The Sun (Surya Deva), is one of the five chief tantrik deities, the others being Ganesha, Shiva, Shakti and Vishnu.

According to Alain Danielou in Hindu Polytheism, the Sun is one of the three chief deities of the vedas but he also receives worship in tantrik literature. He is leader of the nine planets (graha) and, in later times, worship of the Sun by the Saura division of the tantriks became worship of his son, Saturn or Shani, and took on something of a dark colour.

Surya and his band of wanderers circle the sacred Mount Meru

The yantra for his daily puja (above left) consists of a bindu, a triangle, an octagon, a circle, eight petals, 10 petals, three circles and an earthsquare or bhupura. Beloved of the goddess Gayatri, he is the very self of time and the lord of awakeness. He is gold in colour, with a face as bright as the fire at the end of time. He wears a jewelled golden crown, and is seated in the middle of a white lotus, with two (rather than three) eyes. He is adorned with various gems, wears red clothes and has a smiling face. This image varies from the conventional one here, which has Suryadeva as a form of Vishnu. When performing his puja, there are 12 separate nyasas which may be performed. These include planet nyasa, gayatri nyasa, seven horse nyasa, pitha nyasa, veda nyasa and tattva nyasa. He has his own form of tantrik Gayatri, even though he is the self of the vedik Gayatri. This runs: Om hrim suryarupaya vidmahe hrimsah jyotirupaya dhimahe tanno hamsah prachodayat.

When worshipping Surya Deva in the above yantra, it proceeds from the circumference to the centre. The first group are the 10 dikpalas, or guardians of the directions; in the earthsquare, worshipped in the vama direction, are Ganesha, Chandavetala, Lolaksha and Vikarala; in the circles are the different lines of gurus.

In other tantras, the Sun receives worship as Martanda Bhairava, and is pictured here in an Ardhanareshvari form, half of his body being male, the other being female. His shakti is Prakasha Shakti, that is his energy of Light.

The translation that follows is of the Sun's amulet or armour, drawn from the Devirahasya.

Suryakavacha

Shri Bhairava said -
To he who is the god of gods, the lord Sun, the effulgent gem, the Lord of the Gayatri, the source of light, sung of as Savita (1)

tasyaahaM kavachaM divyaM vajrapa~njarakaabhidham.h.
sarvamantramayaM guhyaM muulavidyaarahasyakam.h.. 2..

(I speak) of his celestial armour (kavacha) called the Vajrapanjara (diamond refuge), consisting of all mantra, secret, the essential secret of the root vidya (2)

sarvapaapaapahaM devi duHkhadaaridryanaashanam.h.
mahaakuShThaharaM puNyaM sarvaroganivarhaNam.h.. 3..

Destroying all sin, Devi, destroying sadness and poverty, destroying great ailments, meritorious, dispelling all disease (3)

sarvashatrusamuuhaghnaM samgraame vijayapradam.h.
sarvatejomayaM sarvadevadaanavapuujitam.h.. 4..

Killing all enemies, giving victory over hosts of enemies, full of all effulgence, giving the fruit of worshipping all gods (4)

raNe raajabhaye ghore sarvopadravanaashanam.h.
maatR^ikaaveShTitaM varma bhairavaanananirgatam.h.. 5..

In war, in fear of the king, in terrible (times) destroying all poisons, on a skin encircled by the letters of the alphabet (matrikas), various faces of Bhairava surrounded (?) (5)

grahapiiDaaharaM devi sarvasa~NkaTanaashanam.h.
dhaaraNaadasya deveshi brahmaa lokapitaamahaH.. 6..

Destroying grahas, poisonous things, O Devi, destroying all difficult situations, if worn, Deveshi, he is like Brahma, the grandfather of the universe (6)

viSNurnaaraayaNo devi raNe daityaa~njioShyati.
sha~NkaraH sarvalokesho vaasavo.api divaspatiH.. 7..

(Like) Vishnu-Narayana Devi, in war, conquering the Daityas, like Shankara, the Lord of all the Worlds, and like Vasu also, the Lord of the Day (7)

oShadhiishaH shashii devi shivo.ahaM bhairaveshvaraH.
mantraatmakaM paraM varma savituH saaramuttamam.h.. 8..

Like the Moon, the Lord of Herbs, Devi, like I, Shiva, the Lord Bhairava, this mantra-body is the supreme armour, the highest essence of Savita (8)

yo dhaarayed.h bhuje muurdhni ravivaare maheshvari.
sa raajavallabho loke tejasvii vairimardanaH.. 9..

