You are planning to install solar panels to power your house and wondering how will I get electricity in the night, will solar panels work at night?
In this article we will see whether solar panels work at night? and also look in to ways to use power generated by solar panels at night.
Solar panels does not produce electricity at night because the photo voltaic cells which make up solar panels need sunlight to produce electricity.
However there are two ways using which you can still use solar power at night one is by storing excess power generated by solar panels in the day in a battery and then using it at night when the sun is set and second option is to install a solar on grid system or net metered solar system.
Do Solar Panels Work At Night?
Do solar panels work at night? the short answer is No, solar panels does not generate any electricity at night.
Solar panels are made up of photo voltaic cells which are composed of semiconductor material (Silicon). Semi conductor absorbs photons from the incident sunlight and release electrons which produce electricity. Since at night there is no sun, hence no sunlight, no photons absorption, no release of electrons and no electricity generation.
But there are two popular, tried and tested ways using which you can use the electricity generated by solar panels at night.
- Storing the electricity in a battery (Solar Off grid System).
- Installing a solar on grid system or grid tied system.
First lets start with the battery storage option and then we will go to solar on grid system.
Battery Storage To Use Solar Panels At Night:
This is an obvious solution and probably most of you already know this.
You can use a lead acid, lithium ion, lithium polymer battery to store the electricity generated by your solar panels during the day and use this stored power at night. This is known as Solar Off Grid System.
This sound simple but has several challenges associated with it.
Cons of Storing Solar Power in Battery:
- Batteries have limited storage and are expensive : Batteries offer limited storage meaning you can run your low power consuming appliances like light, fan, TV and all during the night with couple of batteries but to power high power consuming appliances at night using solar you will need to store more electricity which will require more batteries and thus more cost.
- Batteries have a recurring cost : Even if you use a good quality expensive Li Po battery for storage of electricity you will have to replace it in every 4 – 6 years. With time, the discharge rate of batteries increases and it;s storage capacity decreases, so in 5 years your battery will be of no use and has to replaced. The average cost of a 12 volt, 240 Ah battery in India is between Rs 15,000 to Rs 25,000, hence the cost of maintenance is high.
- You cannot run heavy loads like AC, water pump on batteries : Well you can run your AC at night using batteries but it will discharge your batteries quickly hence you will need ample storage to power your AC throughout the night which will cost your more as you will need more batteries.
The second option to use solar power at night is by installing a solar on grid system, lets look how it works.
Solar On Grid System To Use Solar Power At Night:
Solar on grid system is a grid tied system where you are installing solar system parallel to your existing electricity grid, so after going solar you will be having two sources of electricity one is your electricity provider and second is solar.
When the sun is shining during the day time you will use electricity from your solar panels to run your appliances and the surplus energy will be fed in the utility grid (export), but when the sun is not shining (at night and during monsoon) you will pull electricity from the utility grid (import) the same way you do before going solar.
Hence after installing a solar on grid system you will get electricity bill only for the excess units that you are borrowing from the grid (import – export). This type of billing is called solar net metering.
For example if your solar produces 20 unit of electricity during the day time and only 10 units is your live consumption, then the remaining 10 units will be exported to the grid which you can import during the night when your solar is not generating power. Hence your can power your house by solar at night.
If you live in city where there is grid connectivity and not frequent power outage then solar on grid system is best for you to use solar power at night.
Cons of Solar Net Metering:
- The biggest issue with net metered solar system is that since it’s a grid connected system, if your electricity provider cuts your power for some maintenance your solar will automatically shutdown for safety reason this is known as anti-islanding property. Hence no grid, no solar.
- Net metering billing should be available in your region. I live in Mumbai, India here the government has net metering policy hence we can avail net metering benefits but not every place has net metering policy in place, so that’s an issue as well.
- Your house needs to be connected to the utility grid for net metering. If you live in rural areas where there is no grid connectivity then net metering system won’t work for you, you have to rely on batteries to use solar at night.
Pros of Solar Net Metering:
- Solar net metering is a battery free system hence there is no recurring maintenance cost associated with it. Your overall return on investment will be low in comparison with a battery based solar system.
- You can power your AC, Water pump and other high power consuming appliances with solar net metering which is not possible with batteries.
Do solar panel work in rain and cloudy weather?
Solar panels can use direct or indirect sunlight to generate power, though they are most effective in direct sunlight. Solar panels still work even when the light is reflected or partially blocked by clouds.
- In cloudy days solar panels normally generate 30 % – 50 % of their optimum generation and
- In heavy rain solar panels generate 10 % – 20 % of their optimum generation.
Hence be rest assured there will be at least some power production even in stormy rain.
So if in summer your 1 kW solar system was generating 4 kWh of electricity in a day then in cloudy weather the same 1 kW solar system will generate approximately 1- 2 kWh of electricity in a day, whereas in heavy rain it may generate 0.5 – 1 kWh of electricity.
In the table below you will find daily solar panels generation in normal days Vs cloudy days Vs heavy rainy days. The below figure are for Mumbai, India here we receive around 300 sunny days in a year, if you live in a region where there are less sunny days then the generation figures will change.
|Solar System||Daily Solar Generation in Sunny Weather||Daily Solar Generation in Cloudy Weather (50%)||Daily Solar Generation in Rainy Weather (10%)|
|1 kW||4 kWh||2 kWh||0.5 kWh – 1.5 kWh|
|3 kW||12 kWh||6 kWh||1 kWh – 3 kWh|
|5 kW||20 kWh||10 kWh||2 kWh – 4 kWh|
|8 kW||32 kWh||15 kWh||3 kWh – 6 kWh|
|10 kW||38 kWh||18 kWh||4 kWh – 8 kWh|
This is just to give you a rough idea on what kind of generation you can expect from your solar panels during rainy season.
Apart from batteries and solar on grid system there is another way to store electricity for use at night, it is through a solar thermal plant.
In short what solar thermal plant does is it uses a series of parabolic panels to reflect light on to a pipe filled with oil. This oil is heated up during the day and the heat energy is stored in a special type of salt.
At night, you can use the heat stored in salt to heat the oil back again and use this heated oil to heat water and convert into steam. This steam can then by used in turbine to produce power.
Well this solution is neither for residential nor industrial user but for large solar power plants. If this sounds interesting to you then you can read this fantastic article in scientific america from David Biello – Molten salts can store the sun’s heat during the day and provide power at night.
Conclusion On Do Solar Panels Work At Night?:
Does solar panels work at night? No, solar panels does not work at night. However you can use batteries to store excess electricity generated during the day time to use at night when your solar panels s not working.
You can also opt for a solar on grid system with net metering. It allows solar roof top owner to export any excess electricity that their solar is producing during the day to the grid and import the electricity from the grid during night or times when their solar panel is not producing electricity.
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