solar water distillation

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John Bozi   1 MW

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solar water distillation

Post by John Bozi » Dec 20 2020 3:56pm

I am collecting info about my project here as the title says.

I have recently started collecting the rainwater from my roof and am considering it as a source of consumable water. Sure I use it for the garden, but I want to create a solar panel powered device I can take with me into the middle of the bush somewhere one day and have a source of water without filters and tablets etc. (I do not consider roof water safe for drinking routinely and I will be consuming enough minerals in my diet to make up for the disadvantages of distilled water.)

I already have 5kw of solar panels on my roof but that does not stop me from wanting to create off-grid 12v types of projects with the numerous amounts of solar panels that can be found second hand and dam cheap.

My research into distillers etc. goes to the same types of products: for booze and AC 240v etc. The closest thing in that regard is about $70au

Image

I was close to buying one, but as said, I don't want to use AC power for this. I also don't want to use inverters to run appliances. The pictured appliance runs 750w apparently, and my calculations don't make it logical when distilled water can be probably bought at the store cheaper than it takes to run 750w for hours. It seems logical still if power is efficiently harvested to do it...(and stores are not close!)

The way I see it is that the tin roof or the sun itself is already creating a ton of heat in the middle of the day to get the evaporation process on its way. Cheap $10 elements can probably do a great deal of the rest in heating the water up to higher amounts of evaporation. I don't want some neat product to put in the house like pictured.

Some of me considers being able to take 5 litres of water out of a creek somewhere and then hook it up and after a few hours have enough drinking water for a day.

If anyone is interested in this sort of topic or has information to share please let me know.

I have looked around, and there are numerous ways to approach this. I just don't see one that is what I want yet.

As far as creek water goes, I have one in my backyard that I want to experiment with BUT I trust this much less. It is the runoff off the roads and therefore will contain lots of non-organic substances. I have no idea about which other chemicals can evaporate with the H2O...
Last edited by John Bozi on Dec 22 2020 7:57pm, edited 1 time in total.

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ZeroEm   100 kW

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Re: solar water distillation from rainwater

Post by ZeroEm » Dec 20 2020 4:31pm

Water distillation is the best and most energy intensive. Personality would think of filters and UV light to get around the tablets first, would make more water. Interesting project none the less.
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Re: solar water distillation from rainwater

Post by Hillhater » Dec 20 2020 5:00pm

If anyone is interested in this sort of topic or has information to share please let me know. ...
Dont you watch Russel Coit, or Bear Grills ??
...you just filter it through an old sock , and then boil it in an old Billy over a open fire ! :shock:
If it still worries you,..maybe take Chopper Reed’s advice and swallow a spoon full of Cement and harden TF up !
:wink: :D :D
But seriously, what is wrong with those filter systems...most adventurers etc rely on them.
And i am sure that you know most of rural Australia has lived on rain/tank water for generations ! :thumb:
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John Bozi   1 MW

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Re: solar water distillation from rainwater

Post by John Bozi » Dec 20 2020 5:25pm

Sorry but filters aren't something that I want to rely on, as an ongoing free source of energy. //burning fuel is not going to make anyone happy in my neighbourhood ( I do it for BBQs once a week already for taste though)

The old sock for sure will be a part of the process to filter out leaves and larger items that blow into the soup... Funny!

And NO to putting tablets as I already said. I wanted pure H2O or near it.

I should emphasize I have access to very very very cheap solar panels. My dad changed up to a new system and nobody will buy them at a decent price.

I want to use solar energy because as intensive as it is if you had to pay for it, I won't be. The concept is 'endless-sphere' endless-power, endless-water. // not chlorine tablets and drinking dirt.
Last edited by John Bozi on Dec 20 2020 5:30pm, edited 1 time in total.

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Re: solar water distillation from rainwater

Post by john61ct » Dec 20 2020 5:25pm

With common sense precautions

depending on location

rainwater is just fine to drink untreated.

As much as air is OK to breathe

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Re: solar water distillation from rainwater

Post by John Bozi » Dec 20 2020 5:34pm

I believe rainwater is probably for a short period...

Not after a longer period//stored in plastic containers// with rotting bits of organic matter, bird shit and other city dust / chemicals. //

Regardless, I think most comments are not really leading in the right direction. It's not about why the idea is worth exploring. It's about how to do it well.

in a nutshell, I want to make distilled water // near pure that can be drunk long after there has been any rain.

