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On top of the current load shedding, our area has been subjected to frequent power outages due to a troublesome substation and cable theft. I've finally decided to take the plunge and invest in solar power to achieve the following:

1. Continue to run critical components throughout power cuts / load shedding
2. Reduce the reliance on the grid as much as possible to save on electricity costs

Our average daily usage is around 18-22kWh depending on the season. We've also got a gas stove and solar geyser so our peak usage should not be too great. What seems to be the best solution is to go for a Hybrid inverter coupled with a couple of batteries and PV panels.

I've contacted a company that proposed the following solution:
* Sunsynk 8kW Hybrid Inverter
* 2x Pylontech US3000 3.5kWh batteries
* 12x Canadian Solar 365W Poly PV panels

I'm very new to solar energy solutions so please excuse my ignorance with the below questions:

1. Does the above seem like an appropriate solution?
2. How does the Sunsynk 8kW inverter compare to similarly priced inverters such as the Goodwe ES 4.6kW Hybrid Inverter and the Alpha-ESS Smile5?
3. If there are multiple cloudy days (i.e. no solar power being generated) but incoming grid power, will the inverter distribute grid power to both the backup circuits and non-backup circuits?
4. Does the inverter help prevent the backup circuits from power surges due to power outages?
5. How easy/difficult is it to switch an appliance from the non-backup circuit to the backup circuit at a later stage (For example, the solar geyser still has an element that switches on for about 60 minutes in the early morning and evening to give it an extra boost). During these times there would probably be little power generated by the PV panels so it would have to draw from the grid. But if I add additional battery capacity over time, would it be possible or even recommended to then switch it to the backup circuit?
6. How much would the installation of such a system cost and do you have any recommendations for installers in the Centurion/Midrand area?
7. Has anyone dealt with solar-shop.co.za before and what was your experience with them?

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Is your stove all gas, or gas hob abd electric oven? If the latter you will probably have to give up the oven when the grid is down. Big load, big draw from batteries. 

Remember that the system is sized for peak load, not average load. Your installer should advise on this 

Be sure to get a new COC or at least a supplementary COC for the wiring mods. Give your insurers a copy. Dont assume your system is covered by the existing policy, call your broker and discuss. 

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Thanks for the very detailed reply Pietpower.

13 hours ago, Pietpower said:

Yes, but it does not really work like that. Your grid loads are between the inverter and grid and the inverter feeds 'back' to them when you have excess solar. Like a grid tie system it can draw from both inverter and grid.

This really cleared up my biggest point of confusion. I thought the size of the inverter might limit my max peak consumption, even when the grid is on. I think 5kW should be sufficient for our backup circuit needs, or do you think I might regret not going for the 8kW a few years down the line.

Edited by Vleisie
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3 hours ago, Bobster said:

Is your stove all gas, or gas hob abd electric oven? If the latter you will probably have to give up the oven when the grid is down. Big load, big draw from batteries. 

Remember that the system is sized for peak load, not average load. Your installer should advise on this 

Be sure to get a new COC or at least a supplementary COC for the wiring mods. Give your insurers a copy. Dont assume your system is covered by the existing policy, call your broker and discuss. 

It is a gas stove with electric oven. We've made peace with giving up the oven when the grid is down. Also open to adjusting our lifestyle to do things like washing etc during the day when there is a lot of PV input. The only thing I'm unsure about is the geyser. Although it is a solar geyser, it still switches on an element early mornings and evenings to boost the temp if it is too low. But perhaps it is something that can be supplemented from the batteries if I add more at a later stage?

Thanks for bringing up the COC. It was something I didn't think of at all!

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41 minutes ago, Vleisie said:

The only thing I'm unsure about is the geyser. Although it is a solar geyser, it still switches on an element early mornings and evenings to boost the temp if it is too low. But perhaps it is something that can be supplemented from the batteries if I add more at a later stage?

Not a good idea. Heating is a no-no due to the amount of power required.

