Solar Diverter New Zealand  solar panels

Everyone wants free Hot Water.

SunStash is a fully automated solar diverter that diverts excess solar power from your solar panels, to heat your hot water cylinder. Just install it and forget it. 

Batteries are expensive. A Solar Diverter is a cost effective way to store power in your existing hot water cylinder at 100% efficiency. 

"I live in an area where the energy company limits how much I can export. SunStash allows me to maximise solar production by only using energy above that limit for water heating. - Thomas, Auckland"

Product Features

If you have a Solar panel installation, the SunStash Solar Diverter will heat your hot water,  as soon as there is any excess that would normally go to the grid.
(It detects this excess BEFORE it has a chance to tick over the  supply meter)

As hot water is normally 30 to 40% of your average power bill, then eliminating that cost, is a significant saving (More than $1 a day for a couple and more than $2 a day for a family, at typical prices)

The SunStash is totally automatic, once installed you can forget about it, unless of course you are like me and want to look at the numbers. There is a web page on the device provided to do just that.

Don't pay grid prices for your hot water, or get paid a pittance for your exports, install a SunStash today.

**HOT NEWS**       SunStash now supports delayed diversion!

Say your power company only allows (pays for) exports of up to 5kW. You can now set the SunStash unit to only divert power once the excess power is above 5kW. This feature has been added due to customer demand. Normally, SunStash will divert at any excess power above zero.

1.  Automatic power diversion, no user input required.

2.  Evening boost. You can set the start time, anywhere between 1pm and 9pm.

3.  Web page monitoring of the diverter operation. You can see exactly how much power has been diverted, the total solar power for the day, power you are Importing or Exporting, and much more.

4.  SunStash will support Hot Water Elements up to 4.8kW

5.  Continuously variable power delivered to the element. Even if you have as little as 10 watts excess, it will be diverted to the element.

6.  Fully compliant with standards IEC60730-1.

7.  Can be installed by any registered electrician.

8.  Easy installation and connection to your home WiFi network. 

9.  Firmware upgrades.
These will happen automatically, with no user input.

10.  Ability for customers to request a feature they would like. If this feature would benefit the majority, then this would be provided free of charge. We intend to develop the product further over time.

11. Delayed diversion as described above.

How does a solar diverter work:

A Solar Diverter traps the excess power that would normally be exported to the grid. The SunStash diverter continuously adjust the power it delivers to the load (hot water cylinder element) to match what is available from the solar panels at any time, minus the current household demand. The power is continuously adjusted to match supply and demand.  

An example  would be: Say you had a 2kW element in your cylinder,  you currently had 2kW (2000w) of solar power and the house drew 1kW. The SunStash diverter would direct the 1kW difference (solar - house  demand) to the HW element. i.e. The element would be run at 50% power to match the supply. If the solar power increased to say  2.5Kw with the same house load, then 1.5kW would go to the element. i.e. The element runs at 75%. etc

The net effect is that the power from the grid, or exported to the grid, will be near zero while this is happening. It is only when the solar power becomes such that the excess is larger than your element size (2kW in the above case) then you will be exporting power as well as supplying 100% to your element. i.e 5kW Solar, 1kW house load, then 2kW will go to your element (100%) and 2kW will be exported.

In the above scenario, if the HW cylinder thermostat opened, i.e. it reached temperature, then the export would be 4kW.

Some diverters are simple on/off diverters. With this type, a lot of power would slip through to be exported,  were it should have gone to the HW element instead. These diverters are inefficient, so you won't save as much as a continuously variable power model. 

Solar Diverter NZ Graph

Typical Diversion operation.

This graph shows the diversion operation at the beginning of the day. The orange is the diverter activity fitting in-between the house load (blue) and the available solar power (Yellow) from your solar system.  Note at approximately 9:30am, the hot water has finished heating. At 10:06am after more hot water use, diversion starts again. This time at full power, as well as exporting remainder of available solar.

What it looks like.

The SunStash unit is a small box (150mm x 150mm) and is normally mounted next to the switchboard. It is attached to the wall by 4 Tek screws. Wiring is invisible, it is routed via a hole in the rear of the device through the wall to the switchboard. To download or view the installation manual, press button below.

Solar Diverter New Zealand #2
Solar Panels NZ

Device Webpage.

The above image is a screenshot of the devices webpage as it appears on a phone or laptop etc. This screenshot was taken at 5:30pm in the evening, it was a sunny spring day, note the difference between imported/exported and the diverted kWh.


Can the diverter be added to an existing battery setup?

Yes, it can. If the battery charger is a dumb charger, then to the diverter, the battery charger will just look like another household load, and will let the charger take precedence, once the charger current falls to a level where excess occurs, or turns off,  the diverter will kick in. If the charger is a smart charger, then slight changes to how the hot water is wired will need to happen in order for the smart charger not to see the diverter, so they don't fight over the solar. Contact me for details on how to do that, I will provide a wiring diagram. The same applies if you have a smart EV charger.

Does the diverter work on a hot water system that is on ripple control?

The SunStash diverter is designed to go on the normal uncontrolled tariff. You can completely ignore the ripple control supply. There is no need for a night rate. All of the hot water heating is done during the day, apart from a top-up boost during the night (1/2hr..1hr) if required. Even when it is very cloudy, SunStash will heat your hot water.

Where is the SunStash made?

The SunStash in manufactured in Ashburton, New Zealand. 

What countries can this device be used?

The device has  current certification for the New Zealand and Australian market. SunStash is fully compliant with standards IEC60730-1:2013 + A1:2015 + A2:2020 (230/240V AC) Just email me, and I will send the SDOC which your electrician will need to see. NZ/AUS timezones can be selected during installation.

If the device measures diverted power, won't it need to know the Hot Water Element power rating?

Yes, you can set the element power in watts during installation.

How do I buy one?

Just send me an email, or call me, Please see the section below for pricing and contact details.

Solar Diverter New Zealand #4

$499.00 + GST (RRP)
For trade enquires, please email, or call us. 

Pricing is for complete SunStash kit including:

1.  SunStash 
2. Two CT (current Transformers)
3.  Lock for Box
4.  Wiring plugs
5.  Installation/User Manual. 



International: +64 (22) 6017701 
NZ Local: (022) 6017701


Ashburton, New Zealand

Working Hours

8:30 - 17:00    Monday - Friday.   NZST

Our Location

© Copyright 2023 BRM Industries Ltd - All Rights Reserved

Drag and Drop Website Builder