Solar Power Components
Considering buying or upgrading a solar power system for your home or office? It might be useful to have knowledge of the various components that make up a grid connect solar power system. An elaboration on each one of these components can be found below, starting with the most important one.
Solar Photovoltaic (PV) Panels
Solar panels are designed to convert sunlight into electricity through the photovoltaic effect. The photovoltaic effect is the creation of voltage (or electric current) in a material upon exposure to light.
The modules that make up a solar panel are made up of crystalline silicon cells, also known as photovoltaic cells. Typically, these are of two types: monocrystalline and polycrystalline.
Monocrystalline PV cells have been regarded in the past as a superior technology, but nowadays polycrystalline PV cells are improving and are just as good and less costly than monocrystalline PV cells. To read more about the differences in types of PVpanels click here>
Learn how to read a solar panel data sheet here>
Find out the top rated solar panels (according to Photon Laboratories) here>
Solar Panel Prices
Solar panels are essentially a commodity these days, yet there are still small price variations to consider. Drawing comparisons can get tricky, even though we might think it’s much of a muchness– there are discrepancies to be noted. For example, we can only compare the price of a 200W panel with another panel that is 200W. A 250W panel, on the other hand, is like another species, it offers 20% more power than a 200W panel, there is no point in doing a direct price-to-price comparison in this case.
Power aside, there are other reasons that can effect price variations, such as brand, country of origin/manufacture, quality of materials, conversion efficiency and length of warranty. Therefore, picking up a solar panel solely based on price is not recommended.
Solar Panel Conversion Efficiency
There is a distinct conversion rate allocated to every solar panel to denote its efficiency. In most cases, there is a percentage rate that varies from 14% to 21% for most solar panels available on the market, as tested under standard temperature and conditions (STC).
Highly efficient solar panels are ideal for roofs with limited space, but they cost more. If free space on your roof is a non issue, then it may be cost-efficient to go for a cheaper solar panel with lower conversion efficiency, giving you more value for money.
Longevity and Warranties
Solar panels are expected to deteriorate gradually over time. For this reason, reputable solar panels come with a 25-year performance warranty. Manufacturers offer a declining performance warranty rate that normally covers 25 years as seen in the graph below.
The performance warranty percentage declines a percentage or two annually, by the end of the 25-year period the panels will be producing no less than 80% of the energy they were expected to produce in the first year after installation. If any of your solar panels perform below 80%, you can get a replacement immediately.
Another example of the declining warranty structure: If your solar panels perform below 90% efficiency after 15 years since the date of installation (see graph below), then you can, and should, claim your warranty.
Although this is the typical warranty structure offered by the majority of solar panel manufacturers, please allow for variations, and always check the fine print.
What else does a solar power system warranty offer you?
If a company offers a 25-year performance warranty, this means that 25 years is the life expectancy of the solar panels on offer. If the manufacturers believed the system would last beyond 25 years, then they would offer a longer warranty.
Grid-tie Solar Power Inverter
The string solar inverter is simply a box connected to solar panels. It is usually placed on a wall in your garage or a wall outside the garage close to the meter box. Cables run through the cavities of the walls to reach the solar panels. The string inverter converts direct current (DC) into alternating current (AC), turning the power produced from solar panels into power that can be used by your standard household and commercial appliances.
Some string solar inverter specifications to be mindful about:
You should look out for the maximum efficiency rating (normal range lies between 94% and 97%). You should also find out if the inverter has maximum power-point trackers (MPPTs) that help convert the maximum amount of power from the panels.
Central Solar Inverter Warranty
In most cases, centralised solar inverters have a 5-year warranty and consumers are encouraged to upgrade to a 10-year warranty by paying extra.
Micro Inverters are relatively new in market and offer a few different features that are essential. Micro inverters are much smaller – you might notice how there is one attached to the back of every solar panel. They perform the same function, only that they convert DC electricity from just one panel into AC. An AC cable connects all the panels and sends the electricity through to your switchboard.
Here are some of the benefits of installing a micro inverter solar system;
- Each panel has its designated maximum power-point tracker (MMPT), allowing each panel to perform at its best without being dragged down by panels that have a lower performance.
- Micro inverters usually have a warranty period of 10 to 25 years. Because these types of inverters aren’t exposed to high heat loads that are borne by central inverters, they tend to last longer.
- You can easily expand the size of your system if you decide to produce more solar power further down the lane. This way you don’t have to worry about how you will fit in more panels with the inverter you already have.
- Since every solar panel has its own designated inverter, you can use the homeowner’s web-based monitoring of the system to check the performance of every single solar panel. You might be able to see just by looking at the monitor if a panel is performing rather poorly, and investigate to find out if it is so because it isn’t receiving ample sunlight, because of the shade from a tree branch, for example. So it allows you to troubleshoot more conveniently. If the issue isn’t obvious you can always get an electrician to investigate the affected panel, but you will save money because the electrician won’t have to test each panel one by one just to find out which one is faulty.
These are aluminium rails bolted to your roof so that solar panels can be clamped onto them. The mounting is designed to ensure the array of panels can withstand strong winds and other harsh environmental elements common to New Zealand.
You can get solar panel mounting frames with the panels flushed to the roof or if you prefer, you can also get tilted frames to allow your panels to be tilted to a desired angle (as advised by your installer).
A structure for solar panels can be built on the ground as well if you decide it is better than placing solar panels on your roof. This will come at an extra cost that you will need to factor in. If you want, you can build the ground structure out of wood yourself so that it resembles a roof frame on concrete footing. Solar installers will be able to give you the exact specs for a ground mount frame. You can also buy readymade frames made out of galvanised steel. In the case of ground mounted solar panels, a trench in the ground will be required to feed the cable from the solar array to your main switchboard.
This is the wiring between the solar panels, the inverter and the switchboard. This cable is especially designed to be UV and weather resistant and to allow for a maximum permissible DC voltage.
As you must be aware by now, any electricity produced in excess of your needs is exported to the grid (your power supplier purchases this electricity from you). The export meter is a special kind of meter installed by your power company to allow them to measure exactly how much electricity they are buying from you. It is usually placed in your meter box, right next to the regular meter that measures the units of electricity you consume from your power supplier. If you have a new smart meter it may be capable of measure exported power as well, so you might not need anything new here. If you aren’t sure about how to get an export meter, your solar installers can arrange this for you.
Let The Solar Power Companies Pick The Best Components For You
Solar installers companies will generally have a small range of solar power components that they have selectively picked that they think are best for their customers. Generally you are not required to hunt down components yourself. Good solar power installer companies will find components that have the right balance of quality and price. There are alot of junk components out there that are very cheap. Experienced solar installers know not to pick these components, as these components are likely to fail which will look badly on their company and in the long run it will take up more of their time and money replacing faulty items.
To learn about what is required to maintain a solar power system, check out this blog article: Solar Power Maintenance & Monitoring.