9 PV integration into electricity systems
During daylight hours in locations with mainly clear skies, PV power is quite reliable, but in places where passing clouds reduce array output it can be more intermittent. In the UK, most PV power would be produced in summer, when electricity demand is relatively low, but less is produced in winter when demand is higher.
In what ways would national energy systems need to be modified to cope with long, medium and short-term fluctuations in the output of PV arrays?
Studies show that as long as the capacity of variable output power sources such as PV is fairly small in relation to the overall capacity of the grid (around 10–20%) there should not be a major problem in coping with their fluctuating output. The grid is, after all, designed to cope with large fluctuations in demand, and similarly fluctuating sources of supply like PV can be considered equivalent to ‘negative loads’. Fluctuations would also, of course, be substantially smoothed out if PV power plants were situated in many different locations, subject to widely varying solar radiation and weather patterns.
If PV power stations, and other fluctuating renewable energy sources such as wind power, were in future to contribute a more significant proportion of electricity supplies, then the ‘generating mix’ supplying the grid would have to be changed to include a greater proportion of ‘fast response’ power plant, such as hydro or gas turbines, and increased amounts of short-term storage and/or ‘peaking’ power plant.
The subject of integration of PV and other renewables into electricity systems will be covered in more detail in Week 8
And for the last topic this week, you’ll now look at how the global PV market is growing.