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Which solar PV products does Spirit Solar use?

To view our Solar thermal (hot water) products, click here. Read on for information about our Solar PV (electricity) products.

To give you and us peace of mind, we always use high quality accredited products. We do not buy pre-assembled kits; instead we source components individually ensuring we can always buy at the best prices. The following should be taken as a guide only; if you are set on one particular panel or inverter we can usually source it for you.

The key components in a PV system are the solar panels (or roof tiles - see below), the inverter, the mounting system and the monitoring equipment.

For information on each of these read on or click on one of our Quick links.

Solar panels - On-Roof, In-Roof, roof tiles, or ground mounted?

There are three ways of installing solar on your roof:

by attaching solar panels to the roof using "on-roof" mounting brackets which sit above the tiles;
by removing tiles in the area in which the panels are to go, and mounting the panels directly onto the rafters using "in-roof" mounting brackets;
by installing solar tiles directly onto the roof.
In addition a system can be installed on a flat roof, or it can be ground mounted.

Solar panels with on-roof mounting brackets.

Roof integrated solar tiles

Solar panels with in-roof mounting brackets

Ground mounted installation

Flat roof installation

Most people are installing systems to their existing house ('retrofit') and choose to attach panels onto the roof using mounting brackets.

For new build or re-roof situations, or where there may be an issue with planning (eg a conservation area), an in-roof mounting or solar roof tiles may be the solution of choice.

In roof systems use the same panels as on roof systems. The only difference is that the panels are mounted on the rafters, not on the tiles (usually with a metal tray backing between the panels and the rafters). The installer will tile up to the panels, often using lead flashing to make a tight seal around the panels.

In general we don't recommend In-Roof systems for several reasons:

Customers often believe the top of the panels will sit flush with the tiles. This is not the case - usually tiles are a few centimetres thick whereas the brackets and panels stand 11cm off the rafters. So unless the rafters around the PV system have been deliberately built up, the tiles will not sit flush with the roof.
The performance of the system will be reduced by 5-7% relative to an on roof system due to the fact that to operate efficiently, panels need a gap behind them for ventilation. The In-Roof system doesn't provide this ventilation and the performance of the system is compromised as a result.
In order to create a watertight seal between the system and the surrounding tiles, lead flashing usually needs to be used. This is often ugly and defeats the point of using an in roof system in the first place which is usually to create an unobtrusive system blending with the rest of the roof.

If you want your system to sit flush with the surrounding tiles and to blend seamlessly into the roof, you would be better off using solar roof tiles. These are more expensive than an On-Roof or In-Roof system, but are a better bet if you are particularly worried about aesthetics. For example English Heritage have chosen System Photonics roof tiles (see below) for some of their projects.

Systems on flat roofs

Introduction

To many people it seems that flat roofs should be a far simpler basis for a solar system. However, the opposite is actually true. With a flat roof system there are a number of complicating factors:

All flat roof installations require planning permission, whereas sloping roof installations are generally covered under permitted development.
Flat roof systems take up more space than sloping roof systems, as separation between rows of panels is required to prevent one row of panels shading another.
Space becomes even more restricted give the fact that there needs to be a 50cm border between the system and the edge of the roof.
Mounting systems for flat roofs tend to be more complex than sloping roof mounting systems, as they have to lift the panel to an angle (to optimise solar collection), while maintaining a low enough profile and sufficient strength to cope with wind loads.

None of these factors mean that it isn't worth looking at a flat roof system: they simply mean that the process is more involved and it is more important than ever that a system is designed and installed by knowledgeable experts.

Here at Spirit Solar we have undertaken planning applications for, and installed, a large number of flat roof systems, on a variety of properties using different mounting systems, and as such are able to advise on the best solution for any given property.

Please don't hesitate to call our friendly team on 0118 945 9910 for more information or to arrange a free, no-obligation site survey.

Flat Roof Mounting Solutions

Solion Sunmount

Modular system mounted at 10° inclination
No need to fix to roof - aerodynamic design only requires ballasting
Easy to disassemble if any roof maintenance is required
10° inclination is the optimised angle for flat roofs in northern latitudes

K2 East/West System

Novel solution maximises power output per square meter of roof by orienting panels towards the east and west, rather than just south
While this means that each row of panels is slightly less efficient than if it was south-facing, the extra capacity offsets this
No issues with panels shading one another means that rows can be as close together as needed

K2 S-Level

"A-frame" solution with adjustable pitch
Best for large roofs where shading from one row of panels to the next can be mitigated by separating the rows

Which should I choose: Roof mounted or ground mounted?

