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Daves CUMonitor gets an NRGDiverter

Dave’s been running with an CUMonitor for a while now and wanted to investigate driving his underfloor heating using a NRGDivert. On the 15th of May one was installed after some testing we found that the underfloor heater only consumed about 1.4 Amps when fully on.  After further investigations we found out that the under floor heating was controlled by WIFI already and the only convenient place to install the NRGDiverter was before the WIFI underfloor heating controller. This meant that the high speed switching of the supply could damage the WIFI switch. So A 100% on/off mode was added to NRGDivert.

And the WIFI Switch was controlled by a 3rd party App consequently this NRGDiverter was controlling nothing .

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CUMonitor Testing for Badger on RS485

We received and inquiry from the owner of a solar installation Nick Name “Badger” that has a wiring setup where the inverter has been wired to the consumer unit board using a 3 core cable that presents no opportunity to use a current clamp without cutting into the cable. Also there is no ready supply near the consumer unit.

So we have resolved to add Modbus functionality to read the current directly from the inverter using RS485. The functionality on the Inverter allows this.

Testing Results are here    in the badger folder.

We are also trialing Dual logging with second CUMonitor configured to record additional analog traces

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NRG Divert Algorithm

So NRG Divert needs to work as reliably as possible and what work for our use cases new use cases may not work ! So the CUMonitor will allow a record  of the results and a qualitative assessment to be made of those results.

We will publish on our website what Algorithms we are using and you should be able to see the results here


The NRG Divert relies on a CU Monitor to record the two current readings taken from the Consumer Unit feeds. It makes an assessment of the likelihood that the Grid connection is indicating that the CU is exporting to the Grid.

NRG Divert Residual (aggregate current consumption)

NRGDivert calculates the current consumption of the house simply by subtracting the Grid current from the PV generated. Obviously this is only worth doing if the CU is observed to be exporting.

This is then assumed to be a stable value and the remaining “spare” energy is calculated by subtracting the Residual from the total PV generated

The first cut of the NRGDivert software assumes the residual value does not change while it controls the load.

Spare energy and using it

So having calculated the “spare current” how to use it and only it is the next problem:

This is done be turning on a resistive load for some AC cycles every second.

Essentially every second the mains AC signal performs 50 cycles and by selectively turning the load on for these cycles you can consume this “spare energy”. Conveniently 50 cycles means that there are 100 half cycles to chose from every second.



Commanding the Load

Turning a load such as a Immersion heater on  without ensuring that zero current is flowing at the time would give rise to a very noisy electrical signal. So we can only do this as the voltage crosses the zero point to avoid this noise.

The Load is a known quantity (its Resistive load) so you know that the full current requirement will be presented when it is turn on.

This is a  power control solution known as cycle stealing. The consumed power is being monitored by CUMonitor  and we should be able to see this load appear as a change on the Grid Monitored value

Verifying the Load

The NRGDivert software  looks for the load appearing on the Grid monitored value and will only remain controlling the load if the expected value is seen and within acceptable tolerances of what it predicts.

This means if the expected Grid Value is out of the predicted range then NRGDivert will disengage the load and recalculate the residual value.


Proving that the algorithm works

On the electricity meter in Site one (ilog) there is a LED that illuminates when the the Meter is exporting to the Grid. This is recorded in the logs on the second plot as a thick yellow line

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NRGDivert Works

Testing of NRG Divert  is going well this is the latest traces produced by system.

  1. The yellow dotted (meta data) line is the confidence that the system is exporting top the grid
  2. The White dotted(meta data) line is the predicted load value that NRGDivert is expecting to see for the device diverted device after the diversion of power
  3. The Red dotted (meta data) line is t he % the device is turned on throughout most of the test it is registering less than 10% of the device is engaged the device in this case is the purely resistive load of an immersion heater which draws up to 13.5 Amps when fully engaged
  4. The Green line is the Raw solar panel generation
  5. The Orange line is the import/export amperage to the Grid
  6. The SOLID yellow line on the is the LED on the lower graph is the LED on the meter showing that the house  continues to export even though Diversion is taking place
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Energy Diverter NRGDivert

OK so the generic Energy Diverter NRGDivert needs to improve on the existing examples in a cost effective manner.

So lets examine the Pro’s and Cons of  Energy Diversion.


Pros and Cons of existing solutions


  1. Low Cost Energy
  2. Better use of Energy because of grid transmission losses


  1. Requires Wiring changes to you house.
  2.  Limited use case for energy CAR Charging /Hot Water tank
  3. Requires extra hardware

Addressing the CONs for NRGDivert

Con 1 :- By using Clip on current sensors as in the our CUMonitor Kit you don’t need to alter the wiring of you house to sense the usage.

