How to buy the best solar panels for your home

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• Not sure where to begin? See our four steps to get started with solar.
• Want to find out fast which solar panels are the best? See our latest review of solar panels (for members only).
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• Interested in a solar storage battery? See our solar battery guide for more on how they work and whether they might suit your home.

Solar panels are increasingly being installed by homeowners who are worried about rising electricity costs, and who want a system that both cuts their bills and produces greener energy. We explain what you need to know before installing a solar photovoltaic (PV) system on your roof.

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How do solar panels work?

Some materials such as silicon can be made to produce electricity when light falls on them. This is called the photovoltaic effect. Solar panels use this to convert energy from sunlight into direct current (DC) electrical power.

An inverter unit then changes this into alternating current (AC) for your home's electrical circuits. Any excess energy can be fed back to the electricity grid or to your own battery storage system.

What's in a solar panel?

Most solar cells are made of silicon. Solar panels, also called modules, are each made of several solar cells (typically 60 cells, but some have 72 or more), connected together and sandwiched between protective glass and a backing plate. The whole panel is usually surrounded with an aluminium frame. A typical installation includes several panels connected together in an array.

Types of solar panels

Almost all panels used in home solar systems are mono- or multi-crystalline. While there are technical differences between these types, don't put too much consideration into this &#; it's much more important to consider other aspects such as price, rated power output, and warranties.

The rated power output, or capacity, of solar panels has increased over the years as manufacturers find ways to squeeze out more power. Not so many years ago, 250W panels were common &#; now, you'll often be offered panels of the same size that deliver 400W, 500W or even more.

Types of solar panel

The main types of solar panels you'll see on homes are monocrystalline and multicrystalline panels (aka polycrystalline), but there are other types too. Here's a quick explanation of the main solar panel types on the market today.

Most solar panels are DC, meaning they generate a high voltage Direct Current (DC) which goes to the inverter unit (called a string inverter) on your wall, which in turn changes that to Alternating Current (AC) for use in your home's electrical circuits. 

Some panels are classed as AC, which come with a pre-installed microinverter on each panel,  typically an Enphase microinverter. Though the panel itself generates DC power as usual, it's immediately converted to AC by the microinverter. See our solar inverter buying guide for the pros and cons of string inverters vs microinverters.

Monocrystalline panels are typically black and have a reputation for higher efficiency than multicrystalline (or polycrystalline) models, which are typically dark blue and are sometimes said to have better temperature tolerance. The differences come from the manufacturing processes of the silicon cells in each case. Monocrystalline panels are increasingly the common option for home installations.

In practice there's not necessarily a clear advantage either way: as with most high-tech products, solar panels are a complex assembly of many components and the overall performance depends on more than simply the type of cell.

Interdigitated back contact solar cells (IBC), or rear contact solar cells, are a variant of standard solar cells. They can achieve higher efficiency by having all the electrical contacts on the rear of the cell (rather than at the front), so there are no metal contact strips preventing light getting to the cell surface.

A PERC cell, or Passivated Emitter and Rear Cell (also Passivated Emitter and Rear Contact), is a high-efficiency form of solar cell. The back of the cell is more reflective, which means that any light which passed through the cell and missed its chance to cause the silicon to generate electricity can be reflected back through the cell for a second chance. 

There's a lot more to it than that, and there are some potential pitfalls with this technology, but the basics are that PERC cells are generally more efficient at producing electricity than non-PERC cells. 

Heterojunction or HJT is a solar panel design that's been around for many years, and is often claimed to be the simplest and most effective design for improving solar panel efficiency, with the potential to surpass PERC cells for efficiency as the technology continues to develop. It combines layers of conventional crystalline silicon cells with thin film solar cells. 

Thin film solar cells are made from a thin layer of photovoltaic material (such as amorphous silicon, cadmium telluride or copper-indium-gallium-selenide) on a base plate of glass, metal or other substance. 

This technology is evolving and while it promises more flexible applications than standard solar panels, it's so far generally less efficient and is rare in rooftop arrays. It's used in various large and small applications, from building-integrated PV systems to solar-powered calculators and garden lamps.

Bifacial panels have solar cells on both faces, i.e. front and back, as their name implies. When mounted in the same way as a regular solar panel, the front faces the sky as usual, and the back picks up scattered and reflected sunlight from the roof or ground. 

