You don’t specify any particular medium of solar energy. Some decades ago, “solar energy” would be assumed to be thermal, while today, it’s assumed to be electric. So much so that when someone says they installed solar panels, others will assume it’s for making electricity.
Do you really mean solar energy in a broad term?
Solar energy doesn’t differ from other energy, so your question might as well have been “How do I store energy?”
Anyway – solar thermal is mostly forgotten these days, as solar electric panels are getting slightly more efficient but more importantly – cheaper per Wp. But solar thermal is a lot cheaper to produce than solar electric. It’s so simple: You circulate a liquid inside an absorber which in turn is insulated.
Modern electric solar panels are typically harvesting just over 20% of the light they capture. The rest is either reflected, converted to thermal energy or otherwise lost. Certain hybrid solar panels, like PowerCollector – Solarus , are taking both thermal and electric energy out of the same incident light. The efficiency then goes from around 20% to around 60%–70%. You cannot send the thermal electric energy into the grid, though, but you can do other things. Like the most well known usage – heat up the water you use for showering etc.
But since you ask about storing solar energy – look at this installation in Canada:
The excess solar thermal energy is stored in the ground via boreholes, and extracted later when needed. This is the way forward, and this is another way to store solar energy.
Keep the solar electric energy for computers, phones, electric cars, lighting – but then use solar thermal energy for bulk consumption of water and space heating. You can even convert thermal energy into cooling. Yes, a solar panel can directly power an A/C motor which in turn provides cooling. The more the sun shines, the more cooling you get.
Why isn’t this more popular already? THAT is the question that puzzles me. I can only think it’s related to money, irresponsibleness and laziness. Burning fossil fuels makes money for a little rich elite (and provides jobs for many others), while it’s too easy to just start a combustion. And we are too lazy to demand change. Or too uninformed that it’s actually possible.
How do YOU store solar energy? That depends what your needs are. The smart way is to store it in several ways – no-one says you have to pick only one way to store it.