Solar panels have become a sort of rallying flag for those passionate about the environment. And why not? This green tech promises to surpass polluting fossil fuels and power our daily lives in a clean and sustainable way – whether the ‘skeptics’ like it or not.
But despite the increasing awareness and acceptance of this amazing technology, there is still some confusion over what solar panels can do. We all know that they convert sunlight into electricity, but can these panels store this energy too?
Currently, solar panels do not store energy – being limited to strictly energy production. Energy storage is left to second party platforms such as chemical batteries, hydro, heat and solid mass platforms.
As photovoltaics continues to be refined, reaching greater and greater efficiency levels, there may be a time where energy production and energy storage come in the same package. But for now, we must resign ourselves to solar panels being production only devices.
BatteriesWhether it’s your handheld or your house, batteries lead the way in storing energy. And I should know, I have a bank of them in my garage.
Batteries come in a variety of forms, with today’s most popular ‘flavor’ certain to give way to something new tomorrow. But if you’re thinking of storing your own energy onsite, then there are three basic battery options to chose from; lead acid, gel, and lithium.
- Lead Acid – Lead acid batteries are the oldest of the three options. They’ve been around for a very long time. They are not snazzy or techie and will never be ideal for mobile applications as they are incredibly bulky and heavy.
The larger ones smell when they’re being recharged and require regular maintenance when in a unsealed package. But despite both of these things, I still have 24 of these archaic alchemy boxes powering my house.
Because they work!
Lead acid batteries have long held the title for being the best bang for buck when it comes to energy storage. But the thing about titles is, they are never held forever.
- Gel – Gel batteries came about in response to the need for maintenance required on lead acid batteries. Not everyone is comfortable measuring acid density in their batteries every quarter. This process is very time consuming (takes me roughly three hours to measure and record 24 batteries) and is not without risks – especially to one’s eyes.
Also, because gel batteries are generally sealed, they can be oriented in horizontal positions; something impossible for ‘flooded’ lead acid batteries as the critical acid solution would be lost as it spilled out.
- Lithium – There is no better example of lithium batteries being used to store energy from solar panels than the batteries made by Tesla. This ‘power everything’ mindset reaches the vehicle market, the household market and even commercial and utility markets.
It would not be an exaggeration to say that the capacity to store energy brought about by inexpensive lithium batteries is quickly becoming the foundation of our future way of life.
HydroHydro energy storage is actually quite easy to understand in concept. Water is pumped to an elevator reservoir during the day and then released to power a turbine, as the fluid flows back down, during the night.
Having seen one of these facilities personally, I can tell you they are massive in scale. And this size requirement is something of a detriment as not every location is conducive to such facilities.
However, with the ideal conditions being met, it has proven to be a reliable way to store energy. But it should also be noted that not every one of these facilities is, in fact, powered by solar. So while there is potential for this type of energy storage to be completely ‘green’, it should not be automatically assumed.
HeatOne of the best examples of using heat as a means to store energy can be seen with concentrated solar. By focusing a series of mirrors on one specific point, extremely high temperatures can be achieved.
This heat is then stored in the form of thermal energy. However, unlike batteries, thermal energy does not provide electricity directly, but rather needs to be converted first before consumption.
The process is something like this:
- Daylight is bounced off mirrors onto a single focused point.
- This point gets extremely hot! (in some cases up to 1000 deg. F)
- Heat is then transferred to a storage material – commonly salt.
- This material is then stored in an insulated tank.
- The super heated material is later retrieved and then used to heat water – resulting in steam.
- The steam turns a turbine which is connected to a generator, generating electricity.
Solid MassIn solid mass energy storage systems, the need to create steam is eliminated as the solid mass is connected directly to the generator. There are currently two main forms of solid mass energy storage: gravity and flywheel.
- Gravity – There are two common examples of gravity related solid mass energy storage systems and the first is railcars. In this situation, a heavy railcar is moved up an incline during the day when extra energy is available.
Then, when a demand for extra electricity is encountered, the vehicle is allowed to move back down the incline – pulled by gravity. This downward motion is used to turn a generator, thereby producing electricity.
The pros of this type of system is that multiple railcars can be stacked, allowing for more stored energy. The cons of this type of system is that a long and lengthy inclined is required for optimal performance.
Another way to accomplish this is via the mineshaft system. This works similar to the railcar system in that a heavy weight is elevated when extra energy is available and then allowed to fall back down when energy is required.
Only with the mineshaft system, the weight is traveling up and down through a hole in the ground (mineshaft) rather than across open space. This is better for locations with limited space, but can have initially higher costs if a mineshaft needs to be built.
- Flywheel – Energy can be gained whenever a large amount of mass is made to move. This applies to both the railcar and mineshaft systems mentioned above.
However, in flywheel energy storage, this motion happens not by changing physical location, but rather by spinning around a central point.
To picture this, imagine a bicycle that has been flipped over to stand on its handlebars and seat.
If you were to turn the pedal, the back wheel would spin but the bicycle wouldn’t move. Most importantly, the wheel would continue to spin even after you have stopped turning the pedal. That’s because of the heavy wheel having enough mass in motion to continue movement.
Flywheel energy storage works the same way.
A large flywheel (wheel) having considerable mass, is made to spin by any extra energy that is available during the day. Then, when demand for electricity rises, a generator connected to the spinning flywheel is engaged – generating electricity by the heavy spinning flywheel.
ConclusionAt the beginning of any major change, it is not unusual to see multiple concepts working towards a common goal. However, not all of these concepts find their way into use.
I think that this will be true of energy storage.
There are many ideas for storing energy that clearly have potential. But potential is not the sole deciding factor in large scale implementation. Being able to bring an idea/product to the market for consumers to engage with, plays a considerable role in what technology is ultimately embraced.
But that can be a challenge for developers as new technology has a habit of evolving.
In the not too distant past, light-bulbs were energy hungry electric filaments. Today’s light-bulbs are LED devices, some doubling as wifi hot-spots.
While today’s solar panels are strictly energy producing, tomorrow’s could very well be something different.
There is the already proven potential for providing winter heat, by heating water during the summer and then storing it underground for winter use.
Perhaps in the future, solar panels could double as communication arrays… or may even provide a service that has yet to be imagined.
In any case, solar power is here to stay and the ability to store this energy is certain to evolve.