They can also be mounted vertically, for instance facing east-west, to maximise solar power generation all through the day (one side catching the morning sun in the east, while the other side catches the afternoon sun in the west) &#; this may be particularly useful in mass arrays on a commercial solar farm. 

Depending on how they're mounted and how much reflected sunlight is available, they can deliver anything from 5% to over 20% more power than a single-faced panel of the same power rating. Their power output is very dependent on how they're mounted (more so than for regular panels) and industry is still working on an agreed standard method to rate their overall power output. 

We included one in our past reviews as an experiment. The results were encouraging and indicate that when used in a well-designed installation, bifacial modules can indeed deliver more power than an equivalent single-faced panel.

Bifacial modules are fairly new and not widely used yet, but we think it's likely they'll become more common in future. 

How much do solar panels cost?

According to SolarQuotes, these are the current price ranges for good quality solar panel systems.

• 5kW: $&#;
• 6.6kW: $&#;
• 10kW: $&#;13,000

Those prices include the usual rebates and incentives. Expect to pay the higher end of the range if you're going for top-quality components or if your home has unusual installation requirements. 

CHOICE tip: Compare prices for whole systems, not just individual panels.

How many solar panels do you need?

The power output of your whole solar system matters more than the size or number of panels. The higher each panel's nominal power rating (and actual power output), the fewer panels you'll need (or the more power you'll generate).

If you have plenty of roof space, you might find it more economical to buy cheaper panels with lower efficiency and just use more of them. Most solar panels are about 1.6&#;2 square metres in area, but they vary in length, width and power output.

CHOICE tip: Fewer panels can mean a quicker installation.

An example: You could use 20 x 320W panels, with each panel about 1.7m2 in area, for an array of 6.4kW and about 34m2 total area. But you could go for a higher power panel from the same range, such as a 345W panel, and get a 6.9kW system that takes up the same area (though the panels might cost a little more). 

Alternatively, you could make a 6.6kW system using 15 x 440W panels of 2.21m2 each, and it would also take up roughly the same area. 

What size solar panel system do you need?

To size your solar panel system you need to work out how much electricity you use and when you use it. 

As a guide, a typical home uses 20kWh of energy a day. A 5kW solar system would meet most of the daytime power needs of such a home. 

However, these days solar panels are relatively cheap, so it usually makes sense to put on the biggest system that your roof can take and that you can afford. The excess electricity can go back into the grid and earn you some money via feed-in tariffs, or charge a home storage battery so that you have cheap power after sunset. 6.6kW is a common size for new systems, but bigger systems (9 to 10kW or more) are also being purchased. The bigger systems often include a battery. 

Owning an electric vehicle (or planning to own one in the future) is another reason to consider upsizing the solar panel system, to ensure you've got plenty of cheap solar power to charge the car.

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Read more: Sizing your solar panel system

How much money will you save using solar power?

It takes anywhere from two to seven years for a solar system to pay for itself &#; after that is when you can start counting the savings.

Payback times vary depending on where you live in Australia. The infographic below shows averages for capital cities.

Read more: Solar panel payback times

The time it takes for a 5kW system to pay for itself in capital cities.

Perth: 3&#;4 years

Darwin: 5&#;6 years

Brisbane: 4 years

Sydney: 4 years

Canberra: 4&#;5 years

Melbourne: 5 years

Hobart: 5 years

Adelaide: 2&#;3 years

What are the environmental benefits of using solar?

Your home solar panel system has several benefits for the environment. 

Reducing pollution

Power stations fuelled by coal and gas produce a lot of air pollution, in the form of particulate matter, carbon dioxide, methane and more. These have a direct impact on the climate and on personal health. Solar panels don't generate any such pollution. 

There is some pollution generated during the manufacture of solar panels (as with all manufactured items), such as greenhouse gases and run-off chemicals. This is not to be ignored, but in general the amount is very small compared to the pollution produced by coal-fired power. There are also concerns about used and broken solar panels ending up in landfill at the end of their life, resulting in wastage of useful materials and possibly heavy metal contamination. 

As the solar panel industry has grown, however, so has solar panel recycling, and there are now several solar panel recycling plants in Australia and around the world.

Reducing water usage

Australia is famously the driest continent on the planet, and traditional electricity generation in coal-fired power stations uses a huge amount of water (over 158 billion litres per year for New South Wales and Queensland alone). Even more water is consumed in mining and processing the coal itself. Solar panel manufacture also uses water, but once up on your roof and running, the panels don't use any water at all (except for an occasional cleaning, perhaps).

