## Sunday, November 5, 2023

ON/OFF Grid Solar System Diagram

Day by day the price of the solar panel falls gradually. But still, installation of a complete off-grid solar system is costly. So I write this instructable to get all the components of your solar system separately and assemble it all by yourself.

If you are decided to install a solar panel system to cover your home power needs. This tutorial is for you.

I have tried my best to guide you step by step from buying different components to wiring everything by yourself.

Only you have to know some basic electrical and mathematics for designing the entire system. Instead of this, I have attached links of my other Instructables to make the charge controller and energy meter.

Besides the above components you need a few more things like Copper Wire, MC4 Connector, breaker, meter, and fuses, etc.

In the next few steps, I will explain in details how you can choose the above components according to your requirement.

Note: In the picture I have shown a big solar panel of 255W @ 24V, two batteries of 12V @ 100Ah each, 30A @ 12/24V PWM solar charge controller and a 1600 VA pure sine wave inverter. But during the calculation, I have taken a smaller solar system example for better understanding.

Before choosing the components you have to calculate what is your load, how much time it will run etc. If anyone knows basic maths then It is very simple to calculate.

1. Decide what appliances (light, fan, TV, etc) you want to run and how much time (hour).

2. See the specification chart in your appliances for power rating.

3. Calculate the Watt Hour which is equal to the product of power rating of your appliances and time (hr) of the run.

Lets you want to run an 11W CFL for 5hour from the solar panel, then the watt-hour is equal to

Watt Hour = 11W x 5 hr = 55

4. Calculate the total Watt Hour: Just like a CFL calculate the watt-hour for all the appliances and add them together.

So total Watt Hour per day = 365 x 1.3 = 474.5 Wh which can be round off to 475 Wh

Now the load calculation is over. The next thing is to choose the right components to match your load requirement.

If you are not interested to do the above maths then use a load calculator for this calculation. You can use this nice Load Calculator.

The Solar Panel converts the sunlight into electricity as direct current (DC). These are typically categorized as

monocrystalline or polycrystalline. Monocrystalline is costlier and efficient than the polycrystalline panel.

Solar panels are generally rated under standard test conditions (STC): irradiance of 1,000 W/m², the solar spectrum of AM 1.5 and module temperature at 25°C.

RATING OF SOLAR PANEL:

The solar panel size should be selected in such a way that it will charge the battery fully during the one day time.

During the 12hr day time, the sunlight is not uniform and it also varies according to your location around the globe. So we can assume 4 hours of effective sunlight which will generate the rated power.

Total Wp of PV panel capacity needed = 475Wh /4 = 118.75 W

By taking some margin you can choose a 120 Watt, 12v solar panel.

Here you should not confuse with the 12V. I wrote 12V as it is suitable for charging the 12V battery. But actually the Solar panel voltage is around 17V or more.

The output from the solar panel is dc power. This power is generated during day time only. So if you want to run a dc load during day time then it seems to be very easy. But doing this is not a good decision because

>> Most of the appliances need a constant rated voltage to run efficiently. Solar panel voltage is not constant it varies according to the sunlight.

>> If you want to run the appliances during the night then it is impossible.

The above problem is solved by using a battery to store the solar power during the day time and use it according to your choice. It will provide a constant source of stable, reliable power.

There are various kind of batteries. Car and bike batteries are designed to supply short bursts of high current and then be recharged and are not designed for deep discharge. But the solar battery is a deep-cycle lead-acid battery that allows for partial discharge and allows for deep slow discharge. The lead-acid tubular battery is perfect for a solar system.

Ni-MH batteries and Li-Ion batteries are also used in many small power applications.

Note: Before going to choose the components to decide your system voltage 12/24 or 48 V. Higher the voltage lesser the current and lesser will be the copper loss in the conductor. This will reduce your conductor size also. Most of the small home solar systems have 12 or 24 V.

In this project, I am selecting the 12 V system.

A solar charge controller is a device that is placed between a solar panel and a battery. It regulates the voltage and current coming from your solar panels. It is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar panel rises, the charge The roller regulates the charge to the batteries to prevent any overcharging.

Usually, the solar power systems use 12-volt batteries, however, Solar panels can deliver far more voltage than is required to charge the batteries. By, in essence, converting the excess voltage into amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This allows the solar power system to operate optimally at all times.

MPPT Charge Controller is most effective under these conditions:

1. Cold weather, cloudy or hazy days

2. When the battery is deeply discharged

Try to avoid the ON/OFF charge controller as it is the least efficient.

