diy off grid solar system - small home appliances
The price of solar panels is gradually declining every day.
But installing a complete off-grid solar system is still expensive.
So I wrote this instruction book to separate all the components of the solar system and then assemble them myself.
You can find all my projects on it: You decided to install a solar panel system to meet the power needs of your family.
This tutorial is for you.
I have done my best to guide you step by step from buying different components to wiring yourself.
You only need to know some basic electrical and mathematical knowledge when designing the whole system.
In contrast, I have attached a link to the other instructions for making the charging controller and the watt-hour meter.
For off-grid solar systems, you need four basic components. Solar Panel (PV Panel)2.
Charging Controller 3. Inverter4.
In addition to the above components, you need more things like copper wire, MC4 connectors, circuit breakers, meters and fuses.
In the next few steps, I will explain in detail how to select the above components according to your requirements.
Note: In the picture I show a large solar panel of 255 W @ 24 v, two batteries per 12 V @ 100Ah, 12/24 v pwm solar charging controller and 1600 VA pure sine wave inverter.
But in the calculation process, I gave an example of a smaller solar system for a better understanding.
You have to calculate your load, run time, etc before selecting a component.
If anyone knows basic math, it's easy to calculate. 1 .
Decide what electrical appliances (
Lights, fans, TV, etc)
How much time do you want to run (hour). 2.
For rated power, see the specification chart in the device. 3.
Calculate watt hours equal to the product of rated power and time of the equipment (hr)of run.
Example: Let you want to run 11 w cfl 5 hours from the solar panel, then the watt hour is equal to 11 W x 5 hr = 55 4.
Calculate total watt hours: add them up just as the CFL calculates watt hours for all appliances.
Example: CFL = 11 w x 5 hr = 55Fan = 50 w x 3hr = 80 w x 2hr = 160------------------------------------------------
Taking into account the loss of 150 of the energy in the system, the total watt hour = 55 + 160 + 365 = 30%.
Therefore, total watt hours per day = 365x1. 3 = 474.
5 Wh, can be rounded to 475 when the load calculation is over.
The next step is to select the appropriate components that match the load requirements.
If you are not interested in the math above, then use the load calculator in this calculation.
There are a lot of load calculators on the Internet.
I have attached a link like this outside of the grid load calculator.
Solar panels convert sunlight into direct current (DC).
These are often classified as single or multi-crystals.
Single crystals are more expensive and effective than polycrystal panels.
Solar panels are generally rated under standard test conditions (STC)
: Irradiance of 1,000 W/m, solar spectrum of AM 1.
Module temperature at 5 and 25 °c
Rating of solar panels: the size of the solar panel should be selected in order to charge the battery within one day.
During the 12-hour day, the sun is uneven, which also varies depending on where you are on Earth.
Therefore, we can assume 4 hours of effective sunlight generating the rated power.
Total PV panel capacity required Wp = 475Wh/4 = 118.
You can choose a 12 v solar panel of 120 watts.
Here you should not be confused with 12 v.
I wrote 12 V because it is suitable to charge 12 V battery.
But in fact, the voltage of the solar panel is 17 volts or more.
The output of the solar panel is a DC power supply.
This power is only produced during the day.
So if you want to run the DC load during the day then it seems easy.
But it is not a good decision to do so because most appliances require a constant rated voltage to operate effectively.
The voltage of the solar panel is not constant, it varies according to the sun's light.
> If you want to run the appliance at night, then this is not possible.
The above problems are solved by using the battery during the day to store solar energy and use it according to your choice.
It will provide a stable and reliable power supply.
There are all kinds of batteries.
Car and bike batteries are designed to provide short-term high current and then recharge, not for deep discharge.
But the solar cell is a deep battery. cycle lead-
Acid batteries that allow partial discharge and allow slow discharge in depth.
Lead-acid tubular batteries are the perfect choice for solar systems. Ni-
MH battery and Li-
Ion batteries are also used in many small power applications.
Note: please decide the system voltage 12/24 or 48 V before selecting the assembly.
The higher the voltage, the smaller the current, the smaller the copper loss in the conductor.
This will also reduce the size of your conductor.
12 or 24 V in most small home solar systems.
In this project, I chose the 12 v system.
Battery rated capacity: battery capacity is rated in amps hours.
Power = voltage X current watt hour = voltage (Volts)x Current (Amperes)x Time (Hours)
Battery Voltage = 12 V (
Because our system is 12 V)
Battery capacity = Load/voltage = 475/12 = 39.
In fact, the battery is not ideal, so we have to consider the loss.
Let the battery lose 15%.
So the required battery capacity is 39. 58 / 0. 85 =46.
56 AhFor better battery life, they do not allow full discharge (100% ).
For lead-acid batteries full of 60% deep discharge (DOD)
It is considered a good practice.