A better idea is to schedule the geyser element to heat the water during the day when you have excess power available from your PV panels. This does require some fancy footwork with how you do this..

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3 hours ago, Vleisie said:

It is a gas stove with electric oven. We've made peace with giving up the oven when the grid is down. Also open to adjusting our lifestyle to do things like washing etc during the day when there is a lot of PV input. The only thing I'm unsure about is the geyser. Although it is a solar geyser, it still switches on an element early mornings and evenings to boost the temp if it is too low. But perhaps it is something that can be supplemented from the batteries if I add more at a later stage?

Anything that makes an element hot is going to use a lot of power. An electric kettle, for example, uses a surprising amount, but only in short bursts. An element in a geyser will take a large chunk of your battery and at least 3KW of your 8.

Dishwashers usually heat the water early in the cycle. Again this takes up a surprising amount of power, but not for too long. But it all adds up. If you turn on the dishwasher, then decide to have a cup of coffee and meanwhile the geyser element kicks in, that 8KW can get used up awful quick (for a few minutes). Think of the potential peak, not your average use per day.

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With RE systems the power used has to be managed since the power that's available varies and load shedding isn't built into the system!

I haven't read much on this topic on this forum. I have seen comments about time scheduling certain loads but I'm sure there's a smarter way to automate this.

I was referred to this controller to do this: https://www.morningstarcorp.com/products/relay-driver/ 

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On 2020/02/19 at 4:59 PM, Vleis said:

On top of the current load shedding, our area has been subjected to frequent power outages due to a troublesome substation and cable theft. I've finally decided to take the plunge and invest in solar power to achieve the following:

1. Continue to run critical components throughout power cuts / load shedding
2. Reduce the reliance on the grid as much as possible to save on electricity costs

Our average daily usage is around 18-22kWh depending on the season. We've also got a gas stove and solar geyser so our peak usage should not be too great. What seems to be the best solution is to go for a Hybrid inverter coupled with a couple of batteries and PV panels.

I've contacted a company that proposed the following solution:
* Sunsynk 8kW Hybrid Inverter
* 2x Pylontech US3000 3.5kWh batteries
* 12x Canadian Solar 365W Poly PV panels

I'm very new to solar energy solutions so please excuse my ignorance with the below questions:

1. Does the above seem like an appropriate solution?
2. How does the Sunsynk 8kW inverter compare to similarly priced inverters such as the Goodwe ES 4.6kW Hybrid Inverter and the Alpha-ESS Smile5?
3. If there are multiple cloudy days (i.e. no solar power being generated) but incoming grid power, will the inverter distribute grid power to both the backup circuits and non-backup circuits?
4. Does the inverter help prevent the backup circuits from power surges due to power outages?
5. How easy/difficult is it to switch an appliance from the non-backup circuit to the backup circuit at a later stage (For example, the solar geyser still has an element that switches on for about 60 minutes in the early morning and evening to give it an extra boost). During these times there would probably be little power generated by the PV panels so it would have to draw from the grid. But if I add additional battery capacity over time, would it be possible or even recommended to then switch it to the backup circuit?
6. How much would the installation of such a system cost and do you have any recommendations for installers in the Centurion/Midrand area?
7. Has anyone dealt with solar-shop.co.za before and what was your experience with them?

I bought almost everything for my solar setup from Sola-shop.co.za. I was able to setup my system alone with advice from them.

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  • 2 weeks later...
On 2020/02/20 at 4:44 AM, Pietpower said:

Your usage and system sounds similar to mine. I went with a Goodwe.
To get the most out of the solar I have a timer on the geyser to switch on at daytime when the batteries have charged a bit and then switch off in the afternoon not to drain batteries at night.
With hybrid unit the geyser is on grid side of the inverter but it still use some battery power combined with solar power to heat water.  200l is enough for us 4 and still hot the next morning.
Other loads on grid side also drain batteries when grid power is available but I think you can change some settings to not do this.  I've kept it like that to maximise on electrical savings and allow and only drain to 35% in case of load shedding at night.

