Frequently Asked Questions

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 a country'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. In sunnier countries it's even less, and because the power can be generated where it is also used, then transmission losses are also eliminated.

3. Where can photovoltaic systems be built?

A: Large industrial-scale systems are invariably ground-mounted. Smaller commercial generators are 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. Regular rainfall in areas such as in Europe is enough to keep the panels clean throughout the year so washing can be done annually. Dustier countries such as in Africa or the Middle East will require more frequent cleaning to avoid reducing yield.

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 average citizens.

8. Won't the cost of photovoltaic come down in the future? Why build systems now? Maybe we should wait a little longer.

A: The cost of commodity-based energy also fluctuates, so if you think oil and gas prices will fall and stay low for the next 20-25 years, then your economic justification for solar generation may be less compelling. With the easy and cheap oil, gas and coal reserves being depleted however, we think it is more likely that the cost of fossil fuel energy will continue to increase. Many companies we speak to agree and they look to buy solar electricity to protect themselves (or "hedge") against rising energy costs. Furthermore, in countries where renewable energy attracts government support or subsidies, the trend is for these to be reduced as the cost of solar equipment declines. Our view is that if solar electricity is already economically viable for your particular situation, lock those savings in now!

9. Why install photovoltaics in countries such as 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 eliminates transmission losses, and improves the resiliance of the electricity network. Also, large-scale solar generators create both direct and indirect local jobs.

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.