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Re: solar water distillation from rainwater

Post by john61ct » Dec 20 2020 6:35pm

Solar stills have been settled technology for a long time.

Nothing to do with solar electricity, sometimes referred to as "passive" solar, direct application of heat. You don't want to create heat frm olar-produced electricity.

Then you have reverse osmosis "watermakers" that do work off electricity, for powerful pumps to push the source water through fine membranes. Normal input is seawater.

Water can be safely stored for centuries. Do not focus on too much purity, waste of resources, not a healthy obsession.

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Re: solar water distillation from rainwater

Post by spinningmagnets » Dec 20 2020 6:36pm

You don't have to boil water to vaporise it, just warming it a little will work. Of course, at some point, boiling it for sterilization is good too. Here's a good website to start with.

https://www.builditsolar.com/

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Re: solar water distillation from rainwater

Post by John Bozi » Dec 20 2020 6:48pm

john61ct wrote:
Dec 20 2020 6:35pm
Solar stills have been settled technology for a long time.

Nothing to do with solar electricity, sometimes referred to as "passive" solar, direct application of heat. You don't want to create heat frm olar-produced electricity.

Then you have reverse osmosis "watermakers" that do work off electricity, for powerful pumps to push the source water through fine membranes. Normal input is seawater.

Water can be safely stored for centuries. Do not focus on too much purity, waste of resources, not a healthy obsession.
Please share the solar stills you are talking about.

What is wrong with solar producing heat?

I checked the website 'spinningmagnets' I quickly noticed another looming project I have been putting off... solar cooking... lol

yes dont need to boil it. As I said earlier, my tin roof gets dam hot, and the sun directly itself, but with a a simple $10 element it should be able to get it near boiling to quicken... and not need more than 1 panel (which is my aim).

I am all up for this to be done without electricity but at the same time why not use it when I have panels ... I think at least I can run some simple fan on a double pipe or a pump to cool the heated condensation.

Here are some simple passive things:

Image

Just using black and a slope surface caught in a half cut pipe.

For sure I wouldn't use copper, but the idea is kind simple with a small 12v dc fan:

Image

Just swap out the gas for solar powered element and a fan blowing on a bend would be the simplest design (although I'd prefer to avoid the plastic container even if it is safe for water... I am not sure how distilled water sucks on plastics:

Image

---

Image

Since I am infamous for ranting posts, I will just start this project off with total simplicity. I just bought a 12v kettle for the minimum 1ltr (I can accept) / and in stainless which I should be able sit down on the tin roof of the carport to raise the temperature 'passively'. And I bought it also because (I trust details that make sense) it states that 24v will boil up in 30mins/whilst 12v 1 hour. That seems a lot of time to wait but as we said boiling is not essential. I want to keep this as cheap as possible so $36 for a stainless pot with heating element is a good start.

The 24v means my open-circuit voltage of the panel being 23v will be very welcome even if it is only to momentarily plug it in... on load it pulls down ... and also I can interchange my leftover e-bike batteries of 6s or 4s anywhere whenever instead of directly being hooked only to the panel.

*the product description also notes I can cook eggs or noodles in it - haha. . so cool I have another use for it if this project veers

https://www.ebay.com.au/itm/293813943564

The main thing I have to work out is what to do with the automatic power-off when boiling is done.
Auto cut off power when water is boiling and the green indicator lights on.
It will stay hot on the roof regardless and at least won't fry itself.

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Re: solar water distillation from rainwater

Post by AussieRider » Dec 21 2020 7:34am

G'day.
What about my development of the old bushie's solar still? A hole in the ground with a catch can in the middle surrounded by pans of dirty water or even leaves. Cover the hole with a plastic sheet, drop a stone in the middle over the catch can and voila! Water vapour condenses on the sheet & runs down into the can.
Now, replace the hole with a box, the plastic sheet with a black panel shaped like a very shallow cone ( I used an acrylic skylight dome painted black & turned upside down ) & the catch can with a funnel. You've got a continuous system as long as there's sun & you keep the "dirty" water topped up.

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Re: solar water distillation from rainwater

Post by John Bozi » Dec 21 2020 3:00pm

Hey AussieRider,

Yeah mate, I have seen a few youtube videos along those concepts now. One was with gladwrap, a rock and rubber band. And you have seen the pic above with the black painted box.

