Electric Monitors (Sunamp related content!)

[Barney12]

Hi All

 

I want to be able to monitor exactly how much electricity my two eDual 9kw Sunamps are using. Ideally with the ability to log the data (but not essential).

I'm not seeing this as a permanent requirement, just an initial testing/evaluation phase. So perhaps something with a CT clip that I could put round the live supply cable to each Sunamp (Would that work?)? Obviously one of the myriad of 13amp plug type units is going to be of no use.

 

If you're interested in the reason why.............

 

Well the Sunamps are just great in many ways but they have (in my view) a fundamental flaw. That being absolutely bugger all user feedback! Thanks to the (super simple) hack from @JSHarris I can now see if they are demanding power but thats pretty much your lot. How much power, how charged or discharged are they? Well you just don't know! In fact without Jeremy's hack they could be phoning home to ET and watching an episode of Friends on Netflix, you just wouldn't know, just a big dumb white box with its equally dumb little cream friend (the control box).

 

I've gone down the "electric only" route. So my only source for DHW and UFH is the Sunamps. But what I need to do is work out the optimum use of solar and off peak electric. But, without getting a feel for how much demand (say) putting my UFH on for 2 hours is, that currently seems like an impossible task! If I heat my slab at night will I have hot water in the morning, if I'm relying only on solar charging alone?

 

I'm not sure if I'm being overly clear but hopefully you get the drift!

 

Edited November 4, 2018 by Barney12

[Ed Davies]

2 hours ago, Barney12 said:

two eDual 9kw Sunamps

9 kWh.

 

Seems like a job for a @ProDave solution, one or two cheap electricity meters. It'd be cheaper than any current clamp. Bear in mind that even with a current clamp you'll need to mess with the wiring at least a bit to separate out the line (or neutral) to put the clamp on unless there are already big enough loops accessible inside your control boxes. You can't put it on the whole cable (line, neutral and earth) as the line and neutral would cancel out.

 

If you've got room in the boxes then adding something like one these in each might make sense:

 

https://www.bellflowsystems.co.uk/smartrail-x45db-mid.html?category_id=606

[Ed Davies]

PS, if you do go for those DIN rail-mounted meters then I'd suggest putting them in the line to the relay which switches the heater.

 

In the UniQ Heat batteries reference manual ver_20180719_v2.0 figure 6.1 between the connection 1 on the main terminal block at bottom right and connection 2 on R1, the 16A relay with the neutral taken off connection 2 on the main terminal block. This causes the meter to see just the heater's consumption but keeps it powered all the time for the backlight on the display for readability. Dunno, but I'd hope that meter keeps its reading when it's not powered but maybe it doesn't.

[Dudda]

Sorry where's the link to @JSHarris simple hack?

 

Sunamp are working on a SunampOS Qontroller which is “a system controller with advanced Demand-Side Management, app-based system configuration, remote diagnostics, stage of charge indication and other monitoring functions.“

You should contact SunAmp and find out how near this is to release or what stage and get clarification on what exactly the SunampOS will do. Report back as a lot of others (including myself) would be interested in this.

Edited November 5, 2018 by Dudda

[Onoff]

6 minutes ago, Dudda said:

Sorry where's the link to @JSHarris simple hack?

 

Sunamp are working on a SunampOS Qontroller which is “a system controller with advanced Demand-Side Management, app-based system configuration, remote diagnostics, stage of charge indication and other monitoring functions.“

You should contact SunAmp and find out how near this is to release or what stage and get clarification on what exactly the SunampOS will do. Report back as a lot of others (including myself) would be interested in this.

 

Here, his light bulb moment...

 

 

[Barney12]

5 hours ago, Dudda said:

Sunamp are working on a SunampOS Qontroller which is “a system controller with advanced Demand-Side Management, app-based system configuration, remote diagnostics, stage of charge indication and other monitoring functions.“

You should contact SunAmp and find out how near this is to release or what stage and get clarification on what exactly the SunampOS will do. Report back as a lot of others (including myself) would be interested in this.

