Powering Change
Installing since 2010 · 0118 951 4490 · info@spiritenergy.co.uk
We are independent solar panel installers, we are not tied to any individual panel manufacturer. We have chosen a range of manufacturers based on product quality, warranty terms, and the support they provide. This means we can recommend the best solar panels for your specific project and source them at a competitive price.
If you would like to be talked through your options, we have created a video on the best solar panels which you can view here.
Our panel range varies slightly with availability, but the core of our current range is set out in the table below. Unless otherwise stated, all panels are n-type monocrystalline, the current market standard for efficiency and durability.
| Make | Panel | Size | Colour | Watts* | Watts/ m2 | Warranty | Data-sheet |
| AIKO |
AIKO Neostar 3 |
1762mm x 1132mm x 30mm | All-Blank | 490W | 245W / m2 | 30 year product + 90.6% output at 25 years, 88.9% output at 30 years | Link |
| LONGi |
LONGi S10 |
1800mm × 1134mm × 30mm | All-Black | 490W | 247W / m2 | 30 year product + 88.9% output at 30 years | Link |
| LONGi | LONGi Hi-Mo X10 | 1800mm × 1134mm × 30mm |
All Black | 480W | 235W / m2 | 25 year product + 95% output at 10 years; 92% output at 25 years | Link |
| REC | REC Alpha Pure-RX | 1728mm x 1205mm x 30mm | All Black | 470W | 226W / m2 |
20 year product + 92% output at 25 years |
Link |
| Viridian | Viridian Clearline Fusion | 1722mm x 1134mm x 70mm | All Black | 445W | 228W / m2 | 10 years product + 90% output at 10 years, 80% output at 25 years | Link |
Each panel model is produced in a series covering a range of outputs. The wattage shown is the variant we are currently selling based on market availability.
The Viridian Clearline Fusion is an in-roof panel. In-roof systems typically produce around 5% less output than on-roof equivalents due to reduced ventilation and higher operating temperatures.
The best solar panels currently available, in our view, are those made by LONGi and AIKO. Both manufacturers lead the market in n-type cell technology, consistently achieving the highest efficiencies in their class and backing their products with strong long-term warranties.
LONGi are the world's largest solar manufacturer and invest heavily in research and development. Their Hi-MO S10 uses HPBC (Hybrid Passivated Back Contact) cell architecture to achieve market-leading efficiency, while the Hi-MO X10 offers an excellent combination of performance and value with a 25-year product warranty.
AIKO are a pioneer in ABC (All Back Contact) n-type cell technology and consistently push the boundary on cell efficiency. Their Neostar 3 achieves 245 W/m² and comes with a 30-year product warranty, longer than most competitors.
REC is a European brand with a strong reputation for quality control and warranty reliability. Their Alpha Pure-RX uses a heterojunction design for excellent low-light performance and comes with a 20-year product warranty.
With the exception of the premium manufacturers above, most solar panels on the market are assembled from cells produced in a small number of factories, and the differences between mid-range products are modest. As the technology advances rapidly, the best panels are constantly shifting — we assess each project individually and recommend the most suitable option at the best available price.
There are five main factors to consider when choosing a solar panel.
Efficiency measures how much electricity a panel can generate from a given area of roof. This matters most when roof space is limited, a higher-efficiency panel means more total output from the same number of panels. The best panels in our current range achieve 245–247 W/m², compared to around 170 W/m² for a standard polycrystalline panel.
A key development in recent years is the mainstream adoption of n-type solar cells, which now dominate the market due to their higher efficiency and significantly lower light-induced degradation compared to the older p-type standard.
