Nadeem Ahmed from Karachi Pakistan

[nadeem5476]

Assalam o alaikum wa rehmat ULLAH / Hi

This is Nadeem Ahmed from Karachi Pakistan . The Land where the sun shines always ALHAMDOLILLAH .

m here to have some knowledge regarding solar . i m interested to setup the solar energy system at my Home shortly . For which i need some more knowledge i think .

i will ask questions over here to get the answers from the seniors with Thanks

Nice day

Nadeem Ahmed

[russ]

Hi Nadeem - Welcome to Solar Panel Talk!

Russ

[nadeem5476]

Thanks Russ .

[Mike90250]

welcome

i will ask questions over here to get the answers

Great.. We'll have questions too, regarding how much power you will need. Can you use your historic electrical usage as a guide to plan for your future usage ? (we want the monthly KWh (Killo Watt Hours consumed) numbers off your electric bill.

[nadeem5476]

i m willing to start with 1KW only and then to make it bigger and upgrade to around 5 kilo watts system .
i m based in Karachi pakistan where sun shines round the year .
having more than 8 hours of sunshine daily an average .

i heard that POLY panels do great in bright light as compared with MONO (plz keep the location where i reside that i have bright open sun all the time all day) so should i go to POLY instead of MONO ? mono is lil expensive too as compared with poly .

[Mike90250]

i m willing to start with 1KW only and then to make it bigger and upgrade to around 5 kilo watts system .....

Sadly, solar gear does not scale well. Gear bought for 5KW, is inefficient when only powered with 1KW. And then, there may be another layer of permits, parts from 2 years ago are not available now..... You can install 1Kw & 1Kw & 1Kw ... till you reach your goal.

[nadeem5476]

what is this Solar Gear ?
and here in Pakistan there is no need of permit or anything else in this regard from any one

[russ]

what is this Solar Gear ? System components - inverters etc
and here in Pakistan there is no need of permit or anything else in this regard from any one

Nope and what a mess the electric system is.

[Mike90250]

what is this Solar Gear ?......

Solar Gear:
Panels, inverters, batteries, transfer switches, wires, charge controllers .....

Gear that is perfect for a 1KW system, generally cannot be added on to.
If you want a 2Kw system, you design and install a 2KW system.
Or you have to design your 5K system, with large inverters & charge controllers, and only a small PV array and small battery bank. Then in 4 years when the batteries fail, you add more panels and a larger battery bank.

[nadeem5476]

Bought solar panels etc today .

I have bought
2 solar panels 290 watts each in PolyCrystalline
and charge controller EP Solar 40 amps MPPT .

these panels are for 24 volts sytem , the Pmax is 36 volts and Voc is 44 volts DC .
power current is 8.1 Amps and short Circuit current is 8.5 Amps .

Now plz let me know the ideal size of batteries i should buy .

in my thinking , as the total amount of current will b 8 X 2 panels = 16 amps and here in pakistan the sun light day time is around 8 hours these days . So 16 X 8 = 128 AH battery would b sufficient or say 150 AH battery .

plz comments , m i right ?

[Mike90250]

cart before horse = fail

The proper first step, is to determine your loads.
Then the size of your batteries.
Then calculate the solar charging hours in your area.

THEN you buy the panels to charge the batteries.
To size the panels, you match the charge rate to the amount of power the batteries can safely absorb. (about 8-15% of the battery capacity) (And assuming functional MPPT controller)
What you have is 580w of panels, delivering 464w @ 28V =16.5A So battery size would be roughly 165Ah @ 24V Which is close to your 150ah estimate.

As to if your batteries are the right size for your loads, that is a different calculation.

[nadeem5476]

cart before horse = fail

The proper first step, is to determine your loads.
Then the size of your batteries.
Then calculate the solar charging hours in your area.

THEN you buy the panels to charge the batteries.
To size the panels, you match the charge rate to the amount of power the batteries can safely absorb. (about 8-15% of the battery capacity) (And assuming functional MPPT controller)
What you have is 580w of panels, delivering 464w @ 28V =16.5A So battery size would be roughly 165Ah @ 24V Which is close to your 150ah estimate.

As to if your batteries are the right size for your loads, that is a different calculation.

Thanks but i have already made the calculations . i have 175 AH batteries X 2 (12 volts + 12 volts) so i have 175 Amps hours @ 24 volts . my charge controller is 40 amps EP solar EP4210RN mppt .
regarding my load it is hardly 350 to 400 watts in DAY time , and around 200 watts in night time .
please remember i m not DEPENDING whole on solar . i CAN use utility electricty which is more expensive here than solar

using APC inverter for this purpose APC 1500 VA around 980 watts . pure sine wave .

i think my home work was correct so it was not cart before horse

#LOL

[inetdog]

Thanks but i have already made the calculations . i have 175 AH batteries X 2 (12 volts + 12 volts) so i have 175 Amps hours @ 24 volts . my charge controller is 40 amps EP solar EP4210RN mppt .
regarding my load it is hardly 350 to 400 watts in DAY time , and around 200 watts in night time .
please remember i m not DEPENDING whole on solar . i CAN use utility electricty which is more expensive here than solar

using APC inverter for this purpose APC 1500 VA around 980 watts . pure sine wave .

i think my home work was correct so it was not cart before horse

#LOL

OK, so let's add that up:
400W times 8 hours = 3200Wh. 200W times 12 hours = 2400Wh. Total is 7600Wh.
With a 24V battery that is 316AH. 316AH from a 24V 175AH battery bank is not going to go. For sustainable battery use, you should not regularly go below 75% SOC, meaning that you would have only 43AH to work with.
Looking at it from the other direction, 7600Wh daily would and 5 effective solar hours per day would mean 1520 watts of panels IF the full output of the panels could be fed into the batteries and load. That means that the batteries would have to be in the Bulk charge stage for the whole daytime period.

None of this adds up.
Either your estimate of power needs is grossly inflated or your panels and batteries are way too small for the load. Or, as you say, the PV is providing only part of each days power load AND you are running your batteries down into the ground every day. Not good.

[nadeem5476]

OK, so let's add that up:
400W times 8 hours = 3200Wh. 200W times 12 hours = 2400Wh. Total is 7600Wh.
With a 24V battery that is 316AH. 316AH from a 24V 175AH battery bank is not going to go. For sustainable battery use, you should not regularly go below 75% SOC, meaning that you would have only 43AH to work with.
Looking at it from the other direction, 7600Wh daily would and 5 effective solar hours per day would mean 1520 watts of panels IF the full output of the panels could be fed into the batteries and load. That means that the batteries would have to be in the Bulk charge stage for the whole daytime period.

None of this adds up.
Either your estimate of power needs is grossly inflated or your panels and batteries are way too small for the load. Or, as you say, the PV is providing only part of each days power load AND you are running your batteries down into the ground every day. Not good.

Thanks for the explanation , please let me know IF i put a micro inverter with the panels , 580 watts panels So how much watts at 220 volts i could get from them only in day time . ?

any recommendations of micro inverter ?