Solar panels that generate power, rain or shine

Print Friendly, PDF & Email

Chinese researchers add graphene layer to solar cell that allows it to generate electricity from salt ions in rain water, as well as from sunshine.

share
Print Friendly, PDF & Email

A team of researchers in China says it has found way to make solar panels work effectively in both rain and shine, by coating them with a layer of electron-rich graphene that can generate electricity from both sunlight and from salt ions in rain water.

160406075516_1_540x360
Credit: Copyright Angewandte Chemie International Edition; courtesy of ResearchSEA

A report in the journal Angewandte Chemie says that a team led by China’s Ocean University in Qingdao devised the method using a highly efficient dye-sensitized solar cell, coated with a thin film of graphene.

Graphene – an easy to produce, two-dimensional form of carbon in which the atoms are bonded into a honeycomb arrangement – is characterised by its unusual electronic properties, being rich in electrons that can move freely across the entire layer.

These properties allow electrons to move freely (delocalise) and make it a negatively-charged material when in solution.

When rainwater falls onto a solar panel – a condition that traditionally makes them unproductive – the droplets contain positively-charged salt ions of sodium, calcium and ammonia, which can bind with the surface of the graphene layer.

The interaction results in a double-layer which causes the potential energy difference between the positively- and negatively-charged layers – enough to drive the delocalised electrons into producing a voltage and current.

According to this report, the team was able to generate electricity in the hundreds of microvolts range and achieve a solar-to-electricity efficiency of 6.5 per cent from the prototype graphene panel.

The primary challenge facing the team is the relatively low concentrations of salt ions in rainwater compared to the salt solutions prepared in the lab, which will make it difficult for the panel to produce large quantities of electricity.

They are currently working on modifying the technology to handle a variety of ion mixtures that can be contained in rainwater.

The team hopes the results can be incorporated into future solar cell designs and open up new ideas for alternative electricity generating capabilities for solar cells.

Print Friendly, PDF & Email

9 Comments
  1. Gordon 3 years ago

    Salinity of my tank stored rainwater is just 17ppm, I wonder what concentration was used in the experiments to obtain microamps and microvolts?

  2. David Osmond 3 years ago

    It’s worth mentioning that standard solar panels also generate when it rains or is cloudy, just not as much as they do when it’s sunny. It would be nice to know if this new design generates more during these conditions than a standard PV panel, and if so, how much more.

  3. Sam0077 3 years ago

    In process of finding what type in line or multiple+ battery live one house off ocean front too – so salt in air plus gull poo not mentioned anywhere I googled to date. Told poo add to panels $100 each but no mention of salt/ocean. Which since we live mainly around sea edge of continent mainly will count surely? Not that outsiders recognize this think whole continent livable.

  4. nakedChimp 3 years ago

    What happens couple of weeks/months down the road when the surface of the panel starts to be covered by mould?
    Can you clean it without damaging the surface layer?

    How damaging is permanent exposure to radiation/heat/etc..?

  5. Jason 3 years ago

    Electrochemistry was a long time ago, but I vaguely recall that most water solutions become problematic at voltages above 1.5-ish volts. Depending on the electrodes and solution, water breaks up into gaseous H2 and O2 at that point, and things get tricky – more dangerous and less efficient.

    If they can keep it down to 1.5 V, then to produce 100 W they’ll need over 60 amps, which requires a much thicker copper wire than the one on my roof.

    I’m sure I’m overlooking something. I’m not saying they’re wrong; I’m asking what I’m missing.

  6. solarguy 2 years ago

    All a lot about nothing really!

  7. Jo 2 years ago

    Sophie,
    While I usually enjoy reading your articles, this one is off the mark.

    Is this invention really worth discussing?
    Electric power from ions in rain water????
    Not much there. This is very close to nothing.
    Even if it works, this is a one-off after the ions are adsorbed.
    There is a difference between a ‘static’ voltage and continuous power generation.

    While there is a potential to create a tiny voltage (‘hundreds of microvolts ‘ aka less than one mV), as long as there is no continuous current, there is no power.
    For instance in order to produce just 1 W at a voltage of 1mV you need 1000A.

  8. Alastair Leith 2 years ago

    “Graphene – an easy to produce, two-dimensional form of carbon in which the atoms are bonded into a honeycomb arrangement – …”
    So easy it was only discovered a few years ago and won four researchers their nobel prizes. Many groups are still searching for ways to produce commercial volumes of graphene sheets at prices industry will need it at for mass produced products. PV terminals are graphene, graphene supercapacitors not there yet.

  9. Just_Chris 2 years ago

    I had a quick read of the paper. It appears as the rain drops slide down the panel they remove electrons from the surface of the solar cell which are then replaced by electrons flowing in from the lower layers. The raindrop is essentially becomes slightly less acidic in the process. Sounds great only down side is the peak power they achieve is 60 pW. Interesting effect and it might lead to something but probably not power generation – you’d probably be better off collecting the rain drops on you roof and running them through a small turbine at the bottom of your drain pipe. That might give you a couple of watt’s.

Comments are closed.

Get up to 3 quotes from pre-vetted solar (and battery) installers.