Sizing system from the Batterys point

CDN_VT

Hello all ,
I stumbled into a gent who's cabin is off grid.
From what I gather on the few discussions that we have had is He lucked into 6 used telephone backup 2 volt 150A /8hr battery's.
Im assuming that he changed them in from his older battery that is gone etc. After a crawl around , I see a 1000 watt MSW inverter , Morningstar Solar Charge Controller PF-30 & two old 64 watt,3.8 amp, 15.6 volt mono panels (all the spec's they had)Roof mounted .

Now His cabin is in the back woods that see's 5 hrs sun max in the winter (in the Valley of mountains BC wet coast) , Not used much in winter But can be a storm haven. We also get dumps of snow & if not around , so I'm leaning towards suggesting ,Canadian Solar panels because of the better weight to snow load.

What I did bring up is that he is low on panel to battery charging (Very low !!) and will slowly kill some very nice glass 2 volt cells.

NOW that I opened my yap , I have been asked more questions , he is a nice gent so , I don't mind giving him a view.
What I did say is since the system has & is running for 15 years so far , that if you don't want to kill those almost free to him batterys , is to up the panels & the Charge controller.

So with that , if he's happy with the 1000MSW inverter for now , then, so he does NOT slowly destroy his new 12 volt pack , Im suggesting he buys
new panels & CC , rather than adding to a somewhat hard to find matching components. I suggested MTTP controller & new panels to match the batterys.
Then like we post here for the winter months of overcast , dwell on enough to sustain a good charge ratio at that time.

The story went "a few years ago we were here over Xmax & dead" No generator , propane fridge & on demand water heater from creek fed water pressure.

Before I say anything more , or point to our hosts products that he should consider , AM I correct in thinking in what I have posted so far.

Im thinking for between us he should have 2000 watts of panels , 150 Midnight classic just for the care of the batterys ..

VT
Edit 2000 watts , Not 10000
Dinner fix the dozy :-) & the finger furbars

NorthGuy

Re: Sizing system from the Batterys point

CDN_VT wrote: »

Im thinking for between us he should have 2000 watts of panels , 150 Midnight classic just for the care of the batterys ..

2kW of batteries is 160A on 12V system. If his batteries are 150 x 8 = 1200AH (if I understood your correctly) then this is a good match.

The qustion is, if he lived many years with 128W array, does he really need all the energy that 2kW would provide? That's 15 times increase!

niel

Re: Sizing system from the Batterys point

in general i'd say yes. before he commits to a system you will need to know what it is he needs to power per day and the total watt hours the loads will be. goingf just by the battery ah it would be between the 5% and 13% range, but could be slightly upped depending on loads and battery requirements as some batteries do like higher charge rates.

CDN_VT

Re: Sizing system from the Batterys point

NorthGuy wrote: »

The qustion is, if he lived many years with 128W array, does he really need all the energy that 2kW would provide? That's 15 times increase!

Well he's not living there as in every day or weekends , just as breaks allow , But when he use's his Car as the main charging device for all the I-coms of today , then with those Batteries , just so he does not destroy them , he needs better panels , CC for the panels , & then he might get a better amount of power to conserve ..
I understand the battery's came for near free , and he is saying after a few years , they hover around 12.6 V.
I will be visiting up there on the next back country trip , and then I'll get first hand of what I saw months ago.

As with the Loads , Now there is something I'm totally out of touch with. Just what I have spoken with the Gent so far.. Im amazed that the 12v power socket in his car still works with all the units I saw on the passenger seat.

VT

vtmaps

Re: Sizing system from the Batterys point

CDN_VT wrote: »

He lucked into 6 used telephone backup 2 volt 150A /8hr battery's.

May not be as lucky as you think.... those batteries are designed to float and only have a few deep cycle discharges in their lifetime. They are not likely to last very long in a RE environment.

--vtMaps

CDN_VT

Re: Sizing system from the Batterys point

vtMAPs
He has been using these for a few years as I understand.. And I really don't want to tell him anymore bad news,, Just quickly looked at the system at the beginning of the year , I made mention that as I saw it , those two panels on the roof (and they were not directly south facing ) were undersized in my opinion.. The gent was quite happy of his setup over no noise.

