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Date added: 08/20/2017 How to size your solar home system?

This is a sample to show your how to size your solar home system,how much do you need for each solar components.
 
Sample Sizing Calculation
In order for you to size the system correctly, you need to note the power rating of each appliance that will be drawing power from the system.
For this example, we will calculate the power requirements for a campervan with:
2 x 15W 12VDC Fluorescent Lights
1 x 60W 12VDC Water Pump
1 x 48W 12VDC Fridge
1 x 50W 240VAC TV
1 x 600W 240VAC Microwave
(Note that a 600W microwave will consume approximately 900W of power)
1. Calculate Loads
 
Calculate total DC and AC loads:
DC Loads
Lighting - 2 x 15W DC Lights - each used 2 hours per day = 60Wh/day
Pump - 1 x 60W DC Pump - used 1/4 hour per day = 15Wh/day
Fridge - 1 x 48W Fridge - runs 8 hours per day = 384Wh/day
Total for DC Loads = 459Wh/day
AC Loads
Television - 1 x 50W - used 2 hours per day = 100Wh/day
Microwave - 1 x 900W - used 15 min per day = 225Wh/day
Total for AC Loads = 325Wh/day
Allowing for inverter efficiency of 85% = 382Wh per day (ie. 325 / 0.85)
Total for AC and DC Loads = 841Wh per day
2. Calculate Required Solar Input
In Central to Northern NSW expect a usable average of around 5 peak sun hours per day.
 
Required solar panel input = (841Wh / 5h) * 1.4 = 235W
 
Note: The 1.4 used in this formula is a factor we have found that can be used to simplify the calculations for basic systems.
To ensure that adequate power is produced in the winter months, use a figure of around 4.0 to 4.5 peak sun hours per day instead of 5.
3. Select Solar Panels
Select solar panels to provide a minimum of 235W. Always best to go bigger if possible:
2 x 123W solar panels chosen which, when connected in parallel, will provide 246W or 14.32 Amps.
4. Select Solar Regulators
The rated short circuit current of the 123W solar panels is 8.1 Amps each, giving a total of 16.2 Amps.
 
Select a solar regulator that is more than capable of handling the total short circuit current: 16.2 x 1.25 = 20.25 Amps
Solar30 30Amp regulator chosen.
Note that, as described in the notes above, you must allow 25% extra capacity in the regulator rating as solar panels can exceed their rated output in particular cool sunny conditions. A 30A regulator will allow for an additional panel in the future.
5. Select Inverter
Select an inverter that is more than capable of supplying the maximum anticipated combined AC load required. In this example, maximum load would occur if the microwave and TV were running at the same time. Load in this case would be 900W + 50W = 950W.
Note that this calculation assumes that the inverter selected has a suitable surge rating to cope with the start-up surges of the microwave or other loads. A 1000W inverter would appear to be suitable, but a 1200W - 1500W inverter would be recommended.
1200Watt pure sine wave inverter chosen.
Note: A pure sinewave inverter is the preferred choice, but if the budget is tight, a modified sine wave unit could be used.
6. Select Battery
Select a battery, or a matched combination of batteries, that is capable of supplying the total power usage without being discharged more than 70%.
 
In most cases it is recommended that the batteries are sized such that they have around 3 to 4 days back-up capacity. This allows for days with low sunlight and reduces the daily depth of discharge resulting in longer battery life.
With 3 days storage capacity, the battery sizing would be as follows:
Ah Required = (841Wh * 3 / 12V) / 0.7 * 1.1 = 330Ah.
Note: The 1.1 is used in this formula as batteries are generally only about 90% efficient.
Notes:
The appliance ratings used in the above examples may not be accurate. They have been used for example purposes only. Check the ratings on your appliances before performing any calculations.

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Date added: 08/20/2017 Two different types of solar power inverters

Solar inverters produce one of two different types of wave output:
* Modified Square Wave (Modified Sine Wave)
* Pure Sine Wave (True Sine Wave)
 
Modified Sine Wave Inverters
Modified Sine Wave solar inverters are better in typical solar applications when electric motors are not involved. They are not quite as efficient as pure sine wave inverters, but you'll find that they are much more affordable. Unlike pure sine wave inverters, modified sine wave intverters produce a stepped waveform, which isn't really a sine wave at all.
Because the current is not alternating perfectly, the stepped waveform of the modified sine wave inverter causes the inverter to generate an irritating buzz. Take this into careful consideration when purchasing an inverter.
 
Pure Sine Wave Inverters
pure sine wave solar inverters are very efficient and have a very accurate waveform to the pure sine wave. pure sine wave inverters are a little more pricey than modified sine wave inverters because of the reduced noise and their strong compatibility with certain devices, such as electric motors. This is the better option if you value silence, or want optimal performance from electric motors, such as those found in an electric water pump.
Why we only use the pure sine wave inverters on TV,icebox,not modified inverters
 
Fourier Analysis states that ANY given signal (Square Wave, Impulse...etc) in time can be given as a SUM of a certain number of Sine Waves, the number of sine waves can be EXTREMELY large depending on the type of the signal itself. That is why it is called Fourier Series.
 