Roof mounted systems work well because the space cannot be used for any other purpose and planning permission is either unnecessary (see planning requirements) or is relatively easy to obtain, unless the building is listed or in a conservation area.

However roofs can be problematic from a structural point of view as the loads imposed by the system can be significant (both down weight and 'wind uplift'). Many roofs are not over engineered: they are not made to take additional loads that were never envisaged at the design stage. In addition the roof structure or covering may present a problem. Warm roofs are sometimes problematic, as are roofs containing asbestos.

Ground mounted systems are ideal where space is not limited and there is an easy cable route back to the incoming electricity supply. They can be orientated for maximum output and are often looked on favourably by planning departments where a roof mounted system might fail (for example on a listed building).

Solar panels – Which panel should I choose?

The table summarises our most popular panels, giving power output, dimensions and Watts per square metre.

Make	Model	Output	Dimensions (mm)	Area (m²)	Watts/m²	Module Efficiency	Defects Guarantee	Performance Guarantee Term/Min performance guaranteed (as a % of initial output)	Type	Colour	Technical Spec
Sanyo	HIT-N240SE10	240	798 x 1580	1.26	190	19.0%	10	10 yrs/90%; 25 yrs/80%	Hybrid Mono	Black with Black Frame	Download PDF
Sanyo	HIT-H250E01	250	861 x 1610	1.39	180	18.0%	10	10 yrs/90%; 25 yrs/80%	Hybrid Mono	Black with Black Frame	Download PDF
Trina	TSM-DC01	185	809 x 1581	1.28	149	14.5%	10	10 yrs/90%; 25 yrs/80%	Monocrystalline	Black with Silver Frame	Download PDF
Trina	TSM-DC05	235	992 x 1650	1.64	144	14.4%	10	10 yrs/90%; 25 yrs/80%	Polycrystalline	Blue with Silver Frame	Download PDF
Sharp	NU185R1H	185	994 x 1318	1.31	141	14.1%	5	10 yrs/90%; 25 yrs/80%	Monocrystalline	Black with Silver Frame	Download PDF
Sharp	NUR245J5	245	994 x 1652	1.64	149	14.9%	5	10 yrs/90%; 25 yrs/80%	Monocrystalline	Blue with silver frame	Download PDF
Suntech	STP190S-24/Ad+	190	758 x 1580	1.20	149	14.9%	10	5 yrs/95%; 12 yrs/90%; 18 yrs/85%; 25 yrs 80%	Monocrystalline	Black with Silver Frame	Download PDF
Suntech	STP240S-20/Wd	240	991 x 1665	1.65	145	14.5%	10	5 yrs/95%; 12 yrs/90%; 18 yrs/85%; 25 yrs 80%	Monocrystalline	Black with Silver Frame	Download PDF
ET Solar	ET-M572190B	190	808 x 1580	1.28	149	14.9%	10	12 yrs/90%; 25 yrs/80%	Monocrystalline	Black with Black Frame	Download PDF
ET Solar	ET-P660235	235	992 x 1640	1.63	144	14.44%	10	10 yrs/91%; 25 yrs/80%	Polycrystalline	Silver Frame / Dark Blue Cell	Download PDF
Azur	P 230-3 with 2P coating	230	992 x 1655	1.64	140	14.0%	10	Max 2% degradation over 25 year life	Polycrystalline	Blue	Download PDF
REC	235PE Black	235	950 x 1665	1.58	142	14.2%	10	10 yrs/91%; 25 yrs/80%	Polycrystalline	Black	Download PDF

Our recommendations:

Most of the solar cells which make up the panels are made in the same few factories in China / Asia, and in our view, apart from the Sanyo hybrids which are a different technology, and the Azur panels, which have a patented coating, one is pretty much like another. For more information on Azur and Sanyo, see below.

In general there are four main considerations in choosing a panel:

Efficiency, measured in Watts per square metre. In other words, how much space do you need to get a given level of output?

