Some frequently asked questions for newbies.

Q) What are the optimum conditions for a solar system to operate?

Pakistan is a great place to take advantage of solar energy. Systems here will produce more than they would in most places throughout Europe, despite the uptake being higher there. In Australia, a north facing roof between 20 and 30 degrees is the most ideal aspect. Lower or higher pitches can also be used, often to great effect. Panels facing east or west will still generate good yields, typically only 15-17 percent less than they would on the north. Eastern panels will generate power earlier in the day then north and western panels will produce power later in the day. Many people decide to put a portion of panels on the western aspect, as it improves the production later in the day when many appliances are commonly used. Using the power you're producing has financial advantages, which is why it can make sense despite the lower production.

Solar panels work on sunlight, not heat. Hotter days generally have more sunlight and hence better production, but the heat actually has a negative impact on them. Panels will never perform at their peak power output, as the test conditions they are subject to when they receive their rating will never be replicated in the real world (even in Pakistan). This is why suppliers give you an estimated energy yield in kWh (units) per day, as this is what you buy and sell from your energy retailer. In the middle of a perfect day in summer, you could expect to see your panels reach around 85 percent of their peak power output. Early in the morning, late in the day or in overcast conditions, this will be reduced. Your power output will bounce around a lot, so focus on your energy (kWh) yield when looking at the performance of your system.

Q) Can I add batteries to my system?

Yes, however it can be quite expensive if the correct provisions are not made.

An AC coupled or DC coupled system can be retrofitted to almost any solar power system currently installed. However, this is not very cost effective, as it requires extra components in addition to the batteries. There are many more cost effective ways to include batteries (now or in the future) to your system, so if you're considering adding batteries down the track, we recommend discussing this with one of our renewable energy consultants. Different batteries will require specific components to integrate them into your system, and there is often more than one approach that will work. We can determine the most suitable option for you and provide you with a system that has, or has the capability to add, your desired battery solution.

Q) Does shading affect the performance of the panels?

Yes, and it's usually quite significant. Solar panels facing north should ideally be in full sun from at least 9am till 3pm, as this is when they will produce the majority of their power. If they are eastern facing panels, then this changes to 7.30am to 1.30pm and for western facing panels, 11.30am to 5.30pm.

Shading from objects like flue vents, trees and other structures should be avoided where possible. Careful design with a consultant and your install team can help with this. If this is not possible, then consider micro inverters or panel level optimisation, as this will reduce the impact of the shaded panels on the non shaded panels. Most larger inverters will have two maximum power point trackers (MPPTs), which means shaded panels on one tracker will not effect panels on the other. Also be mindful of future shading issues, as new structures may be built and trees often get bigger.

Other objects like power lines and antennas can cast a very thin and small shadow. While not ideal and to be avoided where possible, these will not have a drastic impact on your system. Panels should not be placed directly under antennas though, as birds are likely to perch on an antenna and leave excrement on the panels.

Q) What is an inverter? What sort should I buy?

An inverter performs a variety of functions. Primarily, it converts the DC power from the solar panels into 240 AC power that the house uses. In addition to this, it has a maximum power point tracker (MPPT) that regulates the voltage of the panels to achieve maximum power. Some inverters have two MPPTs, which gives you greater flexibility when designing your system. Inverters also have a screen or counter that enables you to see how much power and energy you have produced.

Better inverters will perform their functions more efficiently, are more reliable, offer more comprehensive monitoring and features. High DC to AC efficiency is good, however it is not the only factor that impacts yield. The MPPT has complex algorithms that determine the highest yielding operating voltage. The better inverters have more refined algorithms from years of development, so they produce more power. Inverters from better manufacturers are less prone to failure, give better support, longer warranties and quicker replacements should something go wrong. They’re also far less likely to fail in fringe of grid or remote areas, where grid fluctuations are more common. Finally, better inverters will offer you connectivity and online monitoring for your system and even provide a way to monitor the consumption in your home in real-time – something which is becoming very popular.

Your situation and roof has a big impact on which inverter you should choose. Solargain has a wide range of inverters, from string, micro and even panel optimised inverters from all across the globe. This wide range, combined with our experience, enables us to recommend the perfect inverter for your project.

Q) How do I tell a good or bad panel? Which panel is right for me?

This can be quite tricky, as they all look very similar and all solar providers will tell you that their panels are high quality. Doing research into your panel is important, as low quality panels often degrade quickly and are prone to manufacturing defects. Also, a 25-year warranty is only as strong as the company providing it, so you need to do some research into the manufacturer as well. Here's a few tips on choosing a panel most suitable for your project.

If solar is a long term investment (three years or more), we recommend choosing a tier one panel. Panels from tier one manufacturers make up the top two percent of the panel market. The companies providing these panels have automated production facilities (reduces defects), are vertically integrated (meaning they have control over the entire supply chain) and have been producing panels for five years or more. There are many brands out there that are considered tier one and choosing a panel from one of these is a great way to ensure you're making a good investment. In addition to this, we recommend choosing a tier one provider that has a strong presence in Australia, as any warranty claims will be much easier to manage if there's local support. Finally, consider how many panels the supplier has installed for the manufacturer - tier one or not. Providers that have installed many panels from their manufacturers will have had to deal with warranty claims themselves. If the manufacturer was consistently not honoring warranties or regularly providing poor products, they would have moved on to another manufacturer. Providers changing panel manufacturers regularly are either frequently getting poor quality products or a consistently shopping for the lowest priced panel in that quality category, rather than a good quality product.

