Panel

Dalekanium panels made up the exterior of the lower section of the Dalek casing. (TV: Daleks in Manhattan/Evolution of the Dalek)

Amount
Generally, the Dalek lower section was composed of fourteen vertical panels which each contained four sense globes, making a total of 56 globes. (TV: The Daleks) The larger Daleks of the New Dalek Paradigm, however, sported only twelve panels, with a vertical column replacing the two back panels, making a total of 48 globes. (TV: Victory of the Daleks)

Opening
By the Time War, the complete opening of the Dalek casing entailed, in addition to the grating section and the weapons platform, the individual panels of the base unit splitting open. Dalek Sec opened his casing as such to envelop Diagoras for the Final Experiment, which proved necessary when Sec's joining with Diagoras resulted in the creation of a Human-Dalek form, who stepped out of the open casing. (TV: Daleks in Manhattan) In the Dalek City on Skaro, a Dalek's casing was opened completely to accomodate Clara Oswald. (TV: The Witch's Familiar)

Variants
Generally, all panels of a base unit were of the same colour, which matched the wider casing including the middle section and dome section. (TV: The Daleks) An exception was the Dalek saucer commander, whose panels were alternately coloured silver and black, with a black dome and silver middle section. (TV: The Dalek Invasion of Earth) Makkith, a humanised Dalek subordinate to the Red Dalek Alpha, had a black and blue casing similar to the saucer commander. (COMIC: Children of the Revolution)

The British Proto-Daleks were distinguished in that they had only three sense globes on each panel of the base unit — with two bulky middle section rings replacing the upper set of spheres, making a total of 42. (COMIC: The Dalek Project)

Individual cases
In 1930 in New York City, Dalek Thay of the Cult of Skaro sacrificed three of his Dalekanium panels for the Final Experiment, replacing them with contemporary metal covering. Attached to the mast of the Empire State Building by unwitting human workers, the Dalekanium was intended to absorb a gamma strike which was to hit the Earth, thus infusing the human corpses that the Cult had collected with Dalek DNA, creating Dalek-Humans. The Tenth Doctor, using his sonic screwdriver, attempted to unfasten the panels only to drop the sonic screwdriver due to weather conditions. He then attempted to physically remove the panels, but was struck by lightning, resulting in his Time Lord DNA mixing with the Dalek-Humans, causing them to turn against the Cult and destroy both Dalek Jast and Thay. (TV: Evolution of the Dalek)

Behind the scenes

 * The unique colour scheme of the Dalek saucer commander from The Dalek Invasion of Earth was not originally intended; the prop for this Dalek was the same prop for the Black Supreme Dalek. The production team did not paint it in time for the show as seen during the attack on the saucer — the Commander went in but the Supreme came out — for it was not seen during the second part of part 2 and the rest of the episode.
 * The colour scheme used for the saucer commander has not reappeared in any subsequent televised episodes to date. However, the "Dalek Patrol Ship" sets released in 2014 by Character Options included an exclusive 3.75-inch bronze "Dalek pilot" figurine bearing a black dome and alternating black "skirt" panels identical to the colour scheme of the saucer commander.