There was a time when there was a big difference between different solar panels manufacturers, both in regards to quality and the performance of the panels. There were signiﬁcant differences in shade performances in particular, and the longevity of the cheaper panels was undoubtedly not as good as, the more expensive brands.
However, this is becoming less and less the case, thanks to set international standards and demand from within the industry for higher-quality panels. While the bigger manufacturers, such as Kyocera, Zanussi, and Sharp is building panels to a higher quality than the smaller manufacturers, the benchmark for everyone has improved over the past five years. It is good news for buyers.
That said, there are still some very cheap solar panels on the market that are worth avoiding. These often appear on eBay at bargain prices. That is not to say that all eBay bargain solar panels are of poor quality, but do ask for the speciﬁcation sheet and ensure that the panels themselves have been independently tested.
Type of solar panels
There are many international standards for solar panels. These include:
UL 1703 is a ﬁre classiﬁcation rating for solar PV panels.
Mechanical stability and compliance with electrical parameters.
Longevity tests to ensure the PV panel will remain electrically and mechanically safety throughout its life.
Salt mist corrosion testing for PV panels.
MCS 005 / MCS 010
The UK Microgeneration Certiﬁcate Scheme Solar PV product certiﬁcate. Often manufacturers will list their MCS Certiﬁcate Number (in the format MCS) which is the speciﬁc certificate number given to the product when tested. Products are only given a certiﬁcate number if they have passed all the tests for MCS 005 and MCS 010.
Not all solar panels are going to have undergone all different tests, as some of these standards are only stipulated for specific regions and many of the tests covered by one set of standards are replicated in another. For instance, the UL testing is carried out to conform to the North American market, while the MC-S testing is speciﬁc to the UK (but is used elsewhere in Europe) and is linked to the Microgeneration Certiﬁcation Scheme.
Building regulations for the United Kingdom and the United States specify that solar panels ﬁtted to residential premises must conform to these standards. Uncertified panels break these building regulations and may invalidate your buildings insurance.
You may also see companies listing ISO 14001 or ISO 9001/ISO 9002 as accreditations against their products. ISO 14001 is a criterion for environmental standards, while ISO 9001 and ISO 9002 are quality standards. Both standards are organizational standards and not standards specifically relating to the solar panels. They are not a substitute for product tests. If you see cheap solar panels on sale on eBay with no other standards listed other than ISO 14001 or ISO 9001 or ‘CE approved for sale in Europe,’ you cannot use these panels for installation on a building. Likewise, panels advertised as TUV Approved or BSI Approved mean nothing Without knowing which standards they have been approved against.
Buying cheap solar panels
There are lots of companies selling very low-cost panels. Most of these are not certiﬁed to any of the international standards and are unsuitable for grid-tie applications. In many cases, certainly in Europe and North America, installing these on the roof of your house will contravene building regulations and may invalidate your buildings insurance.
However, these panels certainly work, and the quality of these cheap panels has improved significantly over the past ten years. For small, off-grid applications where the panels are not being installed on a permanent building, these solar panels can provide cheap energy and can work well for many years.
Of course, the old maxim “you get what you pay for” is as true for solar panels as it is for everything else. Cheaper solar panels tend to have thinner glass, and although it will still be toughened glass, they are more likely to get damaged than more expensive panels. The quality of the crystalline will not be as good as the more expensive panels, and the internal design will be a generation or two older. Cheaper solar panels will suffer more with partial shade, and heat build-up may be higher than expensive panels. In terms of general performance, expect 10-15% less power generation from a low cost, unbranded solar panel, compared to a high-end product.
Yet if you consider these factors in your design, making sure that your panels will not be affected by shade and building larger air gaps behind the panels, these solar panels certainly can be considered for smaller off-grid projects.
solar panels mounting options
Solar panels are designed to be clamped, bonded or bolted, depending on the speciﬁc design of the panel and the precise application. Never drill holes in the solar panels, even the frames, as the vibrations from drilling can create micro-fractures in the silicon and damage your panels.
There are different mounting options for your solar panels:
You can install your solar panels onto a freestanding frame or pole. The panels are typically clamped into position on the frame. There are many beneﬁts of installing your panels in this way: you are increasing the airﬂow around the solar panels, thereby avoiding heat build-up around the panel itself. Many freestanding mountings also allow you to adjust the angle of the solar panels, which means you can get the best performance for your panels for the different seasons throughout the year. Finally, you may find it easier to keep your solar panels clean if they are freestanding rather than installed on a roof.
