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McWidowmaker

Geyserwise *sigh*

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I have 2 solar geysers in series and my first geyser, that preheats the water runs a geyserwise controller and pump with 24 evac tubes in line. I'm on my 3rd controller and / or pump in 18 months and this thing is driving me nuts. I have tried running a small solar panel and pump only, but with the continuous circulation when the sun shines, heating is really crap. Currently the controller / pump setup is giving trouble again and I'm at wits end with the damn thing.

I have an option of an SCR8 controller and 220v pump, but meh, I really dont want to spend R5500 and end up with much of the same. At the moment I am thinking of putting a heat pump on that geyser with a relay on my BMV to kick in when SOC is higher than 90% and trash that solar setup, since its been a pain in the arse since day one and in winter when you really need it it cans most of your gains preventing pipe freeze by circulation hot water through the system and removing the gains during the day.

Does anyone have advice or alternate suggestions before I do that?

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1 hour ago, McWidowmaker said:

At the moment I am thinking of putting a heat pump on that geyser with a relay on my BMV to kick in when SOC is higher than 90%

The one challenge that you will have is on bad weather days you are going to battle with the heat pump unless you run it manual  and on those days you switch it off. What I have done is to check the battery watts , inverter watts  ,available solar watts and charge mode so

If the charger is in Bulk (13) , the geaser switch is off
and Available solar - batt watts - inverter watts >  1100w (the element is 1000 w) then there should be surplus energy , switch on the geyser. 

Then if the Geyser switch is on , check only the batt watts , if it is < 300 w and charger is in Bulk mode and is < 300 w for more than 2 min Switch off the geaser and wait for 20 min reset and check if there is enough energy available. 

So worst case there will be a 2 min draw on the batts  and sofar I haven't had any issues with it that way. I think if you don't have a lot of surplus energy it could be a problem but in my case works very well. The geaser went to 90 deg yesterday :)

 

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I have the SR609 as well. Installed about 5 years ago. 3 years ago lightning struck the house and the remote unit in the roof with the relays did not survive. Replaced the remote unit - got to get the complete kit :angry: Year later, the external probe went bust. Had to cover the 24 tubes to prevent > 185 deg C. Replaced the probe.

About two month ago, the T1 temp shows 0. Replace with spare probe, still 0 deg, so pump does not activate. The rest of the probes all read OK. Got new kit again, and replaced the remote unit again, and all OK now.

Luckily the heatpump helped keep occupants happy.

So I think these systems are not a reliable as they should be, bar the lighting strike.

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Hi Paul, would love to be able to do that with my system, feels ideal to me. I have a full victron setup with the CCGX. I think it is possible to check all that and switched based on it, but I'n not quite sure how.

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@McWidowmaker the way I did it was through some programming and using emoncms to supply the data. I know that the CCGX can turn relays on or off. But programmatically I would not know where to start , @plonkster should be able to tell us what the options are. From what I have seen you the CCGX does send the data via mqtt , again Plonkster can correct us , and if so you should be able build the controller. I used an eps8266 wif modulei with some relays and controlling via mqtt and .js works well for me. But as I said Plonkster might have a much simpler solution. Shucks with the CCGX you might even be able to do a semi grid tie :) .

@plonkster this is your department :) .

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32 minutes ago, McWidowmaker said:

full victron setup with the CCGX

Yeah, most of the data is available on DBUS and you can switch on that. See for example the post I made about controlling the ESS discharge limit so it follows available PV. Here I subscribe simply to the values I'm interested in and when they change a callback is invoked and my little dictionary is updated. I can then install a periodic task (here I use the glib library) to inspect these values and do some things with it.

The majority of things you'd be interested in is on the com.victronenergy.system service. This is maintained by systemcalc-py and maintains the combined figures for the system (in case you have more than one MPPT for example).

First you'll have to root the CCGX.

Then you can use "dbus -y com.victronenergy.system" to see what is available to you.

Also, calling SetValue on /Relay/0/State (after you set it to Manual operation in the gui) can control the relay in the CCGX.

Once #169 is merged (I put it on the list for 2.08 official, but it might have to wait), there will also be a mechanism to start your own services even when the firmware on the CCGX updates.

Now if you had the Venus-GX (the Beaglebone based device), you could even wire the temperature probe directly to one of the analog inputs :-)

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Just looking at the required building blocks. You can query the vebus for the LED status and see that way if it is in Bulk/Absorb:

root@ccgx:~# dbus -y com.victronenergy.vebus.ttyO1 /Leds/Absorption GetValue
value = 1
root@ccgx:~# dbus -y com.victronenergy.vebus.ttyO1 /Leds/Bulk GetValue
value = 0

Trouble is, this assumes you're running ESS. That syncs the MPPT state with VEBUS state. Otherwise you may have to query the solarchargers directly, and I fear I don't know from the top of my head how to do that.

5 hours ago, PaulF007 said:

and Available solar - batt watts - inverter watts >  1100w (the element is 1000 w) then there should be surplus energy , switch on the geyser. 

Another problem is that you might not necessarily know what the available solar power is. If the batteries are close to full and the MPPTs have started throttling power, you don't know how much is available unless you turn on a load. Then, as I've shown before, the MPPTs will sweep the range a number of times attempting to find the maximum power point, so that takes about 30 seconds to a minute. So take this hypothetical situation: The sun comes from behind a cloud and suddenly the battery voltage goes up, we go from bulk to absorb, we're charging the batteries at say 400W and we have a load of 500W, so the MPPT throttles things at around 950W (adding in a little to run the inverter itself).

