Solar Diverter for water heating in NZ? Would appreciate your experiences.

Forums › Home Workshop DIY › Solar Diverter for water heating in NZ? Would appreciate your experiences.

Leandrew

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#249131 26-Apr-2019 21:32

Hi all
I am just new to Geekzone today, so it’s quite possible I have placed this feed in the wrong section.
We have solar and have been using the Iboost diverter made by Marlec UK. We encountered so many issues we decided to uninstall the unit.
We are now looking for alternative options in the way of diverters.
We have also been told that many other units that have been available on the NZ market are no longer being installed because of faults/ glitches.
We are currently looking at the Paladin diverter. We are really interested to hear about your experiences or any advice you could pass on.
We are interested to hear about other units also.
Thanks kindly

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#2225976 27-Apr-2019 01:54

What exactly were the issues that you were having with your old diverter?

Maybe you actually have a system design problem. Or your installer has done something silly, like tried to use the diverter with a separately metered hot water power circuit, circuit that is connected to ripple control system etc. Solar export and loads on different phases maybe?

Leandrew

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#2228468 1-May-2019 10:05

Thanks for your ideas.
The company that installed the Iboost ignored our requests for help with the issues, so we had no choice other than to have it removed. So it is gone and that company will refund us minus $500. We don’t seem to have any say in that. So, as you can imagine we don’t really want anything more to do with Marlec and their Iboost.
We really don’t know if the alternative units in New Zealand are any more reliable than the Iboost.
There seems to be very little known about units, and any attempts of enquiry have been fairly fruitless to date.
The Paladin is one we researched online, but we don’t know much about it’s reliability either.

Aredwood

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#2228610 1-May-2019 11:56

Again, what was / were the problems with your old diversion unit? As there is no way that anyone can recommend a replacement, without knowing what problems you need to solve.

kotuku4

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#2228616 1-May-2019 12:04

Copied from another post

I have solar PV 4.9 kW 20x245w pannels and grid tied 4.8 inverter installed 2013, recently upgraded to a larger 270l hot water cylinder and changed hot water timer to hot water diverter. The power diverter I use is a Paladin, it was cheap and it is not smart. The installer I found usually installer Immersun units for around $1500. Very happy with this set up.

I had no idea how much PV to install, and went for as much as I could at the time, probably about 3kW would have been optimal. And you may be able to expand later.

Before I installed I upgraded my house over time, with additional ceiling insultation, heat pump, double glazed windows. Have always been low power user.

I am considering battery storage as cost is dropping, but it is still expensive. And my power bills amount to around five hundred dollars a year with winter use heat pump and some hot water heating, family of five, modest sized house with one bathroom. We do get power trust rebates of around $300 per year which keep the cost down. I really do hate to pay for power, mostly fixed daily and other charges. Off grid is not logical unless you are at a site and have to pay significant money to get power lines or cables installed and connected.

One of the reasons for all of the above is the environment. Return on investment for any solar is hard to justify, with PV it is a long term solution. You have your own power generation, but have paid in advance for your power. Export buy back rates have been slashed since my install. I consider it paid for now.

We don't have reticulated gas in my location, and I would not ever consider gas. I investigated solar hot water and heat pump options, but not happy with the cost or the durbility/ lifespan of the equipment based on advice for several plumbers/ installers.

I have a hobby 12v sytem in spearate garage that I need to make better use of, just for tool charging and a radio. Using old batteries, could use a decent deep cycle battery. Would like to put up a small 100-300w wind turbine just for fun, possibly a vertical axis version. I have an e-bike and tools, not sure if I should get 12v chargers or an basic 12v to 240 volt inverter for charging.

An electric car is on the wish list too.

Leandrew

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#2228617 1-May-2019 12:05

The unit was constantly going in to warning mode due to overheating.
It was diverting or attempting ( whirring up and down) all night.
It stopped heating our water using solar and would only then heat when in boost mode which defeated its purpose.

mikemix

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#2228664 1-May-2019 12:21

Hi,

I have a 3.1kw Solar PV System and use a eddi solar power diverter to divert my excess solar to my hot water cylinder.

