Medium solar system advice (16kW inverter, 3x5.12kWh batteries, 10x 605w panels)

[NR7]

Posted a while ago about a 5kW Deye system but realized we should go bigger for the long term since our municipality is falling apart.

Our daily use is 18kWh (R2073 pm, add R100 when Ekurhuleni increases it in a month) excluding the stove (roughly R210pm).

Currently looking at
- 16kW 12kW Deye Hybrid Single Phase inverter for everything (plugs, lights, geyser, aircon) except the stove.

- 3 x 5.12kWh Deye SE5 Plus batteries.
I see each of them is rated for 6KW continuous discharge so 18kW in total with 3 of them should be fine right?
Is there a limit to how many batteries, would I be able to add a 4th or 5th in the future as long as the cable lengths are the same?
A single 16kWh battery is cheaper but it peaks at 11.8kW which is a bit low.
Plus if one of the batteries die it's easier to deal with than if one big battery dies.

- 10 x JA 605w n-type TOPCon Bifacial on the north facing zinc roof for 6kWp. Probably 5 panels on each of the two MPPTs, which leaves room to upgrade with another 6 on the third MPPT on the west facing roof if needed in the future (6 of these panels per MPPT is the max when considering their VOC).

Thoughts?

 

[NR7]

Just checked the db board and I see we actually have a 63A main breaker.

I’ve read that with a 63A breaker COCT says no bigger than a 13.8kVa system. I'd assume Ekurhuleni would follow the same or they would in the near-future, so a 16kW inverter isn't worth it for me as there would be even more cost involved in changing to an 80A breaker with thicker wiring.

So that just leaves a Deye 12kW. Should be enough, can always change the geyser to a 2kW element to free some load.

 

[Hazy_Living@79]

Thats a big system. Do you intend on going off grid?

 

[phoneJunky]

Posted a while ago about a 5kW Deye system but realized we should go bigger for the long term since our municipality is falling apart.

Our daily use is 18kWh (R2073 pm, add R100 when Ekurhuleni increases it in a month) excluding the stove (roughly R210pm).

Currently looking at
- 16kW 12kW Deye Hybrid Single Phase inverter for everything (plugs, lights, geyser, aircon) except the stove.

- 3 x 5.12kWh Deye SE5 Plus batteries.
I see each of them is rated for 6KW continuous discharge so 18kW in total with 3 of them should be fine right?
Is there a limit to how many batteries, would I be able to add a 4th or 5th in the future as long as the cable lengths are the same?
A single 16kWh battery is cheaper but it peaks at 11.8kW which is a bit low.
Plus if one of the batteries die it's easier to deal with than if one big battery dies.

- 10 x JA 605w n-type TOPCon Bifacial on the north facing zinc roof for 6kWp. Probably 5 panels on each of the two MPPTs, which leaves room to upgrade with another 6 on the third MPPT on the west facing roof if needed in the future (6 of these panels per MPPT is the max when considering their VOC).

Thoughts?

That is quite a big system I will say. I have a 8kW Inverter and that runs everything I need. I do have a solar geyser though and gas stove.

I would max out the panels first, because that is the most expensive to install and it doesn't change much with extra panels. If you add it later you are going to have to pay a larger install charge again. Batteries you can install later without the CoC/Engineer signature from what I understand.

Of your 18kWh you use, how much of it is during the night? And are there things you can shift toward the day? Like dishwasher/washing machine/geyser on timer etc. If so, you can be lighter on the battery initially.

 

[Zuner]

I have 6.8kwp + 15kwh batteries
and 2x 5kw inverters, stove is gas.
I use about 23kwh per day.

Geyser runs only during the day, I agree with adding more panels now rather than later. I am 99% off grid. Below my eskom import since 08-2024

 

[Hazy_Living@79]

Yup. I'd take an 8kw inverter, and with the difference, add more panels.

I have a similarish system, 9.6kwp, 15kwh battery and 8kw inverter. @Lupus has a bit more kwp and about 20kwh battery if i remember.

Whats your goal here? Im in general inclined to keep Eskom (Eskom direct customer) which supplements my load in extreme circumstances when I have a full house and lots of things are running, then my inverter blends grid, solar and battery. I basically pay line fees, which comes to around R600 pm, which I can live with.