Premium panels are available and should be considered if you demand the best or have no intentions of moving from the home you're installing them on. Premium panels will give you slightly more kWh per kW from day one, degrade less than other panels, perform better in lower light and in extreme heat. These features don't pay for themselves straight away, which is why we believe they're primarily suitable for investments five years or more. Premium panels can come with better warranties, be it longer, less degradation or inclusive of labour costs for panel replacement. They may also be more aesthetically pleasing with darker cells and black frames. Lots of panels claim to be premium, but you won't know for sure until many years down the track. This is why we recommend looking for panels that have good performance in reputable independent tests and have sustained that performance over many years, ensuring the low degradation which many claim.

For people considering a short or medium term (1-3 year) investment, it still makes sense to consider the panels you are receiving. If the panel manufacturer disappears or if you don't know who they are, it can be very difficult to follow up any warranty claims - which can be very likely early in product life. Tier two manufacturers can be a good choice and are obviously cheaper than panels from tier one manufacturers. Tier two manufacturers have been producing panels for at least two years and are still in the top 10-15 percent of the market. These are good choice if you're looking for a cost effective option.

Q) Why is it common to have a higher panel output than inverter capacity?

It’s very common to put more panel capacity on an inverter than its maximum output. There are two main reasons for this, firstly the panels will never perform at their peak rated power (or nameplate) output. The panels get their rating from standard test conditions (STC) which will never be seen in the real world at the same time. Below are some of the conditions in the test compared to what happens in the field:

• The panels are flashed with 1000wm2 light intensity. Even in most places in Australia, we don't often get that amount. It can occur in the middle of a clear day though.
• The panels are in a temperature controlled environment of 25 degrees. The panels would be at about 50-80 degrees in the middle of a clear day.
• The panels are perfectly perpendicular to the rays. In most places in Australia, when panels are mounted on a pitched roof, the sun's rays will not be perpendicular in summer.
• The flash test is done on the panels with minimal cable lengths, resulting in next to no loss here. This is not possible when panels are installed in the field.
• The panels will degrade and accumulate dirt over time. In the flash test they're brand new and have been cleaned.

Due to the above, 6kW of panels installed in most places around Australia would rarely output in excess of 5kW. This is why selecting an inverter that has the same or higher output capacity of your panels is an added cost for no gain. Safety of the inverters is not an issue, as quality inverters are designed for this and are warranted for much higher input capacities. For example, Fronius warrant their inverters to double the DC input capacity than the AC output capacity. This means you could put 10kW on a 5kW without jeopardising your warranty provided it was installed correctly.

The second reason is that while your inverter will never output more than its maximum AC power output, you will generate more yield (kWh) overall. If you did have a case where the panel capacity exceeded the nominal output capacity, it will for a short period of time be able to operate at the maximum output capacity. If this is exceeded, the inverter slows the output (referred to as "clipping") of the panels, converting only what it can. While this may seem like wasted power, it's seldom occurring and is far outweighed by the system turning on earlier, turning off later and producing more power in anything other than perfect conditions. It's a small sacrifice for a big gain.

We tend to see and recommend this with 5kW inverters, as increasing your inverter capacity beyond this point excludes most residents from selling energy back to the grid. The 6th kW in these systems is also by far the most cost-effective and you will rarely, if ever, see any clipping. Also consider that if panels on your roof face different directions, they will reach peak output at different times throughout the day, so it's even more common when this is the case.

Q) Will it cost money to change my meter over?

Yes. The cost varies between states and energy providers. Households that already have a smart meter will be charged a fee to configure the meter to accommodate for solar. If you do not already have a smart meter, your retailer will need to install one for you. Most energy providers have these costs absorbed into your billing so you don't pay a lump sum cost for your new meter.

 Warranties and Guarantees

"Solar Energy World" provides a five year comprehensive warranty on the entire solar power system. This covers both parts and labour for all the components in your system. There are no extra costs associated with maintaining this warranty and while we recommend keeping an eye on the system performance, no scheduled maintenance is required.

The manufacturers also provide a warranty with their products. The panels all have a performance warranty (commonly 25 years) and a product warranty (usually 5-12 years). The product warranty covers any defects of the panel that doesn't impact the performance. After the product warranty, any defects must impact performance before you're eligible for repairs or replacement. Note that the panel warranty typically does not cover the labour costs involved in replacing the panels, although SEW will do this in the first five years as apart of their comprehensive warranty. Some panel manufacturers (like Hanwha QCELLS and Sunpower) can have a labour component in their warranty, but speak to your consultant for more details. Inverters typically have a five year product and labour warranty, however some will have longer warranties or offer them for an additional fee.