A fresh look at solar

A fresh look at solar

Amidst the discussions about solar subsidies, have we lost sight of some of the main benefits of producing your own clean electricity from the sun? How important is sizing when it comes to installing a solar PV system and what are the other ways we can make use of solar power on-site?


Recap of the advantages of solar PV

  1. Reliable energy supply – the amount of sunlight hitting the earth is only expected to vary by 0.1%. This is a known factor and we also know how long each day in the year will last. Weather affects the amount of sunlight (irradiance) hitting our panels. In the UK, daily weather can be highly unpredictable but when you look at the average weather conditions over a longer period of time we would only expect a +/- 10% variation based on historical data. 
  2. A free supply of energy – solar PV systems utilise a free and clean supply of energy from the sun. This means you are not subjected to fluctuating fuel prices and you can guarantee a supply of energy as long as the sun shines!
  3. Low carbon energy – a common misconception is that solar panels require more energy to manufacture than they will produce. This is simply not true and we would expect the energy payback of a good quality panel to be as little as 2-3 years in the UK, even when you take into account the associated carbon from shipping, installation and decommissioning. This means solar can be used in your carbon reduction strategy to help meet targets and legislation.
  4. A fast and flexible energy solution – solar PV is a highly flexible technology that can be used across a range of sectors and in a variety of environments. It is easily scalable and can be installed quickly, with minimal disruption to your business’ daily activities.
  5. Few planning restrictions – unless you are building a multi megawatt solar farm or proposing installation on or near a listed building then your solar PV system should easily be approved for planning and in many instances planning is simply not required. This is contrary to other renewable electricity systems like wind and hydro that can undergo many months of planning before a project can commence.
  6. We know it works and we can prove it – solar PV is a long-standing technology that has been tried and tested in the UK for many years. Every system installed by GMI Energy is fitted with advanced monitoring hardware that enables us to track its performance. We know that our systems are performing 11% above their forecast on average. Furthermore, a 2012 study conducted by the University of Sheffield found that 92% of UK systems monitored for 2 years are performing on spec or above.


Sizing a system to maximise revenue

Although solar has numerous benefits, we need to also ensure that it remains a financially viable solution. Maximising revenue from solar requires a very careful balance between the number of hours of production versus cost, usage and losses when the system is producing more DC electricity than it can output as AC electricity.

For larger sites it is a good idea to consider first installing monitoring equipment to gather the necessary data, such as half hourly readings, that can then be analysed and fed into advanced modeling software before being compared with our existing solar site data to make a recommendation.

It may come as a surprise to know that it often makes more financial sense to over-size your system, despite the fact there will be increased losses when the system is producing at over-capacity (i.e. more DC electricity is being produced than can be converted into useable AC electricity by the inverter). This is because the falling costs of solar panels are completely shifting the traditional metrics of design in solar.

With this type of design there will be a greater period of time when your system is producing the amount of electricity you require on site (baseload) and you will benefit from self use savings (direct savings made by using your own free power supply rather than purchasing expensive electricity from the grid). It is also important to consider that larger systems increase the revenue without increasing fixed costs, such as connection and admin fees, planning etc. The below graph (based on NREL's System Advisor Model) indicates this.


Sizing a solar PV system

Sizing a solar PV system


Of course, we can still export excess energy to the grid through PPAs (Power Purchase Agreements) to earn extra cash but it’s just that the amount you will receive from PPAs (often around 5p per kWh) is far less than the amount you could save when you use the power your self instead of buying from the grid (commercial electricity rates are currently around 10p per kWh). Hence maximising youruse on site through careful design is crucial.


Making the most of your solar power 

Solar PV is a flexible technology that can be easily integrated into a wider energy solution to maximise savings. At present many businesses have not fully considered the full potential of their on-site renewable energy system and how this can be combined with other energy efficiency technologies.

For example, a dairy farmer can use excess production from their solar PV system to provide a chilled water store for cooling milk. In this situation the farmer not only benefits from a free supply of electricity to their mechanised milking parlor but will also make further savings on refrigeration through the provision of a chilled water store. Conversely, where there is a heat requirement the excess solar energy can be used to heat a buffer tank that provides heat and hot water.

It is likely that we will see major advancement of integrated solar PV solutions in the coming months, as installers come up with new and innovative ways to maximise this popular renewable energy technology without such a heavy reliance on subsidies. 

There is no doubt that fears over security of grid supply, rising energy costs and increasingly stringent carbon targets will further the interest and investment in alternative sustainable energy and that solar will play a vital role in delivering the solution to many businesses throughout the UK. 

Even the CEO of Shell recently stated, "I have no hesitation to predict that in years to come solar will be the dominant backbone of our energy system, certainly of the electricity system." And National Grid commented, “because of our involvement in the advanced uses of solar we can confirm that the use of solar in unsupported markets is growing even in the UK.”