The four main components of a solar power system

The vast majority of panels sold these days are ‘monocrystalline half-cut’ panels.  A few years ago someone realised that you can make solar panels a little more efficient and a little more shade tolerant if you chop the square solar cells in half. Hence half-cut solar panels were born. They work so well they’ve pretty much taken over the market.

Pro-tip: There are some benefits to using half-cut or shingled panels over conventional ones if you have shade that creeps up on the solar panels through the day. Otherwise, don’t stress – any cell arrangement will work well.

It doesn’t really matter if you get mono, poly, regular, half-cut or shingled solar panels.

What matters most is that you get a good brand that has a solid support team.

Solar Panel Brands

Now, you probably don’t know a good solar panel brand from a bad one. And why should you?

To get an idea of how buying premium panels will affect your budget, going for a high-end brand such as Sunpower over a budget-end brand like Jinko can add about 30% to the total system cost.

The difference in *performance* between budget and premium brands is marginal. The main difference between the two is:

• How much their energy output will degrade over the years.
• The length of their product warranty, although cheaper brands are catching up on this.

For example, some good 415W solar panels are warranted to have 87.4% of their rated output after 25 years and have a 25-year product warranty.

But Top-end 420W panels are warranted to have 92% of their rated output after 25 years and have a full 40-year product warranty, with output warranted to be 88.3 percent of the rated output at the end of that time.

But – the Top-end costs more than double that of a good panel. Is that slower performance degradation and longer product warranty worth the extra price? That’s a decision for you to make.

Component #2: Solar Inverter

The second main component of a home solar power system installation is the inverter. They come in two main flavours:

• A string inverter, which is around the size of a briefcase
• Microinverters, which are around the size of a paperback book.

Microinverters cost more than string inverters, but bring a number of benefits.

String inverters go on a wall, and all the solar panels connect to it. Microinverters go on the back of, or underneath/beside, each solar panel.

There’s also a third option – ‘power optimizers’. These are a hybrid of the two. An optimizer system has both a string inverter on the wall *and* optimizers beneath each panel – or just some of the panels.

Microinverter and optimizer systems have some benefits over string inverter systems, mainly around design flexibility for awkward roofs. 

But one of the core benefits spruiked by salespeople is around how they handle shade better than string systems. This may be partly true for budget-end string systems; but high-end string systems have advanced algorithms these days that perform just as well in many shade situations.

One unique advantage of microinverters is that they operate at a lower voltage, which is safer if there’s a fault in the installation. But this can be mitigated by choosing a good installer (see below) and getting an inspection every 5 years.

You can read about the pros and cons of each inverter choice in detail here.

Pro-tip: Never mount a string inverter where it will be in full sun. Choose a shaded spot, a cool garage, or ask the installer to build a simple shade over the inverter. Direct intense sunlight kills inverters because it cooks them – and in south Europe the sun is particularly harsh. Installing an inverter where it is exposed to direct sunlight may also void its warranty.

The inverter is the component most likely to fail in the first 10 to 15 years. This is because they work hard all day and they do wear out. If your inverter fails, it will bring down your whole system unless you’re using micro-inverters.

So even if you’re on a limited budget, I’d recommend considering a mid-range or high-end solar inverter. I’m confident they’ll last longer than the cheapest ones. High-end inverters (like Fronius) cost about 1000€ more than budget-end ones.

What about optimiser or microinverter based systems? Expect to pay an extra 2000€ or more than what a budget inverter system would cost.

Component #3: Racking/mounting

What connects your solar panels to your roof? The racking.

There is a wide variety of racking brands out there. At the end of the day, racking is simply aluminium bolted together.

Most brands are much of a muchness, except for premium brands. They provide more flexibility in the system’s design and may corrode less over decades.

The difference in price between a budget end brand and a premium end brand is around 100€ per kilowatt.

The main difference between racking brands is how easy they are for installers to work with, especially with difficult roofs. 

Component #4: Consumption Monitor

Consumption monitors are small devices that sit in your switchboard. They cost around 500€, and measure how much electricity is coming from or going to the grid.

To be clear – you can install a solar system without a consumption monitor. But we strongly recommend getting one. This is because inverters, out of the box, will only tell you how much solar energy your system is producing:

You’re blind as to how much energy your home is using – and when.

If you invest in a consumption monitor, your monitoring app will become much more useful. It will show both production and consumption: