HOW SOLAR GROWTH AFFECTS THE ELECTRICITY MIX

Electricity consumption follows a general, predictable, 24-hour pattern with two peaks — a daytime peak around 1-2 pm, and a nighttime peak around 7-9 pm. In highly urbanized areas during weekdays, the daytime peak is higher than the nighttime peak. Otherwise, the nighttime peak is higher. Either way, the baseload usually occurs around 3-4 am. The top curve in Figure 1 shows this pattern. The highest solar output coincides roughly with the daytime peak.

Grid operators must dispatch power plant outputs so that supply equals demand at all times, while keeping costs as low as possible.

Consider the first scenario (Figure 1). As solar share (orange) rises from zero to 10%, it is displacing flexible plants (green). Since solar is cheaper, this is also pulling electricity prices down. The 70% capacity share of baseloads (gray, blue) is unaffected.

In the second scenario (Figure 2, 30% solar), something significant has happened. The midday solar output is so high that the residual demand (total demand minus solar output) is now lowest at midday. The baseload has shifted from early morning to midday. Also, the baseload is now slightly lower, from 70% to around 63%. Solar is now displacing baseload plants too.

In the third scenario, with solar at 50% of peak demand, baseload share shrinks further to 43%.

THE FUTURE NEEDS MORE FLEXIBILITY, LESS BASELOAD

As the solar share in the mix rises, flexible plants are affected first and their role diminishes.

But as the solar share increases from 20% to 25%, baseload plants are affected next. At 50% solar, baseload share shrinks to 43%. At 70% solar, baseload requirement will only be 23%. At 90% solar, we will need only a few baseloads.

With the baseload share shrinking, the nighttime demand baseloads used to cover must then be met by flexibles. Beyond 25% solar, the role of flexible plants increases steadily. ( Email rverzola@gn.apc. org for the full 0-100% simulation.) Why is this trend so important? First, because it is inevitable. As solar prices drop, solar growth will become increasingly marketdriven.

People will simply decide to solarize their rooftops.

Second, because the DoE remains inexplicably blind to this trend.

DoE’s Philippine Energy Plan (PEP) 2016-2040 still assumes 70% baseload share until 2040.

Assuming 50% solar by 2040, for instance, means a baseload share in the capacity mix of 43%, not 70%, by 2040. DoE’s flawed assumption overestimates the country’s baseload requirement by 63% (70 divided by 43, minus 1), creating a huge bloat in its baseload plans.

DoE’s PEP 2016-2040 includes three more serious flaws, further raising the baseload bloat to more than 100%.

This baseload bloat will lead to stranded assets in the future because those recently constructed coal and nuclear plants will be unable to sell half of their output. The fossil industry, as in the past, will surely try to pass on the cost of these stranded assets to the consumer.

Why buy expensive, dirty electricity from the grid when we can produce cheap, clean electricity from our rooftops?

The next piece will explain the DoE plan’s three other flaws.

Baseload bloat will lead to stranded assets in the future because recently built coal and nuclear plants will be unable to sell half of their output.