 

Yes, I have heard the same but been told there is no release date as yet. 

[Jeremy Harris]

The cheap DIN rail mount energy meters seem to work very well.  I have a few on things like our heat pump and my car charge point and haven't had any problems with them.  If you just want a really cheap solution then these ones look as if they'd do the job OK: https://www.ebay.co.uk/itm/Digital-LCD-50Hz-5-30-A-KWH-Power-Energy-Meter-Reading-Single-Phase-DIN-RailBI42/163318470803?epid=12016019726&hash=item26068a1893:g:GfcAAOSwHcFbxidE:rk:1:pf:1&frcectupt=true

 

There might even be space inside the Sunamp control box to fit one of these to the DIN rail and wire it up internally.

[PeterW]

3 hours ago, JSHarris said:

The cheap DIN rail mount energy meters seem to work very well.  I have a few on things like our heat pump and my car charge point and haven't had any problems with them.  If you just want a really cheap solution then these ones look as if they'd do the job OK: https://www.ebay.co.uk/itm/Digital-LCD-50Hz-5-30-A-KWH-Power-Energy-Meter-Reading-Single-Phase-DIN-RailBI42/163318470803?epid=12016019726&hash=item26068a1893:g:GfcAAOSwHcFbxidE:rk:1:pf:1&frcectupt=true

 

There might even be space inside the Sunamp control box to fit one of these to the DIN rail and wire it up internally.

 

Do you know if these will take a 4mm wire @JSHarris..?? Thinking about one for ASHP and potentially an immersion too

[Ed Davies]

I saw cheaper DIN-rail relays meters on eBay last night but didn't post about them partly because I needed to go to bed but also because I was a bit confused about their current specifications. E.g., from the one @JSHarrisposted about above “50Hz 5(30)A KWH Power Energy Meter” and

 

Basic current (Ib)	5A
Maximum rated current (Imax)	30 or 32A
Operational current range	0.25A-30 or 32A

 

So what's the 5A bit about? And do they really have such a large minimum current? What do they do if the current's less than that, not register? Wish my meter worked like that, as it'd save me ~= £20/a.

Edited November 6, 2018 by Ed Davies
Correct stupid typo of “relays” when I meant “meters”.

[TerryE]

On 04/11/2018 at 21:01, Barney12 said:

I've gone down the "electric only" route. So my only source for DHW and UFH is the Sunamps.

 

Barney,   You seem to imply that a SA option is the only option for electric only.  I don't understand this logic at all and it doesn't make much sense to me.  The slab is a bloody great and very cheap thermal battery.  So why heat it via the SunAmps?  This seems an odd decision to me.

 

OK, if you've got lot's of PV, then there might be a couple of months a year when you have excess over your DHW needs that you could use the SAs to top up the slab during E7 peak periods, but the payback in extra instrumentation and control costs is going to make this a marginal design choice. 

 

Far better to have a low temperature ASHP loop direct (say at 30°C via a PHE) into the slab where you can get a solid  CoP, and where you are operating the ASHP is a gentle regime.  IMO, the 50-60°C PCM isn't matched to ASHP operation as you will been to run it flat out and at a crap CoP.

 

18kWh just isn't enough to heat a reasonably large passive house as the temperatures fall into single digits or lower.   My SunAmps aren't even used in the UFH circuit.

 

52 minutes ago, Ed Davies said:

I saw cheaper DIN-rail relays on eBay last night but didn't post about them partly because I needed to go to bed but also because I was a bit confused about there current specifications.

 

Ed,  A relay might be able to switch low voltage AC or DC at 30A, but definitely not at 230V.  You need special relays to do this 230V switching; they are called contactors not relays (even though they are a type of relay).  This issue is the make / break arcing will knacker the contacts of a normal relay and so they rapidly burn out.  You need a special type designed to take this type of contact -- hence the name.  Designing these circuits is not for the notice because of the back EMFs that can generated during make / break.  These also typically need 24V coil voltage to operate them so you end up cascading them with smaller relays, SSRs, or a Darlington driver.