After getting a few more quotes I've been told the following which I'm unsure about.

* With the Goodwe invertor, it cannot provide more than 4.6kW to the backup loads, even when the grid is available. Is this statement correct? The problem was that I would have liked to put most plugs on the backup circuit but in this case I might not be able to, for example, use the Kettle and washing machine / dishwasher simultaneously, even when the grid is available.
* Apparently there are some 5kW Victron inverters that can achieve this by passing grid power through to the backup loads in excess of 5kW (Just limited to 5kW output when the grid is offline). Do you know what type of Victron inverter this would be?

Edited by Vleisie
Corrected mistake
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Yes the Goodwe can only give 4.6kW or it might be 5kW can't remember the specs.  If you put some of the heavy loads on the grid side then the grid will feed those if the total goes over 4.6/5kW.

Don't know the Victron units. In general if the grid power is supplementing the inverter power then you are blending power same as what a grid tie inverter does.  This is the same as the Goodwe does with grid connected loads. You can feed them from solar and grid but they have no power when grid is down.

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8 hours ago, Vleisie said:

* With the Goodwe invertor, it cannot provide more than 4.6kW to the backup loads, even when the grid is available. Is this statement correct?

we discussed this a while ago. It looks like that newer Goodwe ES inverters can now pass through power from the grid to the back up output. Have a look here (topic is discussed at the end of the page): 
https://powerforum.co.za/topic/4272-victron-easysolar-5kva-or-goodwe-5048d-es/

 

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  • 2 weeks later...
  • 5 months later...
On 2020/02/20 at 1:08 PM, Richard Mackay said:

Not a good idea. Heating is a no-no due to the amount of power required.

A better idea is to schedule the geyser element to heat the water during the day when you have excess power available from your PV panels. This does require some fancy footwork with how you do this..

You could also use a device that send power, that will otherwise be exported, to the Geyser(s).

We have installed an Apollo GEM with two geysers connected and it has diverted over 1 MWh of energy to the Geysers in just over 6 months, keeping in mind this covered the winter period.

Another option is the Solic 200 which looks like a very robust unit, but only has one channel. It also does not have a timer function, but rather a manual "boost" function.

 

 

 

 

AppoloGem.jpg

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3 hours ago, WeNotGood said:

You could also use a device that send power, that will otherwise be exported, to the Geyser(s).

We have installed an Apollo GEM with two geysers connected and it has diverted over 1 MWh of energy to the Geysers in just over 6 months, keeping in mind this covered the winter period.

Another option is the Solic 200 which looks like a very robust unit, but only has one channel. It also does not have a timer function, but rather a manual "boost" function.

I presume this is a grid tie system?

Only in South Africa is a grid tie system not the ideal solution of drawing from/feeding power to the grid. No! We are told we can't feed power back into the grid because Eskom is the only electricity supplier the utilities are allowed to use. (Please correct me if I am mistaken)

So yes, we need an Apollo GEM or Solic 200 to divert our excess energy to a better load..

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I agree with Richard's summary above!

My system usually recharges the batteries by noon (red arrow).  After that I am wasting potential energy as indicated by the solar energy dropping (green graph) to support only the load requirement of my home (blue graph).  Therefore I use my Geyserwise timer to give the solar geyser a boost starting at 12:30 (black arrrow), and it turns off as soon as the geyser hits 65 deg C.

If you run the heater element too early, you're bypassing the whole idea of a solar heating.  Let the sun do its thing, and assist in the afternoon if necessary.  A 65 C geyser in the afternoon equates to >50 C the next morning, even if there's no sun later in the day (as a result of highveld thunderstorms in the afternoon, etc.).  And trust me, 50 C is plenty hot for a bath or a shower.

image.png.40e5f725bbb01f193c8a47cc76eac8d3.png

PS: In case you're wondering: the jagged little spikes in power consumption are fridge/freezer compressors, but mostly the 200W fish tank element that works a lot at night.  We'll probably get cold water fish once the last of the tropical fish die off 🙂

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The problem with old school timers is that a power cut throws them out of kilter.

