Priapus

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You need to have enough storage for the evening. Bad PV days can be overcome by adding more panels. I am looking at adding another four to my current 16 for a total of 7.6 kWp.

I did not mean you need 24hrs of battery storage. My point was you need a generator, because if the PV is really bad during the day, those batteries won't be charged enough to carry you through the night.
 

RonSwanson

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I did not mean you need 24hrs of battery storage. My point was you need a generator, because if the PV is really bad during the day, those batteries won't be charged enough to carry you through the night.
Agreed that a genny is good to have.
My point was that with enough panels (and I guess the capability to use them), you should still be able to charge the batteries, even on a bad solar day. Or consecutive days.
 

Priapus

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Agreed that a genny is good to have.
My point was that with enough panels (and I guess the capability to use them), you should still be able to charge the batteries, even on a bad solar day. Or consecutive days.

Just to add to my argument from yesterday. I don't believe you can compensate with panels only. You need a generator or something else to charge the batteries.

Good example of this is I have 12 x 410w panels. Peak generation from them is 4300 or so. Today is completely overcast and peak is 700w. No where near enough to charge my batteries. So I am relying on the grid today.
 

RonSwanson

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Just to add to my argument from yesterday. I don't believe you can compensate with panels only. You need a generator or something else to charge the batteries.

Good example of this is I have 12 x 410w panels. Peak generation from them is 4300 or so. Today is completely overcast and peak is 700w. No where near enough to charge my batteries. So I am relying on the grid today.
I have 16x 380W, and as at 09H13 they're pumping away at 3189W. More later.

1628666296500.png
 

Priapus

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I have 16x 380W, and as at 09H13 they're pumping away at 3189W. More later.

View attachment 1124142

Right, but that is your very specific case on this very day. It can't be relied on by any means. More panels in a fully overcast day just won't do it. So I guess if you are okay with that risk then you're a braver person than I am.
 

ADrunkTeddyBear

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I have 16x 380W, and as at 09H13 they're pumping away at 3189W. More later.

View attachment 1124142
Nice. I envy your array. But I agree with @Priapus. You just cant rely on it everyday. My PV production yesterday was all over the place. From 2.4kw all way down to 700w in a matter of minutes and then back up to 1.4kw. Cant really charge up a battery when you are battling to meet a 1.5kw base load

EDIT: See attached image

1628667243735.png
 

Priapus

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Nice. I envy your array. But I agree with @Priapus. You just cant rely on it everyday. My PV production yesterday was all over the place. From 2.4kw all way down to 700w in a matter of minutes and then back up to 1.4kw. Cant really charge up a battery when you are battling to meet a 1.5kw base load

EDIT: See attached image

View attachment 1124150

Yup, yesterday it was all over the place.

Monday:
Screenshot 2021-08-11 at 09.37.03.png

Yesterday
Screenshot 2021-08-11 at 09.37.18.png



And today its worse than that. If I didn't have Eskom as a backup; I'd be in a bit of a predicament now.
 

RonSwanson

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Right, but that is your very specific case on this very day. It can't be relied on by any means. More panels in a fully overcast day just won't do it. So I guess if you are okay with that risk then you're a braver person than I am.
No risk, I have done the maths. I have headroom for another 2 panels, maybe even 4 at a push.
 

Skankhunt

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Okay got a 5.1kwh LI battery installed.

What's some good practices to get most out of it, eg lifespan and perhaps save a bit on grid?

The installer set it up to only use battery (drop to 50% at most) between 11pm and 5am.

Will take some photos of the current settings and post here.
 

Priapus

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Okay got a 5.1kwh LI battery installed.

What's some good practices to get most out of it, eg lifespan and perhaps save a bit on grid?

The installer set it up to only use battery (drop to 50% at most) between 11pm and 5am.

Will take some photos of the current settings and post here.

Treat those batteries as backups and not energy storage. If you use them every day they will be dead within 2yrs.
 

Priapus

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No risk, I have done the maths. I have headroom for another 2 panels, maybe even 4 at a push.

We will have to disagree to agree.

Once you get your extra panels - go without Eskom for a week and let me know how that goes.
 

RonSwanson

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Okay got a 5.1kwh LI battery installed.

What's some good practices to get most out of it, eg lifespan and perhaps save a bit on grid?

The installer set it up to only use battery (drop to 50% at most) between 11pm and 5am.

Will take some photos of the current settings and post here.
Cycle it ever day. Lithium batteries don't like being at 100% for extended periods. Those who have Pylontechs know that this is also a condition of the written warranty.
 

Tariqe

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On days when pv production is all over the place , do you guys use batteries to fill the gaps or the grid, meaning do you let the batteries charge and discharge for that particular day or do you use the grid. I do cycle my batteries down to 20% SOC every day
 

Priapus

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On days when pv production is all over the place , do you guys use batteries to fill the gaps or the grid, meaning do you let the batteries charge and discharge for that particular day or do you use the grid. I do cycle my batteries down to 20% SOC every day

Depends how bad it is and what loads I need to run for the day.

Today, for example the PV is really all over the place and I want the be o

Yesterday, I stayed on PV all day even though there were lots of clouds. The batteries are perfectly capable of taking that sort of strain / loads

I cycle mine down to 20% SOC each day too - from 23:00 onwards. But they don't always reach 20% - depending on evening loads. So yesterday they got to 30% SOC before the sun was out enough to take over.
 
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