2 hours ago, King_M said:

Yes, I almost always dip into my fully charged batteries with the midday geyser run and the morning geyser run completely obliterates the batteries down to about 25% or so

Thanks for the info - that's what I expected...

As I said in an earlier reply: "... a 200 liter geyser would require about 4.65kWh to heat the water from 40C to 60C, regardless of the element rating" Assuming a total system loss of 10% (it's probably more...) you would be drawing just over 5kWh (50% of the battery's total capacity) just to heat the water in the morning. Obviously every system is different, but if we (again...) assume your over-night load (fridge, freezer, late night hot chocolate, etc...) is on average 0.25kW, then over a 10 hour winter night this would be drawing another 2.5kWh from the battery, leaving you with only 25% SOC left, just as you've confirmed.

3 hours ago, King_M said:

... I will hold out for now and rather focus on Investing on my own system that will give me enough headroom to run through Winter with enough power to spare.

That certainly would be the best option for you. Regardless or this, however, I would still suggest that you downgrade your geyser's element. Even if you opt for a larger new system, allowing for a 4kW geyser element would certainly require a larger inverter, bigger battery, and possibly more solar panels than what would be necessary if you replace the element with a 2kW unit. In addition to just the additional costs, using the smaller element will also assist in obtaining an extended battery life, due to a shallower discharge of the battery (everything else being equal...)

Good luck with the new system - and choose your components wisely 😁

Edited March 2Mar 2 by HennieL

2 hours ago, HennieL said:

Thanks for the info - that's what I expected...

As I said in an earlier reply: "... a 200 liter geyser would require about 4.65kWh to heat the water from 40C to 60C, regardless of the element rating" Assuming a total system loss of 10% (it's probably more...) you would be drawing just over 5kWh (50% of the battery's total capacity) just to heat the water in the morning. Obviously every system is different, but if we (again...) assume your over-night load (fridge, freezer, late night hot chocolate, etc...) is on average 0.25kW, then over a 10 hour winter night this would be drawing another 2.5kWh from the battery, leaving you with only 25% SOC left, just as you've confirmed.

That certainly would be the best option for you. Regardless or this, however, I would still suggest that you downgrade your geyser's element. Even if you opt for a larger new system, allowing for a 4kW geyser element would certainly require a larger inverter, bigger battery, and possibly more solar panels than what would be necessary if you replace the element with a 2kW unit. In addition to just the additional costs, using the smaller element will also assist in obtaining an extended battery life, due to a shallower discharge of the battery (everything else being equal...)

Good luck with the new system - and choose your components wisely 😁

A person with a solar geyser has no business heating up to 60 degrees in my opinion. My geyser is set to 70 degrees. To heat from 40 to 70 is 6.98kwh. Now think about it, that is about 2.3kWh of energy he is wasting by not increasing the thermostat to 70. That is one shower basically. That is why I was wondering why the 4.65 looks low. With your own math, his battery would be over 40% by morning just doing that one simple and FREE thing of just increasing the thermostat to 70.

Also, keep the exisitng element. It costs 1.6k to get an element swapped factoring labor. You say his inverter will take a hit. I beg to differ, Just heat the geyer for 1 hour at 5am or even 4am to 5am. Why this time? Noone is awake. Nothing will be pulling more power than what the inverter is using except maybe a fridge and a few lights. The inverter wont break. The batteries are lithium. Why are we even talking about extending the battery life if one has lithium? Draining to 80% or even 90% has been shown that you still get over 3000 cycles. Which is still close to a decade. And keep in mind after 3000 cycles the battery still has 80% of its original capacity left.

All of this is FREE. No cost involved and he will be 70% of the way there in my opinion. This is just my take. I have a solar geyser and its set to 70 degrees. The sun is free, why limit yourself to 60? Why not capture the extra 2.3kWh? And for those that say it will scald you. My wife and I have bathed fine for months without issues. I have had a 9 year old shower just fine with no help from adults with 70 degree water. Mixing it is a simple exercise that a 9 year old can do then surely 2 adults can do it.

He will achieve little dropping the element to 2kW as he still has to run it much earlier in the night to be ready for showers around 6 to 8am.

I have had this issue before. I have GEL batteries and I could not heat in the morning even with a 2kW element because I did not want to drain them to 50% DOD. So I did the next best thing, just increased the thermostat to 70. My batteries are drained to 80/85% by the morning with typical evening loads and dont have to heat the geyser with them in the morning as the water is still plenty hot. And despite having the option to assist with heating using the inverter, I haven't needed to use it. I just over paneled the Geysertech controller with 4 panels rather than the 2HV panels everyone puts.

Edited March 2Mar 2 by Denns

If the whole "problem" is not enough warm water, why not just install another 200 or 150L geyser in series with the original one?

The smaler geyser closest to the house for if you ever have to use electricity to heat a geyser in the morning in an emergency, it is cheaper to heat 150L.

During daylight you start heating the primary geyser to max deg available on the thermostat, then you start with the second geyser and heat that to the max sun time available.

I changed my geyser element to a 2kw element so that I can start heating the geyser earlier by just using solar.

Always remember that Nersa controls the gas price also.

Win Win - Change to low flow shower roses, then you'll save electricity and water.

11 hours ago, Vaal said:

If the whole "problem" is not enough warm water, why not just install another 200 or 150L geyser in series with the original one?

The smaler geyser closest to the house for if you ever have to use electricity to heat a geyser in the morning in an emergency, it is cheaper to heat 150L.

During daylight you start heating the primary geyser to max deg available on the thermostat, then you start with the second geyser and heat that to the max sun time available.

I changed my geyser element to a 2kw element so that I can start heating the geyser earlier by just using solar.

Always remember that Nersa controls the gas price also.

Win Win - Change to low flow shower roses, then you'll save electricity and water.

Adding a second geyser driven by a contactor controlled by the thermostat can work very well.

just a note on those water saving shower heads. I tried that and it still backfires. The wife just opens the tap to the maximum position and complained it takes too long to wash off her hair.

The main fix is more storage. Either increase the thermostat to the highest setting for more energy storage. Or more hot water storage as you say. Or more battery storage to heat more at night.

On 2026/03/08 at 8:31 AM, Denns said:

Adding a second geyser driven by a contactor controlled by the thermostat can work very well.

just a note on those water saving shower heads. I tried that and it still backfires. The wife just opens the tap to the maximum position and complained it takes too long to wash off her hair.

The main fix is more storage. Either increase the thermostat to the highest setting for more energy storage. Or more hot water storage as you say. Or more battery storage to heat more at night.

I found that with the low flow rose the long haired people showers a bit longer ut they still use less water in the end. But the trick is not to tell them about the reduced flow rose. LoL

But a second geyser is still a lot cheaper than a extra battery.