Solar panels are a low-maintenance medium of renewable energy. They reduce your electricity bills and increase your property value. It’s no wonder why many consider them a worthwhile investment. However, a hasty decision can mean missed opportunities as there’s more to consider than just the price.
Planning to install a solar energy system can be stressful. To help you on your solar journey, we have for you five major considerations, including what to know about solar panels. Feel free to use this as a guide to getting the most out of solar panels.
Let’s get started with the 5 things to consider when choosing the right solar panels to get the most bang for your buck.
1. Your Current Situation
First up, what do you actually need for your specific situation? Everyone has their own state of affairs. You may love what your neighbour has but it’s not necessarily going to be great for you. Of course, you can get whatever you want but it’s more than likely going to be inconvenient, inefficient or have wasted potential if you skip the evaluation of your situation.
Before proceeding, analyse your current situation to clearly establish what’s best for you.
Wattage requirements
One of the most important things to know is how much power you actually need. Without a number on this, you’ll either be disappointed with a lower power generation or you’ll overspend, leading to waste.
You can figure out your current energy use in watts using your current utility electricity bill.
Panel size & space requirements
Consider the free space you have to mount the solar panels. If space isn’t an issue, you can install multiple cheaper panels with lower efficiency. Space restrictions means you’ll have to look for smaller, more efficient panels. Foldable solar panels could be highly beneficial for you though they will cost more.
Say you’re going for a 5 kilowatt (kW) solar system. You can choose to use 20 x 250 watt (W) panels or go with 12 to 13 x 400 W panels. You’ll need anywhere from 25.5m2 up to 34m2 of roof space to adequately accommodate them. Mix and match accordingly to fit the available space.
Budget requirements
How much will you be spending on your solar modules? Here are some general cost estimates throughout Australia for PV panels of different system sizes.
| System Size (kW) | WA | SA | QLD | NSW | ACT | VIC | Average |
| 1.5 | $2450 | $2792 | $3280 | $2950 | $2770 | $3215 | $2909 |
| 2 | $2710 | $3150 | $3620 | $3230 | $3080 | $3478 | $3211 |
| 3 | $3010 | $3650 | $3860 | $3690 | $3740 | $3984 | $3655 |
| 4 | $3540 | $4185 | $4650 | $4055 | $4180 | $4599 | $4201 |
| 5 | $3650 | $4722 | $4980 | $4450 | $4560 | $5440 | $4633 |
| 6 | $4210 | $5320 | $5638 | $5166 | $5810 | $6650 | $5466 |
* According to SolarQuotes as of October 3, 2021.
A higher budget equals better solar modules with more features, higher electricity generation and more energy efficiency. In this case, you can choose to pay a bit more for everything to look a bit tidier and better overall.
A lower budget means you’re better off focusing on the core functionality rather than any bells and whistles. Do you really need flexible, folding panels instead of rigid panels with higher specs for the same price? Budget restraints influence choosing substance over style.
Climate & shade requirements
The climate and the amount of sunlight in the area determine the overall efficiency of your solar panels. Areas that get too hot during the summer require solar systems that are highly heat-resistant. Areas with shade due to trees or chimneys or occasionally cloudy weather are better off with more efficient solar panels.
Depending on the climate and the shade situation, you may need to install your system differently for maximum efficiency. A good solar contractor should help you assess this.
2. Types of Panels
What do you need to make a solar panel? Photovoltaic cells. These produce electric energy and multiple of these cells are merged together to form a solar panel. Photovoltaics is the branch of technology related to the conversion of light energy into electric current using semiconducting materials. It’s why solar panels are also called photovoltaic modules or PV modules.
Knowledge of the various types of PV modules helps you learn how to choose solar power systems that are right for you. Have a look at the major types of solar panels and what to know about them.
Monocrystalline panels
Efficiency: ~20% average
Why: Energy-efficient, space-efficient and long lifespan
Why not: Expensive and their performance in partial shading isn’t as well as that of amorphous panels
Each monocrystalline solar cell is made of a single silicon crystal, giving off a black hue. This allows for more efficiency while taking up less roof space. Their lifespan is a lengthy 25-40 years.
Polycrystalline panels
Efficiency: ~15% average
Why: Environmentally friendly and cheaper than monocrystalline panels
Why not: Cover a larger surface area, sensitive to high temperatures and slightly less efficient
Each polycrystalline solar cell is made of multiple silicon crystal fragments melded together, giving off a blue hue. Due to a simpler manufacturing process, you get a cheaper cost on these panels. They have an average lifespan of 20-35 years.
