What options do I have - upgrade

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Re: What options do I have - upgrade

Postby Gordon-Loomberah » Fri Sep 08, 2017 4:54 pm

For a single string of 225AH batteries that's nearly as high as you'd want to go with them, but if you have 2 strings in parallel, you could safely double the charging current.

Adding more panels facing north will increase charging current, but if you split an array as a virtual tracker, you keep the maximum current down, and improve early morning and late afternoon charging, as seen in the graphs in the VT thread.
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Re: What options do I have - upgrade

Postby jaahn » Sat Sep 09, 2017 10:04 am

Hi newt :)
You seemed to be getting answers ;) Really the current batteries were selected to match the solar array. If you do a big upgrade then you should expect to have to look at all the part of the system to ensure they operate well. From my limited experience it is easy to under estimate that for a solar system and be a little dissapointed with performance and have to resolve some issues.

As you are going to do a big expensive battery upgrade, perhaps now is the time to look at Lithium. Possibly a bit more expensive but longer lasting. There is plenty of support on this forum for that. Many have done so and documented it, including Gordon. Read a bit on the other forum corner, Components,Instalation and Performance; solar-wind-gear/
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Re: What options do I have - upgrade

Postby Newt » Sat Sep 09, 2017 1:36 pm

Thanks Jaahn

The original batteries were the 2V x 24 expensive jobs - the great tall ones, they had been in 6 years when I purchased the property and were dead, I could hardly keep a 100W light on for an hour after full charge. I replaced them with 8 x 6V Trojan T105's and they lasted about 3 years....then I purchased 12 used ones that I have put together in a series/parallel arrangement....these are still in and still are operative after about 5-6 years. Although I think I stuffed up with my calculations re the series/parallel the bank still operates as a 48V system.

yep....Lithium is very expensive. I think I'll go for 2 strings of 8 batteries, possibly 3 and I can then double/triple the amperage as in parallel as Gordon says. Hopefully with the next upgrade Lithium will be lower priced.

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Re: What options do I have - upgrade

Postby Newt » Sat Sep 09, 2017 1:40 pm

Gordon-Loomberah wrote:For a single string of 225AH batteries that's nearly as high as you'd want to go with them, but if you have 2 strings in parallel, you could safely double the charging current.

Adding more panels facing north will increase charging current, but if you split an array as a virtual tracker, you keep the maximum current down, and improve early morning and late afternoon charging, as seen in the graphs in the VT thread.



It's a very good idea. I was wondering if I had east and west roof arrays, how would I calculate the maximum panel number for midday when both sides will be receiving illumination? I guess that's when the panels would be maxed out - or not? The roof angle is relatively low. Possibly I need to make framework to increase the panel angle.

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Re: What options do I have - upgrade

Postby Gordon-Loomberah » Sat Sep 09, 2017 1:53 pm

Newt wrote: how would I calculate the maximum panel number for midday when both sides will be receiving illumination?


It all depends on the angle, if you tilt them to face 30 deg above the E and W horizon, then the output will be relatively flat all day- thats 120 degrees between arrays, so that the sun is 60deg from face-on for each array at solar noon. Cosine of 60 degrees is 0.5, so each array is ~half output. Max output will be higher if they are not spread so wide.
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Re: What options do I have - upgrade

Postby Newt » Sat Sep 09, 2017 8:54 pm

Thanks Gordon...this is something I will no doubt be asking more questions about some time soon. I have only used the house about 40% of the time roughly since I purchased it 9 years ago...but will be moving in full time soon. Days I'm not there it uses about 1kW, when I'm there 4kW minimum and higher if I'm using power tools, cement mixer, A/C etc. I really need to upgrade it for reasonable living full time....although we are quite frugal and careful with power consumption. I have one of those 240V watts/amps etc testers and use it to check power consumption... I adjusted my flat screen TV to 100W.

