I am writing this as if it were something of an 'informal' Primordial Excellency, which has been proven to help people understand their themes and actions a bit better than some other writeups. Unlike Primordial Excellencies, I'll be adding in what Solars don't do.
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The Solar Exalted!
The Solar Exalted are human heroes. Warriors, Generals, Detectives, Tool Users. Thieves, Ideologues. Traders, Kings and Scientists. Their Charms are elegant in their simplicity. They execute perfect actions. Solars work miracles, but they are comprehended by all.
The Solar is strongest when giving orders to those around them. They are top-down leaders, controlling legions of underlings. They enhance and uplift those around them- the mortal, the fellow Exalt.
Their greatness is expressed with unsurpassed skill. They are the bleeding edge of innovation in all fields. A Lawgiver draws wealth and power from the land and people around her. The Solar is limited by time, resources and attention. They create tools and raise nations as pieces of greater works. A Solar can forge a sword or armor out of sunlight, and so they may function in absence of resources, but gain more for having men and material to hone and control.
Solars are Holy and Chosen of the Sun. The Sun itself does not simply set each night, it creates Night by moving across the sky. In this way the Solars are are mighty and overwhelming, but contained and transitory. Too much exposure to the sun scorches the earth, and Solars are only self-moderated.
The Solar also holds justice and virtue, not as objective terms, but like Holy, subjective as determined by who the Solar directs them towards. She is the personal arbiter of morality within her sight, and passes judgement.
The themes of the Solar Charm are linearand transcendent. They are archetypical. Solar magic is unconcerned with specifics or limitations, only straight-forward executions of tasks. If a Solar must fight, they fight to the extent it is humanly possible and a step beyond.
Their skill is such that they leave the base actions of mortals far behind. A Solar does not merely hide or disguise her grandeur, she erases or replaces herself in the sight and memories of those around her. She is still hidden, but her concealment is not of shadows and moonless nights.
The Solar is the Lawgiver. Her magic does not care the reason, for that is her own to decide, pinned on her will alone. The Solar's right to lead and rule is that of power overwhelming. To see their desires made real. The Solar does not ask, they demand. They sell, convince, contrive and otherwise demolish obstacles between themselves and their goals. The Solar can be arbitrary and fickle, or virtuous and steadfast in their action.
Solar Charms are biased in the Lawgiver's favor. They overwrite the terms of an action. Their magic deals in automatic success. An individual Solar Charm solves problems, they do not solve campaigns.
The Chosen of the Sun do not shift their bodies or minds to alien paths. They do not turn their blood to poison or grow armored scales, as these are not things humans can do. They do not get 'exotic' powers outside the means of mankind. They cannot will water and fire into weapons, or control Fate, save to prevent such from harming themselves or their works.
Solars do not create self-sustaining things. They are the first link and last link in any great work. Others depend on the Solar, even if infrequently. Their limits are based on their own morals and ethics, followed by the actions and reactions of those around her. The Solar suffers when she uses her power incautiously. To kill one king is to make all following kings fear you.
Solars do not win. Instead Solars succeed. To win implies a positive outcome. Success meanwhile means they have not failed a task. The Solar succeeds at steps toward a greater goal.
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I hope you've found this useful and I may go back and add to it later/update a new version as I think on the topic some more. Until then, peace out!