Solar Geysers: Guide me

[FRZ0n]

Hi. This is my first post and i need guidance

 

I am planning to go grid tied over the next few months. I already have an Axpert 5kva inverter and will get my second one this week. Will take a few months to sort out.

I need to probably add about 20kwh max overnight with the inverters and batteries but that will be sorted later.

My problem is I have electrical geysers with heat pumps which are not optimised. No timer switches. I want to convert to solar

One geyser is a 150L Kwikot and the other is a Duratherm 150L (3kw element).

The heat pumps are Tasol TAS4-DU Heat Pump - 5.2 kw models. 

I want to replace the geysers with a solar solution and integrate with the heat pumps. 

Its a minefiled. Not sure what to get.

1) What is the system i should consider. Evacuated tubes or flat panel and with a low consumption backup electrical. With timer switch added.

2) Times for hot water are for afternoon/evening and morning

3) Recommend a company to me to install in Ormonde near gold reef city.

4) I dont want to spend a fortune coz the whole backup solar system is going to cost me a fortune..

5) Dont want to retrofit unless the elements in the existing geysers can be downgraded to say 1kw elements. I hope that can be done.

Any advice would be appreciated

Thx

[Wetkit]

Hi FRZ0n,

Is both geysers close to each other or very far away?

If they close together, I would combine them to give a total storage of 300L. That will work great for solar heating.

Still keep one heatpump and use that for backup, rather than elements.

Through a lot of experimentation I found the best solar water heating to be a pumped system with a decent controller. Vacuum tubes works way better than flat plates, but they do cost more.

I have to ask why such a huge heatpump was installed on a 150L geyser?

[FRZ0n]

Hi FRZ0n,

Is both geysers close to each other or very far away?

If they close together, I would combine them to give a total storage of 300L. That will work great for solar heating.

Still keep one heatpump and use that for backup, rather than elements.

Through a lot of experimentation I found the best solar water heating to be a pumped system with a decent controller. Vacuum tubes works way better than flat plates, but they do cost more.

I have to ask why such a huge heatpump was installed on a 150L geyser?

Hi

The geysers are about 15 m apart on a flat concrete roof. So it's possible to join them or centralise with insulated pipes and the heat pump/s.

Why such a big heat pump? I don't know. I didn't do my homework. The house was built from scratch and with all the mayhem I missed it.

I wouldn't mind at all putting a single large system which would cost less than a 2 seperated systems. 300L or more.

Any recommendations?

[Arandoza]

Hi Frzon,

I use two 150liter glass evacuated tube geysers, and the first geyser has a 2kw backup element. (We have Eskom for night time and backup - prepaid) also a Geyserwise Max installed.

I only turned on the timer of the Geyserwise to run from 3am - 6am for end June and July last year, to make sure no warm but not hot showers. Four people

In the house plus domestic and we did not have cold water yet even on overcast / rainy days where it rained from a Friday to Monday and was extremely overcast in August, did we turn on the power 24/7 for 3 days to ensure no cold surprises.

Been very happy with the external geysers and despite the ice on the roof June last year, from the overflow, the water stays hot and looses only a few degrees overnight.

I am not sure a heat pump is worth the cost, unless you are running large 150l baths 3 X a day?

But with the cost of water also going up, it's better to shower most days and enjoy the baths over the weekend

[Sidewinder]

Hi Frzon,

I did a similar installation as what you have described above.

Started off with a single 150 l geyser. Added 200 l geyser for extra capacity, for family of 4. Installed 2 x 12 tube panels, pumped with controller. Then added a 7.2 kW HP as backup. The trick is to set the temp at which the HP kicks in fairly low, else it will work too hard. My system is in 4 years. 

Problems so far:

1) the temp probe in the panel failed, so the pump didn't function. You have to cover the panels, else you will see temps >185 Deg C up there! Finding a replacement probe was not easy, but got it at the right price in the end.

2) Lightning took out the control box in the roof, so had to get a complete new controller system. at least I now have a spare LCD screen and whole set of probes!(4). My original installer didn't hand over those spares:-(

3) Installer disappeared when 1) happened.

Fortunately, during all these niggling issues, the HP kept everything hot.

Hope this helps, together with the attached drawing. 

 

Solar Geyser & HP Installation V1.1 (2016-02-24).pdf

[Wetkit]

@Sidewinder, you know that you can set your solar controller up so that it can also regulate your panel temp, meaning you can set it to 100C and it will start the pump to "cool" the panels down?

Nice install.

 

[Sidewinder]

Wetkit,

Afaik, that kind of setup is not possible, i think, with these standard solar controllers. They have quite good setup capabilities, e.g.  To take it up to a high temp to kill off any bugs in the water. Legionares Decease or something they call it. The basis of its normal config and operation is based on differential temps. Maybe i need to go and study the manual, and there could even be such a setting.