Con 2:- If the Energy Diverter takes the form at an extension lead that may only be used to power resistive loads see NRGDivert link TBD

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Progress on Consumer Monitor and Energy Divert

The energy monitors have been running consistently and reliably on Site 1 I’m running two copies of the hardware to reduce TTF (Time to failure of the setup and gather more data). They have both been delivering data to the logging website reliably. The second remote has run intermittently but has stayed up for periods of a month and then stopped transmitting without explanation. I’m improving the software of the consumer monitors and will update them soon showing the published data on the Logging Website.

Energy Diverting

So the excess power generated by Solar panels at each site is exported to the Grid. Power companies pay micro generators a very small bounty of a few pence per Kilowatt hour generated and an energy diverter would allow the micro generator to make use of that energy themselves.  If you have a use for this energy there are very few ways that you can get at it. But I can see ways that that this energy can be harvested and deployed beyond current available technology


Existing Energy divert solutions

The following are the existent energy divert solutions.

  1. House Battery Storage : Many solutions
  2. Dump excess energy into your hot water tank Eddi
  3. Charge your Electric vehicle e.g.  Zappi Charger

New Energy Diverter Solution

I’m proposing another energy divert solution that will use our CUMonitor Box and Divert energy to any Resistive  load such as a Hot water immersion heater.

Here is a log recorded from last summer you can clearly see that the chosen points for attaching the current clamps show the record of the PV generated(Green Trace) and the power flow to the Grid (Orange Trace). The Astute will also notice the strong correlation between these two traces.

Also we can see the difference between the two traces  must be the Residual power consumed by the house.

The Solid yellow line on the bottom plot reflects the state of an LED on the electricity meter which indicates power flow to the grid up until the sun goes in at about 3.5 minutes into the trace.

So from the values provided by the CUMonitor we may calculate the spare energy.

Another interesting point on this plot it the switching off of a load in the house at just after 9 minutes it.

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RPGs played in 2022

We tried to expand out poll this year but many facebook administrators decided to block our Survey so the results may be skewed. We got nearly 1600 votes cast and here are the results.

We have generated the 11 winners from all the Voters and we will be contacting you via facebook messenger over the next week. To get a postal address for your free gifts.

Grand prize is a GMLight Core set

Each of the 10 runners up will get a set of Big Bad Golden Tokens

Or may contact us to change this to a 5E Flavour pack for GMLight

Happy new year to you all and have a prosperous 2023.


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GMLight Living with 5E

GMLight 5e the elephant in the room

So GMLight was created to provide a handy way to put together the minimum set of resources needed to Run a Fantasy Role playing Game. Giving a selection 25mm tokens to cover most Random encounters. A select number of 50mm tokens for “Big” monsters. A set of 6 Dungeon tiles that offer a sufficiently large space to draw most maps. A handy Dry wipe pen with inbuilt eraser. Space for a set of Monster cards  giving you monster stats on hand. A standard set of Dice !

The problem with 5e is that DM’s consider two D20s essential to roll with Advantage/Disadvantage and GMLight only includes a single D20 (the minimum required as you can always role twice).

Living with 5e

The problem is that there is a fixed amount of space in the case and the selection of Monster tokens is as comprehensive as we could make it and fit within the case. We did think about how the kit would be used with 5e when we designed the case. If you are willing to not take the BUG tokens an extra D20 will fit in this space.

Future Developments

We are thinking of making a thicker GMLight case that consists of two trays back to back which would offer more resources and open flat. This would be more 5e friendly allowing more Dice cards and resources to be added.  Let me know in the comments if you would be interested in a bigger GMLight case and what additional resources would you like to see space for.

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GMLight 5e Flavour Packs release

Much cut down from our original aspirations we are releasing the 5E flavour pack for GMLight this is a limited Edition in as much as we will be upgrading the Artwork on the front of the DM’s screen and adding artwork for those cards missing it. But that said it does pack a punch with 90 Monster cards  and a Travel DM screen.

The 90 Monster cards are printed double sided with a stat block on each side where we could fit them. Vampires are a bit of a tough one and take up two sides. So the cards have stat blocks and descriptions for 179 ! creatures.

The Monster cards are dry wipe and work with the GMLight Pen. So you can keep track of monster HP right on the card. We’ve added reminder Images in grey behind the text that show a Standard human fighter next to the Creatures and  don’t reduce the cards real estate.

Our aim was to get as much value on the cards as we could.  To provide the user with as much information and value as possible. We could have made them coloured but that would almost certainly rendered the Text unreadable.


We are working on status indicators and are using stickers to provide the combat tracking and extra functionality like character status  see the Rogue next to the Oni in the Image above.

These stickers are a limited edition (we have about 50 of them) and they will be given away free with the 5e Flavour packs until they are gone. The original idea was to get coloured plastic cast into the  shape below but they make a good attempt of fulfilling the intended roles and are a good deal smaller.

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GMLight Gets first Flavour Pack

Surprise its 5E

We have on order the GM screens and Monster cards for the first flavour pack for GMLight.

The should be available on the website in the next week or so !