Whoever should wear it on his shoulder, or on his head, Maheshvari, on a Sunday, he becomes the beloved of kings here on earth, shining brightly, killing his enemies. (9)

bahunoktena kiM devi kavachasyaasya dhaaraNaat.h.
iha laxmiidhanaarogya-vR^iddhirbhavati naanyathaa.. 10..

What point is there of many words, Devi, relating to the wearing of this kavacha? Here (on this earth), it bestows wealth like Lakshmi and is health giving. (10)

paratra paramaa muktirdevaanaaamapi durlabhaa.
kavachasyaasya deveshi muulavidyaamayasya cha.. 11..

Elsewhere (in other worlds), Deveshi, this kavacha of the root mantra, gives supreme liberation and is very hard to get. (11)

vajrapa~njarakaakhyasya munirbrahmaa samiiritaH.
gaayatryaM Chanda ityuktaM devataa savitaa smR^itaH.. 12..

The seer (rishi) of the Vajrapanjara is Brahma, it is said. Gayatri is the metre, it is declared, while the devata is Savita. (12)

maayaa biijaM sharat.h shaktirnamaH kiilakamiishvari.
sarvaarthasaadhane devi viniyogaH prakiirtitaH.. 13..

Maya is the bija, Sarat is the shakti, Namah is the linchpin, Ishvari. The renowned application is that it gives the results of all sadhana. (13)

oM aM aaM iM iiM shiraH paatu oM suuryo mantravigrahaH.
uM uuM R^iM R^IM lalaaTaM me hraaM raviH paatu chinmayaH.. 14..

oM aM aaM iM iiM must protect my head; oM suuryo my body, uM uuM R^iM R^IM my forehead, hraaM Ravi must protect my consciousness. (14)

L^iM L^IM eM aiM paatu netre hriiM mamaaruNasaarathiH.
oM auM aM aH shrutii paatu saH sarvajagadiishvaraH.. 15..

L^iM L^IM eM aiM must protect in the eye; hriiM the Red Charioteer (?); oM auM aM aH the Lord of all the World saH must protect my ears. (15)

kaM khaM gaM ghaM paatu gaNDau suuM suuraH surapuujitaH.
chaM ChaM jaM jhaM cha naasaaM me paatu yaa^rM aryamaa prabhuH.. 16..

kaM khaM gaM ghaM must protect my cheeks, suuM the God worshipped by other gods; chaM ChaM jaM jhaM must protect my nose, yaa^rM (the aditya) Lord Aryama. (16)

TaM ThaM DaM DhaM mukhaM paayaad.h yaM yogiishvarapuujitaH.
taM thaM daM dhaM galaM paatu naM naaraayaNavallabhaH.. 17..

TaM ThaM DaM DhaM (must protect) my mouth, yaM he who is worshipped by Lords of Yoga; taM thaM daM dhaM must protect my throat, naM he who is beloved of Narayana. (17)

paM phaM baM bhaM mama skandhau paatu maM mahasaaM nidhiH.
yaM raM laM vaM bhujau paatu muulaM sakanaayakaH.. 18..

paM phaM baM bhaM must protect my shoulders, maM the embodiment of light; yaM raM laM vaM must protect my arms, and the root mantra Sakanayaka. (18)

shaM ShaM saM haM paatu vaxo muulamantramayoi dhruvaH.
LaM xaH kuxsiM sadaa paatu grahaatho dineshvaraH.. 19..

shaM ShaM saM haM must protect my chest, Dhruva, consisting of the root mantra; LaM xaH must always protect my belly, lord of the day and the planets. (19)

~NaM ~naM NaM naM maM me paatu pR^iShThaM divasanaayakaH.
aM aaM iM iiM uM uuM R^iM R^IM naabhiM paatu tamopahaH.. 20..

~NaM ~naM NaM naM maM must protect my front, the lord of the day; aM aaM iM iiM uM uuM R^iM R^IM protect my navel, the dispeller of darkness. (20)

L^iM L^IM eM aiM oM auM aM aH li~NgaM me.avyaad.h graheshvaraH.
kaM khaM gaM ghaM chaM ChaM jaM jhaM kaTiM bhaanurmamaavatu.. 21..

