Off grid solar system is something many people keen to do and actualize in these days. Everyone has an idea and experience about this subject in line with the research we did.
We are going to create a sample project for off grid solar system in this article. We are going to run 1 LCD TV for 8 hours in one day of the week for the off grid solar system project.
We are going to share all details, how to generate electricity with solar energy, its cost and installation with a simple example in this article. The steps we are going to follow for the off grid solar system are as follows;
- Total AC power calculation
- Total battery capacity calculation
- Total solar panel calculation
- Charge controller power calculation
- Inverter power calculation
We need to determine the products we are going to use in the system for off grid solar system and their power before we start to our off grid solar system project.
We Are Starting the Off Grid Solar System Project
The device we want to operate is one LCD TV and we plan to operate it only Saturdays. We want it to operate for 8 hours on Saturdays. We know that the television power is 80 watts/hour.
Now we know the power of the product, weekly operation time and daily usage periods for the off grid solar system project.
We are going to calculate the off grid solar system project by only considering the 8 months of the year.
The devices and information we are going to use for off grid solar system are as follows;
|TELEVISION||1||80 Watt||8 Hours||1 Day||8 Hours|
We have calculated out total AC power (8 x 80 watt) as 640 watts depending on all of the information about the device we are going to use in our off grid solar system project.
Of course, we do not accept it as 640 watts get 768 watts by multiplying the total AC output power with 1,2. Because there will be some loss in electricity generation with the solar energy system.
Battery Capacity Calculation for Off Grid Solar System
We have found our total AC power and now we are going to calculate battery capacity.
We calculate the weekly battery capacity with the following formula;
( ACt x 1,2 + DCt ) / Battery Voltage = AH / Week
(768 watt) / 12 Volts = 64 AH / Weekly
We have preferred the battery voltage as 12 volts for our solar energy system. Because television is not a device that consumes too much electricity and it is not a device that requires starting current.
It can work quite stable. Our battery capacity will be low for our off grid solar system project. There is no need for unnecessary battery cost by preferring 24 volts or 48 volts.
Now we have found our weekly battery current, how much daily amperage we need? We calculate this with the following formula;
(AH / Week) / 7 = AH / Day
→ We adjust this formula according to our need →
(AH / Week) / 1 = AH / Day
We accept the 7 value in the formula as 1. Because we are going to use the off grid solar system only one day in a week. As a result of the formula, we find out that we need daily 64 Ah battery.
However, actually, the result we found is not our real battery need. Because batteries have a certain loss in certain operating temperatures and none of the batteries are used until to the end. This is why we are going to multiply the battery capacity we are going to use in off grid solar system with 1,50.
64 Ah x 1,50 = 96 Ah.
The total battery capacity is 96 Ah and of course, there is not 96 Ah battery on the market. This is why we have two alternatives. The first one of these is using the off grid solar system economically.
So we can operate the television for 7,5 hours instead of 8 hours. If we use it economically, one 90 Ah battery will be enough for us.
Or we can use 115 Ah battery by using it more generously. Our choice is 90 Ah AGM Deep Discharge Battery and we prefer British company YUASA as a brand.
We have preferred 90 Ah battery capacity for our off grid solar system project. We have chosen AGM Deep Discharge Battery as battery type. And we have decided on British YUASA SWL 2500 FR as a brand.
We have calculated total AC power and total battery capacity for our electricity generation with the solar energy system. Now it is time to calculate the solar panel power.
Solar Panel Power Calculation for Off Grid Solar System
There are many brands and types of solar panels on the market. You can supply all of the solar panel types easily. Since our off grid solar system project is not complex and it will not be used during the 6 days of the week, we do not need a very complex solar panel.
First, we need to decide on the solar panel type. We eliminate the monocrystalline solar panel since it is a little bit expensive and will not be beneficial for our system.
Instead, we are going to prefer polycrystalline solar panels in our off grid solar system project. Because it is easier to supply and it is cheaper when compared to the monocrystalline solar panel.
Well, how many polycrystalline solar panels we are going to use and what should their watts be? Here, we are going to prefer the trial and error method. Firstly, we already have 150 watts Alfa Solar brand solar panel in our hands.
We need to check how many Ah current this solar panel produces. When we check this technical information for the current solar panel we see that it produces 8,62 Ah current per hour.
Our off grid solar system was intended for 8 months. Well, what is the daily sunshine period during this 8-month period? We are going to calculate it as 5 hours per day since the winter season is included in this period.
Because the morning sun and the noon sun are very different. What is important for us is the most efficient sunshine period and this is about daily 5 hours for the area we live in.
