It's difficult to definitively say which country has the absolute maximum usage of solar energy because different metrics are used to measure it.

Here are some factors that influence the answer:

* Total installed solar capacity: China leads the world in total installed solar capacity, but this doesn't necessarily mean they use the most.

* Solar energy as a percentage of total electricity generation: This measure shows how reliant a country is on solar power. Here, countries like Germany, Australia, and Denmark are strong contenders.

* Per capita solar energy usage: This metric considers the amount of solar energy used per person. Countries with high population density and a strong focus on solar might rank high.

Therefore, there isn't a single definitive answer. It depends on how you define "maximum usage".

However, based on total installed capacity, China currently leads the world in solar energy usage.