L^iM L^IM eM aiM oM auM aM aH protect my penis, lord of the planets; kaM khaM gaM ghaM chaM ChaM jaM jhaM protect my waist, O Sun. (21)

TaM ThaM DaM DhaM taM thaM daM dhaM jaanuu bhaasvaan.h mamaavatu.
paM phaM baM bhaM yaM raM laM vaM ja~Nghe me.aavyaad.h vibhaakaraH.. 22..

TaM ThaM DaM DhaM taM thaM daM dhaM protect my knees, o spreader of rays; paM phaM baM bhaM yaM raM laM vaM protect my legs, shining one. (22)

shaM ShaM saM haM LaM xaH paatu muulaM paadau trayitanuH.
~NaM ~naM NaM naM maM me paatu savitaa sakalaM vapuH.. 23..

shaM ShaM saM haM LaM xaH protect my feet, three rayed one, with the root mantra; ~NaM ~naM NaM naM maM Savita, protect all of my body. (23)

somaH puurve cha maaM paatu bhaumo.agnau maaM sadaavatu.
budho maaM daxiNe paatu nai{R^i}tyaa gurareva maam.h.. 24..

May the moon protect me in the east, and may Mars protect me always in the south-east; Mercury protect me in the south, and Jupiter in the south-west. (24)

pashchime maaM sitaH paatu vaayavyaaM maaM shanaishcharaH.
uttare maaM tamaH paayaadaishaanyaaM maaM shikhii tathaa.. 25..

Venus, protect me in the west, and may Saturn protect me in the north west. Rahu, protect me in the north, and Ketu in the north-east. (25)

uurdhvaM maaM paatu mihiro maamadhastaa~njagatpatiH.
prabhaate bhaaskaraH paatu madhyaahne maaM dineshvaraH.. 26..

Mihira, protect me above and Anjagatpati(?) below; at dawn Bhaskara protect, and at midday Dineshvara (lord of the day). (26)

saayaM vedapriyaH paatu nishiithe visphuraapatiH.
sarvatra sarvadaa suuryaH paatu maaM chakranaayakaH.. 27..

In the evening, Vedapriya protect me, and at night Visphurapati; Surya protect me everywhere and Lord of the Chakra protect me always. (27)

raNe raajakule dyuute vidaade shatrusa~NkaTe.
sa~Ngaame cha jvare roge paatu maaM savitaa prabhuH .. 28..

In war, with the king's clan, in litigation, in sexual union, in fever, in disease, protect me Lord Savita. (28)

oM oM oM uta oM{u}{OM} ha sa ma yaH suuro.avataanmaaM bhayaad.h.
hraaM hriiM hruM hahahaa hasauH hasahasauH haMso.avataat.h sarvataH.
saH saH saH sasasaa nR^ipaadvanacharaachchauraadraNaat.h saMkaTaat.h.
paayaanmaaM kulanaayako.api savitaa oM hriiM ha sauH sarvadaa.. 29..

oM oM oM uta oM{u}{OM} ha sa ma yaH Oh Sun, protect me from fear. hraaM hriiM hruM hahahaa hasauH hasahasauH haMso. protect me always. saH saH saH sasasaa protect me from kings, from animals in the forests, from thieves and from wars. oM hriiM ha sauH Lord of the Kulas, Savita, protect me always. (29)

draaM driiM druuM dadhanaM tathaa cha taraNirbhaaMbhairbhayaad.h bhaaskaro raaM riiM ruuM rururuuM ravirjvarabhayaat.h kuShThaachcha shuulaamayaat.h. aM aM aaM viviviiM mahaamayabhayaM maaM paatu maartaNDako muulavyaaptatanuH sadaavatu paraM haMsaH sahasraaMshumaan.h.. 30..

draaM driiM druuM dadhanaM Bhaskara, protect me from fear of the Tarani (the Sun) and Mars (?). raaM riiM ruuM rururuuM from fear of fever, leprosy and acute pain, (protect me) Ravi. Martanda, protect me from great delusion with aM aM aaM viviviiM paraM haMsaH One with a thousand rays, may the root mantra over the body always protect me. (30)

iti shriikavacchaM divyaM vajrapa~njarakaabhidham.h.
sarvadevarahasyaM cha maatR^ikaamantraveShTitam.h.. 31..

Thus is revealed the celestial auspicious kavacha called the Vajrapanjaraka, which is the secret of all the devas and strewn with the the matrika mantras. (31)

mahaarogabhayaghnaM cha paapaghnaM manmukhoditam.h.
guhyaM yashaskaraM puNyaM sarvashreyaskaraM shive.. 32..

