Are these calculations right about solar panel ?

[danishdeshmuk]

Are these calculations right about solar panel ?

To generate regularly (24hrs) 24Amps load , how many solar panels & cells are required ? What capacity battery & battery charger would be required to charge the battery ............

P=V*I = 24*230 = 5520W

Conversion efficiency for DC to AC will limit out at 90%, so you need 5520/0.9 = 6133W into the converter.

Battery storage/recovery efficiency will be a max of 90% since this is a PV application. If we were looking at an electric vehicle, it is a max of 70%. So now, power into storage is 6133/0.9 = 6814W and a day's worth of storage is 24*6814= 164KW-hr

Since the sun only shines part of the day, we will need to generate all the electricity in that part of the day. Assuming no clouds, we can get about an average of 50% of peek power for no more than 8 hours. We need 164KW-hr into storage, so we need to generate 328KW-hr in 8 hours or 41KW per hour for our 8 hour period.

The typical solar cell efficiency is 12%, and the sun is 1.1KW/m^2 so that means we need:

(41/0.12)/1.1 m^2 of cells = 311square meters of cells.

 

[BradtheRad]

Solar irradiation varies widely by geographical location.

Typical watt output of a PV panel is 8 to 12 W per sq ft.

A sq meter is 10.76 sq ft.

Let's say PV output is 107 W per sq meter.

Based on your figure of 41 KW output, you need 383 sq meters of panels.

You can expect maximum charging during summer months when sun is high in the sky for greater hours.
In winter the sun is low, and for fewer hours.

 

[tpetar]

1.1KW/m2 is per day. ;-)

Inverter systems rated with that power should have higher voltage to descrease amperage, we dont build submarine this is solar system. If we dont whant fire to showup then use higher voltage, lower amperage.

 

[ALERTLINKS]

sun is 1.1KW/m^2

Its right! Total energy form sun on a square meter is in the form of heat and light. Its in continuous as long as its shining, that is for example a 1.1KW electric heater will emit same amount of energy as long as it is connected to mains. Or sunlight through a glass window of 1 m2 in aroom will heat equal to 1KW heater.

1.1KW/m2 is per day.

Its right? As pv cell is 12-16 % efficient, it will produce 125 watts and for eight hour sunshine, it totals 1KWH of electrical power / day.

 

[enjunear]

1.1KW/m2 is per day

Not sure if that was sarcastic, but a Watt is an instantaneous measurement... not per hour, day, minute, second, etc.

Its right? As pv cell is 12-16 % efficient, it will produce 125 watts and for eight hour sunshine, it totals 1KWH of electrical power / day.

That math only works with a certain size of PV panel and duration. You are missing the surface are of the solar collector, and are simplifying that the solar power generation of the array tracks as cos^2 of the angle from the PV panel's azimuth to the solar angle.


Brad's and the OP's estimates both appear to track pretty well, and take into account the fluctuation in power generation during the lit part of the day.

One thing to keep in mind, what do you do when you have several cloudy days in a row? Do have have to store enough energy to last 48 hours before a recharging day? Can the system blackout when the sun doesn't shine for several days? These are some complex issues you may need to consider, depending on what your load's availability needs to be.

Also, you may want to make your PV conversion efficiency a little lower to account for physical installation concerns. The cells alone may be 12% typical, but when you put them in a box with a glass cover, that will cut down on the number of photons that reach the solar cells. Also, unless they get cleaned every day, you will have some disturbance from dust/dirt on the protective glass, which will also reduce your solar conversion efficiency. For an installation this size, you consult with someone in that industry. I'd recommend going down to at least 10% to give you some margin (maybe even 8-9% ?).

 

[tpetar]

"1.1KW/m2 is per day"

Not sure if that was sarcastic, but a Watt is an instantaneous measurement... not per hour, day, minute, second, etc.

No you are wrong, you didnt understand W is unit for power, and you can measure and calc amount of that power for some time, then we have KW/h kW/day A->Ah .... its work during some time. (elementar thing) ;-) I supose you know for that, maybe you mistake something.
Of course I apology maybe you have or know where can we buy that revolutionary and new tech solar panels with that producing power 1,1KW/m2 "instantaneous power".

