Questions from a newbie

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Questions from a newbie

Postby Dono2012 » Tue Apr 10, 2012 7:59 am

Hi there...we are about to build a small cottage as owner builders...it is too expensive to connect to the grid where we are in NW NSW so we plan to go off grid solar...I have been reading a lot on solar systems and have a vague idea of how we might go about it but would appreciate some advice from those with more experience...For our battery bank we thought to use 12V 200AH gel deep cycle batteries and I thought I would parallel 5 of them into a bank to give us 1000AH...then I would series connect 4 of these 1000AH banks together to give us 48VDC @ 1000AH...does this seems feasible...I can get the batteries for $320 so the whole bank would cost about $6,400 which is OK for us.
Also can anyone tell us how big our solar panel array would need to be to keep this battery bank charged...I thought to use about 20x200w panels...is this enough?
We also looked at a Selectronics 4000w inverter charger and a Plasmatronics 60A regulator which are quite expensive but then we found a unit from Taiwan for only $1200 (PIP-6048LC is a 6.0kw/48V DC input Pure Sine Wave combined inverter/charger/regulator) and wondered if people would advise against buying it?
Any advice on any of these matters would be greatly appreciated.
Thanks
Dono
12 x 24V x 190W Daqo Mono Panels in 6 strings
Outback FM80 Regulator with RTS
Latronics 24V 3KW Inverter
8 x 6V 600AH Rolls Flooded Batteries (1200AH)
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Re: Questions from a newbie

Postby Gordon-Loomberah » Tue Apr 10, 2012 11:28 am

Welcome to the Energy Matters forums Dono :)

Dono2012 wrote:For our battery bank we thought to use 12V 200AH gel deep cycle batteries and I thought I would parallel 5 of them into a bank to give us 1000AH...then I would series connect 4 of these 1000AH banks together to give us 48VDC @ 1000AH...does this seems feasible...


The likelihood of battery problems/failures increases rapidly with the number of cells, so that would have to be the worst possible way of doing it! You would have 120 cells, when the best number for a battery bank that size is 24 cells. As they would be gel batteries, you cant monitor individual cells, as you can with flooded cells, so when the inevitable weak cell(s) develops, it will be impossible to find. Running 5 parallel strings of batteries is also asking for trouble and would be advised against by all reputable battery manufacturers.

A single (best) or double string of 2V or 4V batteries would be a far superior way to put your battery bank together.

For a 48V 1000AH battery, you should aim to be able to charge it at ~C/10 amps, ie about 100A in the bulk stage. That would be a 4.8kW array, although you would get away with a little under that without any problem.

I currently have Latronics 4kW and 3kW, and also a Selectronics 1.8kW inverters, and all have been completely reliable and with good efficiency, and are Australian made. The cheap Chinese inverters on the market are very inefficient, and as has been shown on other threads here, at least some of them produce very dirty power- ie not a good clean sine wave on the output. Personally, I would not buy one of the cheaper Chinese imports, but it is possible to modify them at some expense, and significantly improve their performance.

If you want the most from your panels, you should buy an MPPT charge controller, that way you are able to get the maximum possible output they can deliver, especially on cold winter mornings when you need it the most. PWM controllers like the PL60 waste up to 30% of the power available from the panels by only operating at the battery voltage, rather than the maximum power point of the panels. MPPT controllers also allow you to run a higher panel string voltage, reducing the losses in the cable between panels and charge controller, and/or allowing you to use smaller less expensive cable. This can be a very important factor for long cable runs.
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Re: Questions from a newbie

Postby Dono2012 » Tue Apr 10, 2012 12:55 pm

Thank you Gordon...very helpful...can you recommend a MPPT charge controller?...do you think the Tracer 40A would match the PL60?
12 x 24V x 190W Daqo Mono Panels in 6 strings
Outback FM80 Regulator with RTS
Latronics 24V 3KW Inverter
8 x 6V 600AH Rolls Flooded Batteries (1200AH)
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Re: Questions from a newbie

Postby lantern » Tue Apr 10, 2012 1:07 pm

Connecting batteries in parallel, not as easy as it sounds!

http://www.smartgauge.co.uk/batt_con.html
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Re: Questions from a newbie

