Hi

 

We're building a house near Kruger and it's hot and sunny year round.

What type of heating system would you do geysers?

We're a family of 5.

Would you go electric and power via solar panels? (we get tons of sun)

Or would you go gas?

It's a new house build so I'd prefer to plan it properly.

Any advice and insight is appreciated!

If you are going to install solar PV, then you may as well add enough solar panels and Inverter power to run your geyser too.
The gas option might sound cheaper now but the gas usage is not cheap either. A basin or shower gas option in addition would help if and when solar is not so stellar.
If you only want to get the geyser off the grid then there are many solar geyser  options available.
However solar geyser options are bespoke, i.e. they do one thing only and that is heat your water.
A dedicated 5kW offgrid type inverter can be had for reasonable prices and with ~5kWp solar panels you could use that to heat a standard geyser with 3kW element and still have spare capacity, and an additional 5kW of power once the geyser is at max temp. You could even have two smaller geysers, i.e 150lt in series and heat them with solar sequentially with a timer. Alternatively your dedicated Inverter could even run both if they had 2kW elements.
You didn't state that you plan solar PV for all your electricity needs.

 

46 minutes ago, zsde said:

If you are going to install solar PV, then you may as well add enough solar panels and Inverter power to run your geyser too.
The gas option might sound cheaper now but the gas usage is not cheap either. A basin or shower gas option in addition would help if and when solar is not so stellar.
If you only want to get the geyser off the grid then there are many solar geyser  options available.
However solar geyser options are bespoke, i.e. they do one thing only and that is heat your water.
A dedicated 5kW offgrid type inverter can be had for reasonable prices and with ~5kWp solar panels you could use that to heat a standard geyser with 3kW element and still have spare capacity, and an additional 5kW of power once the geyser is at max temp. You could even have two smaller geysers, i.e 150lt in series and heat them with solar sequentially with a timer. Alternatively your dedicated Inverter could even run both if they had 2kW elements.
You didn't state that you plan solar PV for all your electricity needs.

Thanks! We're going to add solar for the house as well.

1) Would you go for a 100L or 150L geyser? Since it's so hot here, we often don't use that much hot water.

2) I want to avoid geysers using the battery. Is there a way to only have the inverter power up the geysers? (I want to keep the battery for at night with load shedding)

1 hour ago, AlexanderR said:

Would you go for a 100L or 150L geyser?

Go with the bigger volume.
With a timer you can set when to heat the water. So one would set it for typical daylight hours where you know the solar production will suffice to cover the element's demand. (dependent on how much kWp your panels are), but even in winter you should have enough between 10:00 and 15:00 with lets say 6kWp panels.

 
 

2 hours ago, AlexanderR said:

Thanks! We're going to add solar for the house as well.

1) Would you go for a 100L or 150L geyser? Since it's so hot here, we often don't use that much hot water.

2) I want to avoid geysers using the battery. Is there a way to only have the inverter power up the geysers? (I want to keep the battery for at night with load shedding)

Due to market forces 150L is at times cheaper than a 100L. 

Go for the 150L as you should have enough PV power to heat for free during the day. 

5 hours ago, AlexanderR said:

Thanks! We're going to add solar for the house as well.

Just another tip.
If you can, consider a gas/electric stove. i.e. one that has both or alternatively two stove tops. 
Use gas for cooking when the sun doesn't shine and have electric plates for cooking when the sun does shine.

We have a gas stove/oven  and an induction plate. That induction plate is really nice for when the sun is shining as you can adjust the power from 200w up to 1800w on our model. So I have a stainless steel whistling kettle for boiling water, but you can also do stuff like put a flat bottomed cast iron pot on it and let it simmer all day at low power for making stews and soups etc.  

Also we have a wood burning stove (falkirk jewel) which is very popular in winter, and a wood fired pizza oven which is great for roasting things, baking bread and making pizzas of course!

Edited May 23, 20242 yr by DeepBass9

15 hours ago, zsde said:

Go with the bigger volume.
With a timer you can set when to heat the water. So one would set it for typical daylight hours where you know the solar production will suffice to cover the element's demand. (dependent on how much kWp your panels are), but even in winter you should have enough between 10:00 and 15:00 with lets say 6kWp panels.

 
 

 

11 hours ago, zsde said:

Just another tip.
If you can, consider a gas/electric stove. i.e. one that has both or alternatively two stove tops. 
Use gas for cooking when the sun doesn't shine and have electric plates for cooking when the sun does shine.

Do you have any recommendations for a gas/electric stove? Any SMEG or Samsung ones you know about?

1 hour ago, AlexanderR said:

gas/electric stove?

Have not seen one by SMEG or Samsung locally but there is a South African company that produces them and there is a Bosch model available too.

https://ferre.co.za/product/built-in-hob-100-2/

https://www.bosch-home.com/za/en/mkt-product/cookingandbaking/inductionandelectrohobs/inductionandelectrohobsmixedhobs/PRY6A6B70

2 minutes ago, zsde said:

Have not seen one by SMEG or Samsung locally but there is a South African company that produces them and there is a Bosch model available too.

https://ferre.co.za/product/built-in-hob-100-2/

https://www.bosch-home.com/za/en/mkt-product/cookingandbaking/inductionandelectrohobs/inductionandelectrohobsmixedhobs/PRY6A6B70

Thanks. That Bosch looks neat!

