Are there dangers to using solid fuel on a propane grill?

Yes, there are real dangers, and they come from the mismatch between a gas grill and a fuel it was not designed to burn. A propane grill’s firebox, burners, grease tray and lid are built around a controlled gas flame, so charcoal or wood placed on the grates adds uncontrolled heat, falling ash and embers that the body and drip system were never meant to handle.

The safer published route is a smoke accessory that sits above the burners and holds chips or pellets, and the makers of those accessories state how they are meant to be used. The Best Pellet Grills and Smoke Tubes for Backyard Cooks guide covers several of them.

Heat the grill body was not built for

A propane grill regulates heat at the burner and vents it through the lid. Charcoal or wood burning directly on the cooking grates concentrates heat in one spot, and the steel above and below that spot takes it. Warped grates, blistered paint and a distorted lid are the common outcomes, and the burner tubes underneath are the parts most exposed.

Compare that with a grill built for solid fuel. The Char-Griller AKORN kamado, one of the picks in the Best Kamado Grills for Low Smoking and High Searing guide, is described by its maker as cooking across a 200°F to 700°F temperature range, with triple-wall insulated steel construction that retains heat and limits airflow. That insulation and the sealed ceramic or steel body are what contain solid fuel. A gas grill has neither.

The Weber Summit Kamado S6 in the same guide is listed by its maker with dual-walled insulation for precise, quick temperature changes and a RapidFire lid damper that boosts air flow to reach high heat. Those features exist because solid fuel needs containment and controlled air. Dropping charcoal into a propane firebox skips both.

Ash, embers and the grease tray

Charcoal leaves ash, and ash falls. In a gas grill it drops through the grates onto burner tubes, into the grease tray and against the bottom pan. Ash mixed with grease is a fire load sitting directly under the cooking surface, and embers falling into that tray can light it.

Gas grills handle this with a drip tray and a drain path, not with an ash pan. The Char-Griller AKORN is listed with an EasyDump Ash Pan and a grill grate lifter for charcoal access, which is what a solid fuel body looks like when the maker plans for ash. The Kamado Joe Big Joe Konnected Joe in the same guide is listed with an AMP Firebox and a fiberglass mesh gasket for heat retention and smoke control, plus an ash tool among its included parts.

On a propane grill, none of that collection hardware exists. Ash ends up in the grease management system, and the maker’s instructions for that system assume grease only.

Carbon monoxide and ventilation

Burning charcoal or wood produces carbon monoxide, and a gas grill’s lid and vents are sized for a clean gas flame. Closing the lid on smoldering solid fuel in a body not designed for it traps combustion gases around the food and the user. This is the reason solid fuel grills are outdoor appliances with deliberate venting, and why a gas grill should never be treated as a charcoal cooker indoors or in a garage.

The kamado picks show how venting is engineered. The Kamado Joe Big Joe Konnected Joe is listed with a Kontrol Tower Top Vent that holds steady airflow settings during cooks and dome openings, and the SMOKEWARE SS Vented Chimney Cap in the same guide is described as maintaining its vent setting when the grill is opened and closed. Airflow is a designed part of a solid fuel grill, not an afterthought.

The Char-Griller AKORN is listed with indexed dual adjustable dampers and a built-in temperature gauge for fine-tuning airflow. A propane grill has a burner knob, not a damper, so there is no way to tune the air a pile of charcoal receives.

The accessory route makers actually publish

If the goal is smoke flavor on a propane grill, the published answer is a smoker tube, pipe or box that holds chips or pellets above the burners. The Napoleon PRO Stainless Steel Smoker Pipe is described by its maker as a way to turn a gas barbecue grill into a smoker: remove one end, fill with wood chips or pellets, place the filled pipe on the sear plates above a burner before lighting, replace the grids and use the grill as normal. Its maker also states that spent chips or pellets should cool completely before disposal.

The LIZZQ Premium Pellet Smoker Tube is listed as designed to work in any grill, gas, electric or charcoal, and its maker states it can produce smoke for up to 5 hours of smoking. The Weber Premium Universal Smoker Box is listed as fitting most sizes of grills and allowing chips to be added while in use. These accessories keep the fuel off the grates and out of the firebox floor.

The pellet grill guide lists the LIZZQ tube at 12 inches long and the Napoleon pipe at 12 inches long, both small enough to sit on a gas grill’s sear plates rather than filling the body.

What to do instead

Keep solid fuel out of a propane firebox. Use a tube, pipe or box above the burners, follow the maker’s placement instructions, and let spent fuel cool fully before you dispose of it. If you want to burn charcoal or wood as the primary fuel, use a grill built for it, such as the kamado picks above or a dedicated charcoal grill.

For indoor cooking, the Best Indoor Grills for High-Heat Searing guide covers electric appliances that need no solid fuel at all. The Ninja Sizzle Indoor Grill and Griddle is listed with 500°F max heat, and the Hamilton Beach Electric Indoor Searing Grill is listed with a 450°F sear and adjustable temperature from 200°F to 450°F. Those are electric, not gas, and they avoid the open flame question entirely.

One more point: this site has not tested any of these products, and nobody here has used them. Everything above is what the makers state about their own grills and accessories, plus what follows from those statements.