Gotama
Buddha explained this about the Pacceka-Buddhas!

The muni Vedeha (Ananda) bowing his body, asked the
Tathagata, who was
staying at Jetavana: PaccekaBuddhas exist, yet by what
reasons do they
arise, 0h wise one? Then the best of the omniscient, the
great wise one told
the following to Ananda in a sweet voice:
Those who paid honour to all former Buddhas, without
attaining liberation
during the period in which their teaching was known, who
are wise by means
of sense of urgency, whose intelligence is very sharp,
also without the
instruction of Buddhas, these attain insight alone even
by means of a tiny
limited object of meditation... And furthermore, in this
whole world, there
is no one except me, equal to these PaccekaBuddhas. I
shall clearly express
the following, only an short description, of the
distinction of these great
heroic Munis (silenced ones)...
Listen, all of you, who wish for the highest medicine,
your attention should
be very calm, always directed to their good words, which
are sweet like
fine honey of those great wise men, who are fully &
perfectly enlightened
all by themselves!

These are the explanations of PaccekaBuddhas, who
assembled on Mount
Gandhamadana, pronounced one after the other, about the
sorrow of any
desire and the cause of the overcoming of all craving, &
how they attained
their insight. Conscious of the absence of lust, while
being in the midst of
the objects of lust, their minds are dispassionate in an
infatuated world,
having dumped the proliferations, & subdued all
obstructions, they all
attained insight thus:
Putting aside any violence to all beings, not hurting
any of them, good and
compassionate, with a mind filled with friendliness, one
should live, alone,
like the horn of a rhinoceros...
Their morality are pure, their wisdom purified, their
minds are
concentrated, practicing watchfulness, reflecting,
seeing the
characteristics of the dhamma, they understand it,
having developed all the
elements of the Noble Way and the Links to
Enlightenment...
Having perfected the fulfillment of merit, with the
motive to become a
solitary conqueror, they become PaccekaBuddhas,
self-existent,
independent, such is destination of the wise, who does
not attain the state
of a disciple during the time in which, there still
remains the knowledge of
the SammaSamBuddhas teaching...

Their dhamma being great, being all sublime
manifestations of the core
essential dhamma, powerful are their minds, having
overcome the flood of
suffering, their minds are exalted, seeing the highest &
deepest truth, they
are like lions, like the horn of a rhinoceros...
With serene senses, calm, concentrated, remembering all
beings in remote
border districts, illuminating like lamps in the other
world and in this world,
thus are these PaccekaBuddhas, always good...
Having destroyed all hindrances, these kings of men,
illuminators of the
world, shining like pure solid gold, undoubtedly worthy
of any gifts in this
world, are these PaccekaBuddhas, always good...
There are in this world together with the divine world,
good teachings of
PaccekaBuddhas. Those fools, who after having heard
these, do not act
accordingly, whirl round in suffering again and again...
Those who act accordingly, having heard the good words
of
PaccekaBuddhas, which are like pure streaming honey of
small delicate
bees, become seers of the truths, possessing Wisdom!
Thus spoke the
Gotama Buddha about those solitary ones Awakened like a
rhinoceros horn...
Source: The
Canonical Apadana I 7-14