 

At Jeremy's suggestion, I just use 230V 20A SSRs which are driven by 5V TTL logic.  A lot easier.  These SSRs delay the break timing up to ½ a cycle to position it at a voltage zero-crossing, so there is no instantaneous power at the make / break.   The only downside is that they are not 100% efficient, and so they give off 30W or more each when operating so you need to be careful about thermal design / management of any enclosure.

 

PS. I find that the ½ hourly usage data from my supplier is enough to track the power demands.

Edited November 5, 2018 by TerryE

[Jeremy Harris]

10 hours ago, PeterW said:

 

Do you know if these will take a 4mm wire @JSHarris..?? Thinking about one for ASHP and potentially an immersion too

 

 

Yes, should do with no problem.  I have used the bigger double width ones that have multiple functions (frequency, current, voltage, power, energy total and energy resettable) and they will probably take 25mm² at a guess.

[Ed Davies]

12 hours ago, TerryE said:

Ed,  A relay might be able to switch low voltage AC or DC at 30A, but definitely not at 230V.  You need special relays to do this 230V switching; they are called contactors not relays (even though they are a type of relay). 

 

Sorry, stupid typo on my part: I meant “meter” not “relay” (corrected now) so your answer isn't too relevant.

 

(Actually, I think you'll find you'd need a beefier relay/contactor to break 30 A at, say, 12 V DC than the same current at 230 V AC. E.g., 16 A MCBs for 230 V AC are cheap and plentiful but only a few are rated for low-voltage DC as well. That's because at 50 Hz there'll be a zero crossing along in at most 1/100th of a second to help quash the arc.)

[Guest Alphonsox]

14 hours ago, Ed Davies said:

I saw cheaper DIN-rail relays meters on eBay last night but didn't post about them partly because I needed to go to bed but also because I was a bit confused about there current specifications. E.g., from the one @JSHarrisposted about above “50Hz 5(30)A KWH Power Energy Meter” and

 

Basic current (Ib)	5A
Maximum rated current (Imax)	30 or 32A
Operational current range	0.25A-30 or 32A

 

So what's the 5A bit about? And do they really have such a large minimum current? What do they do if the current's less than that, not register? Wish my meter worked like that, as it'd save me ~= £20/a.

 

Not obvious to me either (The manual doesn't help either).

 

[Jeremy Harris]

Not sure what the 5 A bit is about.  The double width ones I have seem to work over a wide current range, I've run one at 30 A continuous on my car charger and it's worked fine.  IIRC, that one has a maximum current capacity of 60 A.  The 0.25 A doesn't match the spec on the side of the unit that refers to 0.5 Wh being the threshold, either.  Most domestic electricity meters have a 1 Wh threshold, with anything under that not registering; not sure what the time period is though.  The 1 Wh threshold in the spec goes back to the anti-creep resistance built in to the old spinning disc meters I believe.

[Jeremy Harris]

For those interested, I've just traced the meters that I've got, they are these ones from : https://www.ebay.co.uk/itm/5-65-A-230V-50HZ-din-rail-Energy-meter-voltage-current-active-reactive-power-KWH/222966886884?hash=item33e9dcb1e4:g:XLAAAOSwsBda7aPJ

 

They measure power, bi-directional energy, voltage, current, power factor and have two energy registers, one that's non-resettable and one that can be reset.  They also have an isolated data output, that outputs 1600 pulses per kWh, although I've not bothered to use that function.

 

According to the spec they start working at 20mA, so I'm not at all sure what the "5(65) A" thing is about.

[Barney12]

OK, so today I've upgraded my electrics to cope with two 16amp immersions and also added the electric monitors I wanted for each of the Sunamps.

In the end I went with these (Amazon Prime eligible so easy to return if crap!):

https://www.amazon.co.uk/gp/product/B013E007VO/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

They seem to be doing an admirable job.

 

Oh and of course the requisite picture......

