Arukh HaShulchan, Orach Chaim 313:14-21

Sugya Map

• Issue: Bishul (Cooking) via Toldot Hamah (Sun-heated vessels) vs. Toldot Ha'esh (Secondary fire heat).
• Nafka Mina: Whether a utensil heated by the sun requires the same stringent bishul restrictions as fire.
• Primary Sources: Shabbat 39a, Shulchan Aruch, Orach Chaim 318:3, Arukh HaShulchan 313:14.

Text Snapshot

• Source: Arukh HaShulchan, Orach Chaim 313:14
• Leshon: "דדוקא תולדות האש אסור, אבל תולדות החמה מותר" (Only secondary fire is forbidden, but secondary sun-heat is permitted).
• Nuance: The Aruch HaShulchan emphasizes the gezeirah (decree) of Shabbat 39a, pivoting on whether the heat source mimics the intensity of fire.

Readings

• Rambam (Hilchot Shabbat 9:3): Asserts that Toldot Hamah is permitted lechatchila, as it lacks the "cooking" character of fire.
• Magen Avraham (Orach Chaim 318:8): Argues that while Toldot Hamah is permitted, one should avoid Toldot Ha'esh (using a sun-heated vessel) out of concern for dema (resemblance). The Aruch HaShulchan softens this, leaning toward the lenient view of the Rashba.

Friction

• Kushya: If the prohibition of bishul is rooted in the melacha of transforming food, why distinguish between the source of the heat?
• Terutz: The Gemara (Shabbat 39a) establishes that bishul is essentially the act of "fixing" food. Toldot Hamah is not derech bishul (the common way of cooking); it is an anomaly. The prohibition is not the heat, but the process of fire-cooking.

Intertext

• Reference: Shulchan Aruch, Orach Chaim 318:3—The halacha maintains that solar heat is not equivalent to fire.
• Responsa: Igrot Moshe (Orach Chaim 4:74, Bishul 13) debates modern solar ovens, questioning if they are Toldot Hamah or functionally Toldot Ha'esh.

Psak/Practice

The Aruch HaShulchan maintains that while Toldot Hamah is theoretically permissible, we avoid replicating the manner of fire-cooking. In practice, modern solar-heated water is treated as Toldot Hamah (permitted), yet one must be wary of Keli Rishon implications.

Takeaway

Halacha tracks the nature of the act, not just the physical effect; because sun-heating lacks the derech bishul of the Mishkan, it remains outside the primary scope of the melacha.