Reducing our dependence on fossil fuel

Much of Australia's electricity is still generated in coal-fired and gas-fired power stations. But while there are still significant deposits of coal and gas, those supplies won't last forever, and in any case it's becoming less economical to extract them. Gas companies are increasingly looking at fracking to extract more gas, a controversial process with potentially significant environmental risks of its own.

If your solar panel system is set up to export any unused power to the grid (as most are) then not only are you paid for that exported electricity, but it means there's more renewable energy in the system for others to use, and less need to generate electricity from coal or gas. Rooftop solar is increasingly one of the most significant sources of electricity in Australia; in , it delivered 11.2% of Australia's electricity.

All in all, while they aren't entirely problem-free themselves, solar panels are a great option for reducing your home's environmental impact, as well as saving you money.

Rebates and feed-in tariffs

There are two main incentives that can help make your solar PV system more affordable: small-scale technology certificates (STCs) (the "solar rebate") and feed-in tariffs (FiTs). We explain these below. Apart from those incentives, other solar rebates and loans are available in some states and territories:

Australian Capital Territory: Sustainable Household Scheme

New South Wales: Rebate Swap for Solar (households on the Low Income Household rebate can swap it for a solar panel installation on their home)

Northern Territory: Home and Business Battery Scheme

Queensland: Battery Booster program

Victoria: Solar Homes Program

The battery schemes above are included because they can apply to a new solar PV system which includes a battery.

Rebate schemes change from time to time, so it's worth checking the federal government energy website to see what's available in your area.

Always check the terms and conditions for any rebate scheme carefully to make sure you're eligible, and what steps you need to take. For example, many schemes apply only to certain regions or postcodes, may have limited places available, or are only available to households below a certain income level, or you might need to have your proposed system approved by the scheme before it's installed.

What is an STC?

An STC is a form of currency available to owners of small-scale renewable energy systems. Under the federal government's Solar Credits Scheme, eligible households receive money for STCs created by their PV systems. STCs were formerly known as renewable energy certificates or RECs. Currently, the scheme allows you to cash in the certificates you could earn over the next several years straight away.

A new solar PV system will generate a certain number of STCs depending on the size of the system and its location. Generally, the bigger the system and the sunnier the region it's in, the more STCs it will generate. As an example, a 6.6kW system in Sydney installed in will generate 63 STCs.

While the government has set a price of $40 per STC sold through the STC Clearing House, the price you get will vary depending on how you choose to sell your STCs.

Is the STC rebate going to end?

You may see scare campaigns from some solar installers, usually towards the end of each year, urging you to "buy solar now before the rebate ends". The STC scheme isn't about to end, but it does reduce slightly at the end of each year. It was never planned to run forever &#; its purpose is to incentivise more Australians to install solar and help make the solar market mainstream and affordable. It diminishes a bit every year and will eventually become zero in .

How to sell your STCs

Have the installer sell your STCs for you: The easiest and most common option is to allow someone else &#; usually the installer &#; to sell your STCs on your behalf. This may then be applied as a discount to your installation costs (so it acts like a rebate). The benefit is that the process is easy, with all the paperwork taken care of for you. The downside is you're likely to get a little less money per STC as the installer will take a cut of the transaction, or impose an administration fee, for handling the STCs. You can usually expect about $35&#;39 per STC.

Sell your own STCs: The second option is to sell the STCs yourself, which involves considerable paperwork, applications and fees. Depending on the number of buyers and the time it takes to complete the process, it may be months after installation before you receive your funds. There's no way to tell exactly how long you could be waiting, which means unless you have the capital you might find yourself out of pocket. You might be able to get a better price than that offered by the solar installer, though maybe not enough to be worth the effort.

How much money will you make selling STCs?

Using the above example, a 6.6kW system installed in in Sydney will generate 63 STCs. Assuming a sale price of $39 per STC, that's a $ saving off the cost of the system.

CHOICE Tip: To calculate how many STCs your system will generate, use the government's calculator.

A FiT is the rate you're paid for feeding electricity back into the grid (assuming your panels are grid-connected). Nowadays you don't make much money from FiTs, so it's best to maximise your own use of your solar PV and minimise your export to the grid.

