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Posted

Hello, I am looking to purchase a solar system however my biggest challenge is heating. My general lights / TV / Appliances I can get away with a 5kw system, however I want to know the best way to manage an electric geyser and oil heaters. I have read two options:

1. Install a geyserwise type of PV system with 2/3 panels and manage with built in timer. Costs around R20K installed. This therefore means a dedicated system for the geyser and as soon as PV is available, you can heat up your geyser. 

2. Purchase a large inverter (8kw) and add extra 2 panels and this would be less expensive than option 1 above? This would obviously be a deye or sunsynk

However, how do I get option 2 to work as I read the Sunsynk and Deye units have the smart output function however there are criteria of >90% battery charge etc. if lower the output would be off and therein the geyser would also be off and the PV would not charge. Any ideas or what are other people doing in this space of geyser management and thoughts of the above I mentioned?

Then,  oil heaters, how do I manage this for the 3/4 months of JHB winter as I do not want to use gas in the bedrooms as I do not like the smell and risky to run an open flame for the entire night.

Appreciate it folks :)

 

Posted

Thanks for the feedback.. Hear pump is also around 20k odd.. 

Oil heater on low consumes around 1kw and heating is better and lasts longer than aircon and noise is zero.

19 minutes ago, Buyeye said:

Options 3 and 4.

Get a geyser heat pump.

Get inverter aircons.

Profit? I think so.

 

Posted

@Solarcrazy  I would put in the bigger Inverter with the extra panels. The 8kw also allows for much larger pass through power so you can run everything through the inverter.

There are a few other option to spending 20k on Geyserwise. If you are not nervous about learning some Node Red skills, you can install smart switches on your geyser and you can create a flow to switch the geyser on depending on it meeting your criteria. 

Use Time, SOC, solar power being produced/used etc and set the criteria that need too be met before it NR switches the geysers/heavyloads on.

I also use Node Red to cycle through multiple geysers/borehole pump etc  so that I do not have too many big loads all on at the same time and overload my inverter.

If you install smart switches with energy monitoring, Node Red can see when they geysers are no longer drawing power and switch to the next one.  

I have 4 geysers & a borehole pump all running of my 8kw inverter. 

Other option is to just work out how long the geysers usually need to run for and then have them switching on/off using the app.

There are Smart Switches available that run on the eWelink & Tuya platforms which will all work, would just make sure that they can handle at least 30A. The sonoff switches are not suitable as the relays are too small. 

 

Posted (edited)

Thanks for your feedback. Where can I get these smart switches from and more information? 

Also how do you manage heating? Like oil heaters or Aircons? 

Edited by Solarcrazy
Posted
29 minutes ago, Solarcrazy said:

Thanks for your feedback. Where can I get these smart switches from and more information? 

Also how do you manage heating? Like oil heaters or Aircons? 

Leroy Merlin / Builders

https://leroymerlin.co.za/smart-controller-astute-cbi-81457725?sfdr_ptcid=32806_617_672343907&sfdr_hash=98b0565e208fb242782ab03b4d6b5ba7

https://www.builders.co.za/Electrical/Plugs,-Sockets-%26-Switches/Smart-Electrical/ASTUTE-SMART-CONTROLLER-GRY-BLK/p/000000000000744335

You can bring those into Home Assistant if you have it OR just run them off the Tuya / Smart Life app on a time schedule. When do you need / use the hot water most? You COULD put the geyser on non essentials and charge it using excess solar. 

Posted
On 2022/04/11 at 1:27 PM, Sc00bs said:

@mzezman Tried that but my wife was very insistent that hot water was an essential, lol 

Hahaha - i get you man. Mine is on non-ess - so during the day it is warmed up by the sun then the morning warm-up (430-6am) I use Eskom

Posted
1 hour ago, mzezman said:

Mine is on non-ess - so during the day it is warmed up by the sun then the morning warm-up (430-6am) I use Eskom

Same here. I run my geyser during the day, set to 65 degrees, to utilise the sun. Then for the morning warm-up 04:30 to 05:30 I have it set 45 degrees (with the Geyserwise TSE you can have different temps for different times of day). That way it doesn't come on in the morning if we used very little hot water the previous night.

Posted
18 hours ago, mzezman said:

Hahaha - i get you man. Mine is on non-ess - so during the day it is warmed up by the sun then the morning warm-up (430-6am) I use Eskom

What happens when the sun doesn't shine, I assume that it just runs of Eskom power? 

So you work out how long it takes to reach the SOC you set to start feeding into non-essentials when there is loads of sun and then set your timer to only switch it on after that?

Home assistant has got quite a cool "Solar Forecaster" gives a pretty accurate estimate of the days solar production, I use that to work out whether HA should switch the pool pump on or not. 

 

Posted (edited)
4 hours ago, Sc00bs said:

What happens when the sun doesn't shine, I assume that it just runs of Eskom power? 

So you work out how long it takes to reach the SOC you set to start feeding into non-essentials when there is loads of sun and then set your timer to only switch it on after that?

Home assistant has got quite a cool "Solar Forecaster" gives a pretty accurate estimate of the days solar production, I use that to work out whether HA should switch the pool pump on or not. 

