Vacuum Tube Solar Geysers Frustration

What foot print size does this take? I’m assuming it needs quite a bit of outdoor space

It’s the size of an airconditioner outdoor unit. But it is retrofitted onto an existing 200-liter geyser.

If you want the vertical integrated tank solutions, yeah those need a bit of space.

Hey Plonkster, share your gas with me? So why the question. We replaced our electric oven / Hob with gas. Not only did we reduce the electric bill we also have got past the load shedding problem. Our usage per day is at least one to three hours. A 19kg lasts 4 -5 months , and we have a spare 19kg so it months before I go anywhere near a refill. At R500 for a bottle, call it minimum 4 months R125 per month? Does the gas on a shower for say 15 minutes use a lot of gas. Okay granted if you are a tenant then is until there is no more hot water at all … 45 minutes.

But you added a gas bill. Per kwh “heating” they basically cost the same to use.

Agreed Plokster - I’ve never liked gas (I’m not saying its not a good solution - it definitely has its place). Showering is fine - until someone opens a tap in the house somewhere and the water pressure drops and the gas geyser flame goes out - and then you have to close all the shower taps and start the whole process over again -very inconvenient - especially in very cold places like where I live (not to mention the gas always - and i do mean always runs out at 8pm in the middle of winter when your head is full of shampoo!).
As for running hot water baths (woman mostly like to bath) Gas geysers are ok for this, but in very cold conditions, you cant get the bath water warm enough. Remember guys - happy wife, happy life!

I have been running a gas - electric hybrid system for 4 years now. I still have my 150L electric geyser that I use to essentially store any excess PV production and I added an inline Paloma 26L gas geyser fed by a 48kg gas bottle for the cloudy or load shedding days.

The advantage of running the system this way is that in summer my excess PV is enough to heat the electric geyser to 70 degrees C and still run aircons to cool the house. When using the heated water, the Paloma will ignite only briefly and once the hot water passes through it, switch off. In winter when my PV production is lower, The electric geyser will still heat up to roughly 35 degrees C and the Paloma will boost to the set temperature, usually 45 degrees C.

Using this system I have managed to average one 48kg bottle of gas every 12 months or so or roughly R100 a month. This is usually with the family taking three or four showers a day with a bath at night and plenty hot water used in the kitchen daily.

There is also the added advantage of endless hot water.


I mean gas for hot water heating. Gas for cooking is an excellent compliment for PV systems - in my experience.

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Jaco, would you estimate a HOB and Stove/oven use R125 a month? I never did any type of calculations until I was interested in Solar so cannot accurately quote any numbers. You can share your knowledge. Also when I read about the latest Gas technology, This is from the “Sales” Pitch on the product. You use it to complement a Geyser and not stand alone. The burner is off, Then it senses hot water movement and lights the pilot and starts heating of the water flo towards the hot line, but that goes into a existing geyser, as I do have one, I have two , use it only on the main geyser. Feeding in hotwater, but it can be programmed to only operate at night??? Not sure if I am understanding this correctly reading it a number of times. Now that will really work for me and any type of eskom load shedding as during the day my Geyserwise PV does a marvelous job of hot water.

[quote=“Thaelian, post:26, topic:826”]
I have been running a gas - electric hybrid system for 4 years now. I still have my 150L electric geyser that I use to essentially store any excess PV production and I added an inline Paloma 26L gas geyser fed by a 48kg gas bottle for the cloudy or load shedding days.
[/quote] >>>>>>>> This is EXACTLY what I was thinking about Gas. Well that’s answered my doubt about my thoughts on how to use GAS Best!!! Thank you

The tubes that can be used with ITS can be pulled from the existing Geyser without causing any leaks. It fits into a pocket in the Geyser and that pocket is sealed. I am not sure how your low pressure geyser is working but if pulling a tube causes a leak, then I guess it won’t work for the application I described above.

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Yes I do… We use gas for cooking, 19kg cost R990 to refill in Phalaborwa and we refill every 4-5 months…

Its often about Solving a problem and not always do pricing.I sleep better everytime I hear of Eksom saying I must pay more and at the same time use less. Although I dont have the budget of Donald Trump :smiley: The only way to not have a cost would be a lovely pile of wood for every cooked meal, that I got out in the bush. Man going with a reasonably usefull solar was even worse then, Its a cost if you want a proper load shedding solution.

Wow. 19kg = R475 here (refill) if you have an empty. Grahamstown.

Pleasure @RyanG , your mileage may vary of course.

For example, I installed a gas hob for cooking and boiling the kettle. We use a 5kg gas bottle in the cupboard (the largest bottle that would fit) as the hob was installed before the geyser and a 5kg bottle lasts us at least 4 months or R35 a month.

