When Gerdi McKenna learned she had breast cancer, one devoted friend decided to organize a photo shoot for McKenna surrounded by her closest friends.
Unbeknownst to McKenna, her friends were planning more than just a few simple photos; they each decided to shave their heads in solidarity with their ailing friend.
See also: The Cutest Grandma on Instagram Is Battling Cancer With 86,000 Friends
South African photographer and videographer Albert Brendenhann captured the group's surprise in a moving video. The clip below highlights the many reasons the women in McKenna's life chose to shave their heads in her honor. "My heart is full," McKenna's sister told Brendenhann. "If I can do just a little bit for her to feel better, I will do it with love."

The video peaks when McKenna meets her friends for the photo shoot, only to realize what they've done for her. Her story is a testament to strong friendships in times of vulnerability and the power of simple acts of kindness.
Brendenhann shared a image of this stirring moment on Instagram.

Industrial designer Gabriele Diamanti created this award-winning solar household still for developing countries with limited or no access to fresh drinking water. It works somewhat like an upside-down coffee maker: You pour seawater through the opening at the top, and the sun heats it during the day. The pressure forces steam through the nozzle leading to a watertight boiler, and condenses against the lid.
The Eliodomestico provides up to 5 liters of water a day, and because the sun does all the work, there are no operating costs. The still is even made entirely of inexpensive, widely available materials.
Anna Stork and Andrea Sreshta, the founders of LuminAID, created this solar-inflatable light in response to Haiti's January 2010 earthquake. It's designed specifically for those affected by disasters, crises and conflicts.
The LuminAID light packs flat -- 50 lights take up the same space as eight regular flashlights -- and inflates to become a lantern and to reduce the glare of the powerful LED bulbs.
Within the past year, the LuminAID light has been used in humanitarian relief aid in the wake of disasters such as Hurricane Isaac and Hurricane Sandy.
Greenlight Planet's line of Sun King products marry innovation and sleek design. The Eco, Solo and Pro all come with multi-functional stands, high-performance batteries that last up to five years, and either a real-time LCD or LED screen displaying power feedback. Perhaps most useful is the built-in mobile charging unit, aimed at the most ubiquitous gadget across the developing world.
According to the site, Sun King lamps have helped 25% of users increase their household incomes, allowed for an increase in study time for children, and reduced spending on kerosene and off-site charging stations.
Biochemist Daniel Nocera invented the "artificial leaf," a silicon wafer that imitates real leaves by creating energy from sunlight and water. When the you put the wafer in water, it splits the hydrogen and oxygen, and collects the hydrogen in a fuel cell.
The problem with early prototypes, however, was that dirty water didn't work. In April 2013, Nocera announced an updated ("self-healing") version that prevented bacteria from attaching to its surface.
One artificial leaf placed in a quart of water provides up to 100 watts of energy, 24 hours a day.
Social entrepreneurs and scientists aren't the only ones working toward lighting developing countries. Tech giant Panasonic revealed its own solar LED lantern in October 2013, which charges by solar panel within six hours and emits 360 degrees of light.
It can also charge USB-capable mobile phones in approximately two hours (depending on phone's capacity), and shields against dust and water.
The lantern launches first in Kenya, Myanmar, Cambodia, Indonesia, Bangladesh and Malaysia, followed by other countries.
At only 21 years old, Princeton undergrad Eden Full invented this device that rotates solar panels toward the sun throughout the day -- without a motor. She discovered that if the panels faced the sun at all times, the energy output increased by 40%.
The innovative thing about the SunSaluter is that it's an inexpensive, water clock-esque design: Anyone, even people in rural or remote locations, can build it around solar panels.
To learn more about the SunSaluter, watch the video above, which was part of Mashable's "Purpose in Progress" series.
Disclosure: Eden Full and the SunSaluter won Mashable and the UN Foundation's Startups for Social Good Challenge in 2011.
The Portable Light Project enables people in developing countries to create energy-harvesting textiles, which they can adapt to their own needs. For example, locals can weave the flexible photovoltaic cells into bags they carry around during the day, harvesting sunlight, and open it up to light their homes at night.
Developed by Boston-based architecture firm KVA MATx, each kit includes a textile reflector, a photovoltaic material, a battery case with a USB port and an LED light. The battery charges in six hours, providing over 20 hours of light.
The Portable Light Project has launched projects in Nicaragua, Mexico, Venezuela, South Africa, Kenya, Haiti and Brazil, with a specific focus in each region.
The d.light S20, created to replace kerosene lamps in off-grid households, provides eight hours of 360-degree light on a full battery via high-brightness LEDs. Designed to be user-friendly and, most of all, functional for a wide range of people, a detachable handle allows for different placement options.
The solar panel at the top of the S20 simplifies charging, and the impact-resistant lantern design includes two brightness settings, a battery charge level indicator and a glow-in-the dark power button.
Originally designed for African entrepreneurs, San Francisco-based Fenix International engineered the rugged ReadySet Power System to generate the most power at the lowest cost. It charges in 8-10 hours of direct sunlight, and can power lights, radios and mobile phones.
To give you an idea of how powerful it really is, the ReadySet can charge 10 iPhones, power an iPad for more than 12 hours of continuous video play and recharge the solar panel in a matter of hours.
Led by founder Paul Polak, SunWater aims to improve the lives of 50 million people in developing countries by providing an affordable solar water irrigation system for farmers living in poverty. The pressurized irrigation system brings water to a one-hectare plot, increasing cash crops and, in turn, income.
Diesel pumps -- which require fuel and repairs -- are often too expensive for rural farmers, and while current solar pumps don't have the same problems, they can cost upward of $7,000 to install. Using simple, flat-plate mirrors in place of large panels, SunWater will cut current costs by 80%.
Learn more about the project in the video above.
The GravityLight is a slightly different project that the others on this list, as it essentially uses solar as backup rather than a primary energy source. At only $5, the GravityLight works as follows: You fill a ballast bag with rocks, sand or soil, and hang it from the lamp to create energy, lighting the GravityLight for 30 minutes. You can recharge it using a built-in solar panel.
The GravityLight has raised nearly $400,000 on Indiegogo (its target was $55,000). It is currently in trial testing, and will be available in the second quarter of 2014.
SOCCKET doesn't use solar energy, but it's just too cool not to include. As you play with the ball, which is slightly heavier than a regular soccer ball but will never deflate, it converts and stores the kinetic energy for power. Thirty minutes of play can power an LED light for more than three hours.