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prabi-prasad avatar image
prabi-prasad asked

Solar PV OFF GRID system powering 1 ton air conditioners and other electrical loads

Dear Experts,

This is an enquiry from a construction company in Al Ain, UAE who requires a solar PV powered port-a-cabin. I have also attached our system sizing report, Trina solar panel ( 400 Wp) , Midea 1 ton AC and battery datasheet for your kind consideration.

This port-a-cabin is going to be operated at a construction site.The load chart is finalized as per the client’s requirement. All the mentioned load will be working from 6 am to 6 pm continuously 24x7 for 6 days / week. Night time consumption i.e. from 6 pm – 6 am is 0 excluding modem.

Client is worried about the two 1 Ton air conditioners working together with the other loads as mentioned in our case study report at a temperature of 45 to 55 degree Celsius. They are looking for some similar project reference or technical assurance from the inverter manufacturers that their inverter and other related components will be sufficient enough to operate these loads at the afore mentioned temperature conditions.

As per our calculation , battery requirement is in the range of 24 – 28 pcs of 12 V,200 Ah LEAD ACID. In this situation BMS is mandatory to make sure that all the batteries are charging and discharging equally .

We have tried our level best to convince our client by saying that even though your system is working during day time , battery bank should be optimized. Client is having a thought that they can reduce the no.of battery to 12 or 16 pcs. They don’t have a generator or grid as back up.

What is your opinion in this case ?

Please cross check and verify whether our study is correct or not , if not then please suggest us a better solution from your side so as to make it more economical and practical.

Cheers,

Eng.Prabi Prasad

Alain Solar

offgridsolar sizing
system-sizing-details.pdf (608.3 KiB)
midea-1-ton-ac-technical-specification.pdf (332.4 KiB)
12-v-200-ah-battery-datasheet.pdf (2.6 MiB)
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Anil Ghatikar answered ·

I would suggest to swap out the midea AC to one of the more efficient inverter model - such as Daikin or LG they are really more efficient The price difference pays back in 2-3 years.

Inj addition on problematic days the user can USE the AC in save mode ( or gen mode) where it reduces the consumption upto 70 % by sacrificing some cooling power

I would suggest using either OPZV 2 V or LR6 battery sizes as they will be easier to balance. If the budget permits use of LIfepo4 makes more sense given space constraints and cyclic use

Also, have a look at evaporative coolers which may be used to reduce the cooling load. There are closed cycle solutions available which do not increase the humidity in the room





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prabi-prasad avatar image prabi-prasad commented ·

Dear Anil,

Thanks for your reply. Please find my remarks for the same below.

I would suggest to swap out the midea AC to one of the more efficient inverter model - such as Daikin or LG they are really more efficient The price difference pays back in 2-3 years.

We have tried LG dual inverter AC's before.But the demand and availability of 1 ton AC's in the UAE market is less when compared to 1.5 ton and above models.

More than that , the power taken by these AC's @ T3 conditions are much more than what they have mentioned in their standard technical datasheet.You may please cross check the same with any other brands.

Inj addition on problematic days the user can USE the AC in save mode ( or gen mode) where it reduces the consumption upto 70 % by sacrificing some cooling power

This project is just like a prototype study for the client. They don't prefer genset. If it works out then they will make it in large scale. So, they wish to keep the initial cost for these systems as low as possible and to upgrade it later depending on the test run performance at UAE temperature.

I would suggest using either OPZV 2 V or LR6 battery sizes as they will be easier to balance. If the budget permits use of LIfepo4 makes more sense given space constraints and cyclic use

They are planning to put 48 V 600 Ah ( 12 V 200 Ah x 12 pcs ; 3 parallel strings ) or 48 V 800 Ah ( 12 V 200 Ah x 16 pcs ; 4 parallel strings ) for this load .Client is not ready to accept 2V batteries considering their cost and space requirements.

Battery datasheet attached12 V 200 Ah battery datasheet.pdf

Also, have a look at evaporative coolers which may be used to reduce the cooling load. There are closed cycle solutions available which do not increase the humidity in the room

Already considered

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12-v-200-ah-battery-datasheet.pdf (2.6 MiB)

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