If you are considering installing your solar panels on a freestanding frame or pole, ensure that the panels are mounted out of reach of children or pets. You also need to consider the weight and size of the solar panels: you do not want your panels to blow down in a heavy storm because your frame is not sufficiently anchored. Most manufacturers recommend that the structure is installed on a concrete base, built over a compacted hard-core sub-base. If using ground anchors, these should be bolted using 25-30cm (10″-12″) bolts.
Solar trackers are pole mounted and move the solar panel so that it tracks the movement of the sun across the sky each day. Solar tracker installers claim a performance improvement of between 25- 40%.
There are two types of solar tracker: single-axis trackers move the panel in one direction, turning to face the sun throughout the day. Double axis trackers adjust the tilt of the solar panel as well. In most instances, single-axis trackers allow you to manually adjust the tilt of the solar panel from one season to the next.
‘While the performance increases look impressive, solar trackers add additional complexity to your system and can be quite expensive. Unless space is at a premium, it is usually more cost-effective to buy additional solar panels rather than invest in solar tracking devices.
Mounting solar panels on the roof
As previously mentioned, if you are mounting solar panels onto the roof of a house, you need to have carried out a structural survey of your roof to ensure that it is capable of taking the weight and the wind loading of a solar array installation. Installing solar panels onto the roof of a house is a job for the professionals.
When mounting solar panels onto a roof, you must always be aware of airflow around and underneath the solar panels as you wish to reduce temperature build-up to increase performance. A steel or alloy frame is typically constructed on the roof ﬁrst, providing an air gap between the roof and the frame. Solar panels are then either clamped or bonded to this frame.
For smaller installations, you can install a separate frame for each solar panel. Many of these also allow the panel angles to be adjusted. This has the advantage that you can install the panels at the optimum angle for power production at your home, rather than at the angle of your roof, and ensures optimum airﬂow around each panel.
Adjustable frame mounts are ideal for static caravans; tiny homes andﬂat roofed sheds. They can also be used on conventional roofs to adjust the angle of the panels for optimum power production and airﬂow. Below:
Bonded plastic brackets can work well for installations onto the surface. Images courtesy of Baird Innovations.
If installing only one or two small solar panels onto a shed roof, you can purchase various mounting brackets that can be bonded to the panels, using an industrial glue such as Sikaﬂex. The brackets can then be bonded or bolted to the roof of your shed. Small plastic corner and side brackets, as shown at the bottom of the previous page, can work well with smaller solar panels up to around 1000Wp, and are available in a variety of depths to allow sufficient airflow. The mounts shown on the previous page allow an air gap of 2.5cm (1″‘) between the solar panel and the roof. This is sufficient for most installations in Northern Europe. Deeper mounts would be recommended for most parts of the USA or Australia.
Installing solar panels on a car, caravan/travel trailer, boat or creaﬁonal vehicle
If installing solar onto a car, caravan/travel trailer or recreational vehicle, you need to take into account the airﬂow at speed. You need to reduce drag, which at its best creates additional wind noise and at worst can rip the solar panel from the roof while ensuring that an airﬂow around the solar panel still exists.
The First option
One option is to bond ﬂexible solar panels directly onto the roof of your vehicle. This can work if you are bonding directly onto a metal surface. The beneﬁts are that drag resistance is minimal, and the heat from the panel is transferred to the roof of the vehicle, acting as a heat sink for the dissipation of some of the heat.
Unfortunately, this is not as effective as you may hope. The solar panels will heat up, and the performance of your system on hot days will be affected as a result. However, this could be a price worth paying: if you have sufficient roof space, you can install additional solar panels to overcome the lack of efficiency if this is going to be an issue for you.
The second option
The second option is to mount your panels with a spoiler mount to the front of the panel. These mounts deﬂect the air over the solar panel, leaving an air gap beneath the panel to allow an air ﬂow around the solar panel itself. These spoilers are often panel speciﬁc, so make sure that your supplier can provide them for the solar panels you are planning to buy.
In most cases, you will also need additional mounts on the side of the solar panel to ensure that the panels cannot lift off at high speed. It is strongly recommended that you seek advice from your supplier for the specific solar panels you wish to buy.