At this point you don't know if there is 1200W available or 2400w available. Best you can do is turn on the geyser and see what happens. If after two minutes, the BMV measures a negative current, or the battery voltage has dropped, you know there really wasn't enough power. With some tweaking that can be made to work, but on some days you may cycle the batteries a bit :-)

root@ccgx:~# dbus -y com.victronenergy.system /Dc/Battery/Current GetValue
0.40000000596046448
root@ccgx:~# dbus -y com.victronenergy.system /Dc/Battery/Voltage GetValue
26.440000534057617

 

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Also, in my latest version (I should put it on github) I feed the power values through a single pole low-pass filter so that spikes are smoothed away and I get a better average value. You'd probably want to do the same with the battery current to get a better average over the last minute or so, if the battery current remains above zero, you leave the relay on.

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LOL for some reason my text did not get posted ...

What I have is a solar prediction model that posts the values to emon through .js. So from the bottom graph you will see that until about 9h20 the batts was still charging at full capacity and then started to go into flout. At 9h45 there was enough solar available to switch on the geyser relay. at 13h00 the load was to high and the geaser was switch off for 20 min thereafter came back on again until the geyser was at temp and switch off. 

But you could also do some tests to see at what times you will have surplus energy available and then just set it on a timer 

2017-07-17_172601.png

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@McWidowmaker if you have a multi or Quattro you can try using a small Grid tie  Inverter with solar panels and a current sensor - See atttached PDF  -

 

 

The sensor can be similar to this  -https://www.ev-power.eu/Measure-Test-Tools-1-1/Current-Monitoring-Relay-PRI-52-AC-0-5A-25A-CE.html#tab2

A soladin or APS grid inverter will be ideal choice ( 1 KW to 2 KW) - 

http://www.mastervolt.com/products/solar-inverters/soladin-1000-web/ 

APS- http://www.apsmicroinverter.nl/

The idea is that whenever the current sensor senses the Current flowing from PV panels to Multi or from Multi to PV panels the sensor after 1 min will switch off the Powercontactor feeding the water heater/Boiler - The contractor  timer waits for 10-20 min and resets if there is no current flow then the water heater remains connected till the current sensor switches it off

the idea being that in daytime the solar PV inverter will directly feed power to water heater. After midday  when the heater gets thermal cutoff  there is no power draw from heater the excess energy is fed back through multi to loads and battery 

You can set timers( time of Day)  and even a bypass switch to feed the heater directly from Multi in winter or night if some top up heat is required. 

Alternatively, a time of the day timer can be fitted to disconnect heater in the evenings /night to prevent draw from batteries ( in case your multi is not passing the grid to the heater)

 

Since the grid tie inverters have efficiencies between 95-97 % you are using the full yield and compared to the DC heating element you can locate your panels anywhere and heater anywhere in the house as long as they are connected at AC side 

Also, the solar panels can be smaller say 500 watts  ( set current control higher than  the difference of  Panel average yield and heating load)  OR

They can be much larger ( set current control or a lower value say 1 to 2 amps)

 

In my case I  am planning to use a similar setup but instead of heater use it for running an air conditioner - The one advantage I have is that the AC is inverter type. so it ramps up the load from 100 Watt to 900 watts in linear fashion giving ample time to the contractor to act and disconnect if it is a cloudy day 

 

 

20170719191655983.pdf

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2 hours ago, Chris Hobson said:

Is there a way of using a GeyserWise with a Kwikhot geyser?

Don't know firsthand... but I have a Kwikot, and some time ago someone wanted to install a geyserwise for me. Far as I know you swap out the thermostat (a standard item), wire the new thermostat to the geyserwise, and use the geyserwise to switch the power on the geyser. So unless I got something wrong, it should just work.

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8 hours ago, Chris Hobson said:

Is there a way of using a GeyserWise with a Kwikhot geyser?

Yes.

4 hours ago, Chris Hobson said:

The Kwikot I am dealing with has an integrated thermostat there is no pocket.

The geyserwise unit comes with a thermostat that will plug into the Kwikhot element.

Note that you get several Geyserwise versions - one that is a "smart timer" with no solar heating function (I think called the TSE), then you get the MAX which works with a pumped solar thermal system, the DUAL works with the PV heating system, etc

I have limited experience with Geyserwise equipment, if you mention what you are trying to achieve and I may be able to advise further.

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@Chris Hobson there is a fairly recent installation manual for the Geyserwise Max at www.kznsolar.co.za › Geyserwise › pdf which I used recently for installing such a unit. The connections inside the control unit for a 12V pump,battery and solar panel as well as the mains and heater element are different but easy to figure out. Perhaps the manual will help in answering your query.

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On 12/8/2017 at 1:48 PM, Chris Hobson said:

The Kwikot I am dealing with has an integrated thermostat there is no pocket.

@Chris Hobson is there no additional probe that goes into the element? I did a quick search and could not find the element that has a integrated thermostat a picture maybe? You know how most of us think in pictures :P.

Else could you not replace the element with one that does have a pocket , these things tent to be not that expensive and most of it are quite universal.  

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Hello McWidowmaker

I know its maybe too late but did you sort your controllers out.

I can offer you a SR81 & our SunScan 220V circulation pump for around R2750 Ex VAT.

Both products have a 2 year warranty.

Let me know

Stuart
SunScan
stuart@sunscan.co.za

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