For now, majority of the time its just my wife and I, which means I only touch Eskom on the rare occasion. With my kwp, today for instance, my battery was 100% by 13h30, the dishwasher ran, my helper was here ironing and vacuuming, and my geyser heated to 70C.

My 15kwh runs the house till the following morning, with the geyser on for 45 mins after evening showers, and an hour in the early morning to heat back to max.

 

[NR7]

Thats a big system. Do you intend on going off grid?

That is quite a big system I will say. I have a 8kW Inverter and that runs everything I need. I do have a solar geyser though and gas stove.

Of your 18kWh you use, how much of it is during the night? And are there things you can shift toward the day? Like dishwasher/washing machine/geyser on timer etc. If so, you can be lighter on the battery initially.

Will stay connected to the grid. Lots of high draw stuff, I think I would trip an 8kW inverter during power outages when AC passthrough falls away.

Price difference between a 8kW inverter and 12kW inverter would only be about four extra panels.


Of that 18kWh used per day, 7.3kWh is 5pm to 7am which includes one bath, one shower, cooking with airfryer, TV and gaming.

 

[B-1]

The 10 or 12KW inverter is a nice size if you have more than 2 or 3 adults in the house. My 8kw tends to add some grid power when the folks stay over and there are multiple big things running in various rooms and the geyser kicks in.(my geysers also don't switch on at the same time otherwise I would exceed the inverter more often)

I have 4 x 5kw batteries and thats a nice compromise for me. I'm 90% ish off grid and use about 550-600Kwh a month.

 

[phoneJunky]

In this case I would have gone with larger inverter and 2 batteries and add the additional panels. I know the sun profile is better in Gauteng during winter, but in the WC I sometimes do get days in the winter where I don't charge my 10kW fully and my solar array is larger than what you want to put on.

Maybe also load shif your geyser to warm again during the day after your last draw from the geyser with a timer.

 

[NR7]

In this case I would have gone with larger inverter and 2 batteries and add the additional panels. I know the sun profile is better in Gauteng during winter, but in the WC I sometimes do get days in the winter where I don't charge my 10kW fully and my solar array is larger than what you want to put on.

Maybe also load shif your geyser to warm again during the day after your last draw from the geyser with a timer.

Yeah I think I need the extra 6 panels on the west facing roof for 9.68kWp in total more than a 3rd battery.

The geyser can definitely use a timer. The second bathroom will done shortly with a gas geyser for showers which means the electric geyser will just do one bath an evening.

A timer to switch off at sunset and back on at just after sunrise could be very useful for helping the batteries overnight.

 

[NR7]

Okay so made it a little bigger.

- 12kW Deye hybrid inverter single phase
- 16 x JA 605w n-type TOPCon Bifacial panels
- 4 x 5.12kWh Deye SE5+ batteries

The Deye 12kw spec sheet says it has two battery inputs so to connect 4 batteries I imagine it's 2 batteries parallel on each input.

I believe that due to BMS that means I have to keep each input equal? So I can't add a 5th battery as that would be 2 on the one input and 3 on the other.

 

[Soul Assassin]

Okay so made it a little bigger.

- 12kW Deye hybrid inverter single phase
- 16 x JA 605w n-type TOPCon Bifacial panels
- 4 x 5.12kWh Deye SE5+ batteries

The Deye 12kw spec sheet says it has two battery inputs so to connect 4 batteries I imagine it's 2 batteries parallel on each input.

I believe that due to BMS that means I have to keep each input equal? So I can't add a 5th battery as that would be 2 on the one input and 3 on the other.

Have you considered getting 2 x SE-F12 instead of 4 x SE-F5?

 

[NR7]

Have you considered getting 2 x SE-F12 instead of 4 x SE-F5?

Just the weight consideration. I wanted to collect the stuff from the supplier myself (so I know I'm not paying for something that won't arrive ) and it's easier getting a 40kg battery into a hatchback instead of an 80kg battery.

I am tempted to get two SE-F16 delivered for 32kWh, they're not much more than 4x5.12kwh. But knowing my luck they'll send a skinny driver who will leave the two 100kg batteries at the gate and make it my problem to move them into the garage.