Works really well, I am able to program in boost times to always make sure I'm heating the water during my free hour of power with Electric Kiwi.

You appear to be able to run 2 devices off the Eddi, might be handy if we get an electric car.

I believe taspacenery in Auckland are the importers. My Solar guy quoted around $900 installed for the Eddi (very knowledgeable guy too) - let me know if you would like his details - based in Nelson but does installs all over.

Let me know if you would like any more info on my setup

Cheers.

kotuku4

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#2228665 1-May-2019 12:23

Yeah it's good to find an installer who knows about solar power diverters. The Paladin I have is pretty grude but seems to work reliably.

I bought from trademe and the unit sat around for a long time until I found an installer. My electrician and solar installer never showed up to do the install.

The position of the temperature sensor did need changing. Recommend you look for someone who installs Immersun units.

Aredwood

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#2228737 1-May-2019 13:54

Leandrew: The unit was constantly going in to warning mode due to overheating.
It was diverting or attempting ( whirring up and down) all night.
It stopped heating our water using solar and would only then heat when in boost mode which defeated its purpose.

Just to confirm. Do you have solar PV (electric) panels, an inverter, and the diverter controls power to just 1 element in your hot water cylinder, and no other heat sources to the cylinder?

Or do instead have solar hot water, meaning that you have a pump and a controller for it?

As your symptoms make no sense. As there wont be any solar output at night. So the diverter shouldn't be doing anything at night.

How many heating elements does your cylinder have?

Leandrew

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#2236162 13-May-2019 17:36

We are in the process of deciding between Paladin and Eddi solar diverters.
Those are the only two we are aware of.
Paladin doesn’t have a timed boost, so will need a seperate time installed.

Anyone have any other thoughts or experiences with the Paladin or Eddi?
Thanks kindly

Terciops

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#2264986 26-Jun-2019 13:51

kotuku4:

Yeah it's good to find an installer who knows about solar power diverters. The Paladin I have is pretty grude but seems to work reliably.

I bought from trademe and the unit sat around for a long time until I found an installer. My electrician and solar installer never showed up to do the install.

The position of the temperature sensor did need changing. Recommend you look for someone who installs Immersun units.

Hi,

Paladin Dev here. Can you tell me what version of Paladin you have?

I assume by 'grude' you mean crude. Well Paladin is an over-engineered modular marvel and it was never meant to be mounted in the lounge :) It is in a brick of a box and if you took the time to look inside, it is all modular components that can be upgraded easily. Reason, we buy only the best bits from all over the world and totally overspec everything that might fail.

Case in point, I have put in a 40A SSR rather than a 16A TRIAC. 60x the price and 2.5x higher rating than required. But does it run cool? That is why we can use a passive heat sink that looks so 'grude' - but is it ever quiet compared with a tiny little fan whining away all day and eventually burning out a bearing. That heatsink is designed to never go above 50C at 4kW load. The SSR max temp is 125C. MTBF at these specs is millions of hours.

The thermometer is a self contained CPU based probe accurate to two decimal points of a degree. Somewhat better than the erratic resistance probes used by other diverters if they have a temperature sense function at all.

Yes it is reliable. We have 700+ units out there and we have had a few fail, but just a handful, and we replace them automatically so I can do an investigation / autopsy. It is always either the CPU unit because of a voltage spike or the CT because of ham-fisted installation. No problems I fix them and update them to latest specification and send them back. Being a NZ based manufacturing company we can do that easily.

Nominally they have a 3 year guarantee, but in practice I would like to think they will last a lot longer than that, so I always want to see the failures to figure out if we can get a longer lasting component.

As for the temperature probe, it just needs to be at about the same level as the existing thermostat, 6-8cms above the element - above the thermocline inside the tank. The instal docs are quite specific about that.

What temperature have you managed to get your tank thermostat to? Or what is the max temp you see on Paladin at the end of a sunny day?