How feed-in tariffs work

Almost all FiTs around Australia are now net FiTs. This means a household is only paid for surplus electricity fed into the grid after domestic use is subtracted. If your system produced kWh, for example, and you used kWh of electricity in your home during the day (the time when your PV system was generating power), the rate is only paid for the 500kWh difference.

(Gross feed-in tariffs, where households are paid for all the electricity their panels produce, irrespective of their own domestic electricity consumption, are no longer available for new applicants in any state or territory.)

How much money do you make from feed-in tariffs?

FiT rates around the country have plummeted over the past few years. Coming off a high of up to 60c per kWh in some parts of the country several years ago, FiTs are now usually in the range of 4c to 8c/kWh, depending on where you're located and which energy retailer you choose. However, they can go up to 15c/kWh or more, depending on your energy retailer, time of day and other factors.

Note: In some states and territories, newly installed solar PV systems no longer qualify for a guaranteed FiT. However, many energy companies offer a voluntary FiT instead. Check with your energy company or the appropriate regulatory authority in your state:

• ACT: Everyday Climate Choices
• NSW: Independent Pricing and Regulatory Tribunal 
• NT: Territory Renewable Energy
• Qld: Department of Energy and Public Works
• SA: Department of Energy and Environment
• Tas: Office of the Economic Regulator
• Vic: Department of Environment, Land, Water & Planning
• WA: Energy Policy WA

Do you need a solar storage battery?

A home storage battery lets you store the electricity generated by your solar panels to use at night or on a cloudy day.

You may want to consider a system that includes battery storage. The Tesla Powerwall is the best-known solar battery, but there are many other brands in the market. Generally, however, storage batteries don't make full economic sense yet for most homes.

Read more: How to buy the best solar battery storage

Can you get solar in an apartment or rented home?

You can, but there are more challenges to overcome. We outline your options below.

Apartment buildings face more challenges than a freestanding house when it comes to installing solar panels. The elevated roof space may require cranes for access, and it can be complicated to share and meter the solar power between all the apartments. The owner's corporation needs to agree to any such installations and despite the potential benefits of solar, it may be hard to get enough owners to agree to the work.

One solution can be to have the solar panel system supply power to only the common areas, such as lighting in hallways, foyers and carparks, along with lifts, swimming pool pumps and so on. This will help reduce the building's running costs, and therefore keep strata levies down.

If the apartment building is relatively small, it can be possible to install solar panels that directly feed into individual apartments. But this can still be a big project &#; fair allocation of roof space, and the complexity of the wiring, are just two of the hurdles you need to clear.

For more 144 half cut modules cells supplierinformation, please contact us. We will provide professional answers.

Another solution is to engage a solar company such as Allume Energy that specialises in apartment buildings. They can provide an installation that includes hardware and software management of the solar power distribution to make sure it's allocated fairly between apartments (and the common areas) and is metered accordingly. This adds expense to the installation, but may be the only practical option for a large apartment building wanting to provide solar to most or all apartments.

The remaining option for an apartment building is for the solar to be included at design and construction stage. This is still a complex piece of work but can be the best way to truly integrate solar power into the building.

Renters have limited options for going solar. While some rented properties will already have solar panels, most do not.

As a renter, you could put a case to the property owner for getting solar installed. You might offer to pay more rent in return for the reduced power bills you'll get. The owner gets the benefit of increased rent, plus longer-term added value for the property.

Alternatively you could invest in a community solar project or solar farm. While you won't directly get solar power from it, you do get dividends or credits on your electricity bill, and you're helping to add more renewable energy into the grid.

Future changes to the electricity market

The electricity grid in Australia wasn't originally designed to cope with large numbers of homes exporting solar power into it. There are proposals for how to modernise the grid and manage it more effectively and fairly, and these include a possible surcharge &#; or "solar tax" &#; to owners of solar PV systems who want to sell their excess power to the grid. 

What's this all about, and does it mean a storage battery becomes a better option?

What's the problem with the electricity grid?

The electricity grid in Australia was originally built with the expectation that electricity went in one direction only, from power stations to homes and businesses. It wasn't designed to also allow for solar-generated power to flow back the other way. While that's been possible to a reasonable extent so far, the grid is starting to hit the limits of how much electricity it can handle from domestic rooftop solar.