RATING OF CHARGE CONTROLLER:

Since our system is rated 12V, the Charge controller is also 12V

Current rating = Power output of Panels / Voltage = 120 W/ 12V = 10 A

By taking a 20% margin, you can choose a 10 x1.2 = 12A charge controller. But the next rating controller available in the market is 15A. So choose a Charge Controller of 12 V and a current rating of 15 A.

The solar panel (PV) that receives the sun’s rays and converts them into electricity called direct current (DC). DC is then converted into alternating current (AC) through a device called an Inverter. AC electricity flows through every outlet of your home, powering the appliances.

Types

1.Square Wave

2. Modified Sine Wave

3. Pure Sine Wave

Square wave inverter is cheaper among all but not suitable for all appliances. Modified Sine Wave output is also not suitable for certain appliances, particularly those with capacitive and electromagnetic devices such as a fridge, microwave oven and most kinds of motors. Typically modified sine wave inverters work at lower efficiency than pure sine wave inverters.

So as per my opinion choose a pure sine wave inverter.

It may be grid-tied or stand-alone. In our case, it is obviously stand alone.

RATING OF INVERTER:

The power rating should be equal or more than the total load in watt at any instant.

In our case the maximum load at any instant = Tv (50W) +Fan (80W) +CFL (11W) =141W

By taking some margin we can choose a 200W inverter.

As our system is 12 v we have to select a 12V DC to 230V/50Hz or 110V/60Hz AC pure sine wave inverter.

Appliances like fridge, hair dryer, vacuum cleaner, washing machine, etc likely to have their starting power consumption several times greater than their normal working power (typically this is caused by electric motors or capacitors in such appliances). This should be taken into account when choosing the right size of the inverter.

After calculating the battery capacity and solar panel rating you have to wire them. In many cases, the calculated solar panel size or battery is not readily available in the form of a single unit in the market. So you have to add a small solar panel or batteries to match your system requirement. To match the required voltage and current rating we have to use series and parallel connection.

1.Series Connection:

To wire any device in series you must connect the positive terminal of one device to the negative terminal of the next device. The device in our case may be a solar panel or battery.

In series connection the individual voltages of each device are additive.

ON/OFF Grid Solar System Diagram

Day by day the price of the solar panel falls gradually. But still, installation of a complete off-grid solar system is costly. So I write this instructable to get all the components of your solar system separately and assemble it all by yourself.

If you are decided to install a solar panel system to cover your home power needs. This tutorial is for you.

I have tried my best to guide you step by step from buying different components to wiring everything by yourself.

Only you have to know some basic electrical and mathematics for designing the entire system. Instead of this, I have attached links of my other Instructables to make the charge controller and energy meter.

Besides the above components you need a few more things like Copper Wire, MC4 Connector, breaker, meter, and fuses, etc.

In the next few steps, I will explain in details how you can choose the above components according to your requirement.

Note: In the picture I have shown a big solar panel of 255W @ 24V, two batteries of 12V @ 100Ah each, 30A @ 12/24V PWM solar charge controller and a 1600 VA pure sine wave inverter. But during the calculation, I have taken a smaller solar system example for better understanding.

Before choosing the components you have to calculate what is your load, how much time it will run etc. If anyone knows basic maths then It is very simple to calculate.

1. Decide what appliances (light, fan, TV, etc) you want to run and how much time (hour).

2. See the specification chart in your appliances for power rating.

3. Calculate the Watt Hour which is equal to the product of power rating of your appliances and time (hr) of the run.

Lets you want to run an 11W CFL for 5hour from the solar panel, then the watt-hour is equal to

Watt Hour = 11W x 5 hr = 55

4. Calculate the total Watt Hour: Just like a CFL calculate the watt-hour for all the appliances and add them together.

So total Watt Hour per day = 365 x 1.3 = 474.5 Wh which can be round off to 475 Wh

Now the load calculation is over. The next thing is to choose the right components to match your load requirement.

If you are not interested to do the above maths then use a load calculator for this calculation. You can use this nice Load Calculator.

The Solar Panel converts the sunlight into electricity as direct current (DC). These are typically categorized as

monocrystalline or polycrystalline. Monocrystalline is costlier and efficient than the polycrystalline panel.

Solar panels are generally rated under standard test conditions (STC): irradiance of 1,000 W/m², the solar spectrum of AM 1.5 and module temperature at 25°C.

