One or two hours of sunlight are not going to really change anything. If the lights are on anyhow its not like adding a little additional light for such a short time is going to magically cause algea problems. Same for heat. natural light works for nature, it will be fine for your tank for such a short period of time. Your plants may appreciate getting a natural and correct spectrum of light, and the plants will also outcompete any algea anyhow. Don't worry about a thing.
\Dan