Hi all,

I'm in Johannesburg, have a new Solar installation and am looking at putting in a Heat Pump.  

8.8kW Inverter, 4 x 4.8kWh batteries, and 14 x 600W panels.
200l Geyser
50l Geyser (occasional use by gardener)

Thinking about an Alliance 3.6kW heat pump.

On clear(-ish) days I have more than enough energy to heat the main geyser, I turn it on after about 09h30 or so.  Takes 2-2.5 hours to heat.  

When it's raining, I need Eskom to help with power.

Another problem is if someone turns on both geysers, while running the pool pump.  Then washing machine and kettle and so forth causes too much load, and the inverter trips.

I see 5 options:
Solar Thermal like Evacuated Tubes - Cost saving is good, higher up front cost ~ R20-30k
Solar PV - Newer technology - Cost saving is okay, higher up front cost ~ R20-30k
Heat Pump - Cost Saving is excellent, higher up front cost  ~ R25k
Gas Geyser - Cost Saving is not that good, lowish up front cost ~ R10k
Ceramic element - Cost Saving is not that good, very low up front cost ~ R3k

Article below shows Heat Pump as the best cost saving.  But it's sponsored by a Heat Pump manufacturer.  Not disputing the calculations, just taking the source into account.

The two Solar solutions work best when it's sunny, and this is when I don't need to save energy.  Also, if I run out of hot water on a rainy day, then I'll still be heating with a 3.6kW element.  

So, I'm thinking...
3.6kW equivalent heat pump - draws 1.2kW, so keeps the load lower.  Also take the 3.6kW not 5.4kW equivalent.  This is a case when bigger isn't better, I don't care if it takes 2.5 hours to heat the water as long as I'm not tripping my Inverter.

Alliance and ITS seem to be the leading Brands.  A few plumbers I spoke to say Alliance is the best, just wondering about other's thoughts?

Gardener's geyser I'm happy to heat with a normal element, mainly needed on sunny afternoons anyway.  It's too far from the main geyser to parallel the two geysers.

https://zpenergy.co.za/comparison-of-pv-solar-thermal-gas-and-heat-pump-water-heating/

 

Edited April 2, 20231 yr by BluePeter
Posted before proof reading

3 hours ago, BluePeter said:

Hi all,

I'm in Johannesburg, have a new Solar installation and am looking at putting in a Heat Pump.  

8.8kW Inverter, 4 x 4.8kWh batteries, and 14 x 600W panels.
200l Geyser
50l Geyser (occasional use by gardener)

Thinking about an Alliance 3.6kW heat pump.

On clear(-ish) days I have more than enough energy to heat the main geyser, I turn it on after about 09h30 or so.  Takes 2-2.5 hours to heat.  

When it's raining, I need Eskom to help with power.

Another problem is if someone turns on both geysers, while running the pool pump.  Then washing machine and kettle and so forth causes too much load, and the inverter trips.

I see 5 options:
Solar Thermal like Evacuated Tubes - Cost saving is good, higher up front cost ~ R20-30k
Solar PV - Newer technology - Cost saving is okay, higher up front cost ~ R20-30k
Heat Pump - Cost Saving is excellent, higher up front cost  ~ R25k
Gas Geyser - Cost Saving is not that good, lowish up front cost ~ R10k
Ceramic element - Cost Saving is not that good, very low up front cost ~ R3k

Article below shows Heat Pump as the best cost saving.  But it's sponsored by a Heat Pump manufacturer.  Not disputing the calculations, just taking the source into account.

The two Solar solutions work best when it's sunny, and this is when I don't need to save energy.  Also, if I run out of hot water on a rainy day, then I'll still be heating with a 3.6kW element.  

So, I'm thinking...
3.6kW equivalent heat pump - draws 1.2kW, so keeps the load lower.  Also take the 3.6kW not 5.4kW equivalent.  This is a case when bigger isn't better, I don't care if it takes 2.5 hours to heat the water as long as I'm not tripping my Inverter.

Alliance and ITS seem to be the leading Brands.  A few plumbers I spoke to say Alliance is the best, just wondering about other's thoughts?

Gardener's geyser I'm happy to heat with a normal element, mainly needed on sunny afternoons anyway.  It's too far from the main geyser to parallel the two geysers.

https://zpenergy.co.za/comparison-of-pv-solar-thermal-gas-and-heat-pump-water-heating/

 

My call will be a ITS 4.7kW and yes I know the unit as I have mine close to 10yrs. As it aged the power use has gone up a bit to 1.5kW. It is still a lot less than an element. 

Reason for 4.7kW is only due to longer heating time at 0-5 degrees C if you not going to call up the element. I have never used my element and it is not even wired.