1 hour ago, AlexanderR said:

gas/electric stove?

You can consider of course a 4 plate gas hob of your choice/liking and in addition have a 30cm electric 2 plate hob.
https://www.smeg.com/za/products/SE232TD1

If it's a secondary residence - Gas primary for Water heating and cooking,backup electrical options off the Solar

As primary i'd still add both,but change it around a bit to cut costs,more initial capital outlay for longterm savings

On 2024/05/23 at 1:30 PM, AlexanderR said:

2) I want to avoid geysers using the battery. Is there a way to only have the inverter power up the geysers? (I want to keep the battery for at night with load shedding)

When you have solar power installed, the DB gets split into two - essential (backed up at all times), non-essential (not backed up when the grid goes down). 

So first thing is to put the geyser on the non-essential side. BUT most systems will still try to use the inverter and battery to power the geyser whilst the grid is up and there's not enough PV. So maybe add in a timer. And if you're going solar then you have to make use of the sun. I used to have a solar geyser, and we learned the best way to use it was let the sun do the heating and then do the washing of dishes, take showers etc from mid-morning to early evening.

This a general rule for solar anything. If you have solar power then run your dishwasher whilst the sun is up, and the pool pump, and anything else that might use a lot of electricity. Then your battery gets an easier ride through the night. There is an element of personal discipline to this, which is not always easy.

Also think on a heatpump. These require electricity, but much less than the element in a geyser. They draw less, run for less time, are generally more efficient. I run mine on the essential side of the DB, and because we use very little power during the night, there's enough battery to run it early in the morning. 

Downside: Needs electricity
Upside: Still works when the sun isn't so great, or even at 6:30 on a winter morning.

2 hours ago, Bobster. said:

When you have solar power installed, the DB gets split into two - essential (backed up at all times), non-essential (not backed up when the grid goes down). 

So first thing is to put the geyser on the non-essential side. BUT most systems will still try to use the inverter and battery to power the geyser whilst the grid is up and there's not enough PV. So maybe add in a timer. And if you're going solar then you have to make use of the sun. I used to have a solar geyser, and we learned the best way to use it was let the sun do the heating and then do the washing of dishes, take showers etc from mid-morning to early evening.

This a general rule for solar anything. If you have solar power then run your dishwasher whilst the sun is up, and the pool pump, and anything else that might use a lot of electricity. Then your battery gets an easier ride through the night. There is an element of personal discipline to this, which is not always easy.

Also think on a heatpump. These require electricity, but much less than the element in a geyser. They draw less, run for less time, are generally more efficient. I run mine on the essential side of the DB, and because we use very little power during the night, there's enough battery to run it early in the morning. 

Downside: Needs electricity
Upside: Still works when the sun isn't so great, or even at 6:30 on a winter morning.

So you had PV and a solar geyser! Interesting. 

What do you mean think on a heatpump? Is this for the pool?

18 hours ago, AlexanderR said:

So you had PV and a solar geyser! Interesting.

No. In that house I had only a solar geyser. Load shedding had not yet been invented, and Eskom were subsidising the installation of certain types of solar geyser.

18 hours ago, AlexanderR said:

What do you mean think on a heatpump? Is this for the pool?

No. For water heating in your home. I have a geyser, but the element is disconnected and the heating is done by the heat pump.

So I'm back to square one, even with a PV installation....

Gas Geyser - or heat pump?

What would you guys go for?

1 hour ago, AlexanderR said:

So I'm back to square one, even with a PV installation....

Gas Geyser - or heat pump?

What would you guys go for?

Personally, heat pump. Gas availability and price in these interesting times is a non starter for me.

Hello Everyone 

I thought this might be worth a read for you - https://itssolar.co.za/water-heating/a-comparison-of-pv-solar-thermal-gas-and-heat-pump-water-heating-systems/

 

On 2024/05/23 at 11:51 AM, AlexanderR said:

Hi

 

We're building a house near Kruger and it's hot and sunny year round.

What type of heating system would you do geysers?

We're a family of 5.

Would you go electric and power via solar panels? (we get tons of sun)

Or would you go gas?

It's a new house build so I'd prefer to plan it properly.

Any advice and insight is appreciated!

Is it seasonal or are you staying there full time?

 

If seasonal, a Heat pump is the best option (it is also a really good option even if used daily). Heat Pumps can easily be run off a solar inverter/battery system. 

https://www.4solarsa.com/heat-pumps

 

If you stay there permanently, you could go Solar Geyser (although at least 300lt for a family of five).

 

Usually for larger households, a heat Pump is a great allrounder option. It can heat 24/7 in almost any weather conditions, it can be run off an inverter/battery and it can be turned off if not being used.

 

Just a data point: we heat 350L of water per day for 6 people, entirely from a regular Solar Inverter system. This is done across two regular geysers (a 150L 3kW and a 200L 4kW).

