SunAmp: Energy 'leakage'?

[D_T]

Hello all, it's been a while (3 years!) since I signed up and posted on here but I've come back to ask for opinions/experience as this is where I first became aware of SunAmps in any great detail thanks to JSHarris and others. 

 

We had a UniQ 3 and UniQ 6 fitted in December 2018 (full disclosure - it happened, by chance, to be by NickfromWales - hi Nick-  but we ordered direct from SunAmp). After some initial grumbles which I wont go into in this post, we now have a fairly decent setup with an Eddi managing the PV diversion between each unit - 6kWh sitting in our Utility and 3kWh in the En-suite.

 

 

This year we finally got our shower installed and have started using the smaller unit much more frequently. As a result (and the lack of sunshine thanks to Storms X,Y & Z...) we're now in the habit of boosting the unit at 3am each night so that it should be full the next day. 

 

This week we had a good sunny day where we made 9kWh (according to the solar edge inverter). Our Eddi recorded that all of this power was diverted into the smaller unit, despite the fact that this is basically double the capacity of the battery. What's more, that evening we noticed the Eddi indicator wasn't showing the tank as full and we ended up having to boost it for a further hour (i.e. practically a full charge).

 

My question is simply, where is this power going? I can't believe the UniQ is physically losing that much heat, even if the insulation has bowed a bit (I know that's a thing). So are the UniQ's designed to discharge any excess straight back into the grid? Or is this just that a sensor has become uncalibrated (I'm aware the Eddi is relying on a CT clamp).

 

Any ideas? I'm hoping it's not something more serious with the controller units etc. as it's been a long journey to get here.

 

[MikeSharp01]

Sounds odd lets hope there is an obvious answer - like is the Eddi unit mixing up the units?

[Jeremy Harris]

If that much heat was leaking out somehow then it would be pretty noticeable, the case of the Sunamp would be getting pretty warm.  The Eddi has no way of knowing the state of charge of the UniQ at all, this is one of the major issues with the Sunamp, that it's impossible to tell the state of charge, or even know whether the thing is charged at all (unless you take the lid off the controller and see if the call for heat LED is on). 

 

If I had to guess, knowing that there have been a few issues with the firmware in the Eddi controller, I'd say it's more likely to be an erroneous display on the Eddi than anything else, and may possibly be related to the way the Eddi senses power.  The Eddi can only very roughly guess what the Sunamp state of charge is, and can only possibly know one state, which is fully charged (it can probably work this out because the Sunamp controller will stop accepting power).

 

We boost our 9 kWh Sunamp with E7 every night as a matter of course.  We have a 6.25 kWp PV array, but it's rare that we get enough generation to provide hot water in winter.  Today is one day when we have fully charged the Sunamp from PV, but it's the first day for a week or so that this has happened, and I only know that the Sunamp is charged because mine has the controller cover removed, so the LED is visible (I don't suggest doing this, as there are live terminals exposed with the cover off).

[MikeSharp01]

1 hour ago, Jeremy Harris said:

unless you take the lid off the controller and see if the call for heat LED is on

Just for clarity - call for heat means 'heat to store required' rather than 'heat to be supplied to flow now DHW required'? Either way it is worse than crazy that such a signal is not available? I guess they already know though.

 

[Jeremy Harris]

10 minutes ago, MikeSharp01 said:

Just for clarity - call for heat means 'heat to store required' rather than 'heat to be supplied to flow now DHW required'? Either way it is worse than crazy that such a signal is not available? I guess they already know though.

 

 

Yes, in our case it's just an indication that the Sunamp controller has turned on the power relay that allows current to flow to the heating element.  When the Sunamp controller senses that the unit is fully charged, this relay opens and the LED is turned off, indicating that the Sunamp is charged.

[D_T]

Thanks both. Don't worry, I don't plan on removing the cover, however it is so frustrating to not have a charge indicator (although I'm aware of the theory behind how the PCM state is difficult to determine). 

 

What's more concerning is that the SunAmp makes it 'feel' like it is losing heat as a consequence (behaviour, not physical touch). We made 14kWh yesterday, both SunAmps registered as full on the Eddi, so we didn't boost. I had a lovely 10 minute shower in the morning, and then my wife got instant cold water -  so I'm not very popular right now..! 

