How to determine the size of solar panel system you need?

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If you are thinking about going environmentally friendly and economical at the same time, chances are you have thought about switching to solar at some point.

If you are considering going solar, you sure are wondering what size of the solar power system will suit your household needs. The size of the solar panel system doesn’t mean the number of solar panels but the total capacity of your system. The capacity or size refers to the maximum electricity the system can supply.

Understand your electricity consumption

To get a view of what size is suitable for you, you need to understand your electricity usage. You can determine your consumption simply through your electricity bills. Your recent bill will help you understand your daily power usage. Your consumption is also dependent on the number of people living in the house, whether you use gas or electricity for cooking and heating water etc.
Power consumption is measured in kilowatt-hours (kWh).

What time of the day do you use electricity?

Another aspect to understand your electricity consumption is what time of the day you use electricity the most. Is most of the electricity used at night? This could be the case if your house is empty during the daytime when everyone is either off to work, school or college. If this is the case, then using solar would not be efficient enough as your generated electricity is mostly going to the grid. This may be useful in case you have a storage battery.

You also need to think, if you use more electricity on specific days like the weekends. Or when is your electricity consumption more- summer or winter?

Answering these questions will help you understand your usage better about peak hours consumption, seasonal consumption, and so on.

What does your future usage look like?

While getting solar installed, you need to be covered for the future as well. It is a huge investment and it should pay you back well. So, it is good to think about your future needs to plan for a better solar power system.

Upgradation in the future is also possible, but the best option is to go with the biggest system your pocket allows at the moment.

How to calculate the size of the solar panel system?

After you have understood how much electricity and at what time do you need it, you can estimate what capacity of solar power will help cover your usage.
This is with an assumption that your system is connected to the grid to cover for power during nighttime when solar power can’t be generated.

Electricity per kilowatt of solar panels

Solar panels are rated in watts(W) or kilowatts(kW). 1kW of solar panel approximately produces 4kW of electricity each day. Therefore, a 6kW system will produce about 24kWh of electricity per day with good sunshine.

The electricity generated depends on a few factors like your location, amount of sunlight, time of the year, system’s quality, panels’ age, and orientation etc.

How big can you go with your solar power system?

Your solar PV system needs to cover as much of your consumption as possible. It is best to consult your installer for the same. Getting solar installed is relatively cheaper now. So it is best to go however big is possible.

For most homes, 6.6kW systems are gaining lots of popularity. But bigger systems like 8-10kW are being accepted too, mainly because of storage batteries.

Getting a bigger capacity solar system will sure get you some feed-in tariff too. But keep in mind it’s not that generous anymore. What could really help is adding a battery to your system? That will allow you to be independent of the grid electricity.

Online solar calculators are available for you to estimate the size of your solar PV system.

What are grid-connected and off-grid?


Grid-connected systems have solar power systems and are also connected to the main grid for electricity. These are very common in Australia. During the day, the electricity is provided through the solar PV system while during nighttime, it is the grid electricity that powers the house(assuming there is no storage battery). Grid electricity also helps during an overcast day, when solar power can’t be generated.

Off-grid systems

With off-grid systems, households are only powered by solar power. These houses usually rely on some other source of electricity generation as well like wind etc. They are also mostly equipped with a storage battery system.
These are more expensive, complex and require more capacity than a grid-connected system.

Things to keep in mind during installation


North-facing panels work the best as maximum sunlight falls on them. North-East and North-West facing panels will work well too.

Roof surface area

Most houses have a good adequate roof surface, but there may be portions where shading is unavoidable. Panels are worked at correct angles and air circulation. Installers will make the best possible installation as per your roof.

Talk to installers

It will help you if you talk to your installer about the comprehensions you have. While you may have done your own research, getting a few quotes from installers will be good. The right installer will guide you through the entire process and will suggest to you what’s best for your requirement.

Inverters and Battery

An inverter is the main part of a solar PV system. It converts the direct current from solar panels into the alternating current that is used by all electric appliances to function. The capacity of the inverter needs to match that of the solar panel array. There are various types of inverters that can be used depending on your solar panels and consumption needs.

A storage battery helps you to store excess electricity and use it in times when solar electricity can’t be generated. They are relatively expensive and the payback time is longer too. You need to understand your needs well and then go for a battery in your system.

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