Mpfana Manu is a mechatronic engineer who's working in green energy electronics products.
Say you have installed a solar electric system for your home and you're expecting it to last for at least two decades without any trouble, just like the solar technicians said. Then after only a year the solar system starts tripping. I know the feeling. It's unbearably disappointing, considering all the money and effort it took to install it.
But don't knock your head off, you can fix the problem yourself. You just have to know how to troubleshoot the solar power system and how to solve the faults you find. So in this article you're going to learn all that.
Diagnosing a solar system can take a few hours or days before finding what the fault it. The time it takes also depends on the size and nature of your system. This is why it is wiser to start diagnosing the cheap and easy parts of the system.
You wouldn't want to spend hours opening and poking your inverter and then later realise that the fault was just a loose cable on the roof. So I'll show you a procedure you can follow when you troubleshoot your system.
Procedure for troubleshooting your solar power system
- Start with the solar panels.
- Then go for the cables.
- Check the batteries.
- Then the controller (and inverter if your system uses one).
This is just a general procedure you would use when you have no idea where the fault is. There are some instances where the fault is easy to pinpoint using the symptoms of the system. For example, it's easy to tell that the fault is in the inverter when electrical appliances produce a humming noise when powered by the solar electric system.
So it's also important to be aware of the status of all the components of the system before diagnosing anything. This could save you a tonne of time because you'll be having hints of where the fault might be.
I've made a table to give you hints of where the fault might be judging from the status/behavior of the components or the system itself. You'll still need to troubleshoot the supposed component to make sure the fault is there.
Finding the problem using the symptoms of the system
|Symptom/Hint/Behaviour||Component with problem/fault|
Humming electrical appliances that are powered by the solar electric system.
Sudden tripping of whole system during cold weather.
Lower power output levels during very warm or very cold weather.
Loose cable connection
System can power other appliances like refrigerators and lights but the televisions and computers are not responding to power.
Sudden drop in voltage between adjacent components.
Sudden loss of power when you're running high loads.
Solar panels or batteries or controller
Sudden loss of power and the batteries are totally discharged.
The system shuts down and then it turns itself back on after a little while.
The inverter becomes very hot and the system shuts down. When inverter cools, system starts working again.
System shuts down at night, then it switches back up in the morning after sunrise.
Troubleshooting and solving problems of the solar panels
Firstly, just physically investigate the panels and check if there are any cracks or breakages. Wash the panels with soapy water. A fast hose spray with water can do the job well. If there are any cracks on your solar panels, replace the panel. Depending on how bad the crack is, the performance of a panel is so low that it'll alter the power output of the whole array.
When the panels of the array are connected in series, the cracked panel can cause an open circuit and no electrical power goes to the appliances. Unless your solar system is a grid-tied system, electricity supply will be cutoff immediately. Open circuits upon cracking usually happen with small sized panels. Possible causes of cracking are as follows.
- Someone or something heavy stepped/hit upon the panel.
- Sudden shift of temperatures, from very hot to very cold. Happens at the equator but very rare.
When there are no cracks, the next thing to look at are the outputs of each solar panel. You'll need a multimeter to do this. Switch your multimeter to DC mode and test for the voltage across the negative and positive terminals of each panel. See if you're getting the expected reading. Do this during the day when the solar panels give their best.
And please, I repeat, please wear at least class 00 gloves for safety. Safety is extremely important. You could read all about safety precautions when tempering your solar system here.
A solar panel rated 12V should give anything between 8-16V. Any reading close to zero in broad daylight means the solar panel is damaged/malfunctioning and not fit to remain on your array, replace it. If all the panels are working fine and there are no irregularities in the voltages, move to the next part of the system.
Troubleshooting and solving problems of the cables
The cables are like the veins of the system. You'll need them to be physically accessible so that it'll be possible to entirely investigate them. In home solar electric systems, the cables may stretch from the roof through the ceiling to the ground floor. You start with the cabling on the ground, then on the roof and lastly, in the ceiling. The goal is to pinpoint the fault without doing much work and in less time.