This is my Paladin live at home running a screen on the yet to released ESP32 co-processor / comms package on a browser:

https://www.youtube.com/watch?v=Dqr-sWS3IUA

or check out my FaceBook page for Paladin - lots of my geeky articles there :

https://www.facebook.com/groups/1108024512629017/

Ken

PS. This list of features was made up by one of our distributors - not me. I didn't realise that Paladin did so much :)

Use of a Solid State Relay - this means that the switching circuit is in a metal hermetically sealed box and the internal circuitry has a fusible link that prevents Triac-like explosive failures
Overheating is prevented by use of over rated components (SSR designed for 40A continuous use, but rated at 16A)
Larger heat sink than required. Even at 40A at temperature of 50C is maintained, and mild deformation of the enclosure takes place at 150C
The heat sink is mounted in free air with oversized vertical fins - not next to the wall where it can set fire to to wall if it overheats
Automatic Legionella protection (legal requirement) - I know of no competing product that offers this. If they do, then maybe they maintain 60C minimum temperature, dramatically reducing energy storage.
High powered devices are not mounted on a printed circuit board.
Zero-crossing switching that minimises EMF interference and affect on sensitive people
An anti-flicker induced epileptic fit design at prevent flicker (some products have been recalled due to this)
Fail-to-safety design
Only the SSR and the mains transformer/PSU are HV connected, and these are independently certified and imported from the factory as counterfeit products are rife. These same components are sold in New Zealand and subject to SDoC's where required.

Exported to Australia and the USA.

The Functional features are also quite different:

Only Paladin manages the temperature of the hot water cylinder to take into account stratification to store the maximum amount excess PV energy
Pre-emptive top-up to prevent a cold shower. The rate of drop of temperature is monitored and a variable power level is used to manage this. As soon as the temperature stabilise, the top-up slows or stops
Legionella top-up anticipated after multiple low solar days and a top-up taken at the off-peak power rate
Minimum temperature maintained without the need for a manual boost feature
User selectable 50C minimum temperature and special boot
Hybrid Inverter hold off
Max current draw option, particularly for 2-phase installation with a 5400W limit
”Set and forget” (autonomous) operation-no user intervention required
Self diagnostics on start-up and during operation (element blown/max temp reached, no temperature probe etc)
No temperature probe operation (in an emergency to deliver hot water)
Displays solar PV
Optional Auxiliary control of second cylinder element, spa pool heater, underfloor heating, storage heater etc..
Compatible with PV to Electric Vehicle variable charging devices such as JuiceNet (proven in NZ)
Demand Response enabled.

Proven control system microprocessors is used for high reliability, that allows the mains to be monitored 3200 times per second, and power controlled every 20mS with 1 Watt incremental accuracy.

darkasdes2

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#2266217 28-Jun-2019 12:16

Terciops:

kotuku4:

Yeah it's good to find an installer who knows about solar power diverters. The Paladin I have is pretty grude but seems to work reliably.

I bought from trademe and the unit sat around for a long time until I found an installer. My electrician and solar installer never showed up to do the install.

The position of the temperature sensor did need changing. Recommend you look for someone who installs Immersun units.

Hi,

Paladin Dev here. Can you tell me what version of Paladin you have?

I assume by 'grude' you mean crude. Well Paladin is an over-engineered modular marvel and it was never meant to be mounted in the lounge :) It is in a brick of a box and if you took the time to look inside, it is all modular components that can be upgraded easily. Reason, we buy only the best bits from all over the world and totally overspec everything that might fail.

Case in point, I have put in a 40A SSR rather than a 16A TRIAC. 60x the price and 2.5x higher rating than required. But does it run cool? That is why we can use a passive heat sink that looks so 'grude' - but is it ever quiet compared with a tiny little fan whining away all day and eventually burning out a bearing. That heatsink is designed to never go above 50C at 4kW load. The SSR max temp is 125C. MTBF at these specs is millions of hours.

The thermometer is a self contained CPU based probe accurate to two decimal points of a degree. Somewhat better than the erratic resistance probes used by other diverters if they have a temperature sense function at all.