So the required capacity = 46. 56 /0. 6 = 77.
61 AhYou can choose a deep circulating lead-acid battery with a capacity of more than 77. 61 Ah.
You can put the 80 AhA solar charging controller between the solar panel and the battery.
It regulates voltage and current from solar panels.
It is used to keep the proper charging voltage on the battery.
When the input voltage of the solar panel rises, the charging controller adjusts the charging of the battery to prevent any overcharging.
Typically, the solar system uses a 12 volt battery, but the solar panel can provide a much higher voltage than the one needed to charge the battery.
Essentially, by converting the excess voltage into amps, the charging voltage can remain at the best level while reducing the time it takes for the battery to fully charge.
This allows the solar system to operate in the best way at any time.
Charging Controller type: 1. ON OFF2. PWM3.
Of the 3 charging controllers, maximum power point tracking is the most efficient but costly.
Therefore, you can use PWM or maximum power tracking.
The most efficient maximum power tracking charging controller in these conditions: 1.
The weather is cold, cloudy or hazy.
When the battery is discharged in depth, try to avoid the on/off charging controller because it is the lowest efficiency.
Rated charging controller: Since our system is rated monthly V, the charging controller is rated monthly = VCurrent board/voltage of power output = 120 W/month V = 20% profit of monthly Obi, you can choose 10x1.
2 = charge controller.
But the next rating controller on the market is 15A.
Therefore, the charging controller of 12 v and the rated current of 15a are selected.
You can do a PWM charging controller if you want to reduce the cost of the system.
For step-by-step instructions, you can see my instructions on the PWM charging controller.
You may also like my new design on the solar charging controller. Solar panel (PV)
Receiving the sun's light and converting it into electricity is called direct current (DC).
Then convert the DC to AC (AC)
Through a device called an inverter
Each outlet in your home has an AC power supply to power the appliance. Types 1. Square Wave2.
Modified sine wave
Pure sine wave inverters are cheap but not for all appliances.
The modified sine wave output is also not applicable to certain appliances, especially those with capacitors and electro-magnetic devices such as refrigerators, microwave ovens and most types of motors.
Generally, the improved sine wave inverter is less efficient than the pure sine wave inverter.
So choose a pure sine wave inverter according to my opinion.
It may be a plaid tie, or it may be independent.
In our case, it is obviously independent.
Rated power of inveda: at any moment, the rated power should be equal to or greater than the total load in Watts.
In our case, the maximum load at any moment = TV (50W)+Fan (80W)+CFL (11W)
= 141 w we can choose the inverter of 200 W.
Since our system is 12 v, we have to choose an AC pure sine wave inverter from 12 v DC to 230 V/50Hz or 110 V/60Hz.
Note: the starting power consumption of refrigerators, hair dryers, vacuum cleaners, washing machines and other electrical appliances may be several times the normal operating power (
This is usually caused by an electric motor or capacitor in this appliance).
This should be taken into account when choosing the appropriate inverter size.
Design of solar system.
Follow the previous steps to purchase all components at the appropriate rating.
It's time to install solar panels.
First select a suitable location where the roof does not block the sun.
Prepare the stand: you can do it yourself or it's better to buy one from any store.
In my case, I took the painting from the solar panel company and made it near the welding workshop.
The angle of the bracket is almost equal to the latitude angle of your position.
I made a small wooden mounting bracket for my 10 W solar panel.
I have attached photos so that anyone can do this easily.
Tilt: to get the most out of the solar panels, you need to point them in the direction of capturing the maximum sun.
Use one of these formulas to find the best angle from the horizontal position where the panel is tilted:> If your latitude is below 25 °, use Latitude time 0. 87.
> If your latitude is between 25 ° and 50 °, use Latitude multiplied by 0. 76, plus 3. 1 degrees.
For more details on tilt clicks, please first move the stand towards the south.
Mark the position of the leg on the roof.
To get a southern direction, use this android app compasstadt and then use sharp objects to make a rough surface on each leg of the holder.
I made rough surfaces about 1 square foot on the roof of each leg.
This helps the perfect combination between the roof and the concrete.
Prepare concrete mixture: Take 1: 3 ratio of cement and stone, and then add water to make coarse mixture. .
Pour concrete mixture on each leg of the bracket.
To give maximum strength, I made a concrete mixture in the shape of a pile.
Install the panel on the bracket: on the back, the solar panel has a built-in mounting hole.
Match the solar panel holes with the stand/platform holes and screw them together.
Connect the solar panel: on the back of the solar panel, there is a small junction box with positive and negative symbols of polarity.
In large size solar panels, this junction box has a terminal line with a MC4 connector, but for small size panels you have to connect the junction box with an external line.
Positive and Negative terminal connections always try to use wires in red and black.
If there is a regulation of ground wire, please use green wire wiring.
