Energy Monitoring Solution for PV System where Inverter and Meter are far apart

Conor20

I had a Solar PV system installed on the house in October. It's been working great, but one thing I haven't fully figured out is a monitoring system which can monitor the consumption of the house, the generation of the PV and the net consumption from the grid, and send that to the internet.

There are a few products which do this (Owl Intuition-PV, ECO EYE SMARTPV), but they only seem to work with certain configurations of PV system. My problem is basically that the PV inverter, the Fuseboard and the ESB energy meter are too far apart. This is what my setup looks like:

All of the monitoring systems I can find need the inverter and Fuseboard/ESB meter box to be beside each other - all of the induction clamps which go round the cables (output of the interver, cable coming into the electricity meter of the house) are connected to one transmitter. I can't find any monitor that works when the inverter for the PV is in the attic, while the circuit breaker board is in the hall of the house, and the electricity meter is outside the house.

So right now, I have the Owl Intuition PV connected to the output of the Inverter, so I can monitor from the internet exactly what the PV is generating (and remotely turn on the dryer for example, when there's plenty of excess PV), but it would be really useful to have both the PV generation and the demand of the house together (e.g. to know the net import or export at any given time). The other energy monitor I had connected to the line into the house in the meter box gets completely confused by the PV, and registers the demand as the demand + the PV generation (e.g. House demand is 500w, PV is generating 1000w, it registers an "import" of 1500w, when there is actually an export of 500w). It obviously can't detect flow in only one direction (and somehow it "sees" both directions of flow.. I guess this is a property of electricity I don't fully understand).

Would anyone know of such a monitoring system which can (1) Monitor PV Generation and House Demand in real-time and log it to the internet and (2) Support the Inverter being in the attic and the meter box into the house being downstairs some 15 meters away?

Conor.

Conor20

Conor20 wrote: »

It obviously can't detect flow in only one direction (and somehow it "sees" both directions of flow.. I guess this is a property of electricity I don't fully understand).

Alternating current doesn't have a polarity unlike DC. It does not have a direction of flow, it oscillates. PV generation meters are designed to compare the GTI output from the incomer, watch the zero current cross point and calculate from that what is in, out and used in the house. If it is clamping the export meter it subtracts the Export from the GTI to calculate on site use.

Conor20 wrote: »

Would anyone know of such a monitoring system which can (1) Monitor PV Generation and House Demand in real-time and log it to the internet and (2) Support the Inverter being in the attic and the meter box into the house being downstairs some 15 meters away?

Use whichever you prefer and just extend the CT cable, offsetting any voltage drop with a higher gauge.

I'd move the inverter. Attics are hostile environments for electronics.

quentingargan

Surely you have an MCB in the consumer unit from the inverter. The meter connection also comes in at the main trip switch there. I think in that case the OWL is simple enough - the two clamps are in the same place.

How do supplier export meters specifically discriminate between import and export? Twin element meters don't account for self-consumption.

Sunny Beam and some others use bluetooth.

quentingargan

Sir Liamalot wrote: »

How do supplier export meters specifically discriminate between import and export? Twin element meters don't account for self-consumption.

Sunny Beam and some others use bluetooth.

It is done by measuring both voltage and current and seeing if they are in phase or out of phase. See HERE for an explanation.

quentingargan

quentingargan wrote: »

See HERE for an explanation.

Oh dear Q. I feel I ought to add corrections to that.

I probably should have stopped reading after the outline of theory.
...before the Hall sensors and diodes reared their ugly heads. :rolleyes:

So negative power factor = export, positive = import...righto.

Does the export meter assume the installation will never have unity power factor export? Is this impossible to do?

Does immerSUN use the same principle to determine import and export?

quentingargan

Sir Liamalot wrote: »

Does the export meter assume the installation will never have unity power factor export? Is this impossible to do?

Does immerSUN use the same principle to determine import and export?

I guess this system is used by all diversion devices but I've never looked inside a meter..

The cheap ones use two CTs. ImmerSUN has only one, I'm looking at using one on an off grid installation hence the interest.

quentingargan

Sir Liamalot wrote: »

The cheap ones use two CTs. ImmerSUN has only one, I'm looking at using one on an off grid installation hence the interest.

If you are using a grid tied inverter AC coupled in an off-grid scenario, the frequency shifting option can be used to switch on immersions using frequency sensing relays?

