The 142GW in 2020 is an almost 15% rise on the amount of incremental new PV installations vs. 2019, so 2019 was (142/115)*100 = 123GW.
For 2019 that represents a 25% growth in the installed base, and for 2020 a 23% increase in the installed base. Quite impressive if that can be kept up, as that level of growth leads to a doubling about every three years. That would require the growth in incremental new PV installations to grow at about 25% a year, which could possibly happen given that there are no more subsidies to cut in China and a Bernie presidency would be a lot more climate policy friendly.
Solar is about 1% of the total global energy supply, so a doubling every three years would deliver 2% in 2023, 4% in 2026 and 8% in 2029. There is some growth in global energy consumption of about 2% a year, so together with the much slower growth in wind energy and even slower growth in hydro, this would deliver a small yearly fall in fossil fuel usage toward the end the 2020s.
As long as GDP keeps growing its really hard to cut fossil fuel usage. Sales of EVs may help increase the fall in FF usage, but still nowhere near the 7-10% reductions required from today,