In this case I say 1,1KW/m2 for one day production of power, that is writen as 1,1KW/m2 per day.

If someone have device which consume 100W and this device is turned on 24h whole day, what is whole power consuption in one day ? You will say 100W I suppose. Correct is 2,4KW/h.

If someone ask you how much energy some device consume per day you will say 1000W ? Correct answer is KW/h
Or if someone ask you what is capacity of some battery you will say 2A ? Correct answer should be in Ah mAh ...
If someone ask you how much power your solar panel produce power per day ? You will say 100W or 100Wh ?
Of course this unit can be writen as mAh or MW/h.....

Also, you may want to make your PV conversion efficiency a little lower to account for physical installation concerns. The cells alone may be 12% typical, but when you put them in a box with a glass cover, that will cut down on the number of photons that reach the solar cells.

"Solar panels" are already closed in box, like product they are finished, no additional working is needed on them. Second thing is when you buy solar cell and make solar panels, but that is not solar panel (that are cells something like DIY at home). Efficiency is given for finished product by manufacturer.

 

[enjunear]

"Solar panels" are already closed in box, like product they are finished, no additional working is needed on them. Second thing is when you buy solar cell and make solar panels, but this is not solar panels. Efficiency is given for finished product by manufacturer.

I just looked at some terrestrial-grade BP solar panels, and from their specs, they appear to show a nominal 11% efficiency and a minimum of 10%. Better to err on the side of caution and have some margin.

And you can't tell me that a dirty solar panel will yield just as much power as a clean panel. The OP should be cognizant of potential issues that may cause him to add additional solar collector area in order to obtain necessary margin for real-world implementation losses.

 

[ALERTLINKS]

you may want to make your PV conversion efficiency a little lower to account for physical installation concerns

I probably will put mirrors as reflectors around pv panel to double the sunlight falling on it, put assembly on a rotator with sun tracking system with management to water-cool the panel.

 

[tpetar]

I just looked at some terrestrial-grade BP solar panels, and from their specs, they appear to show a nominal 11% efficiency and a minimum of 10%. Better to err on the side of caution and have some margin.

Yes I agree with that.

And you can't tell me that a dirty solar panel will yield just as much power as a clean panel. The OP should be cognizant of potential issues that may cause him to add additional solar collector area in order to obtain necessary margin for real-world implementation losses.

Yes but this is story from end. You can buy car and ask seller yes this specification and max speed of car on road is not true because my car can have flat tire in some cases and he cant reach that speed ?

Each country and place on this planet have calculated and measured values of solar insolation. Somewhere this values can be changed by nature but this is monitored and logged. Also period of year we all know that in winter snow falling, and sun rays are weaker.

I just say that is wrong to start at end. We should take all aspects and parameters I agree with that, but we didnt talk about that in this thread.

---------- Post added at 05:19 ---------- Previous post was at 04:40 ----------

Suntech company
285 watts-290 watts Polycrystalline Datasheet Solar Panel (up to 14,9%) :
http://am.suntech-power.com/images/...285_24vd_ul_superpoly285-290 h4 connector.pdf

Yingli Solar Company
Monocrystalline Module efficiencies of up to 16.2%
Multicrystaline Module efficiencies of up to 15.0%
http://www.yinglisolar.com/us/products/

Canadian Solar
ELPS Module CS6P-255/260/265MM (19,5% Efficiency)
http://www.canadiansolar.com/en/products/product-documentation/

 

[enjunear]

Suntech company
285 watts-290 watts Polycrystalline Datasheet Solar Panel (up to 14,9%) :
http://am.suntech-power.com/images/...285_24vd_ul_superpoly285-290 h4 connector.pdf

Yingli Solar Company
Monocrystalline Module efficiencies of up to 16.2%
Multicrystaline Module efficiencies of up to 15.0%
http://www.yinglisolar.com/us/products/

Canadian Solar
ELPS Module CS6P-255/260/265MM (19,5% Efficiency)
http://www.canadiansolar.com/en/products/product-documentation/

What's your point with this? I'm aware that PV panel efficiencies can be higher then the originally posted 12-16%, but it's poor practice to design without considering the minimum case (or at the very least, the nominal condition).