 

(Note: I really didn't need RCD protection but it was the only CU that they had in stokc which would fit in the space :))

 

 

 

 

[Barney12]

I have another question in relation to energy use and monitoring:

 

Are immersion heater elements 100% efficient? I.e. to use the example of a Sunamp; I have a 9kwh unit which has (i believe) a 2.8kw immersion. 

Thus is it a reasonable assumption that to fully charge this unit from cold it would take 9kwh of electricity? 

I appreciate that it wouldn't be 100% efficient as there is an element of heat loss. 

[ProDave]

A resistance heater is to all practical purposes 100% eficcient.*   But if you put 9KWh of heat into a tank, you will not get 9KWh of hot water out as some of it will have been lost to the room as standing heat losses.  A Sun amp will lose a lot less of it's heat to the room.

 

* this makes me laugh when you see some makes of electric panel heater claiming to be more eficcient than other makes.

[Nickfromwales]

27 minutes ago, Barney12 said:

I have another question in relation to energy use and monitoring:

 

Are immersion heater elements 100% efficient? I.e. to use the example of a Sunamp; I have a 9kwh unit which has (i believe) a 2.8kw immersion. 

Thus is it a reasonable assumption that to fully charge this unit from cold it would take 9kwh of electricity? 

I appreciate that it wouldn't be 100% efficient as there is an element of heat loss. 

The immersion in the SA occupies pretty much the entire floor of the cell. It's a single cell in each unit with a fully immersed heat exchanger for wet energy import / export. 

The immersion is actually entirely submerged /  encapsulated in PCM, so as far as heat transfer characteristics are concerned it should be close to 100% efficient as it can get. No different to how an immersion is directly in the water of a cylinder. 

After initial talks with SA 'back in the day' I was led to believe the heat input should be liner, so a ~ 3kW immersion in a 9kWh SA should take ~ 3 hours to fully recharge. 

Re the element of heat loss, it's only really what ebbs away from the connective pipework really, so negligible but deffo will affect the times albeit only slightly. 

Edited November 11, 2018 by Nickfromwales

[Jeremy Harris]

The efficiency claims for some of the snake oil electric heater adverts really should be regulated, as they are grossly misleading.

 

The losses for a Sunamp UniQ 9 are around 0.7 kWh/24hrs, so you can estimate how much sensible heat you can get out for any given input, depending on your usage.  I would guess that for many households the hot water usage per 24 hours may well only be around 1% to 2% of the time (24 mins to 48 mins hot water draw off time per 24 hours), so just assuming a loss of around 0.7 kWh per day should be close enough.

 

That gives an estimate of efficiency, in terms of energy in to energy out per 24 hours of around 92% to 93% if pretty much all the energy is used each day, so perhaps a bit better than a good battery storage system (I think the best battery storage solutions are currently around 85% round trip efficiency, but they are getting a bit better, I believe).  Realistically, most people may not use all the stored energy each day, so efficiency will drop significantly as usage drops, because the losses are near-constant.

[Onoff]

15 hours ago, Barney12 said:

 

 

 

 

 

I'd have put the labels up the other way to match the kWh... 

[Barney12]

OK, so furthering my quest for understanding......

 

Is there a way to know what (say) an average shower should use in terms of consumption. I appreciate there's lots of variables (i.e. temperature of water).

 

The reason I'm asking these questions is that my Sunamps appear to using huge amounts of electricity. To give that some perspective:

 

Since completing the wiring of the new board my two 9kwh Sunamps have used 34kwh of electricity, thats in less than 24 hours. I've deliberately left both 16amps circuits live (and have removed the solar diverter from the mix for clarity). So whats the consumption been in that period? 

 

Well I've had one shower (this morning), perhaps 5-6 minutes in duration. 

I've run a hot tap for aprox 20 seconds in the kitchen. 

I switched the UFH on yesterday evening for exactly two hours. (To provide further detail; the UFH circuit is fed by a TMV which is at its lowest setting, aprox 40 degrees. The UFH thermostats on the actual manifolds are set at 30 degrees. The temp sensors on the manifold fairly quickly were up to 30 degrees and the return pipe was warm, this would suggest the slab wasn't pulling that much heat from the UFH pipes?)