Yes it is reliable. We have 700+ units out there and we have had a few fail, but just a handful, and we replace them automatically so I can do an investigation / autopsy. It is always either the CPU unit because of a voltage spike or the CT because of ham-fisted installation. No problems I fix them and update them to latest specification and send them back. Being a NZ based manufacturing company we can do that easily.

Nominally they have a 3 year guarantee, but in practice I would like to think they will last a lot longer than that, so I always want to see the failures to figure out if we can get a longer lasting component.

As for the temperature probe, it just needs to be at about the same level as the existing thermostat, 6-8cms above the element - above the thermocline inside the tank. The instal docs are quite specific about that.

What temperature have you managed to get your tank thermostat to? Or what is the max temp you see on Paladin at the end of a sunny day?

This is my Paladin live at home running a screen on the yet to released ESP32 co-processor / comms package on a browser:

https://www.youtube.com/watch?v=Dqr-sWS3IUA

or check out my FaceBook page for Paladin - lots of my geeky articles there :

https://www.facebook.com/groups/1108024512629017/

Ken

PS. This list of features was made up by one of our distributors - not me. I didn't realise that Paladin did so much :)

Use of a Solid State Relay - this means that the switching circuit is in a metal hermetically sealed box and the internal circuitry has a fusible link that prevents Triac-like explosive failures
Overheating is prevented by use of over rated components (SSR designed for 40A continuous use, but rated at 16A)
Larger heat sink than required. Even at 40A at temperature of 50C is maintained, and mild deformation of the enclosure takes place at 150C
The heat sink is mounted in free air with oversized vertical fins - not next to the wall where it can set fire to to wall if it overheats
Automatic Legionella protection (legal requirement) - I know of no competing product that offers this. If they do, then maybe they maintain 60C minimum temperature, dramatically reducing energy storage.
High powered devices are not mounted on a printed circuit board.
Zero-crossing switching that minimises EMF interference and affect on sensitive people
An anti-flicker induced epileptic fit design at prevent flicker (some products have been recalled due to this)
Fail-to-safety design
Only the SSR and the mains transformer/PSU are HV connected, and these are independently certified and imported from the factory as counterfeit products are rife. These same components are sold in New Zealand and subject to SDoC's where required.

Exported to Australia and the USA.

The Functional features are also quite different:

Only Paladin manages the temperature of the hot water cylinder to take into account stratification to store the maximum amount excess PV energy
Pre-emptive top-up to prevent a cold shower. The rate of drop of temperature is monitored and a variable power level is used to manage this. As soon as the temperature stabilise, the top-up slows or stops
Legionella top-up anticipated after multiple low solar days and a top-up taken at the off-peak power rate
Minimum temperature maintained without the need for a manual boost feature
User selectable 50C minimum temperature and special boot
Hybrid Inverter hold off
Max current draw option, particularly for 2-phase installation with a 5400W limit
”Set and forget” (autonomous) operation-no user intervention required
Self diagnostics on start-up and during operation (element blown/max temp reached, no temperature probe etc)
No temperature probe operation (in an emergency to deliver hot water)
Displays solar PV
Optional Auxiliary control of second cylinder element, spa pool heater, underfloor heating, storage heater etc..
Compatible with PV to Electric Vehicle variable charging devices such as JuiceNet (proven in NZ)
Demand Response enabled.

Proven control system microprocessors is used for high reliability, that allows the mains to be monitored 3200 times per second, and power controlled every 20mS with 1 Watt incremental accuracy.

Do you have a diverter for 3 phase power PV systems?

kotuku4

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#2266243 28-Jun-2019 13:02

Hi Ken

Thanks for for post. Part of the issue for me was the hassle of getting someone to install the unit. I eventually found Andrew at Sunshine Solar Blenheim. Andrew did call during the install to query something, the old instructions I had were a but difficult to follow.

Overall the Paladin unit is working well. Probably version 2.1 with 3kW diversion.

My hot water cylinder is narrow 550mm 270 litre Peter Cocks low pressure, single element.

It was not showing much heat, and heating from grid far too much. Ended up cutting a hole in the cylinder case to insert the temperature probe about 300-400mm above the element/thermostat.