 

[tpetar]

What's your point with this? I'm aware that PV panel efficiencies can be higher then the originally posted 12-16%, but it's poor practice to design without considering the minimum case (or at the very least, the nominal condition).

Yes but we must admit that things is not that bad like you present it.

 

[enjunear]

Yes but we must admit that things is not that bad like you present it.

I don't agree. I was part of a solar-powered vehicle team in college. It takes little surface contamination to moderately impact an array's performance. It's routine for teams to spray down the arrays with water at pit stops during long races. The effect was two-fold: 1-cool down the array w/ room temp water and it's eventual evaporation, and 2-wash off occluding contamination.

The team had performed experiments to see how much power was lost from an unclean array. After a day of road testing, the car was stored overnight w/o spraying it down. On the following morning, the array was set up and exposed to a constant light source in the lab. After the power was measured, the array was washed/dried, allowed to return to room temperature, then the power was measured again. The impact was about 2-3% power increase. So, there is some basis of estimate for my remarks.

 

[danishdeshmuk]

I probably will put mirrors as reflectors around pv panel to double the sunlight falling on it, put assembly on a rotator with sun tracking system with management to water-cool the panel.


how would you do that ?

 

[BradtheRad]

Check into what large PV installations do. Some use mirrors. It may double or triple the illumination.

I've read that the blue panels can eventually turn brown after exposure to the heat. I'd be surprised if they water cool them. Seems it would require a continual spray against the back of the panel. This would cool the thin film type, however the crystalline type have a rigid backing and I doubt the cooling spray would reach the PV cells.

 

[tpetar]

One of the reason why in some situations solar panels are not installed on house roofs. ;-)

Max temperature is given by manufacturer for panels and user should respect that, like all others.

All depends from situation to situations.

 

[ALERTLINKS]

Solar PhotoVoltaic mirror concentrators

http://youtu.be/B8pijxtEVTI

Impact of Reflectors on Solar Energy Systems
**broken link removed**

Renewable sources of energy are very important for Pakistan as it is acutely short of fossil fuels. Among renewable sources, solar energy is of special significance as it is abundantly available. However. Minimum solar radiation is received in the North of Pakistan. Then it increases as we move southward and it reaches maximum in the center of Pakistan. After this solar radiation decreases slightly towards the coastal region. The Quetta Valley receives maximum solar radiation throughout the year. The nationwide average is 5.5 kwh/m2/day.

**broken link removed**
http://www.jbaas.com/HTML/Current Issues/Headings/PDF/11-Total global and diffuse solar.pdf

 

[danishdeshmuk]

https://obrazki.elektroda.pl/97_1338398719.jpg

Would you name the components to be used & their schematic ? As told in this above fig.
like temperature sensor, Reflector & Axis sensor , type & capacity of stepper motor , Dc input ? what value 24 V dc ???

 

[BradtheRad]

Since you desire 230 VAC output, consider assembling a battery bank that provides that volt level (positive and negative), using batteries in series.

Multiplying by 1.414, and then by 2, it will be 650 V peak-to-peak. This will require over 100 batteries, each 6 VDC (assuming you use deep-cycle type such as golf cart batteries which are good to use in a PV system).

This will make a lot of things easier. Your converter will be easier to construct, since you need only input 24 amps (instead of 240A).

It will allow you to use thinner wiring (as compared to running 240 amps through thick wires).

I don't know if you wish a sinewave output. This won't necessarily be easy, but it will be within easier reach if you start out with 650 VDC.

Your conversion efficiency will be higher if you start out with 650 V input. Since your initial amp draw is less, this means that losses due to the Peukert effect will be much less.

Your batteries will not be worked as hard if you make a 650 V bank. Battery life will be longer.

 

[danishdeshmuk]

so, what are the conclusions ? For generating the above stated power by solar panels .... without the use of reflecting mirrors or surfaces OR without them