16.4 KWh/day Design for a Household Below The Equator 1

[isnata]

Hello fellow engineers and professionals,

I am currently designing a solar PV system for a residential household that would be needing around 16.4 KWh/day (from my calculation of the household appliances wattage and the amount of hours each is used per day, and then compensated for the inverter 90% efficiency). The PV system is a 12V system with 27 solar panels (250W each) in parallel, generating a total power of 6.7 Wp. All from my sizing.

When I size the battery for this system, I get approximately 91 batteries ( 12 V, 225 Ah Flooded Lead-acid Battery) each in parallel. To me, this does not make any sense and very experience from a financial point of view.

Please I would like some advice, tips, words of good thought and recommendations concerning my calculations. Do you guys (ladies included) think that my PV or battery sizing for this 16.4 KWh/day house is an over kill or just I don't know what I am doing? I did some research online and got those compensation factors from there. Any good book or author recommendation would also be helpful.


Any help or directions will be more than helpful and welcomed.

Thank you all ladies and gentlemen.

 

[itsmoked]

What does 'Wp' mean?

If you want to learn something you should give us all the numbers you used and why.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MikeHalloran]

This thread concerns another house below the equator:

Hot water heater for my solar powered house
thread1528-363623

It's not exactly on point, but there may be some helpful tidbits within.



Mike Halloran
Pembroke Pines, FL, USA

 

[MikeHalloran]

Here's another thread that's a little closer to being on point:

DC to DC upconverter
thread1528-358256

Mike Halloran
Pembroke Pines, FL, USA

 

[sibeen]

To have any idea of the size of the batteries required we would need to know how long an autonomy period you have calculated for and the power requirements.

You state a usage of 16.4 KWh/day which is an average power of less than 1 kW, and yet you have 6.75 kW of panels.

Taking 1 kW as your average usage you would require about eight x 190 amp hour batteries for a 20 hour autonomy.

 

[waross]

Fun with numbers.
Average power = 16.4 kWHr per day
16.4 kWHr per day / 24 Hours = 0.863 kW average usage.
Assume peak demand = 4 times average, 4 x 0.683 kW = 2.732 kW - 2732 Watts peak demand.
2732 Watts / 12 Volts = 228 Amps
228 Amps / 91 batteries = 2.5 Amps per battery at peak load.
A few things to be aware of.
Divide your battery cost by a conservative rating of battery life to estimate average annual cost of replacement batteries.
Do you have facilities to dispose of 15 or 20 batteries a year?
Personal experience with a solar installation close to the equator:
The facility was three large dwellings, a small dwelling and a small four bed hospital.
We used 12 Volt refrigerators to allow the use of smaller inverters.
Two large energy consumers were the water pump and the washing machine.
A diesel generator was used about one to two hours per day to run the water pump (filling an elevated tank) and the washing machine.
The generator also powered a battery charger and was fitted with a 120 Amp alternator which also charged the batteries. (A small charger was fitted to the generator to charge the generator starting battery.)
This allowed the generator to operate at reasonable efficiency and fuel economy and greatly reduced the load on the solar system.
I have used a generator as the sole power supply for a residence and found out that by far the greatest fuel consumption is the hours of light load. It takes a base amount of fuel to keep the generator running and this amount over 24 hours will be the major consumption.
Consider a method of locating failing batteries. Failing and failed batteries may be a significant drain on the system.

Bill
--------------------
"Why not the best?"
Jimmy Carter