Nah, I want the full 2 x 3kW proportional control and 2.5kWp PV GTI isolation via the intelligent relay.

I'm not a fan of hard switching large loads.
Frequency shifting isn't an option, well it is but it's preferred not.

It's a toss up between immerSUN and Hugh Piggott's TriStar Follower atm.

rolion

Hi,

I'm using the iboost for few months now.
I don't have the lovely remote reporting or monitoring features built-in but I've worked around with a third party that works perfect,at every 10 seconds.
Never had any of the scary shutting troubles that everyone talks about.

I have the Owl PV unit, stopped believing in to after I had reports of generating and exporting PV at night time. Could be the residual readings of the cables but gave up.Is very important the location of the remote probes.
As per rtfm,you cannot extend those cables,not sure why.

I'll be worry about a PV inverter in the attic,summer time,when full production may create additional heat,lack of cooling/ventilation.

Have fun.

Conor20

Thanks guys.

quentingargan wrote: »

Surely you have an MCB in the consumer unit from the inverter. The meter connection also comes in at the main trip switch there. I think in that case the OWL is simple enough - the two clamps are in the same place.

Good point. The inverter (in the attic) does obviously have a connection to the MCB (in the hall of the house). It connects to the MCB via a cable which also runs to the electric shower. What I think you're suggesting is to connect the AC Mains clamp of the OWL to this cable where it goes into the breaker beside the inverter? Does the AC "House Load" monitoring clamp of the OWL not need to be connected to the cable coming into the house at the MCB to measure all of the "flow" coming into the house? Or do I understand you correctly, that it can measure the whole house's demand from that cable where it enters the inverter from the MCB?

rolion wrote: »

I'm using the iboost for few months now.
I don't have the lovely remote reporting or monitoring features built-in but I've worked around with a third party that works perfect at every 10 seconds. Never had any of the scary shutting troubles that everyone talks about. I have the Owl PV unit, stopped believing in to after I had reports of generating and exporting PV at night time. Could be the residual readings of the cables but gave up. Is very important the location of the remote probes.
As per rtfm,you cannot extend those cables,not sure why.

I also have an iBoost, and now that you mention it - the iBoost's clamp on the cable coming into the house allows it to know whether there is export, and how much export there is, to divert that amount into the hot water tank. So what I basically need is a monitoring system which uses that type of sensor. Would anyone know of such a system? It's a little less fancy than what I was originally looking for (a system which could measure both PV generation and Import/Export, but I'll settle just for a system which can measure import / export.

nhur

@Conor20 - couldn't you get another OWL and put the clamp around the connection between the PV Generation Meter and the fuse board in the diagram?

air

Openenergymonitor will do everything you want and more.

Conor20

nhur wrote: »

@Conor20 - couldn't you get another OWL and put the clamp around the connection between the PV Generation Meter and the fuse board in the diagram?

When I had the OWL clamp around the line into the house, it was confused when there was PV generation. It was showing the consumption as the house's consumption + the solar generation. E.g.: Demand = 500W, PV Generation = 1000W. OWL would show "1500W" when it should have been showing "-500W". It was "seeing" the electricity flow in two directions, somehow and counting them both.

air wrote: »

Openenergymonitor will do everything you want and more.

Thanks, though when I look through the documentation of setting it up, again, it seems to need the inverter to be beside the fusebox:



I do see a reference to this situation here:"Type 2 solar PV System: When the generation and site-consumption cannot be monitored separately e.g. the PV inverter output is fed into the fuse box and the household loads are connected to other circuits in the same fuse box. If this is the case, the output from the PV inverter and the grid import/export connection will need to be monitored and site-consumption calculated by subtracting.
Type 2 system: Site-consumption = Generation + Grid import (negative when exporting)", but when I look at the hardware supplied with the unit, it looks like there's just one box into which the cables plug, so I can't see how it would work with the inverter in the attic, and the fusebox downstairs.

rolion

Conor20 wrote: »

When I had the OWL clamp around the line into the house, it was confused when there was PV generation. It was showing the consumption as the house's consumption + the solar generation. E.g.: Demand = 500W, PV Generation = 1000W. OWL would show "1500W" when it should have been showing "-500W". It was "seeing" the electricity flow in two directions, somehow and counting them both.

.

You have to "rotate" one of the clamps,not sure which one now,but i had the same issue like you !