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Geyser ROI's. Electric vs Gas vs Solar and all the options and opinions in between


Gutty
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Hi

Please excuse my terminology as I'm am not in the industry. 

I am paying close to R2000 a month on electricity in winter and R1500 in summer.

Currently I have  a 150l Kwikhot geyser + Geyserwise + Flat plate collector/solar panel.

I am staying in a 3-bedroom house, just me and the wife but the might be a baby on the way soon and I am also looking at building or buying a bigger place where my parents can come and stay with us, two or three years from now.  Not sure if it will be in the house or in a garden flat yet.  We both take a 5 to 8 minute shower in the evening and a slightly shorter one in the morning to wake us up before the caffeine has fully kicked in. 

I've done some minor research and it appears to me that a gas geyser might be the best option for heating water especially with current electricity tariffs. I'm paying between R2.72/kWh and R3.14/kWh at the moment in my area depending on monthly consumption.

Has anyone done a ROI or savings calculation on the below to options assuming it is a newbuild and everything would have to done from scratch or is there any existing posts or articles on this that anyone can recommend. I am also considering installing gas geyser on current house for nest 2 to 3 years if the ROI justifies it.

Electric Geyser VS

Gas Geyser VS

Electric Geyser + Gesyerwise + Flat plate collector VS 

Gas Geyser + Flat plate Collector, where the gas only needs heats up the shortfall to +-50 deg C

Thanks

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Roughly calculated  600 X R2.72 = R1632.  

Important  geyser wise is a fancy timer does not truly save electricity.  One can achieve the same with a R350 timer ...

Thus:

  1. The very first step is to install a gas hob.  Oven is not that important as from an hour you might use 35/45 power Gas will cost +/- R100 per month electricity much more.
  2. For geyser you might want to add another collector/tank but that one can only see with more information.
  3. Make sure all you lights are LED/ low power.
  4. Plan your meals a head microwave take a lot of power. Not exact science but a microwave of 1.5Kw uses +/- 1unit per hour.  Do a defrost and check it on your meter.  They DO not SAVE electricity.
  5. If your power is still high use gas kettle

These steps should drop the KWHr below 600 units as a step.  If you are on prepaid do supply me with 1 weeks meter readings please or your electricity bill you can in box me with it.  Below is my solar graph:  The green line is what I put back into the grid during the day.  In Cape Town we had a lot of rain this year and still it was worth it.  The red line is what costly.

image.thumb.png.569f91ec068bcc0ac712fd4f331e97aa.png

You never mentioned you want to fight outages. Therefore if it was me I would 1st do the above.  Once the above is done I would install a grid tie invert..  Depending the way your house faces and other stuff will depend the amount of solar panels.  If you install a5Kw grid tie you will see that your account will drop to less than R300 per month.

These figures are values based on those who I helped and not exact.  One can only do more accurate calculations once one understands:

  1. What other equipment uses electricity pool?
  2. Grinding normally take more power than welding
  3. Fridges use +/-  300W when on depending on the size or .7 units per hour.
  4. Take the meter reading when it gets dark and then again when the sun is up then again when the sun sets.  Take it for 1 week if possible.  Then one can calculate your night usage and recommend a size of solar panels..  Mine is +/- 10 units per night or R600 per month.  During the day if I push back 20 units more than my days usage I get a 0 balance.


I tested a gas geyser yes it saves but it has its issues. If your geyser is totally off during the day and fully heated by the son then you can increase the size and have more water.....    There are many options.  The most important is to get rid of the hob that eats power.

When you do take the readings on the meter take it at +/- the same time  egg  7 at night and 9 in the morning.

Hope this help you it a fairly accurate guesstimate.  If you can provide those figures then I can assist more.

Edited by Erastus
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41 minutes ago, Erastus said:

Important  geyser wise is a fancy timer does not truly save electricity.  One can achieve the same with a R350 timer .

This is definitely not true. A normal timer does not control geyser temperature like you can with geyserwise. The trick is to set up the temps and time it comes on according to how many people need to shower . Follow the usage of water/temps for a while and set the controller parameters accordingly. I have saved atleast 30% on my usage after installing a geyserwise. I was using a normal timer before and its a huge difference. 

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Something on getting back.

Should you go batteries then the basics are very simple to calculate the ROI.  Assuming you use 12 units per night then you require 2 x 5.5Kwhr and 1 2.75.  Then you are covering your bases and not for a rainy day. Thus 2 x +/- R25 000 plus +/-  R 15 000 a total of R65 000. Assuming you would save an average of R 1600 per month to pay the batteries will take at least 40 months if you buy CASH.  (I am not referring to your fin status).  That is 3 1/2 years.  At +/- 4 years you will start getting issues and then it will cost you more money.  To have a good set of batteries with a long life you need more batteries.

