No, the chart you posted clearly shows that in Texas demand for power is highest at around 5-6pm, which is decidedly not when the sun is highest in the sky - it's when the sun is setting and the workday is ending but people are still active and doing things, many of which require electric power - perhaps more electric power than they would use during the workday depending on what the thing is. This is precisely the Duck Curve observation (https://en.wikipedia.org/wiki/Duck_curve) - which was originally coined with respect to the California electricity market but is applicable in many other markets.