The grid needs a lot of work to update it to become flexible enough to take full advantage of renewable energy sources including domestic solar feed-in, but also allow flexibility for all consumers. This work has to be paid for somehow. Currently, some consumers (renters, apartment owners, low-income households) have little access to the benefits of solar power but must still pay for electricity, and to some extent they subsidise the benefits that solar owners obtain.

Solar owners also are disadvantaged by the lack of flexibility and modernisation of the grid, in that in some areas, there is already limited or zero feed-in due to capacity constraints on the local grid. This means that some solar owners get limited or no feed-in tariff income, and their excess solar-generated electricity may be wasted.

What's the solution?

The Australian Energy Market Commission (AEMC) has proposed several changes to how the market and the grid operate, to allow more flexibility in how power is bought and sold, and to better accommodate domestic solar, batteries and electric cars in future.

New electricity infrastructure ("poles and wires") will still be needed, but we also need to use the electricity supply in a much smarter way, and rebuilding the grid so that it properly accommodates solar-generated electricity from homes is part of the solution.

The proposal includes the option of a surcharge to solar PV system owners who export power to the grid (the so-called "solar tax").

The AEMC expects that the proposed surcharge for solar owners will only have a small effect on their overall return from feed-in tariffs (FiTs). For example, a consumer with a 6&#;8kW solar panel system is expected to see their typical return from FiTs drop at worst by $106, from $ p.a. to $ p.a. 

For most solar owners the impact will be less than that, and possibly even a net increase in returns, if they're able to time their solar export to deliver excess energy when the grid needs it, such as late afternoon or evening (when energy retailers are likely to offer a better FiT to attract more exported power). The AEMC has published an explanation of the proposals and modelling.

This situation may make it more attractive to install panels that face partly east or west, to maximise power generation in the morning and late afternoon rather than only in the middle of the day. It may also make storage batteries more economically attractive. If FiTs end up as low as a few cents per kWh during the middle of the day, but increase to much better rates in the late afternoon and early evening when demand on the grid is highest, it may make sense to store your excess power in a battery and sell it back to the energy retailer in the evening.

It will also make sense (even more than it does now) to use as much of your own solar power as possible, as that will reduce any surcharge for exporting power to the grid.

When is all this going to happen?

The roll-out of the new charges and rewards is at this stage still a proposal and won't take effect for a few years, and there will be trial programs and consultations along the way. This is not to say all will be perfect &#; we need to keep watch and make sure the new system truly is fair and reasonable.

But in short, there's no need to panic, and it still makes sense to consider investing in solar power for your home right now.

Solar panel buying guide checklist

• Assess what energy you currently use and the system capacity you need (and can afford).
• Check if your roof faces the right direction. Only north-facing panels will produce their full capacity.
• Make sure there are no trees, power lines or other structures shading your roof.
• Find out what local council approval is needed. Increasingly, local councils have staff on hand to help people make the best decisions on solar.
• Try to figure out your system's payback time.
• The inverter (which converts DC power from the panels into AC power for your home) is a key part of the system. See our guide to buying a solar inverter for all the details.
• If you're considering adding a battery, see our guide to solar storage batteries to understand the pros and cons.
• Get multiple quotes from installers to ensure you're getting a good deal, and make sure your installer is CEC-accredited (see below). 
• Make sure your solar panels meet the required standards (see below).
• Check your solar panels' product and performance warranties &#; see below for what these are.

Installation, standards, warranties and maintenance

If you want to be eligible for small-scale technology certificates (STCs), your solar and/or battery system must be installed by an accredited installer. Previously installers were accredited by the Clean Energy Council (CEC). As of , the accreditation body is Solar Accreditation Australia. You can check whether an installer is accredited with them here.

Look for an accredited company: 

• that is a signatory to the accreditation body's code of conduct
• that has been in business for a while 
• with an established track record
• with relevant experience
• that has specialist expertise
• that has a good reputation.

Solar panels, inverters and batteries must be on the CEC's list of approved products.

See our guide to finding a good solar installer.

Solar panels in Australia work best when they're facing north, pointed directly at the sun, at an optimal angle and not blocked by trees or shading.

Solar panels to suit a very hot climate

Some panels have better temperature tolerance than others (look for a lower 'temperature coefficient') and are therefore a better choice in hot climates.

Although solar panels are meant to sit on roofs in direct sunlight, they actually become less efficient as they get warmer, due to the physics of the photovoltaic effect. So you'll sometimes get less power from the panels on a very hot day than on a mild day (and remember, even on a 25°C day, your rooftop panels could be operating at well above 40°C). Solar panel power ratings are based on standard conditions (25°C panel temperature).

