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I have an idea for a land based mobile organism that moves and uses photosynthesis for its primary means of energy generation. Can a motile organism conceivably get enough energy from photosynthetic processes as its primary energy source to move at a competent speed? 

Said animal doesn't have to be elephant sized, something as small as a rabbit would be fine, but said animal would have to be as fast as average animals of its mass.  For example, venus flytrap wouldn't count, it can't really move anywhere.  [Elysia Chlorotica](https://en.wikipedia.org/wiki/Elysia_chlorotica#:~:text=Some%20members%20of%20this%20group,marine%20heterokont%20alga%20Vaucheria%20litorea.) doesn't count because of its speed, its heterotrophic tendencies,  size, and ocean dwelling habitat. 

According to this [answer](https://scientific-speculation.codidact.com/questions/206856#answer-206857) plants have low energy production rates.  However it seems due to the [square cube law](https://en.wikipedia.org/wiki/Square%E2%80%93cube_law), it would seem that for smaller animals even current efficiencies of photo synthesis should be more effective, especially for a cold blooded animal. 

Additionally lots of plants are known to be primarily CO2 limited^[Ecology of the Planted Aquarium, Walstad], not limited by light, and [indeed too much light can harm plants](https://www.sciencemag.org/news/2005/01/too-much-good-thing#:~:text=Plants%20are%20supposed%20to%20crave,create%20potentially%20deadly%20free%20radicals.&text=But%20if%20the%20plants%20are,that%20can%20destroy%20the%20plant.), causing plants to change in response, such as [turning red](https://buceplant.com/blogs/news/four-tips-for-achieving-red-aquarium-plants).  This leads me to believe that if an organism could make use of that extra energy, the efficiency of photosynthesis may be able to be increased to compensate beyond the levels seen by modern plants.