Therefore Batt should be used IN MY OPINION to fight Eskom load shedding and there are other scenarios.

To get 14Kwhr back into the batteries you need  +/- 17Kw for the day or @ 2 Kwhr 9 hours of sun shine 9 Hours is not always possible therefore the recommended value to charge your batteries is 3Kwhr and to achieve that you roughly require 5Kwhr solar panels. Then you know your batteries are properly maintained (as for charging).

Therefore you will need 16 x 340W panels at +/- R 25 000.

 

The cost then are:

Batt:         R 65 000
Panels:     R 25 000
Inverter:   R  12 000
Total:        R102 000

Thus to pay off the system at R 1500 per month will take at least 68 months or 7 years.

The other scenario is  Grid tied:

Panels:        R 25 000
Inverter:      R 12 000
AMI meter:  R 11 000
Total            R 48 000

Thus to pay off the system at R 1500 per month will take at least 32 months or 3 years.

These are not 100% accurate figures  and can be calculated more accurate with meter readings.

Based on a little experience I would be amazed if there is more than 10% difference.

All other costs will be the same for both systems.

Hope this help a little.
 

 

 

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32 minutes ago, Nexuss said:

This is definitely not true. A normal timer does not control geyser temperature like you can with geyserwise. The trick is to set up the temps and time it comes on according to how many people need to shower . Follow the usage of water/temps for a while and set the controller parameters accordingly. I have saved atleast 30% on my usage after installing a geyserwise. I was using a normal timer before and its a huge difference. 

Oh dear me.  ....

Let me be more specific.  The intention was not to discuss geyser wise as there are far better option than to install geyser wise.

A timer and solar collector for the geyser beats geyser wise hands down.  You have the added feature of the sun heating and then the cost of geyser wise will be off set to your solar collectors.  Which if you are a handy man you can manufacture your self. 

I did not want to discuss geyser wise as the sun generates far more than what geyser wise saves.

One question.  Do you know what the savings are there when you DO NOT WANT your geyser off at night... Lets say you are a shift worker then what will you save?
Its simple a electronic temperature controller at +/- R4xx will do the same if you want to control your temp exactly else not worth it.  That take me back to my statement a fancy timer.  Spend the same money on glass tubes and a manifold that you can expand and the savings are much more even in winter.

Still want to take me on then get geyser wise to send me a unit and I will create a database  and track the two units with scientific facts.  The reality is you need X electrical KwHr to heat up Y l of water .  You can not get away from that.  Therefore you will always pay.  What I am suggesting is that sun during the day does it all for freeeeeeeee

Edited by Erastus
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 I do agree with most of what you say . You should definitely use the sun by all means possible and i forgot to specify that i am using a thermosyphon geyser. The main problem was not knowing the temperature,so it would come on at times when it was not needed ect. Sure you can get cheaper alternatives to monitor/control it  but at R900 the geyserwise was not that expensive. It saved that money in the first 1-2 months of use easily.

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I'm in the same broad camp as @Erastus. There are things you can monitor and control and doing those first may bring you a worthwhile saving.

EG what temperature is your geyser set to? If you've got it jacked all the way up and have to mix in a good amount of cold water to get it comfortable then you are heating that water for nothing and should adjust the thermostat downwards. 

I am reminded of a recent chat on my neighbourhood whatsapp group

Neighbour: Something is going on. Eskom have increased their prices.
Me: No, they get an annual increase which is government gazetted. Besides we are supplied by City Power and their tariffs are controlled by an oversight committee and any proposed increases must be announced well in advance and ahead of said committee ruling.
Neighbour: Well my bill has gone up!
Me: A lot?
Neighbour: hundreds!
Me: And you haven't been using more for heating or had guests?
Neighbour: Well apart from the four electric blankets we bought....

Point is that there are lots of things we can control, should control and don't cost us much to control. And the flip side of that coin (I'm not saying it applies in your case) is that the more stuff we plug in, the more we pay.

Also avoid what should be called "Bobster's pitfall"
It goes like this

  1. get up in the morning
  2. fill the kettle and turn it on
  3. have a shower
  4. turn the kettle on
  5. get dressed
  6. turn the kettle on

etc.. You can see where this is heading. You heat a full kettle half a dozen times and then make one cup of coffee. OK, in a day that doesn't hurt you too badly, but over a month it adds up. I've seen the same with microwaves (mentioned above). The thing goes ping. Then some other stuff happens. Then the meal in the microwave isn't hot enough so it gets a second blast. Then somebody burns their mouth on the now apocalyptically hot meal.

Before I went whole hog to solar, this household already had low consumption (even though we had an alarm and an electric fence) simply because we had disciplined ourselves. And I think most folks, with a little reflection and discipline, can save themselves money on electricity without splashing out a lot.

