In this article, we will get to know how to build an off-grid solar system. But before knowing this, we read little what solar panels system is.
Solar Panels System
A Solar panels system comprises many components but the major are solar plates, inverter, solar batteries, charge controller, and many more. It absorbs sunlight and converts it into electrical energy which is direct current (DC). Then after that, the inverter converts DC into alternating current (AC) which we use to power appliances at home. So because of continuous production, we have to store power and for that purpose, we use solar batteries.
Building Solar Panels System
Today, the prices of solar panels system are quite low but still, people try to save money as much as possible by installing solar panels system by themselves as installation still costs so much. We are gonna give you points that would help you in buying and wiring components and would tell you series too. Major components like solar panels, inverter, solar batteries, charge controller, etc are required. Despite these components are necessary too like wiring, Wire, MC4 Connector, breaker, meter, fuses, and many others. Important steps are following;
Step 1: FIGURING OUT LOAD
For us, it is the most important step and many people skip and regret later. So please figure out how much energy you need. So what you have to calculate is how many appliances you would have to power like refrigerator, TV, fans, bulbs, lights, etc. Figuring out all that stuff would help you to buy the required components. Assess the Watt Hour which is equal to the product of power rating of your apparatuses and time ( hr) of the run.
You can use the following calculators;
Step 2: COMPONENTS SELECTION
We already have mentioned the functionalities of some major components. Here in this section, we are gonna focus on major components one by one.
Solar panels have to produce energy from sunlight then after it, the inverter produces usable energy. You should know how much energy you would require to run your residential necessities. Then there are many types of solar panels, Monocrystalline is costlier and efficient than the polycrystalline panel. So please select panels that are efficient and can produce the amount of energy that even replenishes your solar batteries too after getting an empty state.
And you have to keep in mind that you do not have the same number of hours of sunlight in the winter as you do in the summer. So you should have extra panels for that case you can use them for producing more energy. Energy from the sun for a location is known as “sun hours”. The amount of “sun hours” is the available sun shining on your panels at an angle throughout the day. And we all know the more sunshine, the more solar panels would be efficient.
So now you should know how much power you need, you need to figure out how many batteries you need to store it. Solar batteries store energy so you can use it when there is night or no sun. You have to buy batteries based on how many days you have to store energy and how many appliances would get powered. So when you start caring about nights and the absence of sun, you have to think about winters too, so buy batteries keeping all this stuff. Again use a calculator to assess how much energy/power you would need. And you to keep in mind that solar batteries are different from vehicle batteries. Vehicle batteries designed for a deep discharge and on the other hand, solar batteries enable you for deep slow discharge.
The charge controller manages the flow of power between solar panels and solar batteries. It regulates the voltage and current produced from solar panels. But you need have to consider a bit more while selecting it. The charge controllers are available with two technologies, PWM and MPPT. You can use a PWM charge controller If the voltage of the solar panels matches the voltage of the battery bank. So, if you have a 12V panel and a 12V battery bank, you can have PWM. If your solar panel and the battery bank don’t match, and can’t be wired in series to make it match, you need to use an MPPT charge controller. If you have a 20V solar panel and you have a 12V battery bank, you need to use an MPPT charge controller.
Inverter converts direct current (DC) produced from solar panels into alternating current (AC). You should have an idea of what type of AC power you require. So If you are in North America, the standard is 120/240V split-phase, 60Hz and if you in Europe and Africa and some countries in South America, it is 230V single 50Hz. Always check out the specs of the inverter.
Three types of inverter are following and we have given so you could read more about them;
Other Mini Components
Components like Solar panels, Inverter, charge controller, solar batteries, etc are the major necessities for a solar system. But on the other hand, components like utility power meters, wiring, fuse box connections, disconnect switches are something that without whom a solar system can’t get completed. And there is another thing that matters is how you mount solar panels matters.
So for little bit guidance, we tell some of the key points you must follow while mounting solar panels. First of all, choose a suitable location on the rooftop, or on the ground, where the sun does not face any distractions to reach solar panels. And if you are gonna place them on the ground, then you are gonna have a choice to make stands for solar panels at home. There is another important thing you should keep in mind that you have to make stands in a way that solar panels face maximum sunlight for better efficiency.
Step 3: WIRING
So when we connect multiple solar panels in a 12-60 volt off-grid system, you have a few options: parallel, series, or a combination of the two.
Keep in mind: Solar panels have negative and positive terminals. So current uses to flow from the negative terminal through a load to the positive terminal.
Parallel circuits have multiple ways for the current to move along. If an item in the circuit is broken or not worked, current would use to move along the other pathways. in such a case, the current would ignore the broken path. This type of circuit is used for most household electrical wiring. For example: when you turn off your fan, it doesn’t also turn off your lights.
Wiring Solar Panels in a Parallel Circuit: So for wiring solar panels in a parallel circuit, connect the positive terminal of the first solar panel to the negative terminal of the next one. So It same as connecting all the positive terminals of all the solar panels, and all the negative terminals of all the panels together.. In a parallel connection, the voltage remains the same but the current rating of the circuit is the sum of all the devices. So let us say two batteries of 12v, 100Ah are connected in parallel – then the system voltage remains 12 volts but the current rating is 100 + 100 = 200Ah. Similarly, if two solar panels of 17V and 5 amps are connected in parallel then the system will produce 17 Volts, 10 amps.
Series circuits have only one path or way for current to travel on. So you can say it is the opposite of the parallel circuit. Therefore, all the current in the circuit must flow through all the loads. A series circuit is a continuous, closed-loop – breaking the circuit at any point stops the entire series from operating. An example of a series circuit is a string of old Christmas lights so if one bulb breaks, the whole string turns off.
Wiring Solar Panels in a Series Circuit: So for wiring solar panels in a series circuit, connect the positive terminal of the first solar panel to the negative terminal of the next one. So Lets say 5 12V batteries are connected in series, then the combination will produce 12 + 12 + 12 + 12 + 12 = 60 volts. In a series combination, the current or amperage is the same. So if these devices were batteries and each battery had a rating of 12 Volts and 100 Ah then the total value of this series circuit would be 60 Volt, 100Ah. If they were solar panels and each solar panel had a rating of 16 volts (Osc voltage) and were rated at 5 amps each then the total circuit value would be 80 volts, 5 amps.
We would start wiring from the charge controller. So At the bottom of the Charge Controller, there would be three signs. The first one from the left is usually for the connection of the Solar Panel having positive (+) and negative (-) signs. The second one with plus (+) and minus (-) signs are for the Battery connection and the last one is for the direct DC load connection like DC lights.
Share your thoughts on how to build an off-grid solar system
Join the the discussion in the comments.