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24 or 48 Volts?
#1
Reading through the forums, most of the experienced users recommend 48 Volts.

I know, each KW is only 20 Amps, so 80 Amps will get you 4 KW, nice and tidy using a PIP4048.

However, I am now going to tell You that I have changed to 24 Volts.  Huh

Why?

My first setup was 48 Volts, a PIP4048 and approx 15 KWh of usable lead-acid battery capacity.

In the Summer when Sun was plentiful, PIP´s "household" consumption of 50+ Watts, did not matter at all.  Smile

However, even here in Denmark, we have seasons, and in the Autumn the Sun declines rapidly, and in early November, Sun input starts to struggle keeping up with the PIP´s self consumption leaving almost nothing for everything else.

So, in November, December, January and half of February, I have to charge from the Grid to avoid my Batteries being totally depleted.

This also goes for my present 7P7S100P LiIon storage.

Here is what I calculated:  PIP consumption during "winter": 105 Days times 50+ Watt times 24 Hours = at least 126 KWh with no load at all.

So, I went for 24 Volts, I am now restricted to 3 KW output power in the Winter using only one 3 KW Inverter, but "household" consumption is more than halved.

This gives me almost 70 KWh for consumption or charging saved.

In the Summer with plenty of sunshine, I simply light up one more 3 KW inverter.

I see only one penalty: I need more cables to carry the extra Amperage. 

ChrisD
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#2
Maybe you could consider in winter (November, December, January and half of February) switching back to grid power totally, just use a maintenance charger on the battery packs? No inverter losses at all?

But if the cost difference is big enough with grid power then using the battery systems and charging at low cost times might be better? Does that apply for you?
Running off solar, DIY & electronics fan :-)
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#3
A smaller inverter do consume less. Its rather normal.

Most People offset it with more solar panels like i did. Or even better a proper inverter Smile
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#4
@Daromer.

What do You consider a proper inverter ?

As far as I can see, You Yourself is using at least one PIP4048 ...

Snip "Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x |"

Btw. I considered two PIP 3 KW inverters in parallel. (one in Winter and 2 in Summer, but Peggy told me that each inverter was pulling 100+ Watts, and when I asked for idle current draw, my order was simply cancelled. So, No more PIPs.


I am not as lucky as You. I do not have room for 16+ KW of solar panels. Wink

ChrisD
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#5
Hi Chris, have a read of this similar thread:
https://secondlifestorage.com/showthread.php?tid=8484
Victron is the winner over a few years....
Running off solar, DIY & electronics fan :-)
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#6
(02-08-2020, 08:31 AM)Redpacket Wrote: Hi Chris, have a read of this similar thread:
https://secondlifestorage.com/showthread.php?tid=8484
Victron is the winner over a few years....

Nice Smile   Thanks for the link.

8000+ Euros for a Victron inverter. 8000 Euros will pay my complete Utility bill for 7 Years..

This was the inverter, only.  We then need countless hours to collect, disassemble and test cells. We have to build power banks using cell-holders, we need bus bars, fuses and connecting cables.

One thing is for sure, My Utility company will NEVER accept that my home built battery is connected to the utility grid.

This is why I run my system completely isolated. Separate wiring all the way to consumption.

Sure when I run out of solar power I will have to manually move the plugs from my extension cord back to the wall outlet.

Buying a small utility approved grid tied battery (less than 10KWh) will cost me at least another 8000€, so it stops here.

I do not have this kind of Money.

ChrisD
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#7
Maybe check the Phoenix models prices. Seriously doubt those are 8,000 Euros....
Running off solar, DIY & electronics fan :-)
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#8
Anything but mpp and all those clones. Yes i have mpp hybrid
The pip is gone. Mpp hybrid pulls 240w Idle load..................
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#9
Smile 
(02-08-2020, 06:54 PM)daromer Wrote: Anything but mpp and all those clones. Yes i have mpp hybrid
The pip is gone. Mpp hybrid pulls 240w Idle load..................

Sorry, I thought You still used the PIP, because You still list it.

How much power can You get from the Sun in Nov, Dec and January?

I have 4 KW panels, so by interpolating Your results and mine, I may be able to figure out just how many more panels I need.

Next problem is, where do I find place for these extra panels Smile

On a nice Summer Day, I figure You get more than 100 KWh. After 3 Days all Your batteries are full, or so I guess. Any way of spending this amount of power, or do You just stop charging?

ChrisD
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#10
I get around 5% comparing to Summer.

Yes Summer is around 90-100kwh per Day. Around 10 in waste and then15 is used. Rest goes to battery and excess is sold back to grid or used to heat water with.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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