Geyser next steps

[josievich]

We finally pulled the plug (when stage 6 was announced) and got a solar kit installed. 5 kW hybrid inverter, 2.7 kW of panels (priority was beating load shedding , not decreasing costs yet), and a 7.2 kWh battery pack

I’ve got some questions around the geyser with a 4 kW element, both as a temporary and long term solution

1) Short Term

I’ve been putting the geyser on at around noon and the solar works with the battery (and Eskom once battery drains to 80%) to heat up. This allows hot water for the night but geyser still needs to go on again at 5AM for the morning. Would settings the temp as high as possible be a good idea so we can potentially on have it on once a day (during peak solar output) to maximise solar use?

 

2) Long Term

Would converting to a PTC 2kW element be good enough in the long term? Good enough to reduce the use of Eskom further that is. This is relatively cheap and would allow the geyser to be powered purely by the solar during the day. It would take longer from what I gather, but we only need hot water after 16.00 or so

[Speedster]

1) Yes that will help.

2) you can simply use a standard 2 kW element. I don't get the big push for expensive PTC elements 

Edited August 6, 2022 by Speedster

[josievich]

55 minutes ago, Speedster said:

1) Yes that will help.

2) you can simply use a standard 2 kW element. I don't get the big push for expensive PTC elements 

Oh okay, thanks… somehow didn’t consider a normal 2kW element. If it work then I’ll probably go with that. In theory, will it simply take twice as long to heat up going from a 4kW.. assuming no other losses?

Edited August 6, 2022 by josievich

[KLEVA]

My thoughts, and without seeing the rest of your setup might not be appropriate, so take/leave as you wish:

* The nice thing about lowering your Geyser element to 1.5-2kW is that you would not put high Amperage load on your batteries/invertor - I highly recommend, even if it takes double the time to heat your geyser up, it will save some extra life of your systems with little inconvenience.

* I know I am going to get more flak for suggesting this, but I still suggest switching to a solar geyser and using heat tubes. Many on this forum don't like that approach as using electrical power with heat pumps and other alternatives make more sense to them. However I still prefer a seperate setup, so read and consider the options before powering a geyser with solar electricity. Whether I have power or not, my geyser is 45-70 degrees every morning, even during winter and with no sun for days... UV rays get through cloud cover and still heat my geyser when my solar can't even generate 300W.

[hoohloc]

3 hours ago, josievich said:

Oh okay, thanks… somehow didn’t consider a normal 2kW element. If it work then I’ll probably go with that. In theory, will it simply take twice as long to heat up going from a 4kW.. assuming no other losses?

Speaking from first hand practical experience and not hearsay, your choice of using a PTC element is perfect. I used to have a 3Kw heating element in my 150L geyser, changed that to a 1.5Kw geyser wise PTC element and I can tell you that the performance is way better. The PTC element uses less power and the time to heat up my geyser is the same. In 2 hours my geyser water is so hot that you have to mix it with cold water when taking a shower, which is the same time my 3kw resistive element used to take. Meaning a 1.5kw resistive element will take longer to heat up the 150l of water, when compared to the 1.5kw PTC element. Not really a fair comparison because when I removed the resistive element, it was covered with a layer of scaling which might have caused the poor performance of the element. If you have a 4Kw resistive element, change that with a 2.2kw PTC element 

Oh! and mine has an option to run on DC which uses eleven less battery power, 900W on 48v DC. When the need arise, will figure out how to utilize that or test to see if I will get the same performance. With PTC element you can run your geyser the whole day but you will still need more batteries for morning showers in winter. The water is still warm enough to use but in my case, I had to add gas geyser because the owners of my house wants to shower and bath with boiling water.  

[SYC]

17 hours ago, josievich said:

Long Term

Just my 2 cents worth: I would and have installed heat pumps (use 3.6kw heat pump uses 860w only,which can be supplied by pv easily) If the 5kw hybrid is Sunsynk than I would and have connected heat pump to aux port

[josievich]

Thanks for the replies. Maybe long term is the wrong wording. After paying for the solar, budgets don’t allow a full retrofit or heat pump.

A PTC element looks to be around R2k max and normal 2kW element is around R200. That looks like something affordable in the immediate term, with additional battery/panels/hear pump a consideration for next year perhaps

[Raj35]

On 2022/08/07 at 8:08 AM, josievich said:

Thanks for the replies. Maybe long term is the wrong wording. After paying for the solar, budgets don’t allow a full retrofit or heat pump.

A PTC element looks to be around R2k max and normal 2kW element is around R200. That looks like something affordable in the immediate term, with additional battery/panels/hear pump a consideration for next year perhaps

Just a thought what about a gas geyser so I have flat plate collector with my geyser there is no municipal power to geyser and have a 16 liter gas geyser to boots temp when needed.

[zsde]

On 2022/08/06 at 5:12 PM, KLEVA said:

I know I am going to get more flak for suggesting this, but I still suggest switching to a solar geyser and using heat tubes. Many on this forum don't like that approach as using electrical power with heat pumps and other alternatives make more sense to them.

My solar journey started with a solar geyser conversion. Did I make the wrong choice? Probably should have opted for evacuated tubes instead of the flat panel as the efficiency of tubes is so much better than the flat panel. Having said that, in full sun it does a pretty good job.
Now that I have my PV system, I use the 3kW element to heat the geyser and there is nothing to beat the time it takes to get it to the max element temperature of 65C which is capped by the Geyserwise controller. The Flat Panel then does the further heating. In Winter, hardly any rise occurs, in Summer it will take the Geyser Temp to 80C at which stage the Geyserwise inhibits the circulation pump. (This doen't happen often.)
My experience with the flat panel has been good when the start temp in the morning is around 30C. It will easily take it to 55C over a full sunny day. (150l geyser)

I have more than enough PV power now to always heat my geyser. So my conclusion now (after 4 years of flat Panel) is that the cost of extra PV Panels to power the geyser element is a better option than the cost of a solar geyser. And the element efficiency is exponentially better in terms of heating the water.  Having said that, these are my thoughts once I started with the PV. For someone just wanting to reduce their Grid usage and not spending an arm and a leg, a Solar Geyser conversion or complete solar geyser system remains a fair option. Just don't do what I did, rather spend the extra for tubes instead of flat panel.

Edited August 8, 2022 by zsde

[Nicholas Strachan]

Hi all.

I am in the process of having my 4kw geyser element replaced in my 200 litre geyser for a 2kw one.I am a household of 1 person and my 5.5kw of panels should provide enough to have spare capacity when the new element is in.

I am keen to see the difference in heating time as mine from cold takes about 1 hour 20 min to fully heat up but of course its a big 4kw draw .

[Scorp007]

8 hours ago, Nicholas Strachan said:

Hi all.

I am in the process of having my 4kw geyser element replaced in my 200 litre geyser for a 2kw one.I am a household of 1 person and my 5.5kw of panels should provide enough to have spare capacity when the new element is in.

I am keen to see the difference in heating time as mine from cold takes about 1 hour 20 min to fully heat up but of course its a big 4kw draw .

Please report the NEW time. It should be now 2h 40m plus a slight loss due to the longer time.

[Nicholas Strachan]

Will do.Its being done on Thursday.

[Dylankie]

On 2022/08/09 at 8:29 AM, Nicholas Strachan said:

Will do.Its being done on Thursday.

And then? What did you find?

 

[Nicholas Strachan]

I had a geyserwise system installed as well so i havent used the heating element of the geyser for 4 months