The first thing when checking out a cable are the ends. See if they are connected to the inputs/outputs of the components properly. The connections should be tight and intact. If any connections are loose or pulled off, unscrew, attach and re-screw properly. All connections should be secure and terminated properly. Apply petroleum jelly on open connections to make them liquid-proof.
Please do this wearing at least class 00 gloves to avoid nasty electrocutions. A single electrocution from a high voltage system can send you to the grave so please, put the gloves on.
When you're done with the ends of the cable, take off one glove from your luckiest hand and touch the cable(which should be obviously insulated). Feel if it's warm or hot to your touch. If any cable is warm/hot, wear your glove and replace the cable with a better or new cable.
A warm/hot cable indicates that it has more electrical resistance than it should have and it dissipates electrical energy, thereby reducing the energy output of the system. A lower energy output makes the whole system start tripping when the electrical appliances demand more energy.
The last thing to check on a cable is whether it's conducting electricity or not. There could be a fault within the cable itself so you have to clear the doubt by finding out. You'll need your multimeter to test this. Switch the multimeter accordingly, and test for current in the cable. A zero or irregular/inconsistent reading means you've found the fault.
When all your cables are okay and you still don't find a fault after all the touchy feeling and testing of all your cables, move to the next component.
Troubleshooting and solving problems of the batteries
If your system is less than one year old, you can troubleshoot the batteries last because they are rarely the problem when the system is still young and fresh. When you're troubleshooting the batteries, please make sure of the following for the sake of safety.
- Do not smoke near the batteries.
- Remove metal watches and metal jewelry from your hands.
- Wear long polythene gloves to protect your from any contact with the battery acid. And you should be wearing a work suit for your overalls.
- Keep your toolbox away from the batteries to get rid of any chance of passively putting metal objects on the batteries that might short circuit them.
After ensuring your safety, when you get to the batteries you first check if the place where they're mounted is well ventilated. If there are any obstructions blocking any ventilation air paths, clear them out. (If there is no ventilation, hydrogen from the batteries builds up overtime and only awaits a small spark of fire to explode. You don't want that.)
Clean the batteries with a dry brush or cloth. Usually, batteries are connected in parallel to make a battery bank. Make sure that the connections between the batteries are tight and intact. Apply a layer of petroleum jelly on each connection.
Then use your multimeter to measure the voltage across each battery. If there is no failing battery, there should be no difference in the voltage readings. The maximum difference that you can tolerate is 0.7V. Anything greater than 2V indicates a failing battery. The failing battery should be replaced.
Whenever you replace, do not mix and match old batteries with new batteries. If your batteries are old and you intend to replace one battery, buy a second-hand battery of the same model of all your batteries. The second-hand battery should preferably be of the same age as your other batteries.
Battery manufacturers and DIY shops do sell second-hand batteries. And different models of batteries have different characteristics so stick to one model. In the case where your batteries are very old and have been the cause of your previous solar system failures, just replace the whole stack of batteries with new ones.
Say you haven't found any fault with the batteries(and obviously feeling frustrated by then), you then go to the next component of the solar power system.
Troubleshooting and solving problems of the controller/inverter
There are many different types and sizes of controllers and inverters and that makes it difficult to give you specific instructions here. Moreover, I wouldn't advise you to open and temper the electronics in a controller/inverter if you're not an electrician.
If you're to repair a controller/inverter, you will have to be an electronics engineer first. I am sorry if that was blunt but it's the truth. If you're sure that the fault is in the controller/inverter, the best thing you can do when you're not a professional is to replace the controller/inverter.
If you've done all the troubleshooting you've read in this article and still fail to find the problem with your solar system, then even an electrician will have a hard time finding it.
But I am confident that you'll find what the problem is, especially if your system is still young and has hasn't had lots of problems before. In the case you've done all and still have no idea what's wrong, you can then call for a professional with no shame.