Panels should be installed in a way that allows air to circulate underneath to help keep them cooler.

You should make sure any solar PV system you consider has met Australian and international standards. To be eligible for small-scale technology certificates, your solar panels must be certified &#; ask your installer to supply proof. You can check the CEC's list of currently approved inverters, modules (panels) and batteries to confirm.

Also, the Clean Energy Regulator has partnered with the solar industry and peak bodies to introduce the Solar Panel Validation Initiative. This scheme allows businesses in the Small-scale Renewable Energy Scheme supply chain to check if solar panels are genuine before they are installed. Participating installers and suppliers will be able to use the scheme to provide you with a verified report confirming that the panels they've installed on your roof are genuine and that you're getting what you've paid for.

There are two warranties provided for solar panels: one for the product, and another for its performance.

Product warranty

This is the warranty for the panel itself. It's the typical type of warranty that offers repair or replacement if there are any manufacturing faults. Many solar panel product warranties are for 10 or 12 years, but increasingly we see manufacturers offering 15 years or more, even up to 40 years for certain Sunpower solar panels. As always, a longer warranty is a good indication of the manufacturer's confidence in their product.

It's important to know the difference between the product and performance warranties &#; you'll see a 25-year performance warranty promoted more loudly than a 10-year product warranty, but the product warranty is the one that you're more likely to call on if there's any problem.

Performance warranty

The performance warranty is a guarantee that that as long as the panel is functioning and undamaged, it will still produce a guaranteed minimum percentage of its claimed power rating after a certain period, typically about 80% after 25 years. The warranty usually also promises that the panel will degrade in an orderly, linear fashion &#; that is, it will only lose a small and predictable amount of power output each year.

Most solar panels have 25-year performance warranties, and most solar PV systems should last at least that long (with some maintenance along the way). Some performance warranties now run longer, for 30 or 40 years.

Note that it can be hard to tell whether your panels are truly performing as they should, especially after several years. If you believe your panels aren't performing as expected, the performance warranty may put the onus and cost on you to have the panels tested in order to make a warranty claim.

It's also a question as to whether a manufacturer will still be around in 20+ years to honour a warranty claim. Nevertheless, these warranties do give some assurance that manufacturers are confident in the long-term performance of these products.

Other warranties

As well as the warranties for the solar panels, you should also get a warranty from the installer for their workmanship in installing the system &#; the mounting racks, wiring and connections. This will typically be one or two years &#; which should be enough to detect any major problems &#; but as always, a longer warranty is better.

The inverter will also have its own warranty, typically five years but they can be up to 10 years or more.

Home insurance

Your solar panels and inverter are part of your house and as such are covered by your home insurance. However, you should make sure your home's insured amount is increased, to cover the replacement cost of the solar panel system. See our guide to solar panels and home insurance.

• What is the FiT you'll be paid and how often will you get it? How will you receive it? As a discount off your energy bill or as a standalone cash payment?
• Will you need to change to a new smart meter and what will it cost?
• What is the cost of the electricity you purchase from your retailer (in cents per kWh), and will you lose your off-peak rates if you install solar?
• Will you be charged a higher daily fixed charge if you connect your solar PV system?
• Do you have to pay any additional fees?

Solar panel systems don't need a lot of maintenance, but it's a good idea to check in on the system occasionally to see how it's performing. Your electricity bills and the display panel on the inverter can be enough to tell you whether everything is functioning as expected.

For a more detailed check-up, a solar monitoring system such as Solar Analytics can give you a wealth of information about what your system is doing and when, such as the power produced, how much is being sent to the grid, and your home's power consumption at any given moment. A monitoring system will cost you a few hundred dollars extra though, either as an upfront cost or as a yearly fee.

Unless your panels are particularly prone to being covered with dust, leaves or other matter, there's usually no need to wash them &#; rain will do that well enough.

It's worthwhile having the whole system inspected by a professional (an accredited solar installer) every few years to make sure all is well and the electrical connections are safe. It's also worth doing if you've just bought a property with an existing solar panel system. An inspection can cost up to about $300. Some states and territories have audit or inspection programs to ensure ongoing safety of solar panel systems.

Solar panel specifications explained

When you look at the specs for a solar panel, you'll see a lot of numbers and terminology that you might not understand. Here are the basics.