As you can see from the table, Sanyo hybrids are the most efficient panel.
They use a different 'hybrid' technology, which gives approximately 30% more power per square metre than any other panel. From the table you can see that the Sanyo gives 190 Watts per square metre, compared to around 145 Watts per square metre for the other panels. The downside is that they currently cost around 50p more per Watt - so for a 2 kWp system you will pay around £1000 more if you choose Sanyo. If you are wondering whether to buy Sanyo or not, ask yourself what are you trying to maximise - the total power you can squeeze out of your roof or your financial return? If your objective is simply to maximise the power output from your available roof space without regard to budget, then you should choose the Sanyo hybrids. Don't choose the hybrids if you want to maximise your financial return.
What is the cost?

The Chinese panels - Suntech and ET Solar - are generally the least expensive. Suntech offers the best value, combining high efficiency, quality and aesthetics. Suntech has been producing panels since 2001 and in only a decade it has grown to be the largest producer of panels in the world. The 1.6MW solar farm at Google's headquarters in California was installed by Suntech. ET Solar panels are slightly less expensive than Suntech. ET also make black panels with a black frame, ideal if you are installing on a slate roof or similar. Sharp is one of the longest-established names in the PV market with a factory in Wrexham so many of their panels are assembled in the UK.

As all of our systems are bespoke designed, we are able to advise on, and fit, almost any panel. If you are looking for a panel from another manufacturer please ask as we can probably source it for you.
Performance degradation and performance warranty
- The performance of panels is expected to decline over their 25 year life. The standard performance warranty guarantees that a panel will produce at least 80% of its initial output after 25 years and at least 90% of its initial output after 10 years.
- Some manufacturers do slightly better than this, by offering a 'linear guarantee' the effect of which is that after 10 years, the output is guaranteed at 91% rather than 90%.
- Azur does much much better - Azur panels with a 2P coating guarantee a minimum performance of 98% after 25 years. In other words a maximum 2% degradation over 25 years, rather than a 20% degradation. On average the "net present" value of returns over the life of an Azur system are about 15% higher than the returns from a system using a panel with a higher degradation. The Azur system is more expensive, but overall usually offers a higher lifetime return.
In the unlikely event that it will need to be called upon, do you feel comfortable that the 25 year guarantee will be upheld by the manufacturer?

There are many solar panel manufacturers, and at present, there is over supply of solar panels across the global market. Some of the players may not be around to honour their warranties in the long term and it is therefore worth giving thought to who the stronger players are. Companies such as Sharp and Sanyo don't only do solar, which may be a strength in the long run. Suntech is currently the biggest player and is usually at the forefront of technological changes. Azur is a well established German supplier which has been in the UK since 2005.

Finally, the dimensions of some panels may work better on your roof than others, and you may have a preference for colour (essentially blue or black).

Click here for more information on the different types of panel: monocrystalline, polycrystalline, hybrid and thin film.

Solar roof tiles – products and prices

If you compare the cost per Watt peak of a solar roof tile with that of an on roof solar pv system, you find that the cost per Watt peak of a roof tile system is usually about 60% higher than that of the panels.

In addition whilst panels generate over 134 Watts per square metre, tiles typically generate between 50 Watts and 120 Watts per square metre. So tiles are more expensive and give less output per square metre of roof.

The tiles obviously serve a dual purpose in that they both provide power and they cover the roof. They can only be justified on aesthetic grounds where budget is not important or for buildings where, for whatever reason, panels are ruled out.

There are a few products on offer, as follows:

Solar Century
C21e tile – These are the most cost effective PV tiles we have found. They cost around £5,000 per kWp installed, which equates to about £600 per square metre. This includes everything - inverter, isolators etc. The output is around 121 W per square metre. Compatible with a range of clay tiles - see datasheet for list.

Compatible with a range of natural slates and fibre cement slates - see datasheet for list.
System photonics
– upmarket Italian design which is unique in that it embeds the solar cells into a ceramic tile. Aesthetically the most pleasing on the market, it is available in 16 colours. There are two versions: the first has a power output of 53W per square metre and the second has a power output of 120W per square metre. Plain tiles are available to match. Click here for more information.
Imerys
PVt 60Wp – designed to fit with Imerys clay tiles. Available in one colour (see picture). Output 92 W per square metre.
Redland
Redland do a range of photovoltaic tiles to match their plain tiles.

