# UPS and Approx 1200 watt solar

drraptor
Solar Expert Posts:

**205**✭✭
I want to build a setup with the following

4x 315 canadiansolar CS6U-P http://www.canadiansolar.com/solar-panels/maxpower.html

UPS according to the system either 24v or 48V

2 x 12V 200A flooded batteries or 4 x 12V 200A flooded batteries

MPPT charge controller.

Which will be better 24V or 48V and which MPPT charger controller ?

The load is

4x 315 canadiansolar CS6U-P http://www.canadiansolar.com/solar-panels/maxpower.html

UPS according to the system either 24v or 48V

2 x 12V 200A flooded batteries or 4 x 12V 200A flooded batteries

MPPT charge controller.

Which will be better 24V or 48V and which MPPT charger controller ?

The load is

- 2 x Ceiling fans wattage around 80-120W only one will be used mostly
- 3 x 14W LED bulbs only 2 will be used regularly
- 1 x 5W LED bulb in Washroom

## Comments

3,738✭✭✭✭The real question is how much battery capacity do you need. What about autonomy... how many cloudy days can you go without running the generator?

Once you know your battery capacity, you can figure out a system voltage and battery configuration. The batteries you mentioned are 2.4 kwh each. Four of them at 48 volts is 9.6 kwh. You could also use four 6-volt, 400 ah batteries and have the same capacity at 24 volts. Or get six 2-volt, 800 ah batteries and have the same capacity at 12 volts.

Unless you have plans to expand the system, or have long DC runs, a 12 volt system may be the most reliable system you can build.

--vtMaps

31,063admin- site:http://forum.solar-electric.com/ dc ceiling fan

https://www.google.com/search?q=site:http://forum.solar-electric.com/+dc+ceiling+fan120 Watts for a ceiling fan is a very significant load (if you run it 12 hours per day, that is about the same energy usage as a full size Energy Star rated refrigerator/freezer). A DC fan could be 1/4 that load...

-Bill

205✭✭The cable from Solar panel to Charge controller will be more than 50fts if I place it at ground floor.

I don't have exact wattage for ceiling fans but I will check.

how long I can run these load using these 2x 200AH batteries

1,384✭✭✭✭https://www.energystar.gov/productfinder/product/certified-ceiling-fans

I am available for custom hardware/firmware development

31,063admin- 2x 14 watt LED * 7 hours per night = 196 WH

- 1x 5 watt LED * 2 hours per night = 5 WH

- 1x 120 Watt fan * 12 hours per day = 1,440 WH
- =====================================
- 1,641 WH per day

If you use 12 volt * 200 AH * 2 batteries, with 2 days of storage and 50 maximum discharge, assuming 85% AC inverter (unless you go pure DC). Note, the calculation below is a 24 volt @ 200 AH battery bank (two of your 12 volt batteries in series):- 12v * 200 AH * 2 batteries * 0.85 inverter eff * 1/2 days storage * 0.50 maximum discharge = 1,020 AH per day (nominal)

So, your above numbers (again, just to really show the math, and how reducing fan usage/power can really save you a lot of energy), you would need a ~60% larger battery bank to meet our rules of thumb for balance system design and storage/usage.And I forgot you are in Pakistan (at least your IP Address)... For Islamabad, PK:

http://solarelectricityhandbook.com/solar-irradiance.html

## Islamabad

Measured in kWh/m2/day onto a solar panel set at a 56° angle from vertical:Average Solar Insolation figures

(For best year-round performance)

- 1,260 Watt array * 0.61 DC off grid system eff * 5.91 hours of sun per day (NOV) = 4,542 WH per day (DC system)

- 1,260 Watt array * 0.52 DC off grid system eff * 5.91 hours of sun per day (NOV) =3,872 WH per day (AC system)

And, to finish up, 5% to 13% rate of charge--Recommend 10% or higher rate of charge for full time off grid system:- 1,260 Watt array * 0.77 panel+controller derating * 1/0.05 rate of charge * 1/24 volt battery bank = 809 AH 24 volt maximum battery bank

- 1,260 Watt array * 0.77 panel+controller derating * 1/0.10 rate of charge * 1/24 volt battery bank = 404 AH @ 24 volt nominal battery bank

- 1,260 Watt array * 0.77 panel+controller derating * 1/0.13 rate of charge * 1/24 volt battery bank = 311 AH @ 24 volt minimum battery bank

Notice that I really have not said 12/24/48 volt battery bank... Nominally, I would suggest that >800 AH battery bank, you should step up to the next higher voltage bank.Some of the choice drops back to what you can get for DC appliance voltage (if you stick with DC)--You might find DC fans through China, if you do not have them locally.

-Bill

205✭✭3,738✭✭✭✭Are there any other batteries you can use? A single string of 800 ah batteries at 12 volts, or 400 ah batteries at 24 volts will have the same capacity.

--vtMaps

205✭✭245✭✭✭Wouldn't a pure sine wave inverter better to use than a UPS that may be a modified sign wave to start with.

9,022✭✭✭✭✭|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||

|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar

gen: http://tinyurl.com/LMR-Lister ,

194✭✭✭1. The 48 VDC UPSs are very robust and designed for multiple backup battery packs - so they can operated essentially continuously - especially if not at max load. However, the efficiency (of the older models in particular) are not as high as dedicated off-grid inverters (in general) - especially at low loads.

2. The built in charging systems are limited and are not sufficient for off-grid battery systems. It appears that you are only using the DC/AC inverter section anyway - so this may be irrelevant.

3. All the "Smart UPSs" are sine wave except the SC-450 (the smallest they make) - it is a modified sine wave.

Let me know what UPS you have and I might be able to help determine how good a "fit" it is with your system.

3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter. 2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter. 3000 watts SMA/SPS power. PV "switchable" toMidNite Classic 250ks based charging ofGolf cart + spare battery array of 8 - 155 AH 12V Trojans with an APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.Also, "PriUPS" backup generator with APC SURT6000/SURT003 => 192 volt DC/240 volt split phase AC inverter.