We run a 20 x 455W panel array ie (9100W peak) but 15 panels (6825W peak) would do the job fine if the rest of our household demand were a bit lower. Rain obviously spoils the fun but that's not likely to be an issue in OP's location.

Spare capacity then goes to running the rest of the house, and when the water is hot, the balance of the power goes to charging the 10kWh batteries for night-time use.

Heat pumps still require the same peak power as a regular geyser but they run for far shorter. This makes sense when running on the grid, but less so in the context of a solar PV system.

 

My logic: if you have solar capacity to run a 2kW-3kW Heat Pump then really, that same capacity can go to powering a 2kW-3kW Geyser or two; with the benefit being that regular geysers require no maintenance, are cheaper to install (and are the cheapest option to purchase by far) and when your geysers die of old age, Insurance replaces them quickly at no cost and no fuss. You can also drive up the thermostat of a geyser to store additional heat if you need more hot water; I've done so with one of our two geysers with pleasing results.

The exception would be if you don't get enough sunshine hours in the day or if you can't sustain the required PV peaks: in which case it still might make sense to add panels and go with normal geyser heating.

If I didn't have solar, I'd go for a heat pump for the far shorter run-times (since even with the greater initial outlay and installation costs, a heat pump will pay for itself with reduced grid usage). But with a solar system in place I'd go the opposite way: regular Geysers + Solar Inverter have worked incredibly well for my family - we only pay for water heating when it rains.

 

3 hours ago, Pieter Swart said:

Is it seasonal or are you staying there full time?

 

If seasonal, a Heat pump is the best option (it is also a really good option even if used daily). Heat Pumps can easily be run off a solar inverter/battery system. 

https://www.4solarsa.com/heat-pumps

 

If you stay there permanently, you could go Solar Geyser (although at least 300lt for a family of five).

 

Usually for larger households, a heat Pump is a great allrounder option. It can heat 24/7 in almost any weather conditions, it can be run off an inverter/battery and it can be turned off if not being used.

 

 

4 hours ago, JayMardern said:

Heat pumps still require the same peak power as a regular geyser but they run for far shorter. This makes sense when running on the grid, but less so in the context of a solar PV system.

Are you sure? From what I understand they're running at 1.2 kws or so. I haven't heard about the peak?

 

Thanks for your detailed response. I think it's worth reconsidering the heatpump and rather putting in more panels. That said if it's only 2x 1.3kw for the heat pump, that's. Lot less than the 6kw for 2 geysers and the size inverter you need!

7 hours ago, Pieter Swart said:

If you stay there permanently, you could go Solar Geyser (although at least 300lt for a family of five)

Any recommendations for a solar geyser?

To answer your question, we stay there permanently.

 

Thanks for taking the time to share your insights.

1 hour ago, AlexanderR said:

Are you sure? From what I understand they're running at 1.2 kws or so. I haven't heard about the peak?

 

Thanks for your detailed response. I think it's worth reconsidering the heatpump and rather putting in more panels. That said if it's only 2x 1.3kw for the heat pump, that's. Lot less than the 6kw for 2 geysers and the size inverter you need!

Just my 2c, going out on a limb again. To be checked. I seem to recall somewhere in a different thread you were speaking of multiple aircons to be used, maybe a 36000btu or whatever aircon by day, and 3x18000btu at night, but you had a 40A grid supply limit in the complex.

Is this correct, is it the same house? Because given those figures, I wouldn't go for 3kW or so electrical elements on top of the other loads, whether it's running off PV, or even as backup elements to evacuated tubes, if you could most reasonably/sensibly/legally(?) only fit an inverter of up to a 8kW.

If so, suggestion would be to look into a 3.6kW heat pump like the ITS model, but shop around anyway. Point is, it will consume less than 1kW by itself, and still generate effectively 3.6kW of heating capacity that you could connect to a geyser of up to 200l. I think in your hot climate with regularly higher ambient temps, and generally low usage of water, you could get away with a setup like this.

8 hours ago, AlexanderR said:

Are you sure? From what I understand they're running at 1.2 kws or so. I haven't heard about the peak?

 

Thanks for your detailed response. I think it's worth reconsidering the heatpump and rather putting in more panels. That said if it's only 2x 1.3kw for the heat pump, that's. Lot less than the 6kw for 2 geysers and the size inverter you need!

It'll depend on the model, but real-world draw on a family-size heat pump tends to approach 2kW range, which is equal to the size of a small geyser element. Measurements done here:

In that case, even adding an additional 4 panels (to target a larger 3kW regular geyser) is going to work out cheaper if I'm not mistaken, and that extra power can then go elsewhere (eg batteries) when you're done heating.

Edited June 6, 20242 yr by JayMardern

18 hours ago, JayMardern said:

Heat pumps still require the same peak power as a regular geyser but they run for far shorter. This makes sense when running on the grid, but less so in the context of a solar PV system.

Here's my system so far this morning. Yellow trace is load. You can see the heat pump kick in about 6:30. Total load about 1.5 kW, this includes the house "ticking over", which is 200 to 300W, so the pump is drawing ± 1.3 kW. 

Is that more or less than a regular geyser? Depends on the rating of the element in the geyser.