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How to run a 2Kw geyser from PV daytime and Utility in the evening


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Hi all, 

I'm wanting to run my geyser off my PV panels once the system has been installed. I have 12 x 410W panels that, at 65% will generate enough power to cover the geyser and the house load (Which is roughly 900w constant in the day) 

The problem is, the evening. I don't want to run the geyser off the batteries / inverter - instead have it run once i from the utility. 

Is something like this possible and if so, how?

What I think I need is some sort of change over switch for the geyser - but I don't want to have to remember to do it every day, it should be automatic and not something I need to think about each day. 

Appreciate any feedback. 

Thanks! 

Edited by Rclegg
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Hi, I have a similar intention but first need to take out my old 4kW element and throw it as far as possible! 🤭
I guess in your case it depends on the Inverter and batteries (if any) you will install. You may choose to let the Geyser function as is with it's thermostat as an AC load on the Inverter, and let the inverter switch over to the utility (grid) by means of settings.
For instance, when sufficient battery energy is available at night the Geyser will be supplied via DC but at a selected Voltage (or SOC) the Inverter will switch back to Utility. You can also select for the Utility to charge the battery or wait for Solar to take over in the morning. 

Edited by Jaco P Bloem
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2 minutes ago, Jaco P Bloem said:

Hi, I have a similar intention but first need to take out my old 4kW element and throw it as far as possible! 🤭
I guess in your case it depends on the Inverter and batteries (if any) you will install. You may choose to let the Geyser function as is with it's thermostat as an AC load on the Inverter, and let the inverter switch over to the utility (grid) by means of settings.
For instance, when sufficient battery energy is available at night the Geyser will be supplied via DC but at a selected Voltage (or SOC) the Inverter will switch back to Utility. You can also select for the Utility to charge the battery or wait for Solar to take over in the morning. 

Yes, throw the 4Kw element away. 😂

Thanks for the reply. I currently have the Kodak MkSII 5Kw inverter - which doesn't do blending. I don't want the batteries to ever run the geyser as the intention is for the batteries to keep the house powered until early hours in the morning and then wait for solar to take over and charge them back up. 

 

Thanks for the reply. 

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got it!

I do have a heat pump installed but will supplement it during the winter daytime with the 2kW element. I will install a normal DB timer switch to prevent it also from draining they batteries.
(I have tested this and if you gets the temp high enough it will last until the PV take over again)

I am sure you do get automatic time based change-over switches if you want. But while you will take energy from the grid for the Geyser in any case, you may as well drain your batteries to the point that your home load would have, then let the Inverter switch all load to the grid and wait for PV..

Keep well!

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2 hours ago, Rclegg said:

Is something like this possible and if so, how?

What I think I need is some sort of change over switch for the geyser - but I don't want to have to remember to do it every day, it should be automatic and not something I need to think about each day. 

I believe anything is possible if you put your mind to it.

If you have a Pi running ICC you can definitely do it. Mannie has developed an app called APM which gets values from ICC see below, so you wire the geyser with 1 x 2CH sonoff swicth with 2 x relays 30amp (1 to grid AC and the other to inverter AC) and do the automation on APM. Done.

image.thumb.png.59ccf414ee74ba9a0809b427ecbad801.png

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I reckon this subject is still not resolved. Ideally the geyser should be connected as a non essential load (so if there is enough PV power available it will switch on the geyser element) What type of system you have also has to be considered..

Have a look at this thread on another forum (especially Gerlagh's comments) https://www.4x4community.co.za/forum/showthread.php/330544-Solar-geyser-backup-element-usage

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