Flag etiquette requires that if the American flag is left flying at night it should be lit up. You can get a finial that has lights installed in it. This lights up the flag from above.
You can also get lights that clamp to the flag pole. However the illumination appears to be better when it comes from below. A residential light can be about 12 volts and a commercial 120 volt. flag from dusk to dawn. If there is no light available to showcase the flag the proper thing to do is take the flag down at sunset.
Photo cells in the ground absorb the sunlight and shine the light on the solar power flag lights are very often used to make the flag visible at dusk. The flagpole light should be placed at a distance to ½ the length of the flag pole. So if your pole is twenty feet high, place the light ten feet from the pole.
When it begins to get dark adjust the flagpole light so that it illuminates the flag. It is considered disrespectful to leave the flag up after dark unless it is well lit. A 50 watt 12volt light can last up to 10 hours. You can install sensors that will automatically turn the light on and off at sunrise and sunset.
This way you don’t have to rush home to turn the lights on in the evening or get up early to turn the lights off in the morning. If you don’t like the sensor, get a timer which you can use to set specific times for the light to turn on and off.
The flag should be taken down when a storm is coming unless the flag is made of an all weather material. However if a severe storm with high winds, like a tornado or hurricane, is coming that could shred the flag.
Let me suggest that you purchase as high a quality flagpole light for your pole that you can afford. You don’t want to be replacing bulbs all the time.