Upgrade time, 1 house @ 24v to 2 houses @ 48v

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JMowat
Forum Member
Posts: 5
Joined: Tue Aug 01, 2017 3:07 am
My RE system: Flexmax60 w/2.47kw panels
Flexmax80 w/2.25kw panels
VFX3024E
Hub
Mate1
Mate3
1500AH 24vDC battery bank

Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by JMowat » Mon Sep 09, 2019 2:36 am

Hi All

Looking at doing some changes to my system on my off grid property,
Currently has
FM60 with 9x 275kw panels (2 years old)
FM80 with 9x 250kw panels (7 years old)
FXR3024E
Mate (on shelf) And Mate 3
Hub 10
1500AmpH AGM (24v) battery set (7 years old) seem to be in a good state of health 24.6v a 6am after i microwave my breakfast

Now i am needing to power another house on the property and its time to upgrade to 48v batteries system, would have done it 2 years ago if i'd known there was another house coming.

so trying to work out the best way about going about

Thinking of starting 2nd standalone for the 2 house
2x FXR3048E (to cope when gran turns on the kettle whilst the aircons running in the middle of summer)
1x FM80 with 9x 300w panels (or 12x 275w)
1x FM80 with 9x 300w panels allowing to headroom upgrade to a few more panels if required
hub4
mate
Lithium battery set of approx 10KwH


once im seeing greater loses in my battery bank combine the 2 systems into 1 system for both houses
ADD
1x FXR3048E
10-15kwh of battery storage
Change the FM60 & FM80 in my current system to 48v
Sell off the FXR3024e
Scrap the AGMs


Can anyone give me any guidance around the upgrade,
If i thought i could sell the FXR3024e, FM60, 9x250w panels & the AGM battery bank, I would think about the final solution straight up


thanks for your time
James Mowat

sparksalot
Forum Guru
Posts: 238
Joined: Sun Jul 17, 2016 5:31 am
My RE system: FLEXpower TWO VFXR3648A Grid-Tied and Battery Backup Hybrid

Traction battery FLA 48 volt 805Ahr.

30 SolarWorld 245w mono

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by sparksalot » Mon Sep 09, 2019 8:33 am

Cannot add new and old batteries together ever.

raysun
Forum Czar
Posts: 755
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by raysun » Mon Sep 09, 2019 9:29 am

Are the houses near enough physically to allow both to share a single system? Not much of an issue for distributing AC. Combining PV harvest from the two rooftops (if that's where panels are to be located) may be a limiting factor though higher-voltage strings will reduce losses.

A 7 year-old AGM battery bank is likely close to the end of its service life. Perhaps instead of adding a battery for the "Mother-in-Law" house and later a second for the main house, plan on replacing the AGM with a battery that can supply the loads of both.

Is the AGM battery capable of being reconfigured for 48V operation? Could it be used to supply both house loads until replaced? With the 1100AH rating, what is the typical daily Depth of Discharge?

Upgrading to 48V systems takes advantage of greater battery efficiency, and of greater PV power handling capability by the FM controllers. They can handle twice the panel wattage at 48V than at 24V.

JMowat
Forum Member
Posts: 5
Joined: Tue Aug 01, 2017 3:07 am
My RE system: Flexmax60 w/2.47kw panels
Flexmax80 w/2.25kw panels
VFX3024E
Hub
Mate1
Mate3
1500AH 24vDC battery bank

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by JMowat » Mon Sep 09, 2019 2:40 pm

Cheers Raysun

Both houses are in less than ideal locations for pv on roof. 2 years ago i moved and expanded the pv array onto a large shadeless shed. So would be adding the extra gear there as well. Running a 240v feed to the second house

Atm moment i dont think i have the coin to upgrade my half of a combined battery system. Grans got coin from her downsize move. I am guessing we would need about 25Kwh of combined storage

I think the we are getting close to 80% discharge over night. So idling a whole another house worth stuff might be pushing. Certaining wont cope come summer with aircons running

Battery config is 12x 2v @ 1500ah. So cant set them up as 48v

What sort of pv wattage would you recommend running to a FM80.
Assuming 24v panel x 3s @ total open volts 120v

I may be able to get to get away with less fm80s than i thought. Saving $1k a pop

raysun
Forum Czar
Posts: 755
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by raysun » Mon Sep 09, 2019 4:00 pm

The FM80 is limited to 80A charge current. So at 24V the maximum panel power is 80×24=1920 Watts. At 48V 80x28=3840W.

