|Click on an icon to visit our other websites:|
Solar power calculator
Solar power system components
Let’s start with a brief revision of the major components found in a basic solar power system. This should help you to understand then correctly identify and select the correct size components for your solar power system.
A basic solar powered system:
The solar panel converts sunlight into DC power or electricity to charge the battery. This DC electricity/(charge) is controlled via a solar regulator which ensures the battery is charged properly and not damaged and that power is not lost/(discharged). DC appliances can then be powered directly from the battery, but AC appliances need a power inverter to convert the DC electricity into 220 Volt AC power.
Description of individual solar power system components
Solar panels are classified according to their rated power output in Watts. This rating is the amount of power the solar panel would be expected to produce at STC (standard testing conditions) of sunlight intensity 1000w/metre at 25 degrees centigrade
Different geographical locations receive different quantities of average peak sun hours per day.
The purpose of solar regulators, or charge controllers as they are also called, is to regulate the current from the solar panels to prevent the batteries from overcharging. Overcharging causes gassing and loss of electrolyte resulting in damage to the batteries.
The power inverter is the main component of any independent power system which requires AC power. The power inverter will convert the DC power stored in the batteries and into Ac power to run conventional appliances.
DC to AC power inverters
Just over a decade or so ago, DC AC power inverters were so inefficient and unreliable, many people restricted themselves to 12V lights and appliances.
If you have recently tried to shop around for 12V DC appliances, you will see that there is a very limited selection available.
Today, the efficiency and reliability of the latest DC AC power Inverters, are a far cry from the inverters that were available 15 to 20 years ago.
There are three waveforms produced by modern solid state power inverters. The simplest, a square wave power inverter, used to be all that was available. Today, these are very rare, as many appliances will not operate on a square wave.
True Sine wave inverters provide AC power that is virtually identical to, and often cleaner than, power from the grid.
Deep cycle batteries are usually used in solar power systems and are designed to be discharged over a long period of time (e.g. 100 hours) and recharged hundreds or thousands of times, unlike conventional car batteries which are designed to provide a large amount of current for a short amount of time.
Choosing the right size solar regulator
A solar regulator must be able to handle the maximum current that can be produced by the solar panels. Reflected sunlight and specific temperature conditions can increase the output current of a solar panel by as much as 25% above it’s rated output current. The solar regulator must be sized to handle the increased current.Example: An 80W 12V solar panel has a rated output current of 4.55 Amps and a rated short circuit current of 4.8 Amps.
Minimum solar regulator size for a single 80W solar panel should be:
4.8 Amps x 1.20 = 5.76 Amps.
It is recommended that the regulator selected is even slightly larger than this figure to ensure that it is not constantly operating at 100% of its rating, particularly in regions with higher ambient temperatures.
A good rule of thumb is a margin of between 20 and 30%.
Sizing your solar power system
In order for you to size your solar system correctly, you need to note the power rating of each appliance that will be drawing power from the system.
Let us take some common household appliances like lighting, a TV, and a fridge to see how one calculates the correct size solar system:
10 x 12W globes = 120W operating 10 hours per day. = 1200W.H
2 x TV x 250W = 500W operating 6hrs per day = 3000W.H
Fridge x 250W = 250W operating 24/7 = 6000W/day
Power inverter sizing
Appliance total power draw = 120W(for the 10 lights) + 500W(for the 2 TV’s) + 250W(for the fridge) = a total power draw of 870W.
To provide a small buffer or margin your minimum size inverter choice should be around 1000W.
A modified sine wave inverter with a 1500W continuous power rating will therefore be your obvious choice in this specific solar system design.
Determining the size and number of solar panels
Here we take the total power usage daily = 1200W.H + 3000W.H + 6000W.H
This = a total of 10200W.H
Divide the total daily power requirement by the number of charge hours for that geographic region eg. 10200/5.5Hrs = 1854.54W
Add 20% for inefficiencies = 2225.45 W
This total power value determines the size and number of panels eg. 2225.45/75W panels = 30 x 75W panels.
If you fancied say 125W panels , then 2225.45/125W = 18 panels.
How many batteries?
Well the 75W panels produce 4.4Amps, thus 30 x 4.4 A = 132A x 5.5 Hrs = 726Ah
105Ah batteries, should be discharged to no more than 50%, thus we divide total amps by 105A x 50% = 50A.H
726/50A = 14.5 x 105Ah batteries.
For ease of possible 24V or 48V configuration, this would mean 16 batteries.
What size regulator do we need ?
Let’s say we had 20A regulators at our disposal.
One 75W panel produces around 4.4Amps.
3 x 4.4A = 13.2A
So 30 solar panels would need 30/3 = 10 x 20A solar regulators.
Complete the solar power system
Well we have the following:
Thus we have calculated the solar power system components that you would need in order to cater for your current power usage
How solar power works | Solar power components | Solar panels | Solar power system regulators | Solar batteries | Solar inverters | Calculate you power reguirements | Solar power | Replace electricity mains completely | 4 x4 solar power applications | Power for rural dwellings | Power for game lodges | Power for holiday homes | Power for farm houses | Global warming - food for thought | Global warming - practical suggestions
Copyright © Plan-My-Power (PTY) ltd | webdesign by Cantaloupe web design