In Japan, solar power generation has been spreading rapidly due to FIT(Feed In Tariff) introduced in 2012. Today, approximately, 40GW solar power has already been connected to Grid.
Do we significantly realize the structural and real meaning brought by solar power? Various influences on the Grid by solar power are already pointed out.Thermal power to adjust supply-demand difference is needed more than ever to absorb the difference brought by solar power, which operates irrespective of demand. Grid-constraint problem has become evident because geographical conditions for solar power doesn’t usually meet the Grid already installed.
Grid protective function equipped with solar power is now making serious voltage fluctuation especially in solar-rich region.
Apart from them, we would like to consider the influence by solar upon cost and operation of power generation. The peak of demand in a year is generally recorded on an excessively hot day in summer or on a similarly cold day in winter.
In summer, mainly due to compressor for air-conditioners, in winter,due to electric appliance for heating, light and induction heating cooker, electric demand generally soar. Generation cost is most expensive at that time. They fire relatively expensive fuel in relatively inefficient generators when peak demand occurs. Recently, this situation we are used to has impressively changed. Especially in summer peak time, since solar power generates on a large scale, electric power company doesn’t have generate inefficient thermal power. As a result, generation cost on such time has change dramatically.
Let us look back the generation price on each 30minute dealt in Japan Electric Power Exchange (JEPX). Before the spread of solar power, for example, on summer day in 2010, generation price was highest in between 1:30 and 3:00pm. But as of July in 2017, it is highest in between 3:30 and 4:30pm on many days.
As a result of solar power’s spread, thermal power’s operation has shifted in the evening, accordingly, generation cost dealt in JEPX has evidently changed. Electric power company’s operation of generators has not yet met to huge solar operation.
They are apt to estimate the amount of solar power more conservatively than necessary because the prediction of solar operation is as difficult as weather forecast. The amount of solar connected to Grid and that of Coal or Nuclear which are usually in full-operation are entirely different regionally, so the situation each electric power company is facing is so various.Furthermore, they have to consider how to operate pumping-up hydraulic power generation. They have to gain further experience. The spread of solar power has changed the peak-demand balance between summer and winter in substance, and especially in summer, generation cost is shifting from midday to evening, and predictably, to nighttime. Yearly inspection of generators will shift to summertime in the future.
Electricity rate which is now generally high at daytime will be flatter in the future. Such structural change in generator-inspection and electricity rate is coming invisibly by solar.