Do solar panels need direct sunlight to work?

People have all kinds of questions about solar and doubts whether or not PV modules work in different circumstances. Which only makes sense — solar panels haven’t been around for that long yet. One of the most popular questions is “does solar need direct sunlight?” The answer is no: panels are fine using diffuse radiation, though their output decreases by a bit. There is more to that question though: let’s look at PV modules in different situations and see how they behave.

What time do solar panels get maximum output?

Generally, solar panels produce the most when the sunlight hits them at a 90° angle, which is ideally at noon till 14 hours. Positioning plays a huge role here. In the northern hemisphere you want panels facing south at a 30°-45° angle. It is not always possible — after all, usually you have to work with the roof that you have. 

However, imperfect direction of panels can have its perks. If your panels are turned to the south-west, then you get slightly more energy in the evening. It can be good if you spend most of your day at work and come back in the evening, because the array will be more prepared to support house energy consumption later in the day. On the other hand, if panels face south-east then they generate a bit more in the morning, when it can be important to reheat the house, cook the meals for the day and whatnot. 

Be sure to research local solar roof installers to get the best advice on placement depending on your location and needs. This will ensure maximum output and efficiency of your solar panels throughout the day.

Do solar panels work on cloudy days?

Solar panels work fine even on cloudy days, though their output is lower. The decrease depends on how low the irradiance levels fall. Generally, it is said the clouds can lower the performance by up to 40%. However, panels get better and better at working in low-light conditions. Models from some brands barely lose any production even on a gloomy day. Even if you don’t see any sunlight coming through the clouds, panels still make use of radiation that is invisible to the naked eye — that’s another answer to the question, does a solar panel need direct sunlight or not.

With top-quality solar panels at Kingdom Solar, you can expect your system to still generate a significant amount of energy even on cloudy days. That means that even UK residents, who are used to having cloudy weather most of the year, can still greatly benefit from solar energy.

Do solar panels work in the rain?

Rain also doesn’t really get in the way of producing energy. Panels are sealed tightly and water cannot penetrate the module. However, in wet weather there is a risk of Potential Induced Degradation which is a result of stray currents inside a panel. This phenomenon can bring the output of your array by 20-30% and you can’t really notice it without special equipment. PID was a common problem for most solar manufacturers in the 2010s, but now most modern panels have protection against it.

Do solar panels work in the shade?

Shading is a much bigger problem for solar panels than cloudy weather. Solar cells in panels connected in series which means that performance of one cell depends on the production of its neighbors. If one cell gets shaded, then the performance of the whole panel could go down. This is why manufacturers add bypass diodes into their panels. Diodes split panels into sectors and a shaded cell affect only the sector where it is located. Generally, a solar panel has three bypass diodes.

Half-cut cell design also provides higher shading resistance for a panel. Split cell panel is essentially two small modules that are wired in parallel and operate independently. As a result, in a half-cut cell panel you have six strings instead of three thus energy losses caused by shading are much smaller.

Use of battery backup in a solar system

The time when solar panels absolutely don’t work is at night — there is no sunlight. Before you ask, what the moon reflects is not nearly enough. This is why you have to rely on your grid at nighttime. Fortunately, electricity rates are usually lower at these hours anyway. However, if you can’t or don’t want to use a commercial grid, you can add a battery to your solar system.

To make sure that the battery is safe from the high voltage of the panels, purchase a charge controller. It’s not that expensive and definitely cheaper than buying a new battery every few years. The most popular type of battery to use was a lead-acid type for the past decades. However, lithium-ion batteries slowly but surely rise and soon may take the lead on the market. Which is only fair, since lithium-ion batteries are better in every way, except the price. Yet: lithium-ion energy storage cost steadily declines and becomes more and more affordable for everyone.

Type of inverters used in a solar energy system

Notice, however, that whether or not you decide to connect to the grid is going to determine what kind of inverter you need. Let’s look at four primary types of solar inverters so you can see which one fits your needs.

Grid-Tie inverters

Grid-tie inverters include string inverters and central inverters. The difference between the two is that the central inverter is designed to work with multiple strings of panels and is generally used in commercial and industrial-scope installations. Grid-tie inverters are always connected to the grid and if there is power outage, they shut down as well for safety reasons.

The string inverter is the most popular type of inverter out there. Traditionally, its biggest weakness was always the shading: if one panel underperformed, then the production of the whole string was dragged to the level of the weakest link. However, in most modern models this problem was addressed and solved to some extent. Also you can always add solar optimizers to your panels that minimize the impact of shading on the string and inverter output.

Micro inverters

Microinverters is a modern type of inverter that has only recently risen in popularity. Microinverters go on top of every module you have and convert DC to AC on the spot. Advantages of this type include very easy installation and great production. The downside is that microinverters typically end up being more expensive than a traditional string inverter. The maintenance also can be hard since all of your inverters are on the roof with panels. However, microinverters are very sturdy, compared to standard string inverters, and their lifespan is comparable to that of solar panels. 

Off-Grid Inverters

Off-grid inverters can’t be connected to the grid so their primary function is to convert DC from panels to AC for your appliances. They are designed to be paired with batteries so you can rely on your energy storage when solar panels aren’t active. Off-grid inverters can be very small in terms of output — these models are designed for mobile installations: RV and boat solar systems. 

Hybrid Inverters

Hybrid inverters are the most advanced type, because they can work with the grid and support energy storage at the time. Some models even include a built-in battery. This is a great choice for those who need uninterrupted power supply at all times. When the grid goes down, the inverter switches your house to the battery support.