Your idea with the black covering though, I'm not sure about. I think you don't want the cover being hot though right? Anyways I am hoping to use as much stainless steel or glass touching the final water. I have no idea what UV/heat etc does to plastics over time and what gets released from it. I was just researching that and found a scary article about the amount of micro plastic all around us... https://time.com/5581326/plastic-partic ... led-water/

Today's cloudy so I'm waiting for some sun but I plan to try a passive set up on my carport roof. I want to test the differences of cooling the top/ not cooling it, and black top or clear.

I also just had another thought too. When going out on long e-bike rides into the bush where I do not carry solar panels or want to wait for ages, I might be able to scoop a pot of creek water somewhere and run the distiller off my bike battery.... (voltage testing....) IF a compact version is possible... looking at the all the bits and pieces needed though, probably isn't logical compared to a larger bottle of backpacked water.

Here's a large scale solar still:

Image

Makes me wonder if this would be possible with something like second hand windows... (until we get summer hail)

---

I'm having trouble deciding whether to go with a fan and stainless coil:

Image


or to get a water pump with a condenser pipe:

Image

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Re: solar water distillation from rainwater

Post by JackFlorey » Dec 21 2020 11:06pm

John Bozi wrote:
Dec 20 2020 3:56pm
I have looked around, and there are numerous ways to approach this. I just don't see one that is what I want yet.
Might want to consider Zero Mass Water, a company that makes "water panels" - combined PV and thermal panels that distill water right out of the air. I think it will make about a gallon a day.

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Re: solar water distillation from rainwater

Post by john61ct » Dec 21 2020 11:12pm

Use the heat from the sun directly

making electricity then using that to create heat is like 99% less efficient, water volume per sq ft of insolation

use electricity for fans, pumps etc sure no choice

But really RO processes / filtration are much better than using distillation.

You are getting tons of microplastics in your air and food anyway, too late for that now anyway

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Re: solar water distillation from rainwater

Post by Chalo » Dec 22 2020 2:16am

Rainwater is distilled.
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Re: solar water distillation from rainwater

Post by AussieRider » Dec 22 2020 5:13am

"Distilled" rainwater also picks up dust, pollen, spores & other airborne crap on the way down, then washes the bird shit off the collector.

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Re: solar water distillation from rainwater

Post by john61ct » Dec 22 2020 11:51am

Which is why the first X liters is discarded by the collection system

basic design for many decades

nothing wrong with a bit of organic stuff in your drinking water

I still drink from streams and lakes hiking & camping

The biggest problems are caused by what humans dump into the natural systems, that stuff yes you need to be careful about.

Common sense is usually enough.

All this stupid focus on "purity" is actually harmful to health.

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Re: solar water distillation from rainwater

Post by Hillhater » Dec 22 2020 4:06pm

All this stupid focus on "purity" is actually harmful to health
:bigthumb: :bigthumb:

However,...
Just on a side note, last summer, i cleaned my pool and started to refill it with filtered, clean, cool, clear, tasteless, water from a well bore .
But when i added a small dose of Chlorine it started to discolor instantly..
Image
And within a few hours it looked like this....
Image
Water analysis eventually identified high metal salts , magnesium or Manganese ? ). in solution
Conclusion, ?......... you cannot assume “Clean” water is all that it seems !
(It took months to clean the stains from the pool !) :(
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Re: solar water distillation from rainwater

Post by John Bozi » Dec 22 2020 7:53pm

Man your pool looks horrid.

Do other people use bore water for pools? I wonder what that would do to a vegetable patch over time too.

---

Thanks for all the love in some of the comments :roll: REPEAT WARNING

1. my rainwater looks filled with living stuff, and other crud and you guys can drink that all you like and use whatever filters and tablets in your water. All your focus on drinking dirty water "is stupid" to requote you. One of the greatest threats to humanity is getting clean drinking water, and I'm exploring what is possible. I'm not about to save the world but I thought this topic might be interesting to share with 'endless-sphere'.

If anyone has actual proof that freshly made distilled water is unhealthy compared to tap water or that filtered or chlorinated etc. please share it. There is (fluoride in toothpaste but it doesn't mean I want it in my body), and calcium in my pizza, all the minerals I need are in the food I choose to consume.


2. Yes I agree solar electricity should be minimized, I do also have lots of odd batteries leftover from ebike projects that are not going to add costs to being able to get distilled water when there is no sun out.

---

Thanks for sharing the other panel technology. I should say I am looking at doing this as cheaply as possible, DIY, there's some seriously expensive stuff out there for larger facilities for sure.