RATING OF SOLAR PANEL:

The solar panel size should be selected in such a way that it will charge the battery fully during the one day time.

During the 12hr day time, the sunlight is not uniform and it also varies according to your location around the globe. So we can assume 4 hours of effective sunlight which will generate the rated power.

Total Wp of PV panel capacity needed = 475Wh /4 = 118.75 W

By taking some margin you can choose a 120 Watt, 12v solar panel.

Here you should not confuse with the 12V. I wrote 12V as it is suitable for charging the 12V battery. But actually the Solar panel voltage is around 17V or more.

The output from the solar panel is dc power. This power is generated during day time only. So if you want to run a dc load during day time then it seems to be very easy. But doing this is not a good decision because

>> Most of the appliances need a constant rated voltage to run efficiently. Solar panel voltage is not constant it varies according to the sunlight.

>> If you want to run the appliances during the night then it is impossible.

The above problem is solved by using a battery to store the solar power during the day time and use it according to your choice. It will provide a constant source of stable, reliable power.

There are various kind of batteries. Car and bike batteries are designed to supply short bursts of high current and then be recharged and are not designed for deep discharge. But the solar battery is a deep-cycle lead-acid battery that allows for partial discharge and allows for deep slow discharge. The lead-acid tubular battery is perfect for a solar system.

Ni-MH batteries and Li-Ion batteries are also used in many small power applications.

Note: Before going to choose the components to decide your system voltage 12/24 or 48 V. Higher the voltage lesser the current and lesser will be the copper loss in the conductor. This will reduce your conductor size also. Most of the small home solar systems have 12 or 24 V.

In this project, I am selecting the 12 V system.

A solar charge controller is a device that is placed between a solar panel and a battery. It regulates the voltage and current coming from your solar panels. It is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar panel rises, the charge The roller regulates the charge to the batteries to prevent any overcharging.

Usually, the solar power systems use 12-volt batteries, however, Solar panels can deliver far more voltage than is required to charge the batteries. By, in essence, converting the excess voltage into amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This allows the solar power system to operate optimally at all times.

MPPT Charge Controller is most effective under these conditions:

1. Cold weather, cloudy or hazy days

2. When the battery is deeply discharged

Try to avoid the ON/OFF charge controller as it is the least efficient.

RATING OF CHARGE CONTROLLER:

Since our system is rated 12V, the Charge controller is also 12V

Current rating = Power output of Panels / Voltage = 120 W/ 12V = 10 A

By taking a 20% margin, you can choose a 10 x1.2 = 12A charge controller. But the next rating controller available in the market is 15A. So choose a Charge Controller of 12 V and a current rating of 15 A.

The solar panel (PV) that receives the sun’s rays and converts them into electricity called direct current (DC). DC is then converted into alternating current (AC) through a device called an Inverter. AC electricity flows through every outlet of your home, powering the appliances.

Types

1.Square Wave

2. Modified Sine Wave

3. Pure Sine Wave

Square wave inverter is cheaper among all but not suitable for all appliances. Modified Sine Wave output is also not suitable for certain appliances, particularly those with capacitive and electromagnetic devices such as a fridge, microwave oven and most kinds of motors. Typically modified sine wave inverters work at lower efficiency than pure sine wave inverters.

So as per my opinion choose a pure sine wave inverter.

It may be grid-tied or stand-alone. In our case, it is obviously stand alone.

RATING OF INVERTER:

The power rating should be equal or more than the total load in watt at any instant.

In our case the maximum load at any instant = Tv (50W) +Fan (80W) +CFL (11W) =141W

By taking some margin we can choose a 200W inverter.

As our system is 12 v we have to select a 12V DC to 230V/50Hz or 110V/60Hz AC pure sine wave inverter.

Appliances like fridge, hair dryer, vacuum cleaner, washing machine, etc likely to have their starting power consumption several times greater than their normal working power (typically this is caused by electric motors or capacitors in such appliances). This should be taken into account when choosing the right size of the inverter.

After calculating the battery capacity and solar panel rating you have to wire them. In many cases, the calculated solar panel size or battery is not readily available in the form of a single unit in the market. So you have to add a small solar panel or batteries to match your system requirement. To match the required voltage and current rating we have to use series and parallel connection.

1.Series Connection:

To wire any device in series you must connect the positive terminal of one device to the negative terminal of the next device. The device in our case may be a solar panel or battery.

In series connection the individual voltages of each device are additive.