How to make a solar system

Asalamualaikum

I am planning to make a 2KW solar system.

I want to buy solar cells from ebay and know how to assemble them into panels.

But the problem is I know very little about the specifications of charge controller ,Inverter, Batteries used in such a system.

Kindly guide me in this regard considering my 2KW solar system.

Also i would like to know if during day time when i am using the appliances i've connected to the system, will the power from the charge controller > inverter will go first to the batteries and then back to inverter and the appliance OR charge controller > inverter > appliance (in case of daytime use)..........???

Thank you

Don't worry when you get solar cells they will also provide you manual/user guide with package

2KW is a big solar system. You will need multiple charge contrllers. How much is your load? How did you calculated this 2KW figure? Have you made any allowance for cloudy days or winter?

In day time, power from charge controller will goto batteries and the to inverter. You will need deep cycle batteries and MPPT type charge controllers for better performance.

Unless you have lots of money at hand, this is a foolish endeavor due to the costs involved. Don't be fooled by the promise of free energy. The upfront cost and maintenance costs (primarily replacement of batteries) will cost a shiny buck.

[quote=", post:, topic:"]

2KW is a big solar system. You will need multiple charge contrllers. How much is your load? How did you calculated this 2KW figure? Have you made any allowance for cloudy days or winter?

In day time, power from charge controller will goto batteries and the to inverter. You will need deep cycle batteries and MPPT type charge controllers for better performance.

[/quote]

I am planning to divide the 2KW in 10 panels each of 200 watts.

How many charge controllers will that need?

Daily requirement is

daytime= 1000 watts

night= 1500 watts , these are rough estimates with a ± of 200 watts

I am keeping the extra watts for the resistance that would develop due to temperature rise in the panels(ideal lab conditions = 25 C. after that with every degree rise there is 0.5 % reduction in efficiency due to internal resistance) so a jump from 25 to 75 degree c will mean 25 % less efficiency.

May be latter add more panels to compersate for the 1 % efficiency degradation that occurs in solar cells/year.

So in nutshell will be dealing with 2300-2500 watts.

Will be using the solar system in a grid-tie manner. Means will use wapda for heavy duty stuff like AC etc and for rainy days and stuff and solar for the rest. Will add more batteries with time(currently budget of 200000 Rs), for now i only need 6-7 hours backup…

How much batteries will that require?

Also what is MPPT type charge Controller?

And which type of inverter and of what specs do i need?

Thank You

Ok, let me show you an example of how to calculate proper size for a solar system.

Let's use assume you need to use 1000W in the day for 14hours (we take the day at 14 hours) and 1500W for rest of 8 hours (night time).

Day time Watt-Hours = 1000 x 14 = 14,000 Watt Hours

Night time Watt-Hours = 1500 x 8 = 12,000 Watt Hours

Total Watt-Hours = 26,000

Solar system (fixed installation without any sun-tracking) gives you its peak power for maximum 6 hours in the day time. So if you select 2000W solar panels, you will get 2000W x 6 Hours = 12,000 Watt-Hours only. While you need 26,000 Watt-Hours

So based on your load requirements, your solar system size is much smaller. You need at least 2.5 times bigger system.

If you are still willing to install solar system (by increasing the solar system size or reducing your load), I can go further to show you more on how to chose charge controllers / batteries / inverter and finally overall system efficiency.

 Sorry about my poor maths - I used 8 hours for night while it should have been 10 hours, OK let us assume 2 hours rest time [/Edit]

--

--

[quote=", post:, topic:"]

One more thing, needs sun to produce enough energy. If it is cloudy weather persistently for many days, these panels are useless.
[/quote]

Of course, yes. You need to account for cloudy days. This factor will come into my calculations if OP still wants to install solar panels.

[quote=", post:, topic:"]

To produce such amount of energy, extremely large solar panels are required which may not fit the roof.
[/quote]

Just as an example, I have a 168W Peak Power solar panel which measures 64 x 32 inches. OP will need many panels of this size.

[quote=", post:, topic:"]

^name few
[/quote]

Sorry, didn’t get it.

--

@Ijaz Ahmed: thanks for the detail info.

Now a days in summer there is max sun shine of almost 10 hours. Can use aluminium foil sheets to direct the sun light at odd hours,

Another solution is to use a mobile sun tracking or time tracking platform.

Will the max efficiency increase with these solutions and if yes upto what extent.?

Got a lot of roof space to accomodate the panels but the budget is still limited to making only 2KW system.

Didn't considered this problem into the equation before it's good you mentioned it earlier....

^

Sun tracker improves the output from panels upto 40%, which means if Wp (peak power) is normally available for 6 hours only, you can increase this 6 hours time by 40%

Ok, so fixed budget and lot of roof space - let's go ahead.

For information about MPPT chrage controllers, have a look at http://www.golandcentury.com/mppt

Now you have 12000 Watt-Hours available and you have to store them. To reduce the size of DC wires and thus power losses, let's chose 24V system.

Battery AH capacity = Watt-Hours / Voltage ----> 12,000/24 = 500 AH

So you will need a battery bank of minimum 500AH, better go for 800AH bank.

Regarding invertor, you need to calculate yor peak load. For this application, I would recommend a minimum 3KVA invertor which would be able to supply 1800W continuous power (assuming a power factor of 0.6 for AC loads)

You guys should also post cost of each equipment as it will be very helpful.

@Ijaz Ahmed:

Thanks for the very helpfull information.

If i can increase the efficiency by increasing sun shine time and by decreasing the load i can get desirable results. Later with time i can increase the number of panels and size of the battery bank.

One thing more about the circuit design,

http://www.nonstopecho.com/images/stories/solar/grid-connected-solar-energy-system.jpg

I want to ask whether during the daytime batteries will be bypassed and dc provided from charge controller directly to inverter OR it has to first go to the batteries and than to the inverter because in the later case the batteries will be constantly working which will decrease their life.

Also please specify some good brands for the inverter, batteries and the mppt charge controllers that are available in pakistan.

Thank you.

[quote=", post:, topic:"]

You guys should also post cost of each equipment as it will be very helpful.
[/quote]

2KW solar cells from ebay= 880-980 \$

Shipping= 140 \$

Custom Clearance = 27 %

So total cost 880+140+275 = 1295 \$ = 110075 RS

Assembling them into panels: Roughly 20000 Rs

You need:

Tempered glass

Aluminium casing

and some minor stuff…

Inverter: 2KW : i don’t know the price yet

Batteries:

As for wet batteries: Volta IT 1500 is for 13000 Rs and its 220AH according to the company

So will be needing 4

4*13000= 52000 Rs

About dry batteries: don’t know the price yet

Charge controller: don’t know the price and don’t know either how much will i need for the 2kw system.

So roughly to make a 2kw system you’ll be needing 220000 - 250000 RS…

Provided you are the tech support team all by your self…

P.S: Last time when i checked the price of a 2kw system in pakistan they told me 732000 Rs…

[quote=", post:, topic:"]

So roughly to make a 2kw system you’ll be needing 220000 - 250000 RS…

Provided you are the tech support team all by your self…

[/quote]

After how much time do you think this system will pay back?

Dang! thats enough to make around 10 2KW of desi UPS.

o