Photovoltaic power is an important part of the new energy system, the installed capacity of photovoltaic power is growing rapidly during the 14th Five-Year Plan in China. Photovoltaic power has strong randomness and volatility because of the strong correlation between photovoltaic power and weather, the high proportion of photovoltaic grid- connected increases the difficulty of power balancing in power system. The output characteristics of photovoltaic power under high temperature climate are analyzed in detail, and the view that photovoltaic power generation has a higher daytime peak capacity in high temperature weather is pointed out, and then the rationality of improving the credible capacity of photovoltaic power generation in extreme high temperature weather to participate in power balance is demonstrated. Finally, the calculation verified that increasing the credible capacity of photovoltaic power generation in extreme high temperature weather could reduce the daytime power balance gap, relevant work suggestions about photovoltaic participating in power balance are proposed.