This may be one of the simplest components for a beginner who wants to grow microgreens. When seeds germinate in the wild, they are usually under soil. So, for the first few days, they struggle to get to the light. So, it is built into most seeds to not necessarily need a lot of light for the first few days until the seed leaves form. Some microgreens are harvested so quickly (7 days) that being indoors doesn't hurt your chances of having a decent harvest. A sunny windowsill or even a bright room will suffice.
Of course, if you want to maximize the amount of microgreens you get from each planting, a grow light will certainly help.
A grow light is simply a light designed to mimic the sun. Indoor lights like soft white bulbs put out light on the red end of the spectrum, closer to the look of candlelight. But grow lights give off full-spectrum light that is red, blue, and green. There are two main types, fluorescent and LED.
LED. I personally have a Kingbo 45W Grow Light LED Panel. It has LED lights that cover a larger part of the light spectrum. And it gives off less heat. Most heat it produces comes from the back (or top depending on your perspective). It doesn't use a lot of electricity, and seems to put out just enough light to make most microgreens happy.
Fluorescent. Some need a bit more, especially if they need longer grow times (above 14 days). The 125W Hydrofarm Compact Fluorescent Light is not the cheapest option I have tried. But fluorescent lights are a proven answer to growing indoors. They use more electricity, put off a good bit of heat, and take up a good bit of space. Still, the plants seem to love it and grow beautifully.
For a beginner, I’d recommend getting an LED grow light if possible. It can help to put the green in your microgreens if you are growing indoors. They are simple to use, efficient, and take up the least amount of space. There are lots of options and wattages online, so read reviews and carefully select the right one for your space. I am currently eyeing something a bit bigger, like the Osunby 150W LED Grow Light.
A word of caution, water and electricity doesn't mix. So make sure your set up protects the light and the plugs from getting wet.