These ovens cook in winter and summer. Bright sun works best. Hazy days are okay. Start cooking early in the day. Set the oven ahead of the sun approximately 1 hour.
More food takes more time, less food, less time.
Use typical water ratio. Soak hard beans overnight. Pre-heat oven 1 to 2 hours. Use large rock or brick to absorb heat while preheating. Place bread on top of rock or brick.