If our solar panel can produce 8,62 Ah current per hour;
In 5 hours, it produces 43,20 Ah current (5 x 8,62 Ah).
And our battery received 43,20 Ah current daily.
As total battery capacity is 90 Ah, our battery will be fully charged in about 2,5 days (90 Ah / 43 Ah = 2,1 days).
This means a quick charge. You can use lower power solar panel here. You can prefer a solar panel power where the batteries will be fully charged in 4-5 days. However since this is an example study, we are going to ignore this.
Let us warn again, the solar panel that we use will shorten the life of your electricity generation with the solar energy system.
We do not recommend too fast or too slow charge of the batteries under no circumstances.
We have chosen our solar panel type as polycrystal. We have determined its power as 150 watts and unit as one. Now we are going to choose one solar charge controller in order to transmit the current produced by our solar panel to battery.
Battery Charge Controller Device Calculation for Off Grid Solar System
You should pay attention to the following while choosing battery charge controller device for off grid solar system.
- What is the voltage of the battery connection?
- What is the voltage of the solar panel connection?
Battery voltage is 12 volts since we use one battery. Since we have one solar panel and it is 150 watts, it is again volts. This is why our battery charge controller must be 12 volts.
We have preferred ABAX brand 10 Ah battery charge device as solar charge controller for our electricity generation with the solar energy system. The thing you should pay attention here is you should make your selection in line with the total ah current you receive from your solar panel while choosing your battery charge controller.
Our solar panel provides 8,62 Ah current and since there is no 9 Ah charge controller device on the market, we prefer 10 Ah power device.
If you have placed two parallel 150 watt solar panels in your electricity generation with the solar energy system, then your total current would be 2 x 8,64 Ah = 17,28 Ah. In this case, you should prefer a 20 Ah charge device.
After we have calculated the total AC power, total battery capacity, and solar charge controller, now it is time for the last part, i.e., inverter calculation.
Inverter Power Calculation and Selection
We have to prefer an inverter in line with how much watt power output we want per hour while calculating the inverter power. Our AC output power per hour is 80 watt in our electricity generation with the solar energy system. This means that 80-watt inverter will be enough for us.
However, inverter types start from 150 watts on the market and this is because we have to prefer inverter with at least 150 watts. Inverter voltage will be 12 volts because our battery connection is 12 volts.
We are going to prefer Modified Sine Wave Inverter (square wave generator) as inverter type in our off grid solar system project. Because pure sine wave inverter will be unnecessarily costly for one television and modified sine inverter will do the work easily.
Inverter we are going to use in our off grid solar system project is 150 watts. Its voltage is 12 volt modified sine inverter and its brand is Linetech. There are many inverter types on the market and there are even pre-built circuits and designs that you can make your own inverter.
The reason why we prefer Linetech brand is the fact that the brand has a very good technical service and warranty.
Okay, Equipment for Our Off Grid Solar System Project is Ready But How Do We Connect Them?
I feel like you are asking this 🙂
Now all of the equipment we are going to use for our off grid solar system project is ready, there is only one thing left to do. Connecting all of the equipment and operate it.
You can follow the following steps in order to install the equipment for off grid solar system. It is quite easy 🙂
1. I assume that the direction and angle of your solar panel installed as it should be. There is two cable ends on the solar panel. These are (+) and (-) ends.
Connect the (+) end to PV(+) of your solar charge controller. In the same way, connect the (-) end to PV(-) part of the charge regulator.
2. There are two lead terminals on your battery and these are (+) and (-) ends. Connect the (+) lead terminal of your battery to BAT(+) part of your solar charge controller. Connect the (-) lead terminal of the battery to BAT(-) and the connection between your battery connections and solar panel connection will be completed.
NOTE: We have written down in steps however we recommend you to connect the battery and solar charge controller first and then solar panel and solar charge controller connection.
3. Now it is time for the inverter connection. There is two cable ends on your inverter device, these are (+) and (-) ends. Connect the (+) end to the (+) terminal of your battery. In the same way, connect the (-) end to the (-) terminal of your battery.
You may hear a sound while connecting the second connection, there is nothing to afraid of, this is quite normal 🙂
Important Note: Do not confuse with the (+) and (-) ends while connecting the inverter device to the battery. Your inverter will break down when you connect them wrong. Be careful in this connection and do not hurry up.
Image: A sample study from the solar energy systems we have prepared.
We have prepared all of the equipment and their connections for the off grid solar system. Your system is ready to operate. Now you can produce electricity with solar energy. We hope this article will be beneficial for you. We believe that information is more valuable when it is shared.
Note: This is a unique article, you can use it freely by giving credit.