We finally want to pull the trigger & go Solar

[Lupus]

Yeah 5 of us in the same house standing queue to bath is always going to be a slight problem...I am looking into getting one of these Ceramic type elements that play along nicely with solar setups apparently (LEDARS PTC Element) or an alternative, downgrade from 4Kw to a 2Kw element and run it a little longer when we have surplus output from the panels during the day. I noticed if i run the geyser for 1.5hrs between 12 and 2pm roughly, i can still have a decently hot bath by 6 or 7pm. I am now in the habit of turning the geyser on at 12pm an hour after the battery is 100% - the panels supply 3/4 of whats needed for the geyser and the remaining 1kw+ is covered by the grid - if theres no spotty cloud cover i let the battery supply the remaining 1/4 required (limited to 10%) and it still gets around an hour of PV to recharge back from 90% to 100% before the 3pm slump kicks in (sometimes i only finish up with 96% to 98% battery SOC but its a good SOC to enter the evening with, i try to run everything from battery from there to try and achieve a 40% SOC by 10pm when we get into bed

What is the temp you're trying to get the geyser to and how large is it? A 2kw element seems to be the biggest thing sold as a way to run it on a solar system... Even though technically a 2kw would be one of the reasons you end up using battery or more grid as you've got to run it twice as long as a 4kw. How big is the inverter?

 

[BLG]

we have the geyser somewhere around 55 to 58 degrees from what i can tell, the inverter is 8Kw

 

[Lupus]

we have the geyser somewhere around 55 to 58 degrees from what i can tell, the inverter is 8Kw

So it should've been able to handle the 4kw element? Who said you should change to 2kw? How big is the geyser and batteries?

 

[BLG]

So i mentioned to the installer I am having to almost micromanage certain loads during the day to avoid over cycling of the battery although the system handles the geyser fine I dont like beating the battery with 6Kw sustained load, maybe I am being too cautious with it all being new to me, I dunno? He recommended the 2Kw element as a more solar friendly option, yes it needs to run for twice as long but could mean the difference between it running from panels versus the combination of battery and grid, I am trying to avoid grid as much as possible for geyser since we have to cook and the stove/Oven combo is on non-essential load for the timebeing while we try to save up towards gas conversion (every penny saved from non grid usage is going to help fund this) we've been supplementing alot of stove use with some skottel here and there as well (every bit counts)

 

[BLG]

If my (ChatGPT) calculations are correct we so far managing a 60%+ savings on grid usage - weekly unit usage before versus after:

Before solar:​

• 204 units

After solar:​

• 66 units

Savings:​

• 204 − 66 = 138 units saved

Percentage savings:​

204−66204×100\frac{204 - 66}{204} \times 100204204−66×100

Result:​

That equals approximately 67.6% reduction in grid usage.

 

[Lupus]

So i mentioned to the installer I am having to almost micromanage certain loads during the day to avoid over cycling of the battery although the system handles the geyser fine I dont like beating the battery with 6Kw sustained load, maybe I am being too cautious with it all being new to me, I dunno? He recommended the 2Kw element as a more solar friendly option, yes it needs to run for twice as long but could mean the difference between it running from panels versus the combination of battery and grid, I am trying to avoid grid as much as possible for geyser since we have to cook and the stove/Oven combo is on non-essential load for the timebeing while we try to save up towards gas conversion (every penny saved from non grid usage is going to help fund this) we've been supplementing alot of stove use with some skottel here and there as well (every bit counts)

Problem is the 2kw introduces you needing to run from grid or batteries longer. Cause you're now trying to heat a geyser with a kettle.
Why would it be a 6kw sustained load? What else is running? Plus how much panels and battery do you have? Even a 3kw would've been better than a 2kw, hell spend 21k and get a heatpump it's 900w

 

[BLG]

Problem is the 2kw introduces you needing to run from grid or batteries longer. Cause you're now trying to heat a geyser with a kettle.
Why would it be a 6kw sustained load? What else is running? Plus how much panels and battery do you have? Even a 3kw would've been better than a 2kw, hell spend 21k and get a heatpump it's 900w

maybe slight exaggeration, not sustained but i have seen the usage spike to 6Kw+ for brief periods example geyser running, someone wants coffee and toast - plus other normal loads (500w base load give or take) i been in 2 minds about just keeping the 4kw element and leave things as they are - end of the day we have still cut down massively by moving certain loads to the day (dishwasher, washing machine) and supplementing with battery in the evenings - I'll need to accept that there will always be a certain amount of usage from grid that we just cant avoid

 

[Lupus]

maybe slight exaggeration, not sustained but i have seen the usage spike to 6Kw+ for brief periods example geyser running, someone wants coffee and toast - plus other normal loads (500w base load give or take) i been in 2 minds about just keeping the 4kw element and leave things as they are - end of the day we have still cut down massively by moving certain loads to the day (dishwasher, washing machine) and supplementing with battery in the evenings - I'll need to accept that there will always be a certain amount of usage from grid that we just cant avoid

Well the toaster and coffee won't be a sustained load it would be for 5 minutes at most and an 8kw inverter is for that, otherwise why would you get such a big inverter? I know a guy who runs his 3kw element on a 5kw inverter, though his base load is low and he makes sure the geyser isn't running when other loads are on.
Remember the geyser only runs to warm the water at the temp you set it, so once it's hit 55 degrees it will stop, when it drops to 52 it will start up to warm it back up but this will be minutes to maybe 20. When you've got a 2kw element you've now doubled the length of time it takes to warm the water but you're still using the same amount. With the lower sun hours in winter this will mean you've got more chance of grid usage.

