If you are considering switching to solar energy, this is one of the first questions that would pop up in your mind. And, naturally so. How can a solar energy system work at night without the essential component sunlight?
Once you find the answer to this, so many more are bound to follow. Do solar panels produce electricity on cloudy and rainy days? Does it work on moonlight? If it doesn’t work in these situations, how to manage the power needs?
This article will help you find answers to these questions and more. Let us begin with how solar panels produce electricity?
How does solar power work?
Solar panels use the photovoltaic effect to convert the solar energy from the sunshine falling on it to electrical energy. The photovoltaic effect relates to the formation of the electric field in two oppositely-charged semiconductors joined together at a junction.
The photons in the incident sunlight dislodge the electrons in the atoms, making them move freely. The resultant flow of electrons constitutes an electric current. The electric current formed in individual photovoltaic cells and solar panels are brought together with proper wiring. The power generated by PV cells is direct current or DC.
As direct current is not compatible with most appliances and devices, it needs to be converted to alternating current or AC. The inverter attached to the solar system does this work. The alternating current is then fed into the main switchboard to help it reach all electrical appliances and devices.
Do solar panels work when not in direct sunlight?
Now that we know how solar panels work by tapping the energy in the sunshine to generate power, it leads us to the next question – Is direct sunshine necessary for power generation in solar panels? Or will they work even with indirect sunshine?
The good news is they do. Solar panels can generate power even with indirect sunshine. The scientific explanation goes like this. It is the photons present in the sunshine that acts as a trigger in knocking off electrons in the atoms, creating a flow of electrons and thus, generating electricity. Heat energy in daylight has got nothing to with power generation.
These photons are present in daylight, irrespective of whether it is direct or indirect sunshine. This means solar panels produce electric current even with indirect sunshine. However, the electricity output is bound to be less than when in direct sunshine.
Do solar panels work on cloudy and rainy days?
Cloudy days, rainy days, at night, and in winter months – how will these affect electricity generation?
The solar power system is directly affected by seasonal and weather variations. It works at its optimal level when exposed to bright direct sunshine. Anything less is bound to bring down its output and efficiency and ultimately the current output.
On cloudy days, though direct sunshine is not available, indirect sunshine will still reach the surface of the earth by deflection. Again, the density of cloud cover is also a factor in power generation. The denser the cloud cover, the less the electricity produced.
The same is the case on rainy days. As some sunlight will reach the earth through the rain and by deflection, the solar panels will be able to generate energy, albeit less.
Do solar panels work in winter?
During the winter months, as long as there is daylight, the solar panels will generate power. As explained earlier, the production will be less. However, if it snows on the solar panels, it will obstruct the sunshine falling on the solar panels. The snow will have to melt off or needs to be removed for the solar panels to work.
Colder temperatures are found to increase the efficiency of solar panels. The heat energy present in the sunlight is found to bring down the efficiency level of solar panels and consequently the current generation.
77°F or 25°C is considered the threshold for this. This means a cold climate is optimal for the efficient working of solar panels.
However, the shorter winter days, snowfall, cloud cover, and lower angle of the sun will reduce the amount of sunlight falling on solar panels and thus the efficiency and power generation.
What happens at night if you have solar panels?
Solar panels do not work at night. They require sunlight to generate power. As there will be no sunlight, both direct or indirect, at night, solar panels won’t be able to produce current.
Often, we find the night well-lit by moonlight. This leads us to the question – Do solar panels work with Moonlight?
The short answer is no.
The moon doesn’t radiate light as the sun does. Moonlight is merely the reflection of sunlight falling on it. Moonlight doesn’t have photons that can trigger the photovoltaic effect in solar panels. So, solar energy generation is not possible with moonlight even if it is bright.
What time do solar panels start working? Or, what are the working hours for solar panels?
Anytime when sunlight falls on the surface of solar panels, it will produce current. So, solar energy is possible only during the day. Then the question arises – what about the electricity requirements at night?
How to manage your energy needs at night with solar panels?
At night, when solar panels cannot generate energy, there are two methods to choose for meeting the energy needs – net metering and energy storage using a solar battery.
In the net metering arrangement, you continue to be connected to the power grid using a bi-directional meter. That is a meter to keep tabs on the inflow and outflow of electricity.
During the daytime, when your solar system generates more energy than your usage, the excess energy is fed into the grid. The utility compensates for the exported energy with credits or payments that will be adjusted in the electricity bill.
At night or whenever the solar energy system is not generating power or if there is a shortfall in the power generation, you may draw energy from the grid to power your homes. The energy drawn from the grid will be adjusted against the credits or billed.
The net metering arrangement allows a seamless power supply when connected to a home solar system. It acts as a communal storage solution for the energy generated by solar systems. If there is ample sunshine during the daytime, it is possible to keep the electricity bills zero with the net-metering arrangement.
Batteries offer a personal storage solution for the energy generated by solar panels. The battery, when included in your solar power installation, can store the excess electricity generated during the daytime or whenever there is lots of sunshine and allows you to use it at nighttime or whenever there is a shortfall in electricity generation by the solar panels.
Net metering vs solar battery
Both net metering and solar battery enable a 24×7 power supply using solar energy installation. However, the similarities end there.
While net metering is an energy storage solution at a community level, batteries offer a much simpler and personal solution for energy storage. The difference is substantial on many counts, the most important being having total control over the energy generated and its availability when using batteries for storage.
Though net metering is an efficient solution to energy storage, the rates offered by utility services in many areas are skewed against the consumers. The utility charges higher rates for the energy consumed from the grid, while the reimbursement for the energy exported is less. This means consumers have to export more energy to the grid than they consume to ensure zero billing.
Again, in case of grid failure, access to grid energy is lost. This won’t be an issue with storage with batteries.
Another drawback of choosing net metering is its unavailability in many areas. Even in regions it already exists, utility services are discontinuing the arrangement as it is detrimental to their survival.
Despite the advantages that batteries offer, the fact remains that they are expensive to install and maintain. Net metering offers a cheaper method to ensure round-the-clock power supply with solar installation.
One of the ideal solutions to energy storage with solar systems is to have both – net metering and batteries. When they work in tandem, it is possible to get the best out of both. In such a case, the energy is drawn from the battery before consumption from the grid. This way, the loss from rate difference can be minimized.
Anti Solar Cells
Jeremy Munday, a professor in the Department of Electrical and Computer Engineering at UC Davis along with graduate student Tristan Deppe has come up with an innovative concept of solar cells that work at night.
Published in the January 2020 issue of ACS Photonics, the anti-solar cell is a thermoradiative cell that produces electricity by radiating infrared light (heat) into the cold depths of space. This is a reverse of the process happening in conventional PV cells. Instead of absorbing energy from the sun, it radiates energy into space.
The UC Davis engineers contend that anti-solar cells are capable of generating a significant amount of energy.
Abundant, sustainable, clean, and free – solar energy can help in meeting your energy needs without compromising on your goal of reducing carbon footprint and fighting climate change.
Solar panels do not produce electricity at night. Their efficiency may be below par when it is rainy or when the clouds are blocking the sun. It may not be able to generate sufficient energy at times when there is not ample sunlight. These shortcomings can be rectified with net metering arrangements or batteries. Or, better still with both working in tandem.
You can make the most out of the sun with a solar power installation by pairing it with a battery or opting for a net-metering arrangement.