In a country with load-shedding like SA, this makes them almost useless.

I believe Geyserwise overcomes this problem probably with an internal battery to maintain its clock and so it is a great improvement.

However, there is a recent innovation An astronomical timer is a new type of timer also with a battery reserve that you set your longitude and latitude and date.

From a database it then knows all sorts of astronomical info.

These can be had on aliexpress for relatively cheap.

AFAIK a Geyserwise has an absolute time setting, for example 05:30 AM turn geyser on. 

My understanding of an astronomical timer is that it can be set to a relative time, for example half an hour before dawn turn geyser on. As the dawn time changes throughout the year so the geyser will adjust.

I don't have such a timer, but I have been looking at them for several applications.

Geyser timers, turning on loads at relative to solar noon, switching lights to extend the day for chickens and such-like.

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19 minutes ago, phil.g00 said:

I don't have such a timer, but I have been looking at them for several applications.

I do have one of sorts but this had to be factory pre-programmed for the relative times. It then knows where it is because it has its own GPS.

Google: GPSlightlock.

I think the astronomical timers are much cheaper though, and they look to be freely programmable.

 

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I guess it all depends on your personal needs?

The Geyserwise provides many things that most timers don't.  It offers a temperature probe, multiple timers, separate settings for  for weekdays & weekends, separate water target temps for midnight -> 6 am, 6am -> noon, noon -> 6 pm and 6 pm to midnight, element boil dry protection, holiday mode, real-time water temp readout, etc. Simply put - it was designed to manage water heating systems!

But in my case it does not integrate easily into my home automation system.   I'd like a device that does all of the above, but also allows me to remotely/programmatically enable or disable it based on data inputs from my inverter/batteries, or current/future weather, or even existing load so that it will turn the pool pump & heaters off when I turn the oven on.  That way I will stop drawing electricity from the grid supply when I exceed my inverter's 5kW limit.  I'm probably going to add a Sonoff/Tasmota device in line to disable the Geyserwise's output to allow me to address the "overload disable" bit soon. 

PS: phil.g00, those astronomical timers sound most clever!  In my case I'll simply utilise the Nodered integration with Openweathermap to turn my smart switches on/off whenever I want.  Here's a snip from Nodered's GUI showing sunrise/sunset:

image.png.ef1d8f0e8c2983887d3fea8421ddc802.png

 

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8 hours ago, phil.g00 said:

The problem with old school timers is that a power cut throws them out of kilter.

In a country with load-shedding like SA, this makes them almost useless.

All digital timers these days have backup power (battery) to keep time during power outages. (The one I have keeps it running for months!)

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11 hours ago, ChristoSnake said:

I agree with Richard's summary above!

My system usually recharges the batteries by noon (red arrow).  After that I am wasting potential energy as indicated by the solar energy dropping (green graph) to support only the load requirement of my home (blue graph).  Therefore I use my Geyserwise timer to give the solar geyser a boost starting at 12:30 (black arrrow), and it turns off as soon as the geyser hits 65 deg C.

If you run the heater element too early, you're bypassing the whole idea of a solar heating.  Let the sun do its thing, and assist in the afternoon if necessary.  A 65 C geyser in the afternoon equates to >50 C the next morning, even if there's no sun later in the day (as a result of highveld thunderstorms in the afternoon, etc.).  And trust me, 50 C is plenty hot for a bath or a shower.

image.png.40e5f725bbb01f193c8a47cc76eac8d3.png

PS: In case you're wondering: the jagged little spikes in power consumption are fridge/freezer compressors, but mostly the 200W fish tank element that works a lot at night.  We'll probably get cold water fish once the last of the tropical fish die off 🙂

Is there a possibility that you can overload your PV supply?

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