Thin-film & Amorphous solar panels
Efficiency: ~7-12% average
Why: Budget-friendly, flexible and good performance in low-light conditions
Why not: Less efficient, cover more surface area and degrade faster
Thin film and amorphous cells generate electricity using a very thin layer of photovoltaic material that’s applied like paint on a ceramic substrate. These panels have the smallest thickness but require more surface area. They can handle higher temperatures better but degrade faster than other solar panels, having a small lifespan of 10-20 years.
IBC & PERC solar panels
Efficiency: ~25% average
Why: Highly efficient, low degradation rate and better performance at higher temperatures
Why not: High upfront costs
Interdigitated Back-Contact (IBC) solar cells absorb more solar energy per cell using back-contact technology. Passivated Emitter and Rear Contact (PERC) solar cells use two added layers at the back of each panel to improve electricity production. Both are highly efficient, modern advancements in solar cell technology and, as a result, more expensive. They have an average lifespan of 25-30 years.
Bifacial panels
Efficiency: A boost of 11-27% efficiency on the type of solar cells used
Why: Energy-efficient and space-efficient
Why not: Expensive and not ideal on steep roofs since some space is needed between the surface and the backside of the panels
As the name suggests, bifacial panels have two faces that both generate electricity. The front face is the primary generator but, unlike monofacial panels, a clear back sheet allows for reflected and diffused sunlight to let the back of the panel also generate power. The lifespan depends on the type or types of solar cells used.
3. PV Module Cost vs. Value
As discussed previously, the types of solar cells used in PV modules contribute much to their price tag. Think and choose what’s right for you, not necessarily what everyone else is getting. In addition to this, there are other influencers on the cost and the value you get out of PV modules. Here are some of these factors that will teach you how to select a solar panel that’s best for you.
Conversion efficiency
If two solar panels are virtually the same, including cost, but one has a higher conversion efficiency, go for the more efficient one for more watts per solar panel. In most cases, though, you’ll find that the bells and whistles factor into the cost so go for what you need.
Power tolerance
Power tolerance on solar panels is the measure of electrical production above or below their rated capacity at any time. Suppose there’s a 100-watt (W) solar panel with a -10%/+10% power tolerance. This means its actual production can range anywhere from 90 W to 110 W. Thus, PV modules with a 0% or 0 W negative power tolerance means they should always generate their rated amount of power or greater.
Temperature coefficient
Ironically, the hotter it gets, the less efficient solar panels become. Say a panel has a temperature coefficient of -0.4% / °C and overall efficiency of 20%. This means that for every 1°C above 25°C or 77°F, the panel decreases in efficiency by 0.4%. At 35°C, this panel would be operating at around 16% efficiency.
If your area deals with extreme temperatures during the summer, it helps to keep an eye on the temperature coefficient of solar panels. Overheating also accelerates panel ageing and contributes to Light and Elevated Temperature Induced Degradation (LeTID) so the lower the percentage per degree Celsius, the better.
Durability & warranty
Solar panels are a long-term investment so they need to be durable. They must withstand bad weather conditions such as high temperatures, strong winds and hail storms. Check to see if the modules have been tested to pass mechanical stress tests and proper quality control.
The warranty period on offer will indicate the manufacturer’s confidence in this area. Look for PV systems with a 10-year warranty in addition to the industry-standard 25-year performance guarantee. If a panel suits you, a 5-year warranty should be fine as long as you properly maintain your system to increase its lifespan.
Potential-induced degradation (PID) resistance
Factors like voltage, heat and humidity can degrade solar panel capacity through leakage caused by damage. To easily avoid this, choose panels with inbuilt PID resistance such as solid encapsulation and diffusion barriers. This way, your panels will generate more electricity for a longer time period.
Light-induced degradation (LID) resistance
Trace amounts of oxygen in the silicon wafer of the solar panel, when exposed to a couple of hours of sunlight, can disperse throughout the cell and react with boron. As a result, the panel’s yield decreases. Good PV systems have little to no LID.
Easy maintenance
You’ll find it tedious to clean and maintain your solar panels unless they are installed in a flat, open area. Rainwater may pool around the edges, especially on panels installed at a low angle, and dirt can settle there to make it not only look bad but also less effective.
Consider solar panels with water drainage grooves and any other feature that can help in easy maintenance to save you much tedium down the line.
Embodied energy
Embodied energy factors into the environmental cost – the energy it took to produce the solar panels versus the time it will take to pay itself back. If you’re serious about the environment and going green, it’s something to consider.
