Newbie here needs help with passive solar hot water outdoor shower

Hello everyone , i need some help here please .
Looking for some who can guide me on a passive solar hot water out door shower . Currently have 30 metres of 20mm black irrigation pipe rolled up on a wooden panel facing south and in full sun gives out about 25 lts of scalding water !!!. Question is  , how can i save more hot water in a couple of barrels above the outdoor shower , how can i make the hot water heat up the storage barrels , looking for ideas on the real cheap and how can i control the temp by mixing with the cold input to the coil . It works great but needs more work , HELP.

Several years ago I attended a natural building workshop at The Farm in Summertown Tn. They had an outdoor solar shower that worked great. They put a used gas water heater tank (with all the insulation and outside casing removed first) up-side-down in an insulated, glazed, wooden box which was painted black on the inside. The box was elevated so there was pressure to the shower. The water pipes were attached to the opposite pipes on the water tank (ie. the water inlet pipe was connected to the water exit pipe in the tank, etc.) It all fed into a regular household shower with cold and hot pipes.

Thanks fro reply.
So the tank heated up and then gravity fed a shower , sounds simple and effective , how many gallons was the tank and how long to heat up .

The tank size was about 30-40 gallons. I am not sure how long it took to warm up, but we seemed to always have hot-warm water for showers, even in the early morning. The box also had reflectors on the sides to shine more sun into it and warm it faster. I hope this helps.

Thanks for the reply , more food for thought

If you use a pump and a differential thermostat,  your system will add heat to storage and you can pu the tank anywhere you want.

The fluid in your coil (absorber) will not thermo-siphon and will need to be circulated in order to spread the heat into a larger volume of water and the temp will even out and performance (heat gain will improve)

Our outdoor solar shower for spring to fall had a 4'x 20' pool heating collector as the heater. It would make 150°f water from 50 deg water by noon, 48 gallons.

The Batch type heater with storage and absorber used water heater tank in a box, can be made with a used doorwall as the cover. These  typically have 2"-4" insulation and are very successful and uncomplicated. They have some cold tolerance but freeze protection gets tricky without an insulated cover that can be closed at the proper time.

Thank you for the info , yes i think i may need a pump of some sort , perhaps 12 volt, all i get at the moment is about 5 gallons of ultra hot water on a summers day , the coil is fed dirrect from a spur from our settling tank up the road . The 20mm irrigation tube is clamped to a square wooden board and cliped in with electrical conduit clips , the board sits on concrete building blocks to avoid contact with the soil and is at about 45 deg facing south . the water can get to steam level , very dangerous . So need to add some more low tech to it for a better system.

If your system is pressurised an anti scald valve will blend in cold water to the hot water outlet evening out the output temperature.  Hard to beat the painted black tank with insulation and reflectors

The solar shower I used did not have any pump, it only used the water pressure from the inlet pipe. The same pressure you would find in your house. Why don't you connect your "coil" to the tank and your water input to your coil (sort of a pre-heater)

Hmmm , thoughts here . I think i need to source and old but good tank as a freebe , at least that gets me further than where i am now , this could take some time .

I didnt believe it would survive at first, but i used a 120v sur-flo diaphram pump for the rv/marine industry as the circulator for a roof mounted plastic solar thermal pool heating collector that drained into a 50 gallon poly barrel wrapped twice in reflective double bubble and in a plywood box on the deck.

We installed a float and flag system made from a car radio antenna screwed onto a lid atop a partially filled glass bottle. This indicated fill level from a distance at a glance, so we could chore hound around while we manually fill.

The booster pump was an inexpensive centrifugal pump that discharged heated water to a gardeners spray wand with a splitter that we could adjust on offs and flows from the cold (well) side and hot side to temper the water if needed.

The differential controller has a high temp limit, but we store much more heat in the same volume of water by raising the temp... this requires that you check temps carefully by instrument and feel before jumping in and that you never let un-trained people or the young just have at it. Its kinda one or the other i go for storage density and capacity.

This shower system cost a couple fittings to throw together and was built entirely of scrap from solar installs, a pool heater i picked from the curbside on garbage day, old batteries, a second hand inverter, pumps, and one of our pv panels mounted on a balasted shipping pallet! It was a full bathroom with composting toilet and motion activated lights!

This was built for a family that was staying at our place while finding a home. The pop up campers they had were inadequate in the washroom department.

5 people used this rig for 6 months and until about mid to end of october showers got shaky and we added a livestock bucket heater/de icer as a backup. Some of the best showers ever in our quasi outdoor shower.

The macedonian guy up north just uses an elevated 250 gallon water tank, you know,... the cage-tanks that he painted black and gravity feeds the shower. The tank is above ceiling of a black box with a low wall so you can see beauty while you scrub! No pump noise, no controller, batteries night lights, etc.

It works. You have to get a feeling for how much to fill it seasonally for a good shower that day or just keep the level you know will get reasonably warm and accept it as your shower.

Ill never forget the caribbean showers a friend used a t a vacation resort. The showers were hand pumped up to the roof at night or early in the morning and filled a black barrel that gravity feeds your shower.

The equator is a good place for this, but seasonally, it will work most anywhere with good sun.

This translates to a batch heater and evolves to pumped and flowing water and insulated and glass covered enclosure that boosts gain and limits loss for year round operation in many areas.

Steve Stolz wrote:The solar shower I used did not have any pump, it only used the water pressure from the inlet pipe. The same pressure you would find in your house. Why don't you connect your "coil" to the tank and your water input to your coil (sort of a pre-heater)

But it did have a pump.. the well pump.

Heating shower volumes of water in a single pass requires clever heat exchange. Flow rate must be extremely low or exchanger capacity large.

He basically only has the water in the pipe as storage and low controlability of temp, these make steam!

I have used the internal volume of our pool collector for a shower. It holds about 1.75 gallons of water and this has proved to be enough. The scald though if you leave it a couple minutes too long before hosing off.