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Re: solar water distillation

Post by Hillhater » Dec 22 2020 8:51pm

Sure, lots of folk use bore water for pools, drinking, gardens, etc. often just simple filtering.
Others use softeners to pretreat for domestic use.
I was brought up on unfiltered well water, before moving to an urban area
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Re: solar water distillation

Post by John Bozi » Dec 22 2020 11:21pm

:bigthumb:

OK so had a good bit of sun today to play around with passive condensation.

Things I learnt quickly.

1. The rock shown in videos to make the gladwrap dome the gravity centrally doesn't work when in the sun. The rock gets super hot and the condensation avoids being near it. A similar point is that at all costs cooling must happen to the condesation upper surface, so I have no idea what temps ambient air was in these videos. Today is over 30C so its dam hot. With the sun cooking the gladwrap I think there's a problem, there needs to be some white or other reflective or cooling little roof over the surface.

1 A) this is directly related to the above point, in that having the unit in the sun / shaded or not requires the reverse amount of energy to get it cool on the upper layer, which makes the idea of not using electricity for solar distillation unintuitively wrong. Yes we need heat, but we also need cold. So being in the sun directly does not add value in simple terms. With sophisticated shading of the upper surface there may be a way for directly placing the unit in the sun. So that it sits in the shade but the radiated heat from the surrounding roof still heats the base.

2. I was using a variety of cups inside a variety of containers sitting on my carport roof. The problem is that the inner container is hotter than the outer. Since it has no liquid in it and is still almost touching the hot roof. I tried a glass with a long handle and this is only a little better. Having the catching container inside simply is wrong. It's probably evaporating out the liquid that's already caught.

3. Trying to see extremes I put some ice on the gladwrap top and yes condensation was very fast. Without it, I was waiting for ages to get droplets heavy enough to fall.

4. I had the outer container quite filled with water making it really hard to heat it up even when the roof is too hot for me to stand on. It improved obviously when I reduced the amount of water, but now it's such a small amount to get a mouthful of water.

5. Related to the last point, I am using a mocona jar which is taking on the heat of the roof but I should try to increase the surface contact. (I'm not wasting thermo paste on this experiment but something like that would make a huge difference. Portability of the project would be impossible if I set something to really heat up with the roof.

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Re: solar water distillation

Post by john61ct » Dec 23 2020 4:48am

No one is saying drinking RO or distilled water (same thing) is unhealthy, that "leaching bones" myth is bulldust IRL, reflecting an unhealthy obsession with the micro details of what's going into your body.

I am saying that going to the trouble of **distilling** your drinking water is another similar symptom of that same psychosis

RO watermakers are fitted on tens of thousands of cruising boats, can produce drinking water from a gallon per hour to 30 gph from **sea water**

an tons of DIY HowTo threads are out there.

Obviously pitifully small electric system will only produce lower rates, still 10,000x more practical than solar still and take up way less space

If you can fire up a gennie for an hour and get 20gal in an hour

that is 100,000x more practical than distillation.

I've lived for decades off grid drinking only rainwater stored year round in 10,000gal concrete tanks, in drought times have to reduce consumption to 1gal per person per day including showers dishes clothes

Even then distilling would just be silly.

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Re: solar water distillation

Post by John Bozi » Dec 23 2020 3:29pm

Looking at RO on ebay for the cheapest I can find

Image

https://www.ebay.com.au/itm/5-Stage-Rev ... Swqehe~IUN

Anyone know how long till parts need replacing?

Also what is a gennie?

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Re: solar water distillation

Post by Chalo » Dec 23 2020 5:34pm

John Bozi wrote:
Dec 23 2020 3:29pm
Also what is a gennie?
I think he meant "generator".

Your rainwater is clean, unless you live in a very dusty or polluted place. Your collection apparatus might be grimy, but it doesn't have to be that way.
Likewise, your distilling apparatus isn't necessarily clean unless you keep it clean.
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Re: solar water distillation

Post by Grautuefel » Dec 23 2020 7:04pm

Gennie? I thought you were Australian, its a generator.

As for how long the RO filters last, it really depends on how dirty your water is. From rainwater collected on a tin roof with no leaf litter and away from the city we would get 2 years out of the filters. You do have to clean and sterilise them occasionally.

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Re: solar water distillation

Post by ZeroEm » Dec 23 2020 7:25pm

If this is being done for a home look at water systems for them zero energy homes. They use plants, rocks, sand then thru filters and last a UV light.
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