JMowat
Forum Member
Posts: 5
Joined: Tue Aug 01, 2017 3:07 am
My RE system: Flexmax60 w/2.47kw panels
Flexmax80 w/2.25kw panels
VFX3024E
Hub
Mate1
Mate3
1500AH 24vDC battery bank

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by JMowat » Mon Sep 09, 2019 4:14 pm

Cheers for that Raysun.
I try and work out the panel in just under 4000w blocks per Fm80 at 48v

gtarolli
Forum Guru
Posts: 225
Joined: Thu Dec 21, 2017 11:39 am
My RE system: Outback: off-grid
- 1 GS8048A, Mate3, FlexNetDC, Hub10.3
- 2 FLEXmax 80
- 24 (8x3) 300w panels (7200w total)
- 6 SimpliPhi 3.4 kWh LI batteries (400ah , 20kWh)
- 1 Honda 3000 generator + one spare
Location: Wainiha, Kauai, HI

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by gtarolli » Wed Sep 11, 2019 9:08 am

Li batteries are usually at 50v or more, so you can peak at 4000 watts on the fm80. I have 12 x 300w panels and my normal peaks are 80 amps and 4200w. Once I hit 82 amps 4400+ watts. Very short peaks I hope, no damage so far. So I agree with Raysun, close to 4000w and feel my 3600w is perfect.

raysun
Forum Czar
Posts: 755
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by raysun » Wed Sep 11, 2019 11:23 am

It's my feeling that OB equipment is designed and specified conservatively, a good thing. How conservative are the specs? Somebody else find out experimentally and share with the group. ;)

Maximum rating = magic smoke release point - 1.
Last edited by raysun on Wed Sep 11, 2019 11:35 am, edited 1 time in total.

gtarolli
Forum Guru
Posts: 225
Joined: Thu Dec 21, 2017 11:39 am
My RE system: Outback: off-grid
- 1 GS8048A, Mate3, FlexNetDC, Hub10.3
- 2 FLEXmax 80
- 24 (8x3) 300w panels (7200w total)
- 6 SimpliPhi 3.4 kWh LI batteries (400ah , 20kWh)
- 1 Honda 3000 generator + one spare
Location: Wainiha, Kauai, HI

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by gtarolli » Wed Sep 11, 2019 11:31 am

Yes, I'm hoping their 80a rating is conservative by at least 5=10% , esp. for short peaks. Since peaks come during the day, my batteries are usually over 53v during peaks giving me a little more headroom in terms of watts.

raysun
Forum Czar
Posts: 755
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by raysun » Wed Sep 11, 2019 11:34 am

I never get to see max output. When PV production is maximum, by battery is already in Absorb.

I have to go tell my wife to wash her hair and fire up her hair dryer and also the microwave to get near max output.

She always gives me that look.

gtarolli
Forum Guru
Posts: 225
Joined: Thu Dec 21, 2017 11:39 am
My RE system: Outback: off-grid
- 1 GS8048A, Mate3, FlexNetDC, Hub10.3
- 2 FLEXmax 80
- 24 (8x3) 300w panels (7200w total)
- 6 SimpliPhi 3.4 kWh LI batteries (400ah , 20kWh)
- 1 Honda 3000 generator + one spare
Location: Wainiha, Kauai, HI

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by gtarolli » Wed Sep 11, 2019 11:47 am

I think one of the FM80 screens shows you the peak PV output for the day. I hover my mouse over the FM icon in OpticsRE and it shows me the peak for the day, in amps and watts. Then I don't have to go over to the guest house that has all the hardware in it ....

Just run an AC or dehumidifier for a while in the morning to drain your batteries :-) then you'll see a peak in the PM. Many of my peaks occur when it is partly cloudy, when you get both direct and indirect sun. With direct sun alone I don't think I exceed the PV rated peak by much. So on the partly cloudy days , like today, I won't hit absorb sometimes until 1-2pm, and if there's still some puffy clouds around I can exceed the PV rating at times.

JMowat
Forum Member
Posts: 5
Joined: Tue Aug 01, 2017 3:07 am
My RE system: Flexmax60 w/2.47kw panels
Flexmax80 w/2.25kw panels
VFX3024E
Hub
Mate1
Mate3
1500AH 24vDC battery bank

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by JMowat » Wed Sep 11, 2019 2:10 pm

Thanks gents for the extra points.
Ill keep the FM80 under 4000w which will support 12 panels each.

Whats peoples thoughts on the inverter/charger fxr3048
Most of the time my fxr3024e has done everything we have needed. Including running multiple aircons (staggered started).
Struggled a little when my aircompressor was new on low light days. Now its run in seems to.cope pretty well.

Gran will have only 1 aircon as a large appliance. But with tank water pump and plenty cups of tea with electric kettle

Anyone using the 3048e as a single or stacked ?

raysun
Forum Czar
Posts: 755
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Upgrade time, 1 house @ 24v to 2 houses @ 48v

Post by raysun » Wed Sep 11, 2019 3:30 pm

I use an older FX3048T and it is a trooper.

I can overload its 3kW continuous output, but I have to turn on a couple power-hungry appliances to do that.

Normal house loads are handled with ease.

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