Questions to those that have actually installed Solar

TheJman

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Jul 16, 2011
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Hi all,

I've been looking into this for a few years, there is obviously the knee jerk reaction now of a lot of people because of the loadshedding we were hit with, but I truthfully feel like this is the way forward, even if just to supplement some of your power usage.

So I'm hoping there are some on here that have taken the leap and installed solar at their home / business, and that I (and others), can learn from what you've done and what has or hasn't worked....

So first question up - if you've done a grid-tied system (ie you're still running some of your home or business on eskom but have solar and batteries running other parts), how much have you seen your power usage come down?
 

Sinbad

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Jun 5, 2006
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My panels (10x330w, facing northeast) generate between 12 and 18kwh per day on most days at this time of year. Yield will go down in winter and up in summer. Cloudy days are an exception - much lower generation.
That's 12-18kwh of electricity that I don't pull from the grid, most days.

Whole house runs off the inverter, with grid supplement when the power draw is over 4.5KW or the batteries are at their low water mark (adjusted dynamically daily)
 

REAList_1

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Joined
Oct 12, 2011
Messages
788
The trick is to use the electricity as it becomes available.
This is not so easy as really intelligent distribution boards that can allocate loads are still far into the future.
Solar is expensive and most working people are away from their homes while electricity is generated. The overseas model where the utility providers buy your excess electricity at a fair price will never be available here. You know who to thank for this!
Solar for me is about my personal comfort.
When we start paying R3 (or more - just a figure for now) per kwh it will start making financial sense.
 

Sinbad

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66,400
The trick is to use the electricity as it becomes available.
This is not so easy as really intelligent distribution boards that can allocate loads are still far into the future.
Solar is expensive and most working people are away from their homes while electricity is generated. The overseas model where the utility providers buy your excess electricity at a fair price will never be available here. You know who to thank for this!
Solar for me is about my personal comfort.
When we start paying R3 (or more - just a figure for now) per kwh it will start making financial sense.
That's where lithium batteries come in. Excess production over my consumption is stored, and then used when solar generation is less than demand.
Also, most of my usage is during the day (pool pump, washing machines etc)
 

Verde

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Aug 16, 2006
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997
Whole house runs off the inverter, with grid supplement when the power draw is over 4.5KW or the batteries are at their low water mark (adjusted dynamically daily)
What does this mean. Does the system use what is available from the panels first, and then from the batteries, supplementing only the shortage from the grid. Is this a seamless process.
Why do you mention the 4.5kw power draw? Can you save the batteries for load shedding or the evenings, and restrict your day time usage to pv and the grid (if required)?
 

REAList_1

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Joined
Oct 12, 2011
Messages
788
What does this mean. Does the system use what is available from the panels first, and then from the batteries, supplementing only the shortage from the grid. Is this a seamless process.
Why do you mention the 4.5kw power draw? Can you save the batteries for load shedding or the evenings, and restrict your day time usage to pv and the grid (if required)?
You can set it whichever way you want it.
Batteries are expensive and must be managed and monitored (means more money out of your pocket) and its lifetime depends entirely on its depth of discharge. And they don’t like it when you draw a lot of amps quickly over a short period.
Lithium batteries is the way to go if you can afford them.
I have 4 off 2.4kw lithium batteries and so far so good. Only time will tell if it was worth the money. Once we start paying exorbitant kwh rates it will be worth the purchase price - provided I get 6000 cycles out of it.
It is recommended that you change all your appliances to the energy efficient types i.e. gas for geysers and stoves, led lights and energy efficient white appliances before you look at solar requirements.
I have split my db to run the high kw seperately from the inverter side. The stove, one geyser and plugs are supplied from this side.
The inverter is used for security, tv, lights, pumps and low amp plugs.
 