Shive! It is the destroyer of great diseases and ills, revealed by me. It is secret, splendid, good, and the refuge of all. (32)

likhitvaa ravivaare tu tiShye vaa janmabhe priye.
aSTagandhena divyena sudhaaxiireNa paarvati.. 33..

Dearest One, Parvati! Having written it on a Sunday in (the month) Tishya, in the birth constellation, smearing it with the eight celestial scents and with milky nectar. (33)

arkaxiireNa puNyena bhuurjatvachi maheshvari.
kanakiikaaShThalekhanyaa kavachaM bhaaskarodaye.. 34..

One should write the kavacha on bhurja (birch bark), using good sunflower milk, Maheshvari, or on thorn apple wood, as the Sun rises. (34)

shvetasuutreNa raktena shyaamenaaveShTayed.h guTiim.h.
sauvarNenaatha saMveShThya dhaarayenmuurdhni vaa bhuje.. 35..

One should wrap it into a ball shape using white, red and dark threads, and in gold should enclose it, then wearing it one's head or one's arm. (35)

raNe ripuu~njayed.h devi vaade sadasi jeShyati.
raajamaanyo bhavennityaM sarvatejomayo bhavet.h.. 36..

In war, one conquers enemies Devi, in debates one triumphs, one becomes always brilliant and full of all effulgence. (36)

kaNThasthaa putradaa devi kuxisthaa roganaashinii.
shiraHsthaa guTikaa divyaa raakalokavasha~Nkarii.. 37..

Wearing it on the throat gives a son, wearing it on the hips destroys disease, wearing it in a ball, on one's head, makes one the the subduer of a gathering of kings. (37)

bhujasthaa dhanadaa nityaM tejobuddhivivardhinii.
vandhyaa vaa kaakavandhyaa vaa mR^itavatsaa cha yaa~Nganaa.. 38..

(Worn) on the arm, it gives wealth always, and promotes understanding. A barren woman, or a woman having only one child, or a woman whose new-born dies early, (38)

kaNThe saa dhaarayennityaM bahuputraa prajaayaye.
yasya dehe bhavennityaM guTikaiShaa maheshvari.. 39..

if she should wear it always on the throat, gives birth to many sons. Maheshvari, on whoever's body this is worn in a ball, (39)

mahaastraaNiindramuktaani brahmaastraadiini paarvati.
taddehaM praapya vyarthaani bhaviShyanti na saMshayaH.. 40..

Parvati, obtaining that body one becomes impervious to the great missiles of Indra and Brahma, there is no doubt (?) (40)

trikaalaM yaH paThennityaM kavachaM vajrapa~njaram.h.
tasya sadyo mahaadevi savitaa varado bhavet.h.. 41..

Savita immediately gives boons to whoever reads this Vajrapanjara kavacha at the twilights, Mahadevi, (41)

aGYaatvaa kavachaM devi puujayed yastrayiitanum.h.
tasya puujaarjitaM puNyaM janmakoTiShu niShphalam.h.. 42..

Devi, those ignorant of this kavacha who do puja to the three-bodied one (the Sun), for him puja is empty of merit, and even in ten million births it is fruitless. (42)

shataavartaM paThedvarma saptamyaaM ravivaasare.
mahaakuShThaardito devi muchyate naatra saMshayaH.. 43..

Whoever recites this armour 100 times on a Sunday, seven times, is alleviated from great illnesses and is liberated, there is no doubt. (43)

nirogo yaH paThedvarma daridro vajrapa~njaram.h .
laxmiivaa~njaayate devi sadyaH suuryaprasaadataH.. 44..

Whoever reads this Vajrapanjara armour is healthy and free from poverty, Devi. By grace of Surya, he immediately becomes like Lakshmi, goddess of wealth. (44)

bhaktyaa yaH prapaThed.h devi kavachaM pratyahaM priye.
iha loke shriyaM bhuktvaa dehaante muktimaapnuyaat.h.. 45..

Whoever reads this kavacha daily, with devotion, dear Devi, becomes wealthy in this world, and on dying obtains liberation. (45)

iti shriirudrayaamale tantre shriidevirahasye vajrapa~njaraakhyasuuryakavachaniruupaNaM trayastriMshaH paTalaH .. 33 ..

So in the Shrirudrayamala Tantra, Devirahasya, 33rd patala, the Sun kavacha known as Vajrapanjara.