I am looking for something to overwinter my plants. They are philodendrons, peace lilies, etc. Would this unit need to be heated? We are located in Southern Ohio.

I do not know your climate but my guess is you would need to heat it at least some. The unit will absorb a lot of warmth when the sun is shinning and hold some of this into the night, but when the weather is cloudy or when it has not absorbed enough heat to hold it at a temperature you would need during the night, you would need to heat it. You also need to take care that snow does not build up on it. This can be done by shaking it off with a broom or using heat to melt the snow. Read:

Snow and Wind Warnings: https://shelter-systems.com/warning.html