24 or 48 Volts?


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ChrisD5710

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Sep 13, 2017
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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 Youthat 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, PIPs "household" consumption of 50+ Watts, did not matter at all. :)

However, even here in Denmark, we have seasons, and in the Autumn the Sun declinesrapidly, and in early November, Sun input starts to strugglekeepingup with the PIPs 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 present7P7S100P 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 wentfor24 Volts, I am nowrestricted to 3 KW output power in the Winter using only one 3 KWInverter, but "household" consumption is more than halved.

This gives me almost 70 KWh for consumption orcharging saved.

In the Summer with plenty of sunshine, I simply light up one more3 KW inverter.

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

ChrisD
 

Redpacket

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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?
 

daromer

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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 :)
 

ChrisD5710

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Sep 13, 2017
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161
@Daromer.

What do You consider aproper 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 notas lucky as You. I do nothaveroom for 16+ KW of solar panels.;)

ChrisD
 

ChrisD5710

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Sep 13, 2017
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Redpacket said:
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 :) 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 approvedgrid 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
 

Redpacket

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Maybe check the Phoenix models prices. Seriously doubt those are 8,000 Euros....
 

daromer

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Anything but mpp and all those clones. Yes i have mpp hybrid
The pip is gone. Mpp hybrid pulls 240w Idle load..................
 

ChrisD5710

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Sep 13, 2017
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daromer said:
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 usedthe 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 :)

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
 

daromer

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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.
 

ajw22

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Nov 16, 2018
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Depending on where you live, Solar can really suck during the winter: short days, shallow sun angle, bad weather, possible snow on the panels, higher consumption for heating, lower battery performance. My worst month (Jan) produces just 20% of my best month (May). The worst part is that the output fluctuates unpredictably, with sometimes weeks of continuous bad weather and a good sunny day here and there. Virtually impossible to go off grid, unless you have a massively oversized PV array & battery and a zero energy house to begin with.
 

OffGridInTheCity

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ajw22 said:
Depending on where you live, Solar can really suck during the winter: short days, shallow sun angle, bad weather, possible snow on the panels, higher consumption for heating, lower battery performance. My worst month (Jan) produces just 20% of my best month (May). The worst part is that the output fluctuates unpredictably, with sometimes weeks of continuous bad weather and a good sunny day here and there. Virtually impossible to go off grid, unless you have a massively oversized PV array & battery and a zero energy house to begin with.
Very well stated! So, Itry to keep focus on the good side - the reasonablepower ofspring/fall and amazing power ofsummer - especially city bound with no water or wind or other options:)
 
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