 

If there is minimal sun for the geyser i just run it off Eskom - but i need to be deliberate about it (through the right SOC settings etc) else it will use my batteries - which is not great at all. The ultimate plan is to get HA managing all this - i just havent found the time. My largest loads that can be managed through HA are the geyser and pool pump (and the aircons as well) so ultimately i'll have a system that - depending on PV, switches these on and off as needed

e.g. If solar forecast > 15kWh and battery soc > 60 then switch on device x. It takes my geyser about 2hrs to get to temp - so i can build that into the routine as well. The say if we didnt get the full PV we need, turn on geyser and utilise Eskom

Edited by mzezman
Posted (edited)
On 2022/04/10 at 8:14 PM, Solarcrazy said:

Thanks for the feedback.. Hear pump is also around 20k odd.. 

Oil heater on low consumes around 1kw and heating is better and lasts longer than aircon and noise is zero.

 

Yes even at R20th for heat pump it uses at least 50% less power than an element for heating water. Also due to the 1200-1500w used by it one can easily run from 1000w solar panels and even add a splash and dash from batteries if the power is out and there is no sun.

The geyserwise with 3 panels will not be able to add any heat to the water without sun and cost the same..

So yes a Sunsynk and heat pump will be my call.

Edited by Scorp007
Posted

@Scorp007 R20K for the heatpump = about 7 extra panels @ R3k each.

I would be inclined to just add another 7 panels to the install and stick with the installed geyser. 

Less to go wrong and cheaper to repair if it does, the extra 7 panels will ensure you have enough power even on the marginal days to run everything you need too.  

Posted
21 minutes ago, Sc00bs said:

@Scorp007 R20K for the heatpump = about 7 extra panels @ R3k each.

I would be inclined to just add another 7 panels to the install and stick with the installed geyser. 

Less to go wrong and cheaper to repair if it does, the extra 7 panels will ensure you have enough power even on the marginal days to run everything you need too.  

I cannot disagree with you on the money spend.

My suggestion was merely instead of the 1st option mentioned to use 3 panels and that only to heat water very slowly. But yes 3 of these panels can supply the hot water either during sun periods or via batteries that were charged by the sun.

My heat pump is now 9y old and I hag 1 service done by cleaning of the dust and I ended up doing it myself. Further I had to replace the pump at less than R1800 labour included. I read a lot how expensive a heat pump is to service but never of the service cost for an aircon and yet they are very much the same.

One just need to do the sums and not always allow R2000 pa for servicing which will shift the result. I know those using EV Tubes won't agree.

I just feel heating water at 50% of the normal cost is a big gain.

Many ways to skin a cat.:)

Posted
On 2022/04/13 at 5:18 PM, Sc00bs said:

@Scorp007 R20K for the heatpump = about 7 extra panels @ R3k each.

I would be inclined to just add another 7 panels to the install and stick with the installed geyser. 

Less to go wrong and cheaper to repair if it does, the extra 7 panels will ensure you have enough power even on the marginal days to run everything you need too.  

Thanks for the feedback.. How do I setup the inverter to use the PV power? Must I set it up as essential? However if you here is load shedding I don't want it to go on if there is no sun or raining day so how do I setup my installation for this? 

Posted

@Solarcrazy

As my properties power is not easy to split into essential/non-essential loads, I found that the best way to manage my heavy power loads is by using smart switches & Home Assistant. 

I use HA to only switch the pool on when there is enough solar power forecast for that day.

It is very easy to set up one switch to disconnect all your heavy loads during the day if there is low/no solar power being generated. You could automate that as well but the use case is very limited as it almost never happens and I am usually more aware of power usage when there is load shedding going on in any case. 

I also automated my some Smart LED downlights to change colour when there is no grid frequency so that I know that load shedding has started. 

Posted
8 hours ago, Solarcrazy said:

Thanks for the feedback.. How do I setup the inverter to use the PV power? Must I set it up as essential? However if you here is load shedding I don't want it to go on if there is no sun or raining day so how do I setup my installation for this? 

If you are planning to install a Sunsynk or Deye inverter then you would wire the geyser to the non essential circuit.

The inverter will then use PV to provide power the geyser as long and Eskom is available and the CT coil has (correctly) been installed. When Eskom is not available then all items on the non essential circuit will not receive any power, even if there is sufficient PV available.

Posted
5 hours ago, Saliegh said:

Hey Guys, I hope that this is not a hijack of the topic.

I have my 3kw geyser wired to non-essential atm, and it's fine, except when I want to turn it on during loadshedding at 12pm, where there is sufficient solar generation.

I'm about to have it re-wired to the essential load.

My question is, in the unlikely event that I exceed the inverter capacity (5kw Sunsynk), what will happen? ATM, I do not have sufficient loads on the essential to test this out.

ATM, when essential and non-essential >5kw, the rest comes from Eskom...

The inverter will shut down with and F18 over current warning. If the over current is to significant you will damage the inverter

Posted

@Saliegh The Sunsynk 5kw has a "maximum continuous pass through" of 35A. 

@ 220V that works out to +- 7700W, usually a bit less. 

So when you are connected to Eskom and you pull more than 7700W the inverter will trip out. 

If you are not connected to Eskom and you pull more that 5000W the inverter will trip out.

Running a 3kw geyser of a 5kw is possible but would require some management, especially during load shedding, just needs someone to turn a kettle/toaster on and together with your houses base load you will be over 5kw.

I would suggest using a smart switch and build a Node-Red flow in Home Assistant to ensure that the Geyser does not switch on when there is load shedding i.e. No Grid Frequency - Turn off the Geyser 

You also obviously need to ensure that your batteries are able to supply enough Amps for 5kw - 105A @ 48V

 

 

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