Now, those Sine waves consist of:
1- Fundamnetal Componenet (at desired frequency)
2- Harmonics (undesired frequencies).
 
So, signal = fundamental component + harmonics
 
For a Pure Sine Wave Inverter, basically you end up with one Sine wave signal at the desired frequency (the fundamental component ONLY), this means that all your energy is concentrated in this particualr frequency
 
For Modified Sine/Square wave, you end up with a Sine Wave signal at the desired frequency (Fundamental Component) as well as other sine waves with different frequencies (Harmonics), this means that energy is distributed over a frequency spectrum and you are losing some energy in the undesired frequencies (harmonics). Those frequencies are normally ignored by the power consumer (TV...etc)
 
example:
Suppose that your TV works at 50 Hz freq
With a Pure Sine inverter, the output is a Sine Wave @ 50Hz
With a Modified Sine, the output is a Sine Wave @ 50Hz, as well as some other Sine Waves @ 75Hz, 125Hz...etc, your TV will pick up the 50Hz signal, but of course you lose some energy in the unwanted 75,125Hz...etc
 
So, Pure Sine is the most effecient----> MOST EXPENSIVE.
Modified Sine is more popular because it is more cost effective, and it should work with most of the applications, unless the application is very sensitive to frequency, this is something you can check with the manufacturer of the TV...etc

Date added: 08/20/2017 MPPT solar charge controller

1.What is MPPT solar charge controller?
A maximum power point tracker (or MPPT) is a high efficiency DC to DC converter which functions as an optimal electrical load for a photovoltaic (PV) cell, most commonly for a solar panel or array, and converts the power to a voltage or current level which is more suitable to whatever load the system is designed to drive.
 
2.Main features 
In any applications which PV module is energy source, MPPT solar charge controller is used to correct for detecting the variations in the current-voltage characteristics of solar cell and shown by I-V curve.
MPPT solar charge controller is necessary for any solar power systems need to extract maximum power from PV module; it forces PV module to operate at voltage close to maximum power point to draw maximum available power.
MPPT solar charge controller allows users to use PV module with a higher voltage output than operating voltage of battery system.
For example, if PV module has to be placed far away from charge controller and battery, its wire size must be very large to reduce voltage drop. With a MPPT solar charge controller, users can wire PV module for 24 or 48 V (depending on solar controller and PV modules) and bring power into 12 or 24 V battery system. This means it reduces the wire size needed while retaining full output of PV module.
MPPT solar charge controller reduces complexity of system while output of system is high efficiency. Additionally, it can be applied to use with more energy sources. Since PV output power is used to control DC-DC converter directly.
MPPT solar charge controller can be applied to other renewable energy sources such as small water turbines, wind-power turbines, etc.
 
3.Compare to the traditional solar charge controller
The most traditional solar controller simply monitors the battery voltage and opens the circuit, stopping the charging, when the battery voltage rises to a certain level. Older solar controller used a mechanical relay to open or close the circuit, stopping or starting power going to the batteries.Traditional Solar Inverters perform MPPT for an entire array as a whole. In such systems the same current, dictated by the inverter, flows though all panels in the string. But because different panels have different IV curves, i.e. different MPPs (due to manufacturing tolerance, partial shading, etc.) this architecture means some panels will be performing below their MPPT, resulting in the loss of energy.
 
4.Compared with normal solar controller by Schematic Diagram
MPPT solar charge controller Schematic Diagram: Picture 2 shows typical 12V battery solar charge system V-A curve.
Normal solar controller: Solar Panel works at point A state, the solar panel working voltage is a little higher than battery voltage.
Charge Voltage: UA=13.2V
Charge Current:: IA=9.8A
Charge Power: PA=13.2*9.8=129.36w
Area in drawing: ①+③
MPPT solar charge controller: Solar Panel works at point B state, the solar panel working voltage much higher than battery voltage.
Charge Voltage: UB=18.4V,
Charge Current:: IB=9.3A
Charge Power: PB=18.4*9.3=171.12w
Area in drawing: ①+②
DRAWING
MPPT Schematic Diagram
Comparison: The power B is more than power A.
△P/ PA =(PB— PA)/ PA=32..3%
As a result of different manufacture of solar panels, different solar illumination intensity, different temperature, different efficiency of solar controller and so on. The effective power increase rate is 30%.
 
5.The benefits of MPPT solar charge controller
The benefits of MPPTsolar charge controller are greatest during cold weather, on cloudy or hazy days or when the battery is deeply discharged. Solar MPPT can also be used to drive motors directly from solar panels. The benefits seen are huge, especially if the motor load is continuously changing. This is due to the fact that the AC impedance across the motor is related to the motor's speed. The MPPT will switch the power to match the varying resistance.
 
6.The price of MPPT solar charge controller
MPPT solar charge controller are more expensive that PWM solar controller, but the advantages are worth the cost. If you can afford it, you should definitely use an MPPT solar controller.

Date added: 02/16/2017 Happy Groundhog Day!

Take our very best wishes on this pleasant day.

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