Heats to an indicated 72.2 degrees, often by mid day on a fine frosty winters day.

The unit is not smart, in that there is no BT, Wifi, Ethernet, app to monitor/log how much power is generated, load, how much diverted, water temperature. This is not essential, but other diverters can provide this, plus ability to programme timers, temperature and other functions. But I have no personal experience of other options.

I find myself opening the door and checking water temperature, and if PV being diverted and heating. The heat sink does throw off some heat, this is ok warming the airing cupboard.

I did wonder if needed to install the three way switch Auto, On, Off.

Terciops

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#2266579 29-Jun-2019 05:46

Hi,

Thanks for that info.

It's hard to tell from the photograph, but the top of the manufacturer's cutout would have been fine. I usually just push a phillips head screwdriver between the tank and the insulation vertically from the top to make a pencil size cavity and put the probe there. But whatever you did obviously worked well, since 72C on a Winter's day is excellent.

See if you can get another notch UP on your tank thermostat to allow Paladin to top out at 73C rather than have the tank thermostat take control at the top. This will allow just a little more transfer and avoid the tank thermostat holding off until the water temp drops to probably 67C or so. Mind you with that 270L you are doing some serious transfer numbers anyway.

40C to 72C on a 270L is about 4.65kWh per 15C rise, so over 9kWh of avoided export per day even without natural loses and water use.

Yes the heat sink gets warm, but not so much as to make a measurable difference. At full noise there is about 40W of heat dissipation there, and it is just a cost of doing business when switching 3kW at 20ms. That is why Paladin uses a heat sink. Imagine what the temps are on a circuit board mounted TRIAC :) The whole, old school, cooling circuit is designed to run below 50C to remove any chance of heat stress and subsequent failure; not to mention making it safe to touch.

The next generation Paladin is considerably more sophisticated, and there is comms designed in to work on the local LAN. The whole thing around providing some form of external readout and control has been a nightmare frankly. Bluetooth is a mess and is very spotty particularly around all the pipes and wires where Paladin is usually mounted. So I went with the ESP32 and used that as a secondary processor / comms unit that talks to the main Paladin 'engine' on a hard serial link.

This has been great and it works very well without compromising the core Paladin performance. However getting a reliable Wifi signal in a lot of houses is difficult for the same reasons as above for BT.

The original idea was to mount the ESP32 on the daughter board above the main CPU, but although that works, it is not, frankly, thrilling. I am just testing another daughter board design that puts the ESP32 on a 4 wire electric string that puts the ESP outside the case with a better 'view' of the WiFi signal. This looks very promising and allows the user to see the tiny screen that is part of the ESP32 module, which allows diagnostics on the WiFi and such.

Yes, other units offer comms etc, but if it don't work reliably it is a nightmare and can compromise the main function of the diverter - and actually becomes worse than useless. I am confident that the external, secondary CPU/WiFi unit is the way to go since the main Paladin keeps working normally even if that ESP gets tied up on comms stuff.

My home unit, which acts as a real world beta test is running just about perfectly, and has been for nearly a year, so I am almost confident enough in the reliability and durability to release that upgrade quite soon. The graphics and display on a browser are not that fancy, but I am more concerned about function than form here, and am righteously paranoid about security and simplicity of use, so all the code and pages are internally generated without using external web calls. Indeed the whole thing can still be used without an Internet connection at all, using the ESP's internal access point. However the ESP does 'phone home' to my base server every midnight when connected fully to pick up any changes and can do over the air updates etc - so that is a huge plus.

My real problem at the moment is writing the documentation for the less IT orientated. This is taking longer than the code itself!! The issue is that the ESP has some seriously clever features for managing 24 hour water temp gradients, inverter charger schedules, grid stabilization features, give you accurate running costs and compare alternate electricity plans in real time, an AI engine that can do spot market arbitrage - make tea..... But with the limited memory available in the ESP, the API to control all this can be best described as terse. Not user hostile as such, but certainly not for new players. The documentation is not going to be 'War and Peace', but it will not be 'Noddy goes to the shops' either :)

The 3 way is just there to enable reversion to manual, thermostat controlled water heating to bypass Paladin should it fail. You are effectively just joining the two mains wires on the SSR together to provide continuous current to the element/thermostat as pre-Paladin. If all is working well, you don't need it.