Last edited:

Sinbad

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What does this mean. Does the system use what is available from the panels first, and then from the batteries, supplementing only the shortage from the grid. Is this a seamless process.
Why do you mention the 4.5kw power draw? Can you save the batteries for load shedding or the evenings, and restrict your day time usage to pv and the grid (if required)?
It's a system called Victron ESS - does a lot of stuff. In "Optimised" mode it works as follows:
Firstly, it enforces a minimum state of charge on the battery (unless there is grid failure). It manages this SoC minimum level based on whether the batteries achieved a full SoC during the day - if they did not, it bumps it up 5%, if they did it bumps it down 5%. Objective behind this is to ensure your batteries have optimum life by keeping them charged to 100% regularly.
4.5kw power draw as that is the capacity of the inverter itself. If the load is greater than 4.5, then the first 4.5kw is powered from solar/batteries and the remainder comes from the grid.
So, in the morning when the sun comes up, the first thing it does is start charging batteries off solar - it's already been running loads off the grid as the battery is at min SOC. Once the batteries go 5% above min SoC, it will then divert the solar energy to loads, supplementing the solar with battery if the demand is more than solar generation. If the battery drops to min SoC again because of this, it goes back to running load off grid again. If the demand is lower than solar generation, then the batteries continue to be charged. Then, when the sun goes down, demand is pulled from batteries until they get down to min SoC, and the new min SoC is calculated.

Then it has a mode to "keep batteries charged" - you do this when you expect grid failures, eg during load shedding.
In this mode, batteries are charged at max current according to the battery management system until they are at 100% - for mine it pulls 3kw from the grid just for charging, and all solar output ALSO goes to charging, so I can charge at about 6.5kw (120 amps at 54v). Then once the battery is full, solar power is diverted to running the load, with supplemental power coming from grid. It's less efficient than optimised, because if your batteries are at 100 and your solar yield is higher than demand, that excess energy is wasted. (The system can feed back to the grid, but it's not enabled in my case because Joburg).

It's all seamless. I don't even notice when the grid goes off - so I get notifications from the system, to ensure that high load stuff is turned off as I can only provide 4.5kw without grid assistance.
 

TheJman

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Joined
Jul 16, 2011
Messages
3,276
It's a system called Victron ESS - does a lot of stuff. In "Optimised" mode it works as follows:
Firstly, it enforces a minimum state of charge on the battery (unless there is grid failure). It manages this SoC minimum level based on whether the batteries achieved a full SoC during the day - if they did not, it bumps it up 5%, if they did it bumps it down 5%. Objective behind this is to ensure your batteries have optimum life by keeping them charged to 100% regularly.
4.5kw power draw as that is the capacity of the inverter itself. If the load is greater than 4.5, then the first 4.5kw is powered from solar/batteries and the remainder comes from the grid.
So, in the morning when the sun comes up, the first thing it does is start charging batteries off solar - it's already been running loads off the grid as the battery is at min SOC. Once the batteries go 5% above min SoC, it will then divert the solar energy to loads, supplementing the solar with battery if the demand is more than solar generation. If the battery drops to min SoC again because of this, it goes back to running load off grid again. If the demand is lower than solar generation, then the batteries continue to be charged. Then, when the sun goes down, demand is pulled from batteries until they get down to min SoC, and the new min SoC is calculated.

Then it has a mode to "keep batteries charged" - you do this when you expect grid failures, eg during load shedding.
In this mode, batteries are charged at max current according to the battery management system until they are at 100% - for mine it pulls 3kw from the grid just for charging, and all solar output ALSO goes to charging, so I can charge at about 6.5kw (120 amps at 54v). Then once the battery is full, solar power is diverted to running the load, with supplemental power coming from grid. It's less efficient than optimised, because if your batteries are at 100 and your solar yield is higher than demand, that excess energy is wasted. (The system can feed back to the grid, but it's not enabled in my case because Joburg).

It's all seamless. I don't even notice when the grid goes off - so I get notifications from the system, to ensure that high load stuff is turned off as I can only provide 4.5kw without grid assistance.
Now that is incredible!! I'm glad our tech is at this level, because that is exactly what I would want it to do!!

