Clean Power

Published on September 6th, 2011 | by Charis Michelsen


Using Sunlight to Dry Clothes – Indoors

September 6th, 2011 by  

Solar energy is a common method of clothes-drying in many parts of the world. However, hanging clothes on a line costs time, rather than money, and depends on the weather. The German company Miele has removed the weather and the extra time from the equation altogether by designing the world’s first solar-heated dryer.

A conventional heat or air dryer uses quite a bit of energy, but, in exchange, it’s quick and super convenient. The Miele system reduces energy use by at least half, according to a study undertaken jointly with the solar heating system manufacturer Solvis, with a corresponding reduction in cost. The results – and the dryer – will be presented at the IFA 2011, and the dryer is available next fall.

The solar dryer can be installed directly into the SolvisMax solar heating system, which places the solar cylinder in the center (as opposed to having the furnace there). Solar energy always takes precedence, with the furnace kicking in only when solar energy is insufficient.

The clothes-drying process is a little more complicated than just letting the heat from the sun evaporate water from clothing, and it is applicable to not only dryers, but other household appliances, including washers and dishwashers.

First, water runs through pipes in solar panels and is heated by the sun. The hot water then flows through a perpendicular pipe with dispenser valves to the solar cylinder. The hot water stays at the top, warm water in the middle, and cool water is at the bottom. Heat for the dryer is supplied directly from the hot water in the top later, and as the water cools it sinks to the bottom.

The low temperature necessary to condense the moisture sucked out of the clothing is present thanks to the cool water at the bottom of the cylinder – which is then pumped back through the solar array and reheated.

So – using the sun to dry clothes regardless of weather? Yes, please!

Source | Picture: Sonnenseite


Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

Tags: , , , , ,

About the Author

spent 7 years living in Germany and Japan, studying both languages extensively, doing translation and education with companies like Bosch, Nissan, Fuji Heavy, and others. Charis has a Bachelor of Science degree in biology and currently lives in Chicago, Illinois. She also believes that Janeway was the best Star Trek Captain.

  • Kyle Field

    This came up in a google search for line drying clothes. I like the concept…but would personally not see the benefit of installing a proprietary solar drying system when you can just install solar PV panels and get an electric dryer off the shelf. (which is what I did. It uses ~5.7kwh/load.

  • Pingback: Shake Remote, Turn Off Television | CleanTechnica()

  • Anumakonda Jagadeesh

    Innovative(but costly and complicated) way of using solar energy for drying clothes inside. In developing countries we dry clothes in a case of urgency inside the house under ceiling fan. It is air motion that dries the clothes quickly. In the west you always think of designing systems which are complicated. In the east we use methods which use less energy. For example a house wife uses limited water to hand wash the clothes.

    Dr.A.Jagadeesh Nellore(AP),India

    • Breath on the Wind

      Namaste, There are many places in the East where your weather is warm and your air is more than sufficiently without moisture to allow clothes to dry effectively. In these environments it is certainly more efficient to dry clothes indoors under a fan or even outdoors under the sun.

      But even in these environments efficiency can give way to a different standard and many times in my travels, I have noticed that clothes return from cleaning more than slightly damp.

      In the West, environments are often wet and cold. I can recall times in my youth when it would take days for clothes to dry outside-sometimes through freezing and thaw cycles. In cities, such clothes might eventually be recovered quite dirty from the environment.

      In the Winter, drying clothes and air quality can both improve because the heated air causes relative humidity indoors to drop to arid levels. Sadly then, it is space and time that become the primary issues that may also benefit from the wisdom of the East.

    • Anonymous

      Interesting comment. In Poland, where I live now, we always dry clothes on a drying rack indoors — generally takes a day (without the use of a fan). Quite easy and efficient. However, there are times when we wish we could dry them more quickly (you have to plan ahead sometimes) and, spoiled as i may be, i don’t like that they are much harder than when i used a dryer in the U.S. (but that may be due to other factors?).. All in all, i do agree that we should just get back to line-drying in most cases. But this new tech is a pretty sweet-looking drying options 😀

  • Breath on the Wind

    I first saw this information elsewhere and was extremely intrigued with HOW it works. In some ways it is similar to a dehumidifier which first heats the air with the condenser and then dries it (by cooling and lowering the temperature to the dew point) with the evaporator. Refrigerant is just a phase change material and by substituting a phase change material like the acetone used in vacuum tube collectors we might create an absorption system that could be even more effective. (and provide air-conditioning as well) using thermal collectors.

    But even more intriguing is that by applying just a little intelligence as in this system we can avoid the wast of simply blasting our clothes with lots of excess heat that may be simply wasted. It is a good example for other industries.

    Now as the unit has no outside vent, what are we going to do with the lint not captured by a simple screen?

  • Mark Welsh

    I have a very small solar company in Berlin NJ. My son & I have been struggling to get it off the ground with limited success due to the economy. We have a 30 year old company restoring historic buildings and we wanted to branch out and have been studying solar classes at the Solar Living Institute in Hopland, CA over the last 4 years. We are very sincere about our efforts to embrace solar for a multitude of reasons.

    Here is an idea that came to me years ago and it coalesced in my thinking yet again just recently regarding surpassing the 20% window of energy collected by our best solar panels.

    I was reading how Mandelbrot’s research and book, “The Fractal Geometry of Nature”, inspired a young ham radio operator to bend antenna wire into a simple fractal shape for better reception.
    His hope was to copy how nature uses 3d space to maximum efficiency of energy flow, be it water, wind, plant patterns through fractal patterns.

    His efforts were shockingly effective. It seems the fractal shapes that repeats in nature imposed on the wire, lead to a greater collection capacity of all wavelengths for his ham radio.

    I am sure you are very aware where that per chance experiment lead to in the antenna world of cell phone development. Early cell phones needed a separate antenna for every function but now, due to science adopting fractal patterning of the cell phone antenna wafers, Iphones and every kind of wireless communications are possible.

    So I wondered… If these very fractal shapes, inherent in nature, were so successful in collecting radio frequencies, could fractals be used in the development of nanoscale solar antennas? Could the solar cells themselves or the antenna shapes, be configured to these self similar fractal patterns, boosting efficiency of nano antennas to collect infrared solar energy?

    Is any work being done combining nano antenna solar and fractal patterning?

    Please run with this if it is viable.

    Thanks for your time,
    Mark Welsh

    • Breath on the Wind

      Mark what you are suggesting may have some value for Solar PV cells and arrays to recieve different wavelengths of energy and increase efficiency. I am not entirely sure where you might apply this to solar thermal which is the focus of this article.

Back to Top ↑