Long term we need to get your unit upgraded, but there is no rush or practical benefit until I roll out the WiFi version. When that happens we will contact you and there are a couple of ways this can happen :

The fastest is that we will send you a new motherboard and CPU unit that is just a plug in replacement. It does require opening up the case - with the mains OFF !! Removing original motherboard and CPU unit and replacing that with the new parts. All the other connections are the same, plus there is another CT to clamp onto your PV input line - but not essential as this is info only on the screen. This a screwdriver, sharp knife and common sense job. There are no changes to the mains connections at all, just the 5v circuit.

Second best is that you send us your old unit and we will do all that for you.

Costings are still not finalized, but the aim is to do this at cost since our policy is not to make a profit on upgrades. The whole Paladin modular concept is rather like my Grandfathers axe.... $50-$100 will be my best guess. But as I said, diversion, performance wise there is no practical benefit. Paladin works so well, it is difficult to get measurable improvements.

More later...

kotuku4

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#2267013 29-Jun-2019 21:49

One little comment, when a lot of hot water is used, in the morning it will heat from grid, when i know it will be a nice sunny day. I could use rcd timer to stop this occuring, so it switches on later when solar is active. Would you recommend controlling the time the Paladin operates in this way?
Thank you for your development effort and replies.

Terciops

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#2267089 30-Jun-2019 07:08

You bring up a recurring theme that surfaces about this time of the year. Deferring a top-up sequence so that Solar can do the work later in the morning.

Later versions of Paladin do address this is various ways. Mainly, I produced a different set of firmware versions with different minimums that could be loaded. This satisfied the cognitive dissonance, but never did change the laws of Physics :)

Currently there is a set of DIP switches on the daughter board that allow the user to set a minimum temperature of 10C, 20C,30C,40C. The very latest Beta using the ESP32 allows you to take this even further and to specify a minimum temperature for every hour of the day.

But the bottom line is that at some point in time you have to pay the Piper and changing minimums only defers a problem and never solves it, except for some specific times of the year and weather patterns.

Solar insolation is, unfortunately a huge variable, whereas our use of hot water - not so much. This question and the debate around it this actually valuable though, since it highlights just how much energy we use in the quest for the luxury of a hot shower.

If you defer the top-up to minimum to wait for the PV transfer, this only does any good if you are regularly reaching max temperature before the end of the day. The logical fallacy is to think on a day to day basis rather than in a much longer period. The larger the hot water tank, the better off you are in this regard since you can overcome a day or two of poor solar transfer values without a significant top-up.

But you have to get that 60C every 72 hours for Legionaire's protection anyway, so nothing really is gained by running the average tank temperature down.

The original Paladin concept catered for this and you will see that minimum temperature top-ups only use just enough power to keep the water above the thermocline just about perfectly at 40C. Hence the use of an accurate and responsive thermometer and an 8 second monitoring cycle. Unlike, say a thermostat unit as normally fitted which have a gap of around 7C between ON and OFF.

If your Paladin is regularly topping up in the morning after showers and you reached top temperature the day before, then yes, lowering the minimum might work periodically. But remember it is only the bottom strata of the water column that has dropped initially, and it is only that lower stratum that Paladin is topping up. Because of the short duration of the top up, there is not enough thermal change to induce mixing, so the amount of energy required is small.

However, if you keep on doing this then you will hit the Legionaires trigger and take a large topup to 60C regularly and that is not the best way to run your tank at all.

So if you want to avoid that top-up, the best solution, apart from taking Naval Showers - which is a good trick to teach the kids, is to ensure that your original tank thermostat is set ABOVE 73C so Paladin can make the best use of the tank capacity when solar is good. The tank thermostat then just becomes a backstop rather than a controller.

Hope this helps.

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