 

[BLG]

We didn't want issues with trips and overloads, rather have a bit extra to give on the odd occasion (last sunday was a test (my dad who lives on the property was busy with washing, we had washing to do as well and the dishwasher was running and geyser schedule kicked in i think we saw 7.2Kw draw) - a 5Kw wouldnt have been very happy with that. What I am beginning to suspect is, it might just be more worthwhile to leave the geyser running 24/7 as opposed to trying to schedule it daily - and have to reheat daily even if not from scratch it can run from anywhere between 1.5 hours to 2 hours i have noticed, whereby 20 minutes several times a day might be better

 

[Lupus]

We didn't want issues with trips and overloads, rather have a bit extra to give on the odd occasion (last sunday was a test (my dad who lives on the property was busy with washing, we had washing to do as well and the dishwasher was running and geyser schedule kicked in i think we saw 7.2Kw draw) - a 5Kw wouldnt have been very happy with that. What I am beginning to suspect is, it might just be more worthwhile to leave the geyser running 24/7 as opposed to trying to schedule it daily - and have to reheat daily even if not from scratch it can run from anywhere between 1.5 hours to 2 hours i have noticed, whereby 20 minutes several times a day might be better

Well besides the draw times when you use the hot water

 

[Tomtomtom]

I am looking into getting one of these Ceramic type elements that play along "better" with solar setups apparently (LEDARS PTC Element) or an alternative, downgrade from 4Kw to a 2Kw element and run it a little longer when we have surplus output from the panels during the day.

The reason people recommend a smaller element is because your power draw is spiking above your solar production. If you can flatten the demand so it fits under the purple curve - move the blue shaded area into the green shaded area - then you won't pull from grid as often.



But your hot water consumption is so high that 2 kW might not be able to keep up. Probably 3 kW would be better.

Either way your system is on the small side to both heat your geyser and charge your batteries, so you'll have to choose. Just note geysers are "leaky", so you definitely don't want to heat water in the evening after everyone is done.

 

[Lupus]

The reason people recommend a smaller element is because your power draw is spiking above your solar production. If you can flatten the demand so it fits under the purple curve - move the blue shaded area into the green shaded area - then you won't pull from grid as often.

View attachment 1912572

But your hot water consumption is so high that 2 kW might not be able to keep up. Probably 3 kW would be better.

Either way your system is on the small side to both heat your geyser and charge your batteries, so you'll have to choose. Just note geysers are "leaky", so you definitely don't want to heat water in the evening after everyone is done.

Get more panels, as a smaller element is silly, if you're on a 100l geyser maybe, but anything over is not going to get warm in time, over 4 hours for a 2kw element is most of the day.

 

[BLG]

Get more panels, as a smaller element is silly, if you're on a 100l geyser maybe, but anything over is not going to get warm in time, over 4 hours for a 2kw element is most of the day.

its a big boy, 200 litres, so the one benefit is it holds onto the heat for quite a while - today it only ran for around 45minutes (compared to the 1.5 hours it usually needs) which is great since the PV has been choppy today. I guess the main thing is, we are definately offsetting alot of this load that was previously running straight from grid. We'll grow the system over time but for now this is what we have to work with. Im pretty chuffed, we managed for the first time lastnight to run completely off battery considering we're a relatively busy household of 6 people running from a 10kwh battery

 

[Lupus]

its a big boy, 200 litres, so the one benefit is it holds onto the heat for quite a while - today it only ran for around 45minutes (compared to the 1.5 hours it usually needs) which is great since the PV has been choppy today. I guess the main thing is, we are definately offsetting alot of this load that was previously running straight from grid. We'll grow the system over time but for now this is what we have to work with. Im pretty chuffed, we managed for the first time lastnight to run completely off battery considering we're a relatively busy household of 6 people running from a 10kwh battery


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200l with a 2kw element??? No wonder you were having issues with it. How hot are you setting it up at?
here's an example of 30 degrees to 55



So as you see the more you add element wise the quicker it heats, but ultimately it is still the same amount of energy used anyway.
Running for 45minutes?

 

[BLG]

I reckon we didnt do too bad today, but tomorrow is going to suck

 

[BLG]

200l with a 2kw element??? No wonder you were having issues with it. How hot are you setting it up at?
here's an example of 30 degrees to 55
View attachment 1912593
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So as you see the more you add element wise the quicker it heats, but ultimately it is still the same amount of energy used anyway.
Running for 45minutes?

nope its a 4Kw element - yep ran for 45mins today as we hardly used it yesterday, when we use it for a bath it runs for 1.5 hours the next day, roughly

 

[BLG]

definately a difference between 45 minutes and 1.5 hours of run time

 

[Lupus]

nope its a 4Kw element - yep ran for 45mins today as we hardly used it yesterday, when we use it for a bath it runs for 1.5 hours the next day, roughly

View attachment 1912600

4kw is good enough for a 200l

 

[Tomtomtom]

Get more panels, as a smaller element is silly, if you're on a 100l geyser maybe, but anything over is not going to get warm in time, over 4 hours for a 2kw element is most of the day.

I said that:

But your hot water consumption is so high that 2 kW might not be able to keep up. Probably 3 kW would be better.

OP should still ideally get his geyser + baseload power below his solar generation (~4-5 kW) to avoid drawing from grid unnecessarily, and maybe also to create some headroom on his inverter.

But definitely more panels too.

I would still personally have the geyser on a separate system. With this much consumption maybe even a second geyser in series.

 

[BLG]

I said that:



OP should still ideally get his geyser + baseload power below his solar generation (~4-5 kW) to avoid drawing from grid unnecessarily, and maybe also to create some headroom on his inverter.

But definitely more panels too.

I would still personally have the geyser on a separate system. With this much consumption maybe even a second geyser in series.

I still love this idea and have been looking into the GeyserTech range of products for a next step upgrade path