4. Inverters
The electricity that your solar panels produce is essentially useless without inverters. Solar inverters or PV inverters convert the variable direct current (DC) into usable alternating current (AC). You have different options to choose from but your situation dictates what’s best for you. These are the major inverter options available.
String inverters
Also called grid-tie inverters, these small units connect a string of solar panels to generate an AC output. With power ratings ranging from around 2kw to 80kw, the string inverter is the ideal choice in most cases due to the lower power ratings of household PV systems. These are also cheaper than central inverters and easy to service.
For a rooftop or smaller system, going with the closest power rating string inverter is often the best choice.
Central inverters
Central inverters are larger units with typically higher power ratings. They focus all power into one place and are more expensive per unit than string inverters but you don’t need many of them. For instance, you may need hundreds of string inverters for a 20MW utility-scale project or just 5-7 central inverters.
Central inverters are credible and have been used in the market for a long time but they are more expensive to replace and have higher serviceability costs. If you’re considering this, make sure your PV system actually makes full use of it.
Microinverters
Microinverters are tiny units that are installed underneath your PV panels allowing them to be monitored individually. They function just like string inverters but you need one for each panel. Unlike standard string inverters, microinverters don’t limit electricity generation of your panels by the lowest producing panel on your roof so each panel can contribute their maximum efficiency.
You can choose this if your PV system has to deal with a fair amount of shade. It’s also great for expandability as you won’t have to worry about capacity management or adding in identical panels. However, they don’t come cheap and offer better value over time.
Power optimisers
Power optimisers are added to each of your panels to optimise the current travelling along your solar string and to constantly track the maximum power point (MPPT) of each individual PV module. They are inverters so you’ll still need a central inverter or string inverter but they offer microinverter benefits to your PV system.
If some of your panels are mounted in a shaded area or have more tilt, you can use power optimisers to increase your solar output. These tend to be more costly than using string inverters but slightly cheaper than microinverters.
5. Miscellaneous & Supplementary Inclusions
After examining your situation requirements, the various types of panels, PV module cost vs value sentiments and the inverter options, you may find these additional considerations useful.
Solar storage batteries
Solar storage batteries let you store the electricity your panels generate. This way, you can use it at night or on days when the sunlight isn’t as strong.
Aesthetics
Depending on your building type and roof space, you may need to consider what colour and look of solar panels to go for. Some may look great but not be as effective for you while others may ruin the look of your house even if functionally they work splendidly.
Return on investment
On average, solar panels pay themselves off in around 3½ years. Some systems can take as low as 2 years while others may take up to 7 years to pay themselves off. You can also go for interest-free finance where it’s like paying your regular electricity bill for a couple of years, after which you own the PV modules.
Solar panel direction
In Australia, North-facing solar panels produce the most electricity whereas South-facing solar panels produce around 17-28% lesser. PV systems facing west and east are around 15% less efficient and those facing north-west or north-east are only around 5% less efficient than north-facing systems.
In order to maximise self-consumption and use the least amount of grid electricity possible, consider your northerly facing roof space.
Solar rebates & tariffs
Depending on the state you’re in, the Small-scale Renewable Energy Scheme (SRES) can help you immensely with installation costs.
| System Size (kW) | Small-scale Technology Certificates (STCs) | Rebate Amount | |
|---|---|---|---|
| NSW, QLD, SA, WA | VIC, TAS | ||
| 2.5 | 35 | $1435 | $1225 |
| 4 | 56 | $2310 | $1906 |
| 5 | 71 | $2870 | $2485 |
| 6.1 | 86 | $3535 | $3010 |
| 7 | 99 | $4060 | $3465 |
| 10 | 142 | $5775 | $4838 |
* According to SolarQuotes as of October 3, 2021.
For more information, you can check out the small-scale systems eligible for certificates page on the government’s Clean Energy Regulator website.
Conclusion
Now that you’ve gone through the 5 things to consider when choosing the right solar panels, you should have a far better idea of how to proceed with your solar setup. Let’s go through a brief recap, which can also serve as your basic to-do checklist before making your final decision.
- Your current situation
Determine your wattage, space, budget and location requirements. - Types of panels
Learn what to know about solar panels and identify which suit you best. - PV Module cost vs value
Decide on the PV module after analysing its cost versus the value on offer. - Inverters
Choose the inverter that’s best suited for your solar setup and situation. - Miscellaneous & supplementary inclusions
Extra considerations to improve your solar panel setup.
Don’t let the planning and all the thinking stress you out. After these 5 considerations, you’ll almost certainly be getting the most out of your solar panels. If you need help with any of this or prefer to leave it to the experts, Gravity Solar is here to help.
