Number of solar panels needed 1

[dianad]

I there,

Does anyone knows how can i calculate the number of solar panels that i need? what kind of data do i need to perform this claculation.

Thanks for the attention!

 

[OperaHouse]

Count on only being able to get 60% of the wattage indicated by the manufacturer.

 

[dpc]

Your first step is determining the power requirements of your electrical load and if you are going to have any kind of battery system for power storage.

 

[dcasto]

The solar panels have the peak rate in watts. There are sites where you can get average light availability. But typically, you'll get less than 30% of the maximum stamped watts on a fulltime basis.

 

[Warpspeed]

First you need to know the typical averaged insolation for your particular location. Google will help here, something like this:

http://www.solarpanelsplus.com/solar-insolation-levels/

Then you need to know the rated efficiency of the solar panels you plan to use, probably in the 10% to 15% range.

From that you can calculate the average yearly output in watts per square metre.

But realize that at night or during mid winter, electrical output will be effectively zero for inconveniently long periods, so some sort of battery storage will almost certainly be required.

Working out the panel area and battery size also depends heavily on the pattern of electrical usage, and that is usually the toughest thing of all to nail some hard figures on.

 

[GregLocock]

A rule of thumb in temperate Australia is that a panel with a total indicated power of 1 kW will give you 7 kWh per day in summer, and 3 kWh per day minimum all year round.

However on hot days the power will drop.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dianad]

dpc and dcasto,

It was my mistake, but i was talking about thermal solar panels. Thanks anyway for the replies.

Warpspeed,

I have exactly that data in kWh/m2/day, but even using an average you still have kWh/m2/day. How can you make the change to kW of power installed through thermal solar panels?

GregLocock,

The same question that i mentioned to Warpspeed, i made it to you also. please comment.

Thanks all!

 

[IRstuff]

I'm confused by your statements. You have kWh/m^2/day. Multiply by area, and you have kWh/day = kW*hr/24hr = kW/24.

To be rigorous, you have do the calculations as recommended by the previous posters. An hour by hour insolation will get you the peak power output. Whomever you got the data from should also provide with the insolation data as part of the dataset.

TTFN

FAQ731-376

 

[dianad]

Thats the problem, i don't have that area to multiply for...
That area, is the one that i want to calculate, to define the number of panels.

Thanks

 

[IRstuff]

Then where did your kWh/m^2/day stuff come from? You made it sound like the information came from the manufacturer.

TTFN

FAQ731-376

 

[Warpspeed]

The Kwh/day insolation is measured by the actual temperature rise of a black body absorber, and is the total incident energy for twenty four hours. It approximates a bell curve between sunrise and sunset. The figure given for insolation will be the total area under the curve.

A solar thermal system works in a very similar way, you just need to convert total watt hours into calories to estimate theoretical water heating capacity. That part is fairly easy.

The problem is that collector efficiency will vary hugely over a wide range with water temperature, and the type of collector. High water temperatures create high losses. It depends greatly on the required water temperature, and the application.

 

[BIPVguy]

Google the following.....

NRCAN (2002), Photovoltaic Systems – A Buyer’s Guide, Natural Resources Canada, Canada

You will find a fruitful source of calculating the No PV panels.
Thanks Sasa