1. I've heard that solar panels take more energy to produce than they collect over their lifetime, is that true?
A: No, that's a persistent myth, which comes from the very beginnings of the use of photovoltaics. Todays's panels earn back the energy required to make them in about 1.5 to 3 years, depending on the specific technology. Given that they can be expected to operate for 25 or more years, there is time enough to earn back the energy invested - plus a very healthy "energy dividend".
2. Wouldn't it take vast amounts of land if one wanted to cover more than a small fraction of the UK's power needs from photovoltaics?
A: No, actually it would not take much land. Generating 10% of the power consumed in the UK - maybe a realistic interim target for photovoltaics - would require only about 0.5% of the land surface area of the UK.
3. Where can photovoltaic systems be built?
A: Commercial PV systems are commonly installed on large roofs such as airports or factories, on sound barriers along rail tracks of motor ways, on top of car parks or simply on the ground. What's required is a space with little to no shading, a stable surface to build the system on, someone or something that needs power - or access to the electricity grid.
4. Wouldn't hail or lightning destroy a photovoltaic system?
A: Photovoltaic modules use glass that can withstand hail. They are designed to withstand the impact of ice projectiles with diameters from 12.5 to 75mm and a velocity of up to 140 km/h. Lightning strikes represent a risk to any electrical system, not only in the event of a direct hit, but because the electromagnetic fields that accompany lightening can induce currents. It is important to design a photovoltaic system with adequate lightning protection - which can be done.
5. What is thin film photovoltaics?
A: Every photovoltaic module has a light-absorbing layer, where the conversion of light to electric current happens. Most modules installed today use cells where this layer is about 0.2 mm thick. Thin film photovoltaics uses significantly thinner light-absorbing layers, to gain a manufacturing cost advantage. However, so far this comes at the expense of some efficiency. Therefore, a thin film installation requires a somewhat larger area. Which technology is "better" needs to be decided on a project by project basis.
6. Does a photovoltaic system need to be washed regularly?
A: Usually not, and in a country with regular rain fall like the UK, that should be enough to keep the panels clean. If there is an event that causes heavy soiling - nearby construction, for example - it can be advisable to clean the panels, much like one would clean windows.
7. How much CO2 does a photovoltaic system save?
A: For the UK, a photovoltaic system of one megawatt capacity would save about 500 tons of CO2 per year. That's the total CO2 emissions of about 60 of us, on average.
8. Won't the cost of photovoltaic come down in the future? Why build systems now? Maybe we should wait a little longer.
A: There are three answers to the question. Firstly, looking at the profitability of a single project, the renewable energy cashback is set to decline in the future precisely to compensate for anticipated cost reductions. There is therefore little point in waiting. Secondly, as a country, the UK could wait and continue to let others install systems in the early phase, when costs are high - which is what we've been doing for the last 10 years or so! In that way, we of course also miss out on all the technology development that comes with deployment. Thirdly, how much time do we think we have to build up alternatives as pollution builds in the air and fossil fuels run out?
9. Why install photovoltaics in the UK? Wouldn't it make more sense to install this technology in sunnier countries, and transmit the power?
A: Yes and no. Clearly, photovoltaic systems installed in Greece or Spain have higher yields - about 1.5 times higher than in the UK. On the other hand, installing generation capacity close to demand has advantages because it saves transmission, and gives the electricity system more resilience. Also, jobs will be created in the UK if systems are installed here.
10. Does a photovoltaic system cause electromagnetic pollution?
A: Like any electricity conducting installation, photovoltaic systems cause measurable electromagnetic waves and fields in their immediate environment. However, at a distance of about half a meter, the magnetic fields are weaker than the Earth's natural magnetic field. Also, at night, there is no electricity generated and therefore, there are no fields or waves at all.
Some answers to questions that often come up