Postby franks » Tue Apr 10, 2012 1:15 pm

look at getting 16 Surrettes S600 flooded cells 8x2 will give you 1200amp hours at 48 volts..for a capital cost of $10k good for 57.6kWhr of storage..assume 50% DOD and 4 days automoty..thats 7.2kWhr per day aprox 3000 cycles
with 70% gross effecency and 4PSH you need a 2.6kW array (14 of 190watt panels) as a min..I would go for at least 20 panels..aprox $5k capital cost.
3.04kW Grid Tie system 16 of 190W PVs, Samil 3.3kW
3.8kW PV Stand Alone Off Grid.. 5-8kWHr Per day
24 of 190W PVs
Midnite Classic 150 & Lite MPPT
8 of 6V 600 AH flooded cells (24 volt 1200 AH)
Outback VFX3024E Inverter Charger
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Re: Questions from a newbie

Postby Gordon-Loomberah » Tue Apr 10, 2012 1:20 pm

I use, and recommend Outback MPPT controllers (no, I'm not being paid to say that ;) ), I have an FM80 and will be adding another sometime soon for a new 2kW array on a tracker I'm building. I also have a BlueSky SB50 that's operated for about 5 years without problem too, but it is of smaller capacity.

I don't have any experience with the Tracer40A you mention, but it would be too small in capacity for your system anyway. A single FM80 with ~4.5kW of panels (into a 48V battery) would do the job for you, delivering only a little under the recommended C/10 charging rate for a 1000AH batery.
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Re: Questions from a newbie

Postby Dono2012 » Tue Apr 10, 2012 2:04 pm

Thanks all for the advice...I am reading as much as i can find on the net to educate myself but it helps to hear from those with experience....I am considering going to a 24V battery bank instead of 48V although I am not sure of the advantages or disadvantages...maybe someone could enlighten me...and I would also like to run 12VDC for the lighting as well as the 240V for the appliances but not sure if thats possible..is there somewhere in the control gear that allows a 12V output?
Thanks
12 x 24V x 190W Daqo Mono Panels in 6 strings
Outback FM80 Regulator with RTS
Latronics 24V 3KW Inverter
8 x 6V 600AH Rolls Flooded Batteries (1200AH)
Dono2012
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Re: Questions from a newbie

Postby franks » Tue Apr 10, 2012 2:20 pm

As a general rule under 1kWhr per day use 12volt, 24volt for 1-4kWhr 48 volt for 4kWhr+ per day
Current draw from the battery bank should be around 100amps max..max inverter output demand 1200watts@12 volts, 2400watts@24volts, 4800watts@48volts. (keeps fusing and cabling resonable)
so if you plan to run a microwave or hair dryer go for 24 volt battery at least..nowdays 48volts is the most flexible with demand and surge.
for 12 volt applications use 24or48volt to 12 volt DC DC converter..20 amp converter around $200 vear cheap option for running 12 volt DC gear.
3.04kW Grid Tie system 16 of 190W PVs, Samil 3.3kW
3.8kW PV Stand Alone Off Grid.. 5-8kWHr Per day
24 of 190W PVs
Midnite Classic 150 & Lite MPPT
8 of 6V 600 AH flooded cells (24 volt 1200 AH)
Outback VFX3024E Inverter Charger
franks
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Re: Questions from a newbie

Postby Dono2012 » Tue Apr 10, 2012 3:23 pm

Thanks all...now here's what I have come up with and I welcome any criticism
20x24V/190W panels
2x12VDC(3x4V) 1380AH Raylite Batteries
1x Outback FM60 MPPT Regulator
1x Latronics 3000W Inverter
1x Victron Centaur 24/60 Charger
1x 24VDC to 12VDC Convertor (for lighting)
Sunlock Racking
Plus various distribution boards with circuit breakers and isolation switches and fuses and cable etc
Thanks
12 x 24V x 190W Daqo Mono Panels in 6 strings
Outback FM80 Regulator with RTS
Latronics 24V 3KW Inverter
8 x 6V 600AH Rolls Flooded Batteries (1200AH)
Dono2012
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Posts: 111
Joined: Tue Apr 10, 2012 7:37 am
Location: Coonabarabran NSW

Re: Questions from a newbie

Postby Gordon-Loomberah » Tue Apr 10, 2012 4:12 pm

You would want the FM80 rather than the FM60, which doesn't have enough capacity for your system, and isn't much cheaper than the 80.

Why go with 12V lighting? There is a much larger range available in 230V, most of it probably less expensive, and you dont have to run DC wiring in the house, as well as 230VAC. IMO and experience, 12V lights are good for camping and other portable applications, but if you want good lighting in a house, go with 230V.

The Latronics inverter has a demand start feature, so it doesnt have to be energised all the time if no appliances are running, but some new refrigerators do need the power to be on all the time. Also, some tools wont bring it on, such as my Bosch 1100W angle grinder, but that isn't an issue for me, as I have mine set to be on all the time, as I have a laptop monitoring my electrical system and weather station 24/7.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
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