This is the amount of power (electricity) the panel should deliver under standard lab conditions (25°C, sea level air pressure and a specific amount of sunlight or irradiance). It's measured in watts (W). When you see a panel described as 350W or 400W, that's the nominal power rating.

The higher the number, the more electricity you'll get from the panel.

Note that real world conditions on your rooftop are rarely very close to the standard lab conditions; temperature, humidity and the amount of sunlight will all vary depending on the time of day, the weather and the season, and on average each panel will usually deliver less than its rated amount. But in ideal conditions (such as midday on a cool, clear, sunny day), the panel should deliver close to its rated power.

A measure of how efficient the panel is at converting sunlight to electricity; or looked at another way, it's the panel's electricity output (in watts) compared to its surface area. The bigger the number, the better. Due to the physics and engineering of solar cells, a large amount of the sunlight energy can't be converted directly to electricity; efficiencies of about 19% to 22% are common.

This is how much you can expect any individual sample of the panel to vary from its nominal power rating. Small variations in the manufacturing process mean that not every panel is identical. For example, a 400W panel with a claimed power tolerance of 0 to 5W should deliver at least 400W under standard lab conditions, but could actually be up to 405W. So the rated nominal power is actually a minimum rating in most cases.

This shows how well the panel responds to higher temperatures. The hotter a solar panel gets, the less efficient it becomes. A panel with a lower temperature coefficient will be better suited to operating efficiently in hot climates. The temperature coefficient is shown as a percentage change per degree Celsius, such as -0.37%/°C. In this example, for every degree the temperature rises above 25°C, the power output of the panel will drop by 0.37%.

That doesn't sound like much, but it adds up; even on a mildly warm sunny day of 25°C, the temperature of a black solar panel on your rooftop could be up to 50°C. In this example, (50-25) x 0.37 = 9.25. So the panel has lost 9.25% of its capacity due to the heat; for a 400W panel, that means it's effectively operating at 363W.

Typical panels on the market today have temperature coefficients ranging from -0.30%/°C to -0.40%/°C.

Don't worry too much about this number, but if you live where the rooftop temperatures are often going to be fiercely hot, then it's worth considering panels with a good (low number) temperature coefficient.

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Installing Solar Panels for your home or business is an important and long-term decision; you will see the effects of this decision for a long period of time. On the other hand,  there are lots of information regarding purchasing solar panels and many manufacturers that can confuse you when you want to build your solar power system or choose the best solar panels in Canada. 

This article is a comprehensive guide, but easy to read, that you can find out everything you need to know before investing in any solar power system on top of your roof, for your business and many more.

What Factors Should We consider when buying Solar Panels?

Living off-grid has been increasingly popular in recent years, and a reliable source of energy is one of the essential requirements. Solar energy is the most widely used of the few energy options currently accessible for obvious reasons, including its extraordinary flexibility and dependability of operation, as well as the ease of installation.

 To build a solar PV system for residential or commercial purposes, you need to consider these four essential parts: 1- Reliable Solar Panels 2- Choosing the best Solar Inverters 3- Having an efficient Battery bank 4- Installing Solar Charge controllers. Although we have some other components, like Battery monitors, that help you run your PV system properly, we can not sort them on the must-have list if you have a limited budget.

In this article, we will help you find the best solar panels available on the market, and for the rest of your PV system, you can refer to our previous blog posts and read about Lithium batteries, Inverters, Charge Controllers and many more.

Installing Solar Panels and producing your clean electricity is a costly investment in a few first steps but think of it as a long-term investment. By installing solar panels, you are not only saving money on your electricity bill and removing your Carbon footprint but also increasing your property value for the future.

On the other hand, buying solar panels is, going to be a one-time action for the long term, and it needs your full attention and, consequently, a wise decision. In this regard, in the following paragraphs, we will review some factors you should consider regardless of the level of your technical knowledge.

Warranty

The first and foremost factor you need to consider is the warranty period the solar panel has support from its manufacturer. Everything degrades and loses efficiency over time, including solar panels. Many manufacturers will promise that their panels' power output won't drop below a specific level over the course of 25 years. In case the panels themselves fail, several panel manufacturers also offer a materials warranty.

Generally, we have two types of warranty: 1- Performance Warranty and 2- Product Warranty. So when you are choosing solar panels for any purpose, just make sure to check both warranties. The industry standard is 25 years for performance and ten years for products/materials. It is evident that the more years you get support from the manufacturer, the more relief you will have for the future of your solar power system.