I took a trip up to the back area this summer , but didn't stop in at the cabins (your not to go MT handed) . I did notice that many other cabin folks were on gen sets, idling by I could make out the Din.

Thanks for info gents that Im close in my thinking of 2kw for the size of the battery string.

I just wanted to make sure that I was a least close before I answered his question of "how big should I get ?"
I did bring up power consumption , but that was a unknown fact , plus he use's the 12V for radios seeing the wire's & pressure pump if i remember I heard now.

Thanks again. VT

Cariboocoot

Re: Sizing system from the Batterys point

Double-checking battery bank:

He has six 2 Volt cells rated at 150 Amp hours @ 8 hour rate? That will be approximately 165 Amp hours at the 20 hour rate, and a 12 Volt system.

So using the 10% rule of thumb you get 16.5 Amps peak charge current. On a PWM controller that would be (16.5 * 17.5) around 288 Watts.

The two 64 Watt panels are inadequate (7.6 Amps or 4% and a Vmp too low for a 12 Volt system) but I don't see how the calculations got up to 2kW array and a 60 Amp charge controller?

zoneblue

Re: Sizing system from the Batterys point

Those great big glass cased telecom cells have been running a mates place for the last decade and remember they were second hand to start with. Charging source wasnt that spectacular either 500W solar, 500W hydro. If you were in the right place at the right time youd get them for $600. Dont think telecom uses them any more though.

westbranch

Re: Sizing system from the Batterys point

Coot I agree with you, 2 140 w panels would get him ~ 15 amps @ 12 V which should be a minimum to recharge those 150Ahr batteries.

But without a tally of loads it is a far guess.. loads could suggest more PV. If the MN KID [mppt] or the BRAT(?)[psw] models were out they might be a good fit. The PS30 [pwm] would work with up to 4 panels as listed above

CDN_VT

Re: Sizing system from the Batterys point

Cariboocoot wrote: »

Double-checking battery bank:

He has six 2 Volt cells rated at 150 Amp hours @ 8 hour rate? That will be approximately 165 Amp hours at the 20 hour rate, and a 12 Volt system.

So using the 10% rule of thumb you get 16.5 Amps peak charge current. On a PWM controller that would be (16.5 * 17.5) around 288 Watts.

The two 64 Watt panels are inadequate (7.6 Amps or 4% and a Vmp too low for a 12 Volt system) but I don't see how the calculations got up to 2kW array and a 60 Amp charge controller?

I was using 5 hrs max charge in the Mountains of Vancouver island in winter time.
I figured if he spent money on a classic MPPT charger & some decent panels , he could forgo the true south & still keep them mounted high , plus have enough power to have the huge glass 2 Volt cells around for years. In the 1970's while stationed in The Queen Charlotte's we had these and BCH&PA.. they were work horses in the winter storms..

With thinking about how much overcast the Alberni upper valley gets and it's micro weather from the forest , we can see one month of grey dayz .. Enough to make people get on edge..
So with that in mind , I figured a good watt to keep them up. In full summer he's only seeing direct sun from 9 till 6pm .. My cabin is for survival if you go down on one of 3 flight paths , Add Its high up .. & about 50K from his lower valley setting. (mine is on a trap line from my neighbour) .

So that's why a posted 2kw of panel & a decent controller , So he may add later also.

What say you Mr Coot ?

VT

I did check his battery numbers and had him take a smart phone picture of sticker on the glass. 2 volt 150A /8hr are the numbers.
Edit add.

stephendv

Re: Sizing system from the Batterys point

CDN_VT wrote: »

I figured if he spent money on a classic MPPT charger & some decent panels

The cost of an MPPT charger only starts to pay for itself with 1kW or bigger arrays. Given that your friend is not at the cabin most of the year, I'd say he'd be better off with more solar and a larger PWM controller, because of the relative low price of solar vs the price of an MPPT charger.

Blackcherry04

Re: Sizing system from the Batterys point

I haven't seen a Glass Jar Battery in 50 years, I guess there must still be some out there. Who is producing them ??

Cariboocoot

Re: Sizing system from the Batterys point

CDN_VT wrote: »

I was using 5 hrs max charge in the Mountains of Vancouver island in winter time.
I figured if he spent money on a classic MPPT charger & some decent panels , he could forgo the true south & still keep them mounted high , plus have enough power to have the huge glass 2 Volt cells around for years. In the 1970's while stationed in The Queen Charlotte's we had these and BCH&PA.. they were work horses in the winter storms..

