Panels: what actually matters
The solar panel market has matured. Most panels from established manufacturers will perform well for decades. The differences between brands are real but smaller than the marketing suggests. Here is what to focus on.
Efficiency
Efficiency measures how much of the sunlight hitting the panel is converted to electricity. Higher efficiency means more power per square metre of roof — which matters if your roof space is limited. Modern panels range from about 20% to 24%. The difference sounds small but adds up over a full array. If you have plenty of roof space, a slightly lower-efficiency panel at a lower price can be the better deal.
Power output (wattage)
Panels are rated in watts (e.g. 400 W, 440 W). Higher wattage means fewer panels for the same system size. This matters mainly for installation cost and roof layout — fewer panels means fewer mounting points and a simpler install.
Warranty
Look at two numbers: the product warranty (covering manufacturing defects, typically 12–30 years) and the performance warranty (guaranteeing the panel still produces a minimum percentage of its rated output after 25–30 years, usually 80–87%). Longer is better, but a warranty is only as good as the company standing behind it — which brings us back to choosing established brands.
Temperature coefficient
Panels lose efficiency as they get hotter. The temperature coefficient tells you how much — a lower (more negative) number means more loss in hot weather. This matters more in hot climates. Most modern panels are in the −0.30% to −0.35% per °C range; premium panels can be as low as −0.26%.
Brand and bankability
There are hundreds of panel brands. A few rules of thumb: buy from manufacturers that have been making panels for at least 5–10 years, that have a local warranty and service presence in your country or region, and that appear on recognised industry tier lists. Your installer should be able to explain why they chose the brand they’re quoting. See our panel product directory for specs on common models.
Inverters: the brain of the system
The inverter converts the DC electricity your panels produce into AC electricity your home uses. It also manages safety, grid compliance, and monitoring. Inverters fail more often than panels and have shorter warranties, so the choice matters.
String inverters vs microinverters vs optimisers
There are three main types:
- String inverters — one central unit. Simple, reliable, cost-effective. Best when panels are on one or two roof planes with no shading. If one panel is shaded, it can reduce the output of the whole string.
- Microinverters — a small inverter on each panel. Each panel operates independently, so shade on one doesn’t affect the others. More expensive but better for complex roofs or partial shade.
- Power optimisers — a middle ground. Optimisers sit on each panel to maximise output, but a central inverter still does the DC-to-AC conversion. Similar shade benefits to microinverters, often at a lower cost.
For most straightforward installations, a quality string inverter is the best value. If your roof has multiple orientations or shading issues, microinverters or optimisers are worth the premium.
Hybrid inverters
If you plan to add a battery now or in the future, a hybrid inverter is usually the right choice. It handles both solar and battery in one unit, saving you the cost of a separate battery inverter later. Even if you’re not installing a battery today, a hybrid inverter “future-proofs” the system at a modest extra cost.
What to look for
- Warranty — typically 5–12 years. Some brands offer paid extensions to 15–20 years. Since inverters are the component most likely to need replacement, a longer warranty has real value.
- Monitoring — most modern inverters include an app or web portal that shows real-time generation and usage. Make sure this is included.
- Brand reputation — established brands with local support are important. An inverter failure with no local service can mean weeks without solar. See our inverter product directory for common models and specs.
How much should brand influence your decision?
Brand matters — but less than you might think, and less than your installer. A mid-range panel from an established manufacturer, installed well by a reputable company, will outperform a premium panel installed badly by a fly-by-night operator.
Use brand as a filter (stick to established manufacturers with local warranty support), then let your installer recommend the best value option for your roof and budget. The questions in our choosing an installer chapter will help you gauge whether their recommendations are trustworthy.