I also think the efficiency of the gas appliances is directly linked to the cost and quality of the appliance.

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Wow @JacoDeJongh thats ROUGH!

I pay R28 a kg! Changes the picture quite a bit

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I still cook with gas. On paper, it should not be cheaper than electrical, but as you pointed out, it removes the load-shedding obstacle, and come on… it’s just such a pleasure to cook on gas.

I used to constantly burn stuff on the stove, chopped beans and rice mostly, when cooking on an electric stove. I cannot quite explain why, but on the gas stove I haven’t ruined ONE dish yet in the 18 months we’ve had it. I think it has to do with the better heat control, not having just 6 discrete settings where 5 is too hot and 4 isn’t hot enough.

With that out of the way, it was the hot water that killed it for us. I estimate I was about halfway through the 48kg bottle when we switched in November (ish) last year. I’m STILL on that bottle, now that it is only being used for cooking.

My calculation is fairly simple. The calorific content of LPG is 46MJ/kg, which is equivalent to 12.8kWh, or 115kWh in a 9kg bottle. It costs R225 to refill that 9kg bottle (I refilled last night). So the cost per kWh is 225/115 which is darn near R2/kWh. At face value, that is LESS than I pay for electricity, because I pay closer to R2.80 for electricity.

But, the efficiency of a gas geyser is so much less. I have heard varying estimates. I personally estimate it at around 60%, but even at 70%, that puts the gas on par with normal resistive heating with electricity.

Still it is not the whole story. An electrical geyser has a standing loss. A gas geyser does not. You pay for around 2kWh of hot water that you don’t get to use. So the gas geyser has a bit of a head start.

It all comes down to the efficiency. If the efficiency is as low as I think it is, heating water by gas is around R3.30/kWh (equivalent energy in the water). I get 2kWh worth of water free, but I pay more for heating the rest. In my estimation, it came down to swapping an electricity bill for an equivalent gas bill. It’s very close to being the same.

Just to test it, I swapped the electrical geyser back into the circuit (this was before installing the heat pump) and we were running 12kWh a day on hot water. 12kWh a day is 360kWh a month on hot water. Meanwhile the gas should be equivalent to over 600kWh of energy, yet it wasn’t lasting that long, indicating that my efficiency numbers are probably not far off…

In any case, the heat pump has a COP of close to 4. There really is no comparison. It beats the pants off gas. Does cost significantly more, and of course, people often point out that if the heat pump needs replacement or a large service, the math isn’t as simple as “divide by 4” :slight_smile:

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Guess it all depends on what you want from your system?

I’m not interested in ROI or how much I spent or saved. I’m more interested in convenience - as in no load shedding crap / no hassles with geyser timers or how many people can shower before hot water runs out or “oh shit” no hot water etc.

I also hate escum like all other corrupt anc run crap - so I don’t want to use pay them for heating my water - I’ve got the hottest thing in our galaxy to do that for me. My setup is a decent solar geyser + decent gas geyser.

I pump my solar geyser water through a temperature bypass valve, so depending on the season, hot water from SG goes straight to the house (summer) or from SG via the GG (winter) to the house, so I get better gas “mileage” because I’m not heating frigid ground water up to 60 degrees, but rather warm 35 - 40 degree SG water to 60 degrees.

This gives me 3 hot water options:

  1. SG direct to house = tempered to 60 degrees (summer)
  2. GG direct to house = tempered to 60 degrees (anytime)
  3. SG + GG mix - direct to house = tempered to 60 degrees (winter)

the benefit or rather convenience for me is hot water 24/7 x 365 days a years regardless of load shedding or seasons.


As far as I know, the tubes don’t get into contact with the High pressure water. At the center of the tube is a heat pipe which is pushed into the manifold with some thermal paste. The only thing that matters is the tube and heat pipe should be of similar diameter to the one you trying to fit them into.

When I did my EV install last year, I stayed away from those all in one units for exactly this reason. If anything breaks, you basically lose most of your investment.

Went with a diy approach from the local plumbing store of a standard kwikott geyser and their own rebranded tube / manifold. In summer when days are long and suns up in the sky, water can get to 90 degrees. In winter, it does almost nothing and at best case increases the temperature around 20 degrees. Other problem is if you go away for a few days in summer, need to cover the tubes else you tend to rest

If I were to do it again, probably wouldn’t choose an EV system.

I’m doing PV grid tied only in my new house heating conventional electric geysers. The main drawback is that if the grid is off, there is no hot water. I would probably add a heat pump or ITS EV sometime in the future.

What I do want but haven’t seen on the market is a heat pump that can work together with an aircon. In summer this would be ideal, using the same energy to heat your water and cool your home.