 

I had thought that a 3kWh unit could handle 2 modest showers on a full charge. So either the capacity is less than we thought or the unit is registering as full too early in the cycle. 

 

For now we'll revert to boosting as a matter of course, but it really does seem like the battery either isn't charging or isn't staying warm overnight. 

[Jeremy Harris]

36 minutes ago, D_T said:

Thanks both. Don't worry, I don't plan on removing the cover, however it is so frustrating to not have a charge indicator (although I'm aware of the theory behind how the PCM state is difficult to determine). 

 

What's more concerning is that the SunAmp makes it 'feel' like it is losing heat as a consequence (behaviour, not physical touch). We made 14kWh yesterday, both SunAmps registered as full on the Eddi, so we didn't boost. I had a lovely 10 minute shower in the morning, and then my wife got instant cold water -  so I'm not very popular right now..! 

 

I had thought that a 3kWh unit could handle 2 modest showers on a full charge. So either the capacity is less than we thought or the unit is registering as full too early in the cycle. 

 

For now we'll revert to boosting as a matter of course, but it really does seem like the battery either isn't charging or isn't staying warm overnight. 

 

 

As you have two Sunamps, could it be that one is charging and the other isn't?

 

There are a couple of known problems that can cause a Sunamp UniQ to stop charging.  First is that on the early models the over-temperature cut-out could be prone to tripping.  This is located behind the terminal cover at the base of the main unit, on one side.  The cover has a couple of socket screws holding it in place, and the reset for the cut out is at the end, a push button that should click when pressed in if it has popped (make sure the power is isolated when checking this, as there are potentially live terminals behind this cover).

 

The other know problem is one that I had, which is that the contactor in the controller can fail.  The only way to check this is to remove the cover from the controller, and do the following (it's OK to remove the cover and power the unit on, as long as you take care not to touch anything inside).  First check to see if the controller is calling for heat.  There is an LED under a relay to the right that will be on if the unit is discharged and calling for heat (one of the status LEDs in the photo below, usually the middle one of the three):

 

 

If this LED is on, yet the Eddi is indicating that the Sunamp is charged, then that pretty much proves that power is not getting to the Sunamp heating element.  If the over-heat cut-out hasn't popped, then the next thing to check is to see if power is getting to the Sunamp controller heating circuit.  Set the Eddi to boost, and with a meter carefully check to see whether power is available at both the incoming and outgoing sides of the contactor.  The contactor will probably be a Finder one, and look a bit different to the ABB one in the photo below, but the connections should be the same (the Finder contactor in our controller failed, hence the ABB replacement):

 

 

Terminals 1 and 3 at the top of the contactor are the incoming mains power from the Eddi.  Terminals 2 and 4 at the bottom of the contactor are the power feed to the heating element in the Sunamp.  If the contactor is energised then there should also be mains voltage across terminals A1 and A2, as these are the contactor coil.

 

Only do these tests if you feel confident in using a meter around mains voltage, and don't try to check voltages with one of the voltage detector pens, as it almost certainly won't work reliably for this task.

 

For more information, this is the point in the other Sunamp thread where I found that the Finder contactor had failed and replaced it:

 

 

and this thread has more info on fault finding that may help, including a very useful tip about the Eddi settings that may be useful in your case:

 

 

[Dan G]

On 28/02/2020 at 16:23, D_T said:

I had a lovely 10 minute shower in the morning, and then my wife got instant cold water -  so I'm not very popular right now..!

 

I had thought that a 3kWh unit could handle 2 modest showers on a full charge. So either the capacity is less than we thought or the unit is registering as full too early in the cycle. 

 

I don't know if this was ever resolved but for the benefit of anyone wondering by via Google (as I am!), a ten-minute shower requires right around 3kWh of energy.

 

You wouldn't get two such showers from a 3kWh Sunamp!

[SteamyTea]

7 minutes ago, Dan G said:

a ten-minute shower requires right around 3kWh of energy.

Depends on the flow rate and the temperature lift up from mains water temperature.

3 kWh seems high, but then a 10 minute shower seems long to me.