After calculating the battery capacity and the rating of the solar panel, you must route it.
In many cases, the market cannot provide calculated solar panel sizes or batteries in the form of a single unit.
So you have to add small solar panels or batteries to meet your system requirements.
In order to match the required voltage and rated current, we must connect in series and parallel. 1.
Series: to connect any device in series, the positive pole of one device must be connected to the negative pole of the next device.
Our equipment may be solar panels or batteries.
In a series connection, each voltage of each device is attached.
Example: Let 4 12 v batteries connect in series, then the combination will produce 12 = 48 v.
The current or amps are the same in the series combination.
Therefore, if these devices are batteries with a rated voltage of 12 V and 100 Ah per battery, then the total value of this series of circuits will be 48 V, 100Ah.
If it is a solar panel, the rated voltage of each solar panel is 17 Volts (Osc voltage)
And the rated current of each circuit is 5 amps, then the total circuit value will be 68 volts and 5 amps. 2.
Parallel connection: in parallel connection, you must connect the positive terminal of the first device to the positive terminal of the next device, connect the negative terminal of the first device to the negative terminal of the next device.
In parallel, the voltage remains the same, but the rated current of the circuit is the sum of all devices.
Example: Let the two batteries of 12 v, 100Ah be connected in parallel, and then the system voltage remains 12 v, but the rated current is 100 100 = 200Ah.
Similarly, if two solar panels of 17 Volts and 5 amps are connected in parallel, then the system will produce 17 Volts of 10 am ps.
I made the above inverter and battery stand with the help of the Carpenter.
The design idea I got from this Instructure.
This design is really helpful to me.
On the back I made a big round hole behind the inverter fan to take fresh air from the outside.
Later I covered the hole with a plastic screen.
There are also very few small holes used to plug the wires of solar panels, charging controllers and inverters into the battery and output the AC to the appliance.
3 horizontal holes are set on the panels on both sides for full ventilation.
Glass windows are provided on the front to view different led indications in the inverter.
On the bevel of the inverter holder, I installed the charging controller.
I will also install my own electric energy meter in the future.
The first component we want to connect is the charging controller.
At the bottom of the charging controller, there are 3 signs in my Charging Controller.
The first one on the left is for connecting positive solar panels (+)and negative (-)sign.
The second plus (+)and minus (-)
The logo is a sign of battery connection and a sign of direct DC load connection such as DC lights.
Always connect the charging controller to the battery first, according to the charging controller manual, as this allows the charging controller to calibrate to a 12 V or 24 V system.
Connect red (+)and black (-)
Connect to the charging controller from the battery pack.
Note: First connect the Black/negative wire on the battery to the negative terminal of the charging controller and then the positive wire.
After connecting the battery to the charging controller, you can see that the charging controller indicator led lights up to indicate the battery power.
Connect this inverter terminal for battery charging to the corresponding positive and negative terminals of the battery.
Now you have to connect the solar panel to the charging controller.
There is a small junction box on the back of the solar panel and 2 connecting lines with positive electricity (+)and negative (-)sign.
The length of the terminal is usually small.
To connect the wire to the charging controller, you need a special type of connector, commonly referred to as the MC4 connector. Look at the picture.
After connecting the solar panel to the charging controller, the green led light will light up if there is sunlight.
Note: always connect the solar panel to the charging controller while facing the panel away from the sun, or you can cover the panel with dark material, to avoid a sudden high pressure from the solar panel to the charging controller could damage it.
Safety: it is important to note that we are dealing with DC current.
So positive (+)
Yes and positive (+)and negative (-)with negative (-)
From the solar panel to the charging controller.
If it gets mixed up, the device can explode and catch fire.
So you need to be very careful when connecting these wires.
It is recommended to use 2 color wires I. e.
Red and Black on the front (+)and negative (-).
If you don't have a red and black wire, you can wrap the tap in red and black on the terminals.
The DC load or emergency light is finally connected.
Additional protection: Although the charging controller and inverter have built-in fuses for protection, you can place the switch and fuse in the following position for additional protection and isolation. 1.
Between the solar panel and the charging controller.
Between the charging controller and the battery pack.
Between battery and inverter metering and data recording: If you are interested in knowing how much energy the solar panel generates, or how much energy your appliance consumes, you must use the electric meter.
In addition to this, you can monitor different parameters in off-grid solar system by remote data loggingFor diy electric energy meter. You can see my instructions on the electric energy meter, which has the functions of metering and data recording
After wiring everything, the off-grid solar system can be used.
I found a well-documented solar PV design worksheet on the renewable energy innovation page.
This is a simple booth design worksheet.
Solar photovoltaic system.
It explains the design process and explains some of the practicality of building the system.
I hope it will be useful.
Thanks entirely to the author of Re-
Thank you for reading my instructions.