Diverting excess PV generation to geyser

[Youda]

Hi guys,

It's a well-known fact, that a water heater / geyser is an appliance with a very high monthly energy consumption.

Example: geyser is 36% of the weekly energy consumption here:

Based on the above, I have two simple questions:

1. Do you use some device that is able to divert excess PV energy into a geyser's heating element? I found that there's a lot of such smart devices commercially available, for example "Solar iBoost".
2. What kind of diverting device are you using for off-grid installations? The commercial solutions quite often need a CT clamp on the grid and are operating by measuring the grid feed-in, which is not available for the off-grid systems, of course.

Thanks beforehand!
Youda

[Arandoza]

Use a Geyserwise with 2kw element connected to my first online evacuated tube geyser to heat water to 65 deg c from 9:30-14:00. 

Usually from 9am we are generating around 3kw plus, so can safely spare the power. We use sonoff basics via timers to max out the solar without switching back to grid.

On cloudy days one simply turns of the Geyserwise, and powers it back on once the clouds have dissipated.  

[Youda]

So a typical solution is just a timer and ON/OFF relay, okay?

Nobody is using a device that's able to sense the grid export/import and then proportionally adjust the power going to the geyser?

Something like this:

 

 

 

 

[Gerrie]

Looked on web at i boost but, seems its for grid tied system only.

In my opinion I would also agree with Pietpower. If your bigger loads like say washing machine or kettle is switched ON the geyser will switch OFF via the load-shed relay. But I would suggest you will still need some sort off timer otherwise your geyser will come on at night when there are no PV Watts available.

I have a similar issue but I want to run my underfloor heating during the day with the extra power. Its easy for me on weekends when I’m at home to manually switch it on but when I’m at work I want this to happen automatic.

It seems most suppliers only have monitors to monitor just about anything but they don’t have control functions to control these type of scenarios. 

 

[Off Grid Farmer]

I used a 1500 watt Ac element connected to a timer set to go on at 10:00 to 15:00 with a separate breaker. If it is to cloudy i use my LP Gas geyser for hot water. 

[Youda]

3 hours ago, Pietpower said:

Tried looking on the web what that unit does.  It is expensive though.

It seems to work with grid tied or hybrid systems and switch on the geyser when you are feeding power back into the grid.   Don't know how you would connect this with an off-grid system?

 

Yes, this unit uses clip-on current transformer as a probe, therefore it works only with the grid-interactive inverters. In other words, inverter must be a hybrid with the grid feed-in enabled or on-grid. The geyser-side of the diverting unit contains a high-power Triac or an SSR relay, that is modulating the AC power going to the geyser according to excessive PV power. So the batteries are not drained, nor is the energy being pulled from the grid. It works just like a variable speed trigger on the cordless drill

 

To be honest, I'm quite amazed that a similar device is not being used widely
In my country, almost every PV system has a similar (cheaper) device included in the setup. It's called "Wattrouter":

 

For the off-grid systems a lot of people here are using a different diverting device, that's monitoring the battery voltage and current. When the battery is full, the device gradually increases AC power for the geyser, and looks whether this action caused the voltage drop on the battery or not. If no voltage drop is observed, the power to the geyser is increased and vice versa. The name is "GreenBono AKU":

 

Cool is, that both diverting methods (based on the AC export / battery state) are able to automatically react to the weather and clouds, while at the same time they utilize almost every watt of the sunshine. And the end of the day, your batteries are fully charged and the geyser is full of hot watter

 

Which leads me back to my original question: Do you know any similar device, available world-wide, that I can safely recommend to someone living in SA, USA, etc.?

Of course, I can always recommend the two devices above, but they are local-products so I bet that their import to the non-EU countries will be a bit complicated...

 

Thanks guys!
Youda

 

 

 

 

Edited July 19, 2019 by Youda

[Arandoza]

On the open energy monitor there is this item that maybe similar - An Energy Diverter

 

https://learn.openenergymonitor.org/pv-diversion/introduction/choosing-an-energy-diverter.md

https://mk2pvrouter.co.uk/

But it appears to be Grid Tied as well?

 

 

[PeterP]

Locally Solar MD is introducing this solution. It can be set it up on Solar MD's logger V2 if you are running a Solar MD Lithium Ion battery - system can be set to allow geyser to switch on once battery has reached an adjustable pre-set SOC and the PV exceeds load by sufficient watts to run the geyser. I believe you can add two relays and it' works on off-grid systems.

I want to run pool pump and EV charging like this.

I will be testing this in the near future and will report back.

[howsmybud]

On 2019/07/19 at 2:22 PM, Youda said:

Yes, this unit uses clip-on current transformer as a probe, therefore it works only with the grid-interactive inverters. In other words, inverter must be a hybrid with the grid feed-in enabled or on-grid. The geyser-side of the diverting unit contains a high-power Triac or an SSR relay, that is modulating the AC power going to the geyser according to excessive PV power. So the batteries are not drained, nor is the energy being pulled from the grid. It works just like a variable speed trigger on the cordless drill

 

To be honest, I'm quite amazed that a similar device is not being used widely
In my country, almost every PV system has a similar (cheaper) device included in the setup. It's called "Wattrouter":

 

For the off-grid systems a lot of people here are using a different diverting device, that's monitoring the battery voltage and current. When the battery is full, the device gradually increases AC power for the geyser, and looks whether this action caused the voltage drop on the battery or not. If no voltage drop is observed, the power to the geyser is increased and vice versa. The name is "GreenBono AKU":

 

Cool is, that both diverting methods (based on the AC export / battery state) are able to automatically react to the weather and clouds, while at the same time they utilize almost every watt of the sunshine. And the end of the day, your batteries are fully charged and the geyser is full of hot watter

 

Which leads me back to my original question: Do you know any similar device, available world-wide, that I can safely recommend to someone living in SA, USA, etc.?

Of course, I can always recommend the two devices above, but they are local-products so I bet that their import to the non-EU countries will be a bit complicated...

 

Thanks guys!
Youda

 

 

 

 

Did you ever discover a solution to this, there is the SOLiC 200 which is able to operate Grid Tied or Offgrid modes. Maybe this is what you are looking for if you haven't found something already. https://www.earthwiseproducts.co.uk/solic-200/ 

[LumexClipsal]

On 2020/07/25 at 1:07 PM, howsmybud said:

Did you ever discover a solution to this, there is the SOLiC 200 which is able to operate Grid Tied or Offgrid modes. Maybe this is what you are looking for if you haven't found something already. https://www.earthwiseproducts.co.uk/solic-200/ 

Wondering if anybody locally ordered and installed this device or something similar?

Looking for a local equivalent if anybody knows.

 

Thanks