If you want to generally have as little to do with Eskom as possible and to mitigate against power interruptions, then go for a hybrid solar system for your house and move your geyser to solar or to heat pump. I have a heat pump and in the morning it takes about 40% of the electricity of a regular geyser to get up to a nice, comfortable 55 degrees.

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@Erastus, I have a Sunsynk with a 6.4 kWp array and 4.8 kWh batteries, my max production is +-29 kWh nowadays ( on a sunny day ), which i don't use up every day, depends if the washing machine/tumble fryer/dishwasher gets used, would love to feed back to the grid, but the roi does not seem to make financial sense, and also would I not be running the inverter at full tilt, shortening it's life.

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4 minutes ago, Tariq said:

and also would I not be running the inverter at full tilt, shortening it's life.

What's this please? Do we shorten the life of our inverters by not making them work hard for their living? It's 11:30 and my batteries are already 100% SOC. So now all the inverter has to do is run the swimming pool pump (OK... if we ran the dishwasher it would work a bit harder).

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Technically it won't run full tilt.

When you throw a max load on the inverter while on batteries, then it will be running full tilt converting that 48v DC to 220v AC and at the max capacity.

When running on Sun and feeding back, you should be closer to 480v most of the sunny part. However this time it just have to down convert from 480v DC to 220v AC and that takes less effort. Also, only at the max it get from the sun minus house load. Not specifically at the limit the inverter can do.

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From what I have seen/read about, a majority of the solar installations around the world are grid tied only and feeding into the grid, so you are right, feeding in should not be an issue for the inverter.

   So that is why I am waiting for @Erastusto tell us how he makes feed in to the grid feasible.

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I installed a Solar System, i can not say it saves me more than 50% of electricity usage. In winter most of the heating happens through the element and the geyser has to kick on in the mornings anyways.

I regret going solar over a heat pump, the heat pump should give an instant 75% savings on electricity.

 

 

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6 minutes ago, Basil Katakuzinos said:

I installed a Solar System, i can not say it saves me more than 50% of electricity usage. In winter most of the heating happens through the element and the geyser has to kick on in the mornings anyways.

I regret going solar over a heat pump, the heat pump should give an instant 75% savings on electricity.

 

 

Solar is nice, but if i had to choose between the one or the other, i would choose the heat pump.

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12 minutes ago, Basil Katakuzinos said:

Solar is nice, but if i had to choose between the one or the other, i would choose the heat pump.

When you say solar, do you mean solar geyser specifically or solar for house that also covers the geyser?

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12 minutes ago, Tinuva said:

When you say solar, do you mean solar geyser specifically or solar for house that also covers the geyser?

Solar Geyser!

I love my electric solar system.

Am a proud owner of a MultiPlusII 5kva and 12 450W JA Solar Pannels. 

Edited by Basil Katakuzinos
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2 hours ago, Basil Katakuzinos said:

Solar Geyser!

I love my electric solar system.

Am a proud owner of a MultiPlusII 5kva and 12 450W JA Solar Pannels. 

When heating water and I refer to solar it is preferable glass vacuum tube with an collector in it heating the water..  Solar to voltage to element is +/- 20% effective.  Simple old comparison.  Put a chocolate on your cars dash measure the time till its melted.  Then do the same with a 150W panel and then you try and melt a chocolate with that.

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15 minutes ago, Erastus said:

Never.  On a rainy day you do not generate the same heat as when you heat via vacuum tubes...

Hi you might have seen my posts about growatt inverters. I was powering my 3kw geyser element with my 5kw growatt inverter and about 6kw pv panels which works on sunny days but sucks ass when it's not.

So I invested in a heat pump got one installed by local guys here in the midlands. I'm very impressed.

I never overload my inverter anymore, it takes 30 minutes to an hour to heat a 200l Geyser to 55celcius compared to 2 to 3 hours with a traditional element which was set to 60 Celsius. I can also power the tiny 1200 watts the heat pump uses with batteries without any issues. I have 10kw storage.

I would recommend it to everyone.

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7 hours ago, Nexuss said:

 I do agree with most of what you say . You should definitely use the sun by all means possible and i forgot to specify that i am using a thermosyphon geyser. The main problem was not knowing the temperature,so it would come on at times when it was not needed ect. Sure you can get cheaper alternatives to monitor/control it  but at R900 the geyserwise was not that expensive. It saved that money in the first 1-2 months of use easily.

If I understand you use geyser wise to lower the temperature from lets say 65 C to 60C and then you save power. Can I not do that with a R20 thermometer with 3l of hot water?

What am I missing. You sau I must spend R900 what I can do with a basic thermometer .  I guess that says it all.   I can have a very nice Sushi for less than that and still use my "koors pen".

Ohh dearame, dearame, dearame  the sales team sure knows how to "smokkel" with peoples minds.

Maybe I am to dumb to understand the real workings of geyser wise but they will not fool me like that.

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