The table below summarises how efficiency varies across different panel technologies:
| Panel type | Module efficiency (W/m2) | Relative cost | Typical performance guarantee | Typical product guarantee | Typical colour |
| N-type monocrystalline (TOPCon/HPBC/ABC) | 235–250 |
Medium -High | 88–92% | 25 - 30 years | All Black |
| Monocrystalline (standard) | 210 - 230 | Medium | 85-90% | 10 - 25 years | Black / Black frame |
| Heterojunction (HJT) | 220-240 | High | 92%+ | 25 years | Black cell. white backsheet |
| Polycrystalline | 165 - 170 | Low | 80% | 10 years | Blue cell, silver frame |
The key considerations in choosing a panel are as follows:
LONGi and AIKO panels represent excellent value, combining very high efficiency with strong warranties at a competitive price point. As a general rule, higher efficiency panels can also be more cost-effective overall on complex or space-constrained roofs, since they minimise the number of panels (and therefore installation labour) required.
All of our systems are bespoke, so we can advise on and install almost any commercially available panel. If you have a specific manufacturer in mind, just ask, and if you want a comparison quote between two systems, we are happy to provide one.
All solar panels degrade slightly in output over time. The industry minimum is 80% of rated output after 25 years, but the best manufacturers now significantly exceed this.
The panels in our range carry performance warranties ranging from 80% after 25 years (Viridian, in-roof) up to 88.9% after 30 years (AIKO Neostar 3 and LONGi Hi-MO S10). When comparing panels, pay attention to both the product warranty (how long the manufacturer covers defects) and the performance warranty (the guaranteed output over time).
The rate of annual degradation is an important detail often buried in the small print. The best n-type panels now guarantee a maximum degradation of around 0.40–0.45% per year, compared to 0.55% for older monocrystalline technology, a meaningful difference over a 25–30 year lifespan.
A 25 or 30-year warranty is only as good as the company behind it. The solar industry has seen significant consolidation, and not all manufacturers will still be trading in two or three decades. We are comfortable recommending all the manufacturers in our current range, and we only supply panels from companies with a strong global presence and, where possible, insurance-backed warranties.
The vast majority of panels in our range are all-black, which provides a clean, modern appearance on most roof types. Panel dimensions also matter, a panel that fits more neatly into your available roof area may deliver more total output than a technically superior panel that leaves more wasted space.
The theoretical efficiency limit for a single-junction silicon solar cell is around 32% (equivalent to 320 W/m² at standard test conditions). In practice, commercial panels come in at 20–25%, with losses arising from surface reflection, cell interconnection, and thermal effects.
The most efficient panels currently available in our range achieve 245–247 W/m²:
Both panels represent the current state of the art in residential and commercial solar, and offer a significant efficiency advantage over standard monocrystalline panels.
For more detail on the most efficient solar panels on the market, see our dedicated high-efficiency solar panels page.
You may have seen the term 'Tier 1' used when specifying solar panels. Here is what it means.
Bloomberg New Energy Finance developed a tiering system to reflect the 'bankability' of solar manufacturers, essentially, whether banks are prepared to finance large projects using their panels. Bloomberg defines Tier 1 manufacturers as those that have supplied own-brand, own-manufacture panels to at least six projects financed non-recourse by six different banks in the past two years. The list is reviewed quarterly.
It is important to understand that Tier 1 is a measure of industry acceptance and financing track record, not a guarantee of product quality or long-term company stability. We do not restrict our supply to Tier 1 manufacturers, but we only recommend panels from reputable companies whose products meet the requirements of each individual project.
Bifacial panels expose solar cells on both the front and back of the panel, capturing reflected light from the ground or roof surface. This is not practical for standard flush on-roof or in-roof installations, but can deliver a meaningful output increase on flat roof and ground-mount systems. Find out more in our bifacial solar panels guide.
The majority of customers now request all-black panels, and this is reflected in our range, all of the panels in the table above are available in an all-black finish. All-black panels use black monocrystalline cells with a black frame and backsheet, giving a clean, uniform appearance that works particularly well on slate, dark tile, and flat roofs.
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For in-roof installations, the Viridian Clearline Fusion is our recommended option. It is specifically designed to integrate with the roof covering, giving a flush, built-in appearance. Note that in-roof systems are most suited to new builds or properties already undergoing roof refurbishment.
For on-roof installations, all-black or black-frame is our default specification across the range.
Learn more in our blog post on black solar panels.