Technology

When it comes to technology, reading through various factors and technical information can be overwhelming for many customers. All technical details have been written on any solar panels spec sheet, but reading for a non-technical customer is quite tricky. You can just ignore all those bulky files and use this as a technical guide to picking the right panel tailored to your needs.

Solar panels can use different Cell types, cell arrangements and cell efficiency: 1- Monocrystalline, 2- Polycrystalline, 3- Half-cut, and 4- Shingled. We will briefly review two famous types and their pros and cons. 

Monocrystalline: The most efficient ones

As the most effective choice, monocrystalline solar panels are frequently recommended and work best when placed for bigger energy systems in commercial and residential buildings. Monocrystalline might nevertheless be employed in smaller systems because panel sizes do vary.

Due to their high silicon purity, monocrystalline solar panels are the most effective at converting light into energy. Despite this, monocrystalline solar panels are frequently the most expensive; if you want the highest productivity and cost, choose this kind.

Polycrystalline

Polycrystalline solar panels, as their name suggests, are made by melting many pure silicon crystals together. However, having more crystals isn't necessarily better. The efficiency of polycrystalline panels is actually lower than that of monocrystalline panels. However, given that they are available in a range of power levels from 5W to 250W and above, they make a viable choice for both modest and large-scale installations.

Moreover, the "greenest" panel choice is polycrystalline solar panels since they make full use of the silicon used in their production. Although they are not quite as efficient, polycrystalline solar panels are also less expensive than monocrystalline ones.

Size

Solar Panels come primarily in two sizes: 1) 60-66 cell Residential Size and  2)72 cell commercial size. Despite the name, you can use either on a residential roof, but commercial-size panels are a bit bigger and heavier than the residential ones. 

Their advantage is they can pump out more watts so that you can squeeze more power out of fewer panels on the roof. But the downside is because they are bigger and heavier, they are challenging to work.

Efficiency

The amount of light converted into electrical energy by a solar panel determines how much power your system will produce. The better, the more effective (and more expensive). Purchasing the largest and most effective solar panel is not always the best option since you risk paying more money than necessary to meet your energy needs.

You should evaluate your needs and choose the solar panel that best meets them. This means that you shouldn't undervalue your requirements but also shouldn't overestimate them either. If you need any further assistance in this regard, our experts in Volts Energies in Canada are ready to help you determine and choose the system you need.

Temperature Coefficient

Temperature Coefficient is about how heat affects a solar panel's operating effectiveness after installation. The lower the percentage per degree Celsius, the better, as solar panel warming hastens their ageing.

The best Solar Panels available on the market

Various types of solar panels are available on the market, and they produce different types of Solar panels in different sizes. Among Brands like LG, CanadianSolar, SunPower, Peimar and Renogy, we will review the top efficient and highest-quality brands that our solar experts have tested in Volts Energies in Canada.

For all home and commercial uses, LG Solar Panels from LG Electronics have a remarkable power output. All solar energy products from LG, including the Neon and bifacial solar panels, benefit from the company's most recent cell technology, which offers the most robust performance in the market over a 25-year warranty. The minimum output of LG solar panels is guaranteed to be between 86% and 88.4% after the 25-year warranty period.

You can get the ideal blend of high efficiency and adaptability from Italian-made Peimar solar panels. These solar panels operate remarkably well and guarantee maximum output even in bad lighting and weather situations because they make use of high-quality solar cells. Installation is straightforward because of the sturdy yet incredibly light frames. In either home, commercial, or large-scale situations, these panels offer a sturdy installation.

The high-efficiency Peimar monocrystalline solar panels offer clients maximum output and super high performance (over 20% efficiency) by combining revolutionary production processes and cutting-edge technical approaches. This makes it possible to utilize fewer panels to produce more energy, which is useful if space is limited or there are difficult environmental conditions. 

Conclusion

One of the most concerning questions or concerns among people who want to go green and install solar power systems on top of their residential or commercial buildings is how they can find the best solar panels on the market. 

This article is a thorough 101 guidance for those who want to know more about the critical factors that make a solar panel worth buying before any investment. If you have any further questions or need a more personalized consultant, contact our experts, who will help you build your dream Green home.

For more information, please visit Solar Panel 350 Watt.