Solar geysers - are they a scam?

Splinter

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Oct 14, 2011
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bullshyt! you clearly don't get it!

I DO NOT use eskom to heat my water. I disabled the eskom powered heater element and bought a gas geyser as backup.

My gas install also supplies my gas stove & gas heater and only if the solar geyser drops below 40 degrees in winter, then gas geyser kicks in and heats up the water.

so watch my lips - I have hot water all year round WITHOUT the need for eskom!

Umm, the fact that you bought a gas geyser to replace required electricity needed, is not exactly disproving what I'm saying.
 

phoneJunky

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Splinter

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To start with, no, they are absolutely not a scam. We noticed an immediate saving once our solar geyser was installed.


OK, now for the long bit...

Firstly, there are two main types of solar water heating - thermosyphon, and split system. The thermosyphon system usually has the geyser on the roof above the collector, so the difference in temperature will push the hot water from the solar collector to the geyser. No pump involved. The drawback, of course, is that your geyser is exposed to the elements, which will cause the water temperature to drop significantly overnight.

Split systems keep the geyser in your attic like a traditional geyser, but have the collector on the roof - to get the cold water to the collector and the warm water back into the geyser, it requires a tiny pump. Ours is a Grundfos AC pump using 24W max. The pump cycles on and off in the daytime only, depending on the temperature differential (ours is set to start pumping when the solar collector is 10 degrees warmer than the geyser, and stop pumping when it's 2 degrees warmer). There are two temperature probes in our system linked to the solar heating control module, one in the geyser, and one in the collector's manifold. This replaces the traditional geyser thermostat.

We frequently see in-geyser temperatures of over 75 degrees Celcius, with some days pushing the water temperature up to 82 degrees. Due to better insulation of the geyser, this then drops to around 65 degrees Celcius overnight. You can also set at what temperature and which times the electric backup element should turn on - default is 55 degrees turn on, 60 degrees turn off, and our geyser is set to only ever use the backup element between 18:00 and 22:00. In other words, if all the parameters are not met (time outside of schedule, in-geyser temperature higher than 55 degrees Celcius), you will not use any electricity to heat the water, just the tiny amount of power used by the pump cycling on and off. Our system as gone for weeks at a time where the backup element never has to switch on, which means our water has been heated at virtually zero cost. If we had a DC pump and solar panel, it would actually be completely free.

Hi Splinter,

I installed my Solar geyser in August 2011 when we still got the rebate. My Solar Geyser cost R16999 after the rebate. My normal geyser burst and then I opted for solar. My electricity bill was then in the order of R500-R900 (2011 R) with 2/3 people living in it (757 kWh was R909.73 from a bill back then - compare that with the prices today).

I have a 250L evacuated tube thermosyphon system that used a geyserwise TSE controller. This is nice in that it shows me the temperature of the water. My geyser is set up to heat with the element if my water is not above 50 degrees and then it will heat it up to 55 degrees at 20:00-21:00 and 4:00 to 6:00.

There is a pump on my system, but it is not for pumping the warm water into the collector, it is to pump water back when the temperature outside is under 2 degrees I think. This is to protect the evacuated tubes during times where there is frost collected on it.

My last months bill is R82 for electricity with 2 people staying in the house. Sure everything in my house is energy effecient, but it was more or less the same before I put in my Solar Geyser. My highest electricity bill the last year is 150kWh (R251.95 - 2019 R) to put it into perspective. My geyser paid it self off in just over 3 years.

I have had 1 problem with my system during this period. My geyserwise broke which was replaced under warranty/maintenance by the installers. Even when my suburb had a week or so of no electricity because of a substation issue in winter I had hot water.

My temperatures still reach 60-70 degrees on hot summer days and on the odd day it goes over 83 after which my pump activates to pump back the warm water in the tubes so that it can loose some heat over night. There is a vacation mode that can be activated that also does this so that heat doesn't build up to much. But if I leave for more than 3 days in the summer after the return my water is at around 90 degrees. Then I have to open the warm taps to release the water.

My friend has a split system in one of these estates and they aren't allowed to have the geyser outside. His system doesn't get near to the temperatures that I get but he still also gets decent temperatures.

Also, you to get the best out of your geyser you want to draw all the warm water at the same time. So everyone showers directly after another which we do in my household by default.

You also won't see these temperatures if you have someone at home drawing water during the heating time. You will still probably reap the benefits on you bill, but it won't be so clearly visible. But in this is your case a heatpump is probably better suited for you anyway. A solar geyser only supplies one full tank with hot water. Heatpump give you cheaper hot water for all your water. So look at what work the best for your situation.

Why, thank you for the informative replies.
 

Speedster

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Just remember for solar you want 50L * number of people + 50L. That was the guideline we used when I installed mine.

There is no pump in that solution, so you will need to buy it seperately. Also you will still have to pay the installation cost. Maybe check with an installer what their price will be.
Pump kit is included, as is a solar panel and backup battery.
 

isie

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Umm, the fact that you bought a gas geyser to replace required electricity needed, is not exactly disproving what I'm saying.

and the solar panel is also used to replace the electricity needed
 

Sinbad

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They got lost among all the heated posts...
Must be all the solar....

I have an evac tube geyser, indirect, thermosiphon.
The element is disconnected. It uses 0 electricity.
It boils in summer.
I have an in line gas geyser as a booster for when the geyser isn't hot enough.
A 48kg cylinder (R1000) lasts 5 months. And that is also used for stove and oven daily.

So even discounting the cooking completely that's R200 per month on water heating at the worse case. That's less than 100kwh.
How is this possibly a scam?
 

Speedster

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Speedster's option is probably the best for you. My friend did this and it cost him R11000 a few years back. But as I said, his doesn't seem to get as warm as mine. Even though we have the same number of tubes etc.
There could be a number of factors affecting effeciency, which include panel size, positioning (angle as well as direction), water usage, insulation etc etc. Mine is a 300l retrofit system and I get between 60 and 80 degrees most days.
 

Splinter

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Must be all the solar....

I have an evac tube geyser, indirect, thermosiphon.
The element is disconnected. It uses 0 electricity.
It boils in summer.
I have an in line gas geyser as a booster for when the geyser isn't hot enough.
A 48kg cylinder (R1000) lasts 5 months. And that is also used for stove and oven daily.

So even discounting the cooking completely that's R200 per month on water heating at the worse case. That's less than 100kwh.
How is this possibly a scam?

See, now this is far more convincing than "what a load of crap" :p

So you are spending say R150 (being more conservative here). How much do you reckon you would pay if you used electricity and a normal geyser?

Then, of course, how much did you pay for your solar set up?
 

Sinbad

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See, now this is far more convincing than "what a load of crap" :p

So you are spending say R150 (being more conservative here). How much do you reckon you would pay if you used electricity and a normal geyser?

Then, of course, how much did you pay for your solar set up?
My monthly average usage went down from over 1500kwh to under 1000kwh.
I paid R16000 and got a R9000 rebate from Eskom, probably 10 years ago now.
 
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