Tell me though, how long does it take to get batteries from min SOC to 100% on an average summer day compared to a winter day?
 

Sinbad

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Now that is incredible!! I'm glad our tech is at this level, because that is exactly what I would want it to do!!

Tell me though, how long does it take to get batteries from min SOC to 100% on an average summer day compared to a winter day?
I've had the system exactly 12 days ;)

The charging time is going to depend on your battery capacity, your minimum SoC level and the amount of charge current you put into it.

For example, if my min SoC is 20% and I can charge at 2KW, then I will fully charge in 4 hours (10kwh battery). However, I don't have enough solar capacity to charge at 2KW unless the house is empty and idle. So in a couple months when I have some spare cash I am going to add another 10 panels + mppt, to double my solar generation (ie, 30-36kwh/day, which is actually what my household uses on average).
 

Neuk_

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Jan 23, 2018
Messages
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It's a system called Victron ESS - does a lot of stuff. In "Optimised" mode it works as follows:
Firstly, it enforces a minimum state of charge on the battery (unless there is grid failure). It manages this SoC minimum level based on whether the batteries achieved a full SoC during the day - if they did not, it bumps it up 5%, if they did it bumps it down 5%. Objective behind this is to ensure your batteries have optimum life by keeping them charged to 100% regularly.
4.5kw power draw as that is the capacity of the inverter itself. If the load is greater than 4.5, then the first 4.5kw is powered from solar/batteries and the remainder comes from the grid.
So, in the morning when the sun comes up, the first thing it does is start charging batteries off solar - it's already been running loads off the grid as the battery is at min SOC. Once the batteries go 5% above min SoC, it will then divert the solar energy to loads, supplementing the solar with battery if the demand is more than solar generation. If the battery drops to min SoC again because of this, it goes back to running load off grid again. If the demand is lower than solar generation, then the batteries continue to be charged. Then, when the sun goes down, demand is pulled from batteries until they get down to min SoC, and the new min SoC is calculated.

Then it has a mode to "keep batteries charged" - you do this when you expect grid failures, eg during load shedding.
In this mode, batteries are charged at max current according to the battery management system until they are at 100% - for mine it pulls 3kw from the grid just for charging, and all solar output ALSO goes to charging, so I can charge at about 6.5kw (120 amps at 54v). Then once the battery is full, solar power is diverted to running the load, with supplemental power coming from grid. It's less efficient than optimised, because if your batteries are at 100 and your solar yield is higher than demand, that excess energy is wasted. (The system can feed back to the grid, but it's not enabled in my case because Joburg).

It's all seamless. I don't even notice when the grid goes off - so I get notifications from the system, to ensure that high load stuff is turned off as I can only provide 4.5kw without grid assistance.
We must chat, we are looking at a Victron system at the moment with what sounds like similar requirements to yourself, from an electricity use and functional point of view.
 

MEIOT

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Joined
Feb 27, 2018
Messages
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I've had the system exactly 12 days ;)

The charging time is going to depend on your battery capacity, your minimum SoC level and the amount of charge current you put into it.

For example, if my min SoC is 20% and I can charge at 2KW, then I will fully charge in 4 hours (10kwh battery). However, I don't have enough solar capacity to charge at 2KW unless the house is empty and idle. So in a couple months when I have some spare cash I am going to add another 10 panels + mppt, to double my solar generation (ie, 30-36kwh/day, which is actually what my household uses on average).
Can you perhaps share, if not already done in another thread, costings, specs etc ?
 

Sinbad

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Jun 5, 2006
Messages
66,400
Can you perhaps share, if not already done in another thread, costings, specs etc ?
Victron Multiplus 5000/48/60-100 inverter
Smartsolar 250/60 MPPT
BYD B-Box 10.24kwh battery cabinet unit
Victron CCGX control unit
10x JA Solar 330W panels

Cost was around R190k. There are quite a lot of sundry costs over and above the components above- mounting rails for panels, huge cables and fuses (my battery fuses are 180A, 50mm2 cables), CoC, AC cabling, installation, surge protectors, etc.
Battery was by far the most expensive single piece of kit.
 

