panels (Source: The SolarBlogger) a huge 65% of the electricity ends up on the electricity grid. In a balancing act this surplus sunshine causes gas-fired and other fossil fuel power stations adding to the grid to shut-down, meaning the electricity grid becomes less carbon intense and more ‘green’. This is great for our carbon targets but can cause the paradoxical situation where we have too much electricity on the grid. But that isn’t the only issue, another issue is that it causes us to ‘overestimate’ our carbon reductions. With every new set of solar panels that are installed on roofs around the country, the amount of carbon dioxide they are actually displacing goes lower and lower. This year the fossil fuel stations may be off for only a handful of gloriously sunny days over the year, but in a few years time they may be off when it’s overcast. At this point, any extra solar panels that we add to the grid don’t reduce any of our carbon emissions, as there are no more fossil fuel power stations left on the grid to disable. The electricity has no carbon reduction value, whatsoever.
However, if we continue as we are adding solar panels to the roofs of the 100,000’s of new homes we are building around the country, all in the name of carbon reduction, we won’t actually be achieving any, or at best not as much as we think. Don’t misunderstand me, solar power is a great thing, and every home owner should consider solar panels, but once we pass a certain point with the grid, we are not reducing carbon emissions, we are just pretending we are.
The problem is in the way that carbon emissions are accounted for, especially in new build homes and in the giant excel spreadsheet which is called, the Standard Assessment Procedure (SAP). In this document electricity produced by any home with self-generating technology can create ‘carbon’ credits, that can then be drawn down over the course of the year. By this method you can have a net-zero carbon home, the emphasis here is on the ‘net’ part, meaning your self-generating technology has generated more electricity than you have used over the course of the year. In the case of solar panels, this means your panels have produced more electricity in the summer than you use all year round. And therein lies the problem, when solar panel power was guaranteed to reduce fossil fuel power plant emissions, you were indeed reducing carbon emissions in the summer, to cover what you were producing in the winter. However, as more solar power goes onto the grid this no longer holds true. Additional Solar power exported to the grid could have zero effect on the carbon emissions throughout the summer, thereby not offsetting real carbon emissions in the winter. This means we think we have reduced carbon, whereas we actually haven’t, it’s just an accountancy error. Taken to the extreme, we could have every house in the country with solar panels, producing a huge amount of ‘credit’ in the summer, but this doesn’t make our carbon emissions from our heating in the winter disappear.
The SAP could adjust, it should adjust. It could either place hard limits on the number of new houses that can be built with solar panels or reduce the average carbon saving of every house with solar panels. The former suggestion is sensible and makes a gap for other energy saving technology to flourish, but seems rather harsh and clinical, while the latter has a flaw in that developers might react to a decreasing carbon saving per panel by just putting more panels on, thereby accelerating the problem. Metaphorically, it is like coffee addiction, you either decide to limit your caffeine intake so you can enjoy the buzz, and give you space to enjoy another type of drink during your break, or you can just keep drinking more and more in the hope that it’s still making a difference.
About this blog
I have been involved in the field of energy for nearly 20 years, so I have a deep relationship with the subject.