I looked at my battery bank and it seems I did manage to arrive at 48V via a series/parallel mix, albeit somewhat oddly and no doubt not really maximal, but I did want to use all the 12 batteries. Also I forgot that 6 batteries were T-125 and 6 were T-105, 240Ah vs 225 Ah. I put the lower amperage T-105's into the two parallel sets. I thought they were close enough to get away with......they came as a set for $1200 so I grabbed them.
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Re: What options do I have - upgrade

Postby australsolarier » Sun Sep 10, 2017 12:23 pm

newt,
to me it seems you might want to start from anew for island system.
your heart will be a non chinese made inverter, and a lithium battery bank.
you can then add solar chargers and panels as power requirements increase. solar panels are rather cheap, in particular if you buy them by the pallet. and pick them up yourself.

so you can then cook eletrically, heat pumps for heating the house etc as a long term target. the winter months are the tight months. if it is designed to tide you over in the winter, you will have large over generation during summer months.
all this might look expensive upfront. but you won't have to worry about power bills, lpg, petrol or diesel for generators. and divided through 20 years, your 50.000$ investment will look much more attractive and reasonable.
it is not a good idea to add batteries to your existing battery bank. adding solar panel arrays and control chargers at the other hand is easy.
buy a 8kw inverter. you are probably thinking at the moment a 2 kw inverter is plenty or so , as you only use so and so much power. you will soon want to use more electricity. and concerning the battery bank, most of the solar people here on the forum have a 400ah lithium battery bank. this seems to be the ideal capacity.
the battery is only good for overnight use and not long term like more for 2 days. for longterm cloudy days you will have to design your solar panel capacity.
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Re: What options do I have - upgrade

Postby Gordon-Loomberah » Sun Sep 10, 2017 4:38 pm

Newt wrote: 6 batteries were T-125 and 6 were T-105, 240Ah vs 225 Ah. I put the lower amperage T-105's into the two parallel sets.


That's a far from ideal arrangement! The batteries that are in series will be getting a much harder workout than the parallel ones, so I'd expect them to start failing first. If they are only being discharged a little bit overnight, they will probably last a while, but if you start to use them a lot at night, then they'll start to fail much sooner.
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Re: What options do I have - upgrade

Postby jaahn » Mon Sep 11, 2017 8:39 am

Newt wrote:Thanks Jaahn
The original batteries were the 2V x 24 --they had been in 6 years --and were dead,-- I replaced them with 8 x 6V Trojan T105's and they lasted about 3 years....then I purchased 12 used ones that I have put together in a series/parallel arrangement....these are still in and still are operative after about 5-6 years.--the bank still operates as a 48V system.
yep....Lithium is very expensive. -I'll go for 2 strings of 8 batteries, possibly 3 ---
Cheers

Hi Newt :)
Your systems batteries have been a sad tale ? But despite the current odd arrangement it has lasted best. So lets not disparage that too much. :roll:
I guess that you must decide on a battery setup that caters for your needs sufficiently that the normal daily DOD will give you a long life combined with enough solar input to normally fully recharge them every day. That really needs a bit of estimation of your needs for living. This may be best done first rather than after you see there is a problem to fix again.
The plan may include a future expansion of the system but by doing it first you can accommodate the required wiring size and positioning of the items correctly rather than having to redo some work. You might be pretty frugal with the power but may expand that useage with your system expansion. But chasing a deficit put the batteries at risk as history shows you. I would think that this is just common sense. :roll:
Cheers Jaahn
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Re: What options do I have - upgrade

Postby Newt » Mon Sep 11, 2017 2:45 pm

Thanks folks.....

Yes, the last oddly arranged lot of 12 used batteries have lasted better than the first normally arranged series of 8. I have pulled them too low on too many occasions, which doesn't help. The used lot have now gone through about 3X the kWh of the first 8....and for the money were well worth it and they are still going. Good to experiment with cheaper battery setups in order to learn how it all works than spend big $$ and bugger them up.

I was thinking of building a concrete box under ground to house the batteries in order to keep their temperature down as we often have many 40C plus days and with CC rapidly surging ahead these days who knows how hot it will be in 10 years time. Simple solution I thought and should be effective.

I dont have access to big $$ and am very unlikely to be greatly increasing power consumption, no intention or desire to cook electrically, we have LPG gas top and I am half way through a pizza oven...I prefer to keep things basic, I'm not into having everything the Jones' have.


I think an average consumption of 8kWh per day would be more than enough. So about 27kWh storage for a 30% DOD. I like the idea of the Lithium batteries, but they are quite pricey.....I may go that way I'll wait and see.

Thanks for all the
advice.
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