I’m sure we are all aware by now that solar photovoltaic (PV) power is a major player in the renewable energy market. There are solar powered gismos everywhere we look nowadays, from pay and display machines to solar powered lights in our back gardens. What I want to look at, however, are the possibilities and innovations for powering our homes and businesses using solar power. More than simple solar panels on the roof, I will look at how we can build renewable energy technology into the very fabric of our buildings.
While hopefully of interest to the homeowner, this article is aimed more at small businesses looking to invest in renewable technology. I want to talk about some of the newer technologies that exist, how much they may cost and the amounts of energy they can produce. Without venturing down the path of Tomorrow’s World and telling you what you may be seeing on the house of the future; almost everything I am going to highlight is currently in production and available for purchase. Look at this piece as catalogue for the solar connoisseur. First of all though, connoisseurs aside, and seeing as this is a learning portal, I will give a very brief description of what solar PV is and how it works.
What is solar PV and how does it work?
The word photovoltaic is derived from photos, the Greek word for light, and volt, the force that causes an electric current. Photovoltaic, or PV, solar is not to be confused with solar thermal energy; PV creates electricity from the light present in solar radiation, whereas solar thermal energy utilises the heat. This is why solar PV will work on a cloudy day – albeit a lower strength – whereas solar thermal energy will not.
In the most basic terms, a solar PV cell is made up of two pieces of silicon crystal, each ‘doped’ with an impurity (usually phosphorous and boron) to create a p (positive)-type crystal and an n (negative)-type crystal – these form what are called semiconductors. These are then placed together with a wafer thin layer of p-type silicon attached to a thin layer of n-type silicon. When particles of light energy (photons) hit the solar cell, the electrons within it get excited and start to move around leaving ‘holes’. As the electrons roll downwards to fill the holes and the holes drift upwards, you effectively have a flowing electric current. So, you then connect your cells together to match the appropriate power required and form a solar array, hook up an electrical devise, let the sun shine and away you go. Got it? Great. Obviously it’s a lot more complex than that, but what I want to concentrate on here is the technology itself. These following examples incorporate solar PV technologies far more advanced than that described above. What I have explained are the very basics of solar PV. Presently on the market and in development are thin film PV technologies, flexible PV cells and even PV based around nanotechnology – cool. Anyway, back to present…
Solar roof tiles
It is possible to have solar tiles, or solar slates as they are also called, installed on the roof of a building. These work in the same way as regular roof tiles except for the fact that each one is a small PV module. From what I have seen there are two types of solar slate: One looks very similar to a more conventional array, except that it fits flush with the roof, as opposed to being mounted on the roof. The second type of solar tiles actually resemble ordinary roof tiles in size and colour, although they have a distinctive blue hue to them. Solar PV tiles can make up either a part of the roof, or the whole thing, and will not alter the shape of a building in any way. If integrated into a roof they will almost always be at the right orientation, although a solar array should ideally be installed on a South-facing roof. Additionally, it will save on costs significantly if the tiles on the roof need replacing anyway, this way you can offset the price of the PV tiles against the price of new traditional tiles.
Solar cladding
Solar cladding is primarily of use to the business that lacks enough space to lay down a solar array. It consists of solar PV arrays that are specially constructed to provide the façade of the building while simultaneously powering a proportion of it. The PV modules are fitted over the building’s frame (stone, brick, render, etc.) and then connected up to the electrical system. Using solar cladding will increase the potential space available for the placement of a PV system and should also be considered by those who do not have a roof to mount a solar array on, for instance those based within an office or apartment block. It will also give a building that ‘futuristic’ look – a great way of shouting “look at me, I’m saving the planet!” and also offers the opportunity to turn your building into a local landmark. Costs wise, the technology itself will be on a par with roof-mounted systems, but the fitting to the building (instead of the roof) will cost slightly more.
Solar PV windows
My personal favourite of these technologies are solar windows. OK I admit this is a little look to the future, but solar PV windows really are just round the corner. They work by adding a solar PV module onto the windows of a building using thin film technology, or replacing the window altogether. The upshot is that you can turn all of your widows in to PV panels, using the sunlight that comes through them to light the building, heat the building and power the building. The downside to this technology is that the windows become a little foggy, but hey, you can’t have everything. There is also talk of dyes in the window glass that can concentrate the photons and direct them into PV cells within the window frame itself, thus reducing the need for the whole window to be covered in PV cells. Clever. This is, unfortunately, not yet commercially available.
Although they will be expensive, solar windows are an option for those wishing to start generating their own electricity, who perhaps don’t have a suitable roof or own a listed property. I have already written an article on double glazed sash windows for period properties – perhaps we could someday see double glazed solar sash windows (You heard it here first).
The costs
It’s no secret that PV energy is expensive to install. However, there are ways of making it cheaper. The first one is to look for a grant. There are many of them out there and a quick Internet search should soon prove rewarding. There is also the feed-in tariff (although this will probably replace the grant). Feed in tariff arrangements allow the renewable energy user to sell back any unused electricity to the grid as well as paying for any electricity created. I hope to write a separate article on this very subject, so watch this space.
An average solar PV system will cost around £8000 – £14000 (Energy Savings Trust), but these prices can vary a lot. It is completely dependant on the energy needs as to how much PV has to be installed, but a supplier will be able to give an estimate.
Searching the various suppliers on the Internet has given me some very approximate figures for the above technologies. These are only a rough guide for information purposes and will vary depending on factors such as the type of system to be used, the size of the installation or the company doing the work. You would need to have your own survey done to get a more exact figure.
Solar Tiles £140 – £250 per m2
Solar Cladding £100 – £120 per m2
Solar windows – £TBC (Expensive, I would imagine)
The savings
The general consensus on solar PV – if the system is sized correctly – is that it will generate about 40% of domestic energy requirements. For businesses this figure will depend on the electricity requirement and the size of the system installed, but you should also be looking at about 40% savings on your bills. As a rule of thumb, when working out the carbon savings that can be achieved, you can assume that for every 1000kWh of electricity created from renewable sources, you will save just over half a tonne of carbon. To maximise the amount of useful energy from a PV array, it pays to use as many energy efficient appliances and light fittings as possible. It’s also worth noting that solar PV is particularly good for businesses that operate within normal working hours, i.e. 9 to 5, as the demand (electricity) is in sync with supply (sunlight). It is possible to connect batteries to harness any surplus power, but these are expensive and space consuming. Setting up a feed-in tariff to return surplus electricity to the grid is probably a better option. It also reduces the need for that electricity to be produced form burning fossil fuels, saving on carbon emissions and pollution.
One quick note about maintenance: there are no moving parts in a PV array so they require very little maintenance, except a good clean every now and then.
In summary then, if this article hasn’t persuaded you to immediately run out and purchase the latest in solar PV cladding, then I at least hope it has been informative, maybe sparked a little interest in solar power and shown that renewable energy is more than simply wind turbines and solar panels. There are all sorts of up and coming technologies out there and if you look around the learning portal you are bound to find lots more. I appreciate this article may seem set slightly in the realms of the future, but why should it be? The more people who jump on to the solar bandwagon now, the cheaper it will become. Those who invest in these technologies now will be seen as the trailblazers of new solar technologies – that’s sure-fire way to improve your green business’s brand, is it not? So, if you are I the market for solar PV, don’t simply think in terms of roof-mounted systems; there are many options available.