With thinking about how much overcast the Alberni upper valley gets and it's micro weather from the forest , we can see one month of grey dayz .. Enough to make people get on edge..
So with that in mind , I figured a good watt to keep them up. In full summer he's only seeing direct sun from 9 till 6pm .. My cabin is for survival if you go down on one of 3 flight paths , Add Its high up .. & about 50K from his lower valley setting. (mine is on a trap line from my neighbour) .

So that's why a posted 2kw of panel & a decent controller , So he may add later also.

What say you Mr Coot ?

VT

I did check his battery numbers and had him take a smart phone picture of sticker on the glass. 2 volt 150A /8hr are the numbers.
Edit add.

I say 2000 Watts of panel and a $600 charge controller is a waste of money in this case.
Batteries will only accept so much current, so the peak charge rate would have to be limited to avoid this when the sun shines bright. As for using an extremely large array to make up for a lack of sunshine, it's not economical at all; the current fall-off from low insolation is drastic.

Better to put in the right size array with proper orientations (which is not necessarily solar South) and a PWM controller. Then spend that extra money on a generator which will charge the batteries no matter how uncooperative the weather is.

BTW, even southern Van Isle doesn't have 5 hours of charging available in Winter.

Cariboocoot

Re: Sizing system from the Batterys point

stephendv wrote: »

The cost of an MPPT charger only starts to pay for itself with 1kW or bigger arrays. Given that your friend is not at the cabin most of the year, I'd say he'd be better off with more solar and a larger PWM controller, because of the relative low price of solar vs the price of an MPPT charger.

This is not accurate. Since the price per Watt on "GT" panels is far less than that of "standard" panels the MPPT controller will start to be a trade-off in investment around 400+ Watts. It is just possible that with this system a Rogue 3048 and 500-600 Watts of "GT" panel would be best, giving maximum charge rate for the small battery bank without investing a huge amount in solar that will not be utilized much of the time.

stephendv

Re: Sizing system from the Batterys point

Cariboocoot wrote: »

This is not accurate. Since the price per Watt on "GT" panels is far less than that of "standard" panels the MPPT controller will start to be a trade-off in investment around 400+ Watts. It is just possible that with this system a Rogue 3048 and 500-600 Watts of "GT" panel would be best, giving maximum charge rate for the small battery bank without investing a huge amount in solar that will not be utilized much of the time.

Depends on the prices of your panels and price of the MPPT controller. I just sourced some big off-grid 24V suntechs for about 5% more expensive than the cheapest grid tie panels. With that kind of price difference it would take a bigger array to make up the mppt controller price difference.

Cariboocoot

Re: Sizing system from the Batterys point

stephendv wrote: »

Depends on the prices of your panels and price of the MPPT controller. I just sourced some big off-grid 24V suntechs for about 5% more expensive than the cheapest grid tie panels. With that kind of price difference it would take a bigger array to make up the mppt controller price difference.

You don't live in Canada. And I'm sure you're ever-grateful for that.

stephendv

Re: Sizing system from the Batterys point

Cariboocoot wrote: »

You don't live in Canada. And I'm sure you're ever-grateful for that.

Bah, I don't buy the propaganda. I'm sure it's a tropical paradise with solar as cheap as chips, you just want to keep foreigners out

Cariboocoot

Re: Sizing system from the Batterys point

stephendv wrote: »

Bah, I don't buy the propaganda. I'm sure it's a tropical paradise with solar as cheap as chips, you just want to keep foreigners out

Paradise was -6C this morning.

westbranch

Re: Sizing system from the Batterys point

stephendv wrote: »

I'm sure it's a tropical paradise with solar as cheap as chips, you just want to keep foreigners out

Nah, all the Ex Pats go straight to Victoria, a place more British than Britain (almost) leaving paradise to us cool weather types alone, other than that wimp 60 miles south of here...:p:-) heck once the ice fog lifted its rather balmy today + 15C

CDN_VT

Re: Sizing system from the Batterys point

Blackcherry04 wrote: »

I haven't seen a Glass Jar Battery in 50 years, I guess there must still be some out there. Who is producing them ??

Gould Is the name I made out .