# Solar dehydrators Question



## PNWKatie (Aug 4, 2012)

I'm interested in building a solar dehydrator instead of having to use our convection oven. Does any one have one and how well does it work to dehydrate your veggies and make jerky? I'd like something about the size of a fridge is there a certain way to make sure you aren't getting more room than you can heat? I guess Is there a certain "ratio" to make sure you are producing enough heat for the size dehydrator you want.


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## Sanza (Sep 8, 2008)

This is how I made an excellent solar dryer. If I seal up the top around the glass it would make a great solar oven too. I use old recycled sheer curtains to place the food on so it doesn't stick to the racks - I used the coated hardware cloth, and I cover the food with another sheer to keep the bugs off  It takes about 4-5 hours to dry thin sliced veggies.


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## PNWKatie (Aug 4, 2012)

Thanks. I really think making one of these will be on our list first thing next spring! I'd love to dehydrate without using electricity and warming up the house during the hottest month of the year next year! LOL


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## WesleyDS (Feb 16, 2013)

[ame]http://www.youtube.com/watch?v=oVTcnCuX2Qc[/ame] 
This is the type I plan to build this spring


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## unregistered358967 (Jul 17, 2013)

I just made a small one but with limited success so I need to tweak it. I used a small pizza box, painted black and a piece of glass on top. Things took too long to dry though, so I need more research, plus it was really small scale...I want more!


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## PlicketyCat (Jul 14, 2010)

The best design depends on what you're intending to dry, how & how long you intend to store it, whether you intend to use any additional preservative, how much sun you normally get and for how long, what is your average ambient temperature and your relative humidity.

There are pros and cons to each solar dehydrator based on your answers.

Simple tray dehydrators with clear or screen-only tops expose your food to UV radiation which can increase oxidation and nutrient loss, so may not be the best method if you intend to store your food long term. These models can also reach extremely high temperatures very quickly and severely damage the food in areas with very intense uninterrupted sunlight.

Simple opaque-covered tray dehydrators often do not have adequate passive airflow to brittle-dry food, especially in cooler or humid climates, so may not be the best method if you intend to store your food unrefrigerated long term.

Updraft tower dehydrators may only provide adequate airflow to brittle-dry foods before molding or spoilage when you have plentiful solar gain, higher ambient temperatures and lower humidity.

Downdraft tower dehydrators may only provide adequate airflow to brittle-dry foods for long term storage if there is low humidity or no condensation point on the food or the ambient temperature outside is lower than the solar gain temperatures inside.

Of course, wetter foods dry slower than drier foods, which can leave foods moist enough long enough to increase spoilage and mold growth opportunities if conditions are less than ideal. So drying a whole berry or a half a peach takes higher temps for longer periods with lower humidity and more airflow than drying some garden herbs or thin apple rings. Conversely, too high a temp for too long a period with too low humidity or airflow can ruin what you're trying to preserve.

If you're in the PNW, you're likely experience intermittent sunlight at moderate temps and relatively high humidity (at least that was what I had in Seattle). The downdraft tower worked best for me there more consistently... the updraft tower worked fairly well but only on clear sunny days in summer during the "droughty" periods when it was warm and dry. I didn't have any success with the flat models except for herbs and flowers, all moist and semi-moist food (esp. fruit) molded before drying.

(ETA: in the video linked above, the first one is an updraft design, and the last two are downdraft designs).


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## dkhern (Nov 30, 2012)

my gm dried apples and peaches on sheet of tin over 2 sawhorses. cover at night to keep dew off. watch for summer showers. never had a problem.


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