 

If what is written in this thread is right then I could conclude that both Sunamps were depleted twice! Yet, as I've been monitoring closely neither unit went in to its cold start phase and none of my pipework ran cold. 

 

(I've checked the electric meter and that tally's to the din rail meters I've installed, so all working OK there)

 

Confused! 

 

 

[Jeremy Harris]

25 minutes ago, Barney12 said:

OK, so furthering my quest for understanding......

 

Is there a way to know what (say) an average shower should use in terms of consumption. I appreciate there's lots of variables (i.e. temperature of water).

 

The reason I'm asking these questions is that my Sunamps appear to using huge amounts of electricity. To give that some perspective:

 

Since completing the wiring of the new board my two 9kwh Sunamps have used 34kwh of electricity, thats in less than 24 hours. I've deliberately left both 16amps circuits live (and have removed the solar diverter from the mix for clarity). So whats the consumption been in that period? 

 

Well I've had one shower (this morning), perhaps 5-6 minutes in duration. 

I've run a hot tap for aprox 20 seconds in the kitchen. 

I switched the UFH on yesterday evening for exactly two hours. (To provide further detail; the UFH circuit is fed by a TMV which is at its lowest setting, aprox 40 degrees. The UFH thermostats on the actual manifolds are set at 30 degrees. The temp sensors on the manifold fairly quickly were up to 30 degrees and the return pipe was warm, this would suggest the slab wasn't pulling that much heat from the UFH pipes?)

 

If what is written in this thread is right then I could conclude that both Sunamps were depleted twice! Yet, as I've been monitoring closely neither unit went in to its cold start phase and none of my pipework ran cold. 

 

(I've checked the electric meter and that tally's to the din rail meters I've installed, so all working OK there)

 

Confused! 

 

 

 

An average shower probably uses around 100 litres of water at around 38 deg C.  I measured the shower at our old house to come up with this number, and found that our shower delivered around 10 litres/minute at that temperature, and I take 7 or 8 minutes to shower, my wife takes 10 to 12 minutes, so 10 minutes seemed a reasonable estimate.  With incoming mains cold water at 8 deg C (may be lower than this in some areas) the temperature increase required is 30 deg C.  The energy needed to raise 100 litres of water by 30 deg C is 3.48 kWh.

 

A single Sunamp UniQ 9 fully charged should be able to deliver around 2.58 to 3 one hundred litre showers with a 30 deg C temperature uplift.  Two should be able to deliver about double that.

 

Using 34 kWh in 24 hours on hot water alone sounds extremely high to me.  Is there is some sort of thermo syphon on the DHW side that's been accidentally created and is increasing the heat loss dramatically, perhaps?

 

 

Edited:

 

Just realised that I think you're running the UFH off the Sunamps, too.  The slab can hold a lot of heat, so if the UFH has only just been turned on then it's quite possible that the slab may have soaked up quite a few kWh.  34 kWh still sounds very high, though, especially as the UFH was only on for a couple of hours.

 

Edited November 11, 2018 by JSHarris
Didn't spot the bit about UFH

[ProDave]

That does sound a lot, BUT in the initial 24 hours is the heat up from cold of the sun amps, so the next 24 hours will be more representative of your actual usage.

 

For us (as a comparison) we seem to be using a pretty constant 22KWh per week heating hot water with the heat pump.  Even guessing an optomistic COP of 3 that would be 66KWh of hot water, so just over 9KWh of hot water per day. That's for 3 of us.  It is probable less than  that as I doubt the COP is much more than 2 when heating hot water (unfortunately mine does not even guess at what the COP is at any given time)

[Barney12]

1 minute ago, ProDave said:

That does sound a lot, BUT in the initial 24 hours is the heat up from cold of the sun amps, so the next 24 hours will be more representative of your actual usage.

 

No, the Sunamps were pretty well charged at the point of wiring up. 

 

I agree further testing is required and thats the reason for installing the meters as I've had a sense something doesn't stack up.