3KW or 5KW setup - please advise

lexity said:
Well, on my radar is specifically the 5kw off-grid version. Cheaper since we don't need to feed back into the grid.

I'm also wondering whether - being on the edge of an 8Kw inverter instead of a 5kw - opting for 2x 5kw luxpower OG inverters. This would be cheaper than an 8kw hybrid e.g. Axpert and it may - correct me if I'm wrong - get us 10kw instead of 8kw.

I know the DC/AC inverters operate from battery voltage spec e.g. 48v. So...

1) is this feasible, given a 2x hubble am2/equivalent battery bank, and

2) what would that do to the mppt side of things? Going from 2 mppts to 4.
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The off grid sacrifices something else , the blending of solar/eskom

Which isn't a big deal but install dependant

ie i have an off-grid kodak
With a small array ,it covers my load on sunny day ,on rainy days not, then the battery has to assist

So then you may end up with less battery reserve if you aren't home to switch over , like in the event that the switch to grid was configured for most savings

So what most do is to set the switch to eskom sooner leaving more battery reserve , but in the process sacrificing solar savings on sunny days

Having remote management capabilities does help here being able to switch modes if the weather turns out different than anticipated , with a big array where output easily matches load ,not a problem

1 with both batteries in parralel and both inverters pulling/charging to and from is not a problem

2 having more mppt channels makes managing panels facing different directions easier , and naturally having enough expansion space for panels later
 
Rouxenator said:
I think you could be right actually - two more panels will... maybe a DC element added to the old geyser....
The first solar geyser burst around the start of May after 10 years of service. The old 150L Franke is still up there but disconnected. If I knew then what my PV plans would be a month later, I would have gotten the Franke wired up again and ditched the solar geyser.

So, I get your point. Sadly, I already invested a lot in that solar geyser this year so I'll see what I can reap from it.


1) The max from the panels should be 2.18kW, maybe I will reach that in summer when the sun is at a more optimal angle. Being MPPT I am pretty sure the inverter will draw as much load as it needs. Voltage is the big concern with MPPT and panels in series and I am very much on the lower to mid range of what this Luxpower can handle with my 4 panels :
View attachment 1568092

2) For a single panel, or those connected in series, shade does negatively affect it. Yet here is an interesting thing I observed so far. When it is a dry night and there is no dew on the panels, the 4th one that has shade on it till 11am keeps the power down until it has full sunligh, as is the case with the graph below:

Just before 11am and it's still only doing 1amp from the panel array.
View attachment 1568094

Today however there is dew on the panel, and I get a much smoother increase in power from as early on as 9am, which leads me to believe the dew is helping some what?
Hitting 1kW much earlier than on a day with no dew.
View attachment 1568096

View attachment 1568098

Thanks, to be honest it was your last post about going 5kW instead of 3kW even if it means squeezing in that 4th panel into creative spots. Which is when I looked into that nook below the chimney. Very glad I did.
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Yup, the dew helps - the colder your panels the more efficient they are.
 
Rouxenator said:
Time of posting - 1pm

Was cloudy up to then but clear sky since.
View attachment 1574452
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Thank you for this.

I have the same inverter and my roof space is also a bit limited like yours. So this will really help me make some calculations. I'm always looking at different installations and what they produce ect. When the finances settle and I can afford the solar part I will have a much better idea what I want(can) do.
 
redbullall1 said:
Thank you for this.

I have the same inverter and my roof space is also a bit limited like yours. So this will really help me make some calculations. I'm always looking at different installations and what they produce ect. When the finances settle and I can afford the solar part I will have a much better idea what I want(can) do.
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You are most welcome, as you may have seen my roof if a hodge-podge of solar panels, but if you can find the space for at least 4 of the big (500+ watt) panels then this inverter will work beautifully.
 
redbullall1 said:
Thank you for this.

I have the same inverter and my roof space is also a bit limited like yours. So this will really help me make some calculations. I'm always looking at different installations and what they produce ect. When the finances settle and I can afford the solar part I will have a much better idea what I want(can) do.
Click to expand...
Rouxenator said:
You are most welcome, as you may have seen my roof if a hodge-podge of solar panels, but if you can find the space for at least 4 of the big (500+ watt) panels then this inverter will work beautifully.
Click to expand...


Maybe look at Bifacial panels (650/675w) they are lot more expensive but really help when space is limited and if you can mount them at an aggressive angle they perform better especially in cloudy weather
 
isie said:
Maybe look at Bifacial panels (650/675w) they are lot more expensive but really help when space is limited and if you can mount them at an aggressive angle they perform better especially in cloudy weather
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Yeah I saw those are now available. Makes me wonder how much power they will be able to get from a 2.2x1.1 panel in a year or two from now.
 
Mzezman said:
You may have the opposite worry though
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There are a multitude of reasons I am doing it, firstly because I am crazy like that.
Secondly is I need to get a setup like this over at the beach house considering it is where my folks spend most of their time these days now that they are retired and in their 70s.
Third, the bigger battery will also last longer since we will not discharge it as much.
Lastly, even with my limited panel array, and the neighbours roof casting a shadow on the one panel until late morning, on some days I still find that with my current battery starting at 25% it is fully charged around 2PM meaning the whole afternoon's sunshine is going to waste.
So yeah - I used that as reasons to justify this shy of R60k expense.

Next up will be the challenge of getting the 5KWh battery to the holiday house. But considering my wife and I managed to get a 200Ah lead acid battery out of the car at the start of the year, I think we will manage.

Quick question - storing my 5KWh battery, is it best to have it fully charged or around 50% SoC? I think it will be for a month or so.
 
Rouxenator said:
There are a multitude of reasons I am doing it, firstly because I am crazy like that.
Secondly is I need to get a setup like this over at the beach house considering it is where my folks spend most of their time these days now that they are retired and in their 70s.
Third, the bigger battery will also last longer since we will not discharge it as much.
Lastly, even with my limited panel array, and the neighbours roof casting a shadow on the one panel until late morning, on some days I still find that with my current battery starting at 25% it is fully charged around 2PM meaning the whole afternoon's sunshine is going to waste.
So yeah - I used that as reasons to justify this shy of R60k expense.

Next up will be the challenge of getting the 5KWh battery to the holiday house. But considering my wife and I managed to get a 200Ah lead acid battery out of the car at the start of the year, I think we will manage.

Quick question - storing my 5KWh battery, is it best to have it fully charged or around 50% SoC? I think it will be for a month or so.
Click to expand...
The biggest issue is you may not have enough panels to fully charge the bigger battery. Remember production starts dropping off after lunch and is only at peak around midday...
 
Mike Hoxbig said:
The biggest issue is you may not have enough panels to fully charge the bigger battery. Remember production starts dropping off after lunch and is only at peak around midday...
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This ^

Getting a 3rd 5kWh battery was the best move I've made but I feel like my I probably couldn't go much bigger without upgrading with more panels too as.
 
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