Inverters

Many people spend many hours wondering which panel they should choose and don't give a thought to any other component of the system. However the real heart of the system is the inverter, a very clever piece of kit which costs between £1000 and £2000 on a typical small scale / domestic system (depending on size). For this money it's worth a read on what you are buying!

The role of the inverter

The panels generate DC (direct current) electricity. However the national grid and every electrical item in the house runs on AC (alternating current) electricity. The main task of the inverter is to convert DC into AC, synchronized with the supply voltage. It also has important safety features to protect your system and to protect men working on the national grid in the event of a power cut on the grid.

Our inverters

Sounds simple but if you read on you will start discover some of the clever bits.

Hopefully when you have read them you will understand why we always use the market leading inverters. The best two 'standard inverters' on the market are the Sunny Boy inverters, made by the German company SMA and the Fronius inverters made by the Austrian company Fronius. They typically come with 5 year warranties extendable to 25 years. Our standard package includes a warranty extension to 10 years.

We also use SolarEdge inverters. These optimise the performance of each panel using Power Optimisers. They can improve the output of a system by a few percentage points just by operating the system more efficiently. On a shaded system SolarEdge inverters can add 5-10% (or more) to the output.

If you read our guarantee you will see that we guarantee to investigate any fault with your system with no call out fee for five years. We do this with confidence – we really are not expecting to visit because we use high quality, well engineered, market leading inverters.

Fully automated operation

After sunrise, as soon as there is sufficient output generated by solar modules, the control unit starts monitoring the utility line voltage and frequency as well as the available energy in the panels. Once enough sunlight is received, the solar inverter starts feeding the utility transmission grid. Depending on the type of installation, a few watts of solar power will be enough do the job!

The inverter will now continue to work such that it always draws the maximum of power from the solar modules. This function is called MPPT (Maximum Power Point Tracking) and is carried out with a rate of accuracy of more than 99%. After dark, when the energy offered is no longer enough to feed the utility transmission grid, the inverter automatically cuts the connection to the grid and stops operating, of course with all settings and data being conserved.

Grid monitoring, safety cut out

Inverters need to meet minimum safety standards and conform to industry standard protection settings. This means that they need to monitor voltage and frequency and stop operating in case of irregular grid conditions (e.g. utility outage, interruption). If any protection setting is breached they stop the feed into the grid. This is important. In the event of a power cut engineers will work on the electricity transmission lines to find the fault. Obviously they can't do this if your system is still pumping electricity into the grid.

The inverters also feature a high frequency transformer that ensures a galvanic separation of the DC side from the utility transmission grid.

Monitoring Equipment: tracking your generation

One of the most important features from a customer point of view is the data display enabling you to track the energy generation of the system.

Every system is fitted with a generation meter. This is the official meter reading which you give to your electricity company to claim the Feed-in Tariff.

However the generation meter doesn't give you the instantaneous power output of the system; nor does it record 'historical' data and produce graphs of daily output.

A user friendly data display allows you to check that the system is working and enables you to keep track of how much electricity you have generated / Feed-in tariff you have earned. It also tells you when it's a good time to put the washing machine on!

In general we recommend the monitoring system made by the relevant inverter manufacturer.

SMA Sunny Beam / Sunny portal

The lowest cost option for SMA inverters is the Sunny Beam Bluetooth wireless display monitor (see opposite) which you can position anywhere inside your property. This allows you easily to view instantaneous and historical usage wherever you are.

More comprehensive tracking is available online via the Sunny portal. You can see an example of this at

www.spiritsolar.co.uk/track-customer-systems-real-time.php

SMA and SolarEdge both offer online tracking systems. These provide data with varying degrees of complexity, ranging from simple output data (current power, accumulated output etc) to detailed technical information (operating voltages etc).

SolarEdge PV Monitoring Portal

SolarEdge inverters have a complete online tracking system, allowing you to view and analyse both live and historical generation information.

Because SolarEdge tracks each panel independently, you can also see precisely how each individual panel is performing.

Which mounting system?

We have selected our mounting kits with an eye to robustness and quality. We have also selected kits which are designed for British roofs taking into account rafter design and typical wind loads.

In general this has led us to use German made mounting kits from K2, Schletter or Renusol.

On flat roofs we use either A frames or Solion mounts.

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