Sinbad

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Jun 5, 2006
Messages
66,400
We must chat, we are looking at a Victron system at the moment with what sounds like similar requirements to yourself, from an electricity use and functional point of view.
You're welcome to pop round if you want to have a look and chat...
 

TheJman

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Jul 16, 2011
Messages
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I've had the system exactly 12 days ;)

The charging time is going to depend on your battery capacity, your minimum SoC level and the amount of charge current you put into it.

For example, if my min SoC is 20% and I can charge at 2KW, then I will fully charge in 4 hours (10kwh battery). However, I don't have enough solar capacity to charge at 2KW unless the house is empty and idle. So in a couple months when I have some spare cash I am going to add another 10 panels + mppt, to double my solar generation (ie, 30-36kwh/day, which is actually what my household uses on average).
That's the other thing I love about the systems, it seems that as long as you have the right size inverter, you can do do a modular installation, adding as you can, especially with the panels.
 

Sinbad

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Messages
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1553689668946.png

Real time state of the system at the moment. Pulling 165w from grid (you can set your grid target checkpoint for optimised mode - some prepaid meters really don't like backfeeding, and there is some lag in system response to changing load so you give yourself a margin of error here). 701W of the load coming from batteries, 443W coming from the panels.
 

Verde

Senior Member
Joined
Aug 16, 2006
Messages
997
It's a system called Victron ESS - does a lot of stuff. In "Optimised" mode it works as follows:
Firstly, it enforces a minimum state of charge on the battery (unless there is grid failure). It manages this SoC minimum level based on whether the batteries achieved a full SoC during the day - if they did not, it bumps it up 5%, if they did it bumps it down 5%. Objective behind this is to ensure your batteries have optimum life by keeping them charged to 100% regularly.
4.5kw power draw as that is the capacity of the inverter itself. If the load is greater than 4.5, then the first 4.5kw is powered from solar/batteries and the remainder comes from the grid.
So, in the morning when the sun comes up, the first thing it does is start charging batteries off solar - it's already been running loads off the grid as the battery is at min SOC. Once the batteries go 5% above min SoC, it will then divert the solar energy to loads, supplementing the solar with battery if the demand is more than solar generation. If the battery drops to min SoC again because of this, it goes back to running load off grid again. If the demand is lower than solar generation, then the batteries continue to be charged. Then, when the sun goes down, demand is pulled from batteries until they get down to min SoC, and the new min SoC is calculated.

Then it has a mode to "keep batteries charged" - you do this when you expect grid failures, eg during load shedding.
In this mode, batteries are charged at max current according to the battery management system until they are at 100% - for mine it pulls 3kw from the grid just for charging, and all solar output ALSO goes to charging, so I can charge at about 6.5kw (120 amps at 54v). Then once the battery is full, solar power is diverted to running the load, with supplemental power coming from grid. It's less efficient than optimised, because if your batteries are at 100 and your solar yield is higher than demand, that excess energy is wasted. (The system can feed back to the grid, but it's not enabled in my case because Joburg).

It's all seamless. I don't even notice when the grid goes off - so I get notifications from the system, to ensure that high load stuff is turned off as I can only provide 4.5kw without grid assistance.
Thanks, incredibly helpful info an enviable setup.
 

TheJman

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Jul 16, 2011
Messages
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View attachment 638270

Real time state of the system at the moment. Pulling 165w from grid (you can set your grid target checkpoint for optimised mode - some prepaid meters really don't like backfeeding, and there is some lag in system response to changing load so you give yourself a margin of error here). 701W of the load coming from batteries, 443W coming from the panels.
That is simply incredible, I don't know why, but I love it! I wanna see my entire north facing roof covered in panels one day
 
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