Solar PV for Offices

Solar Panels for Office Buildings

Solar Panels for Offices

There are a huge number and variety of office buildings across the UK, from small industrial units with an office room, to grand high-rise blocks and sprawling low-rise complexes.

Even more than for other classes of building, solar systems for office buildings always have to be assessed specifically for the site in question because every office building is different. Because of the wide range of possible building types that fall into this category, I’ll approach my analysis of the benefits and challenges associated with solar PV systems slightly differently here. Instead of a short list of advantages and potential problems, I’ll cover some key things that you’ll need to look out for if you’re considering solar PV for your building.

Things you want to find

Top of the list of things that you’ll want to have if you’re considering getting solar PV is a suitable piece of roof or wall where it can be fitted. Solar PV is getting steadily more efficient, but it still takes up a fair bit of space to get enough panels on a building for it to generate enough energy to make a dent in that buildings energy consumption.

The ideal space for a solar system in the UK is a South facing piece of roof that is pitched at about 30 degrees. However, the performance of modern panels is good enough that it’s likely still worth installing on to walls that face roughly south or a piece of roof that faces well off south. If you’re thinking about getting solar on a south facing piece of roof then it’s possible that it will be worth considering covering the north face as well simply because it’s a lot less expensive to install more panels onto a building whilst you’re there anyway than it is to begin a new installation, for example 200 panels will cost only about half again as much as 100 panels not twice as much. This makes the overall financial rewards of the solar PV system better, even though a North facing roof will not perform as well as a South facing one in a lot of cases.

The next thing you’ll want to find is a good sized loft or plant room. There are other elements to a solar PV system that just the panels. One of the most crucial of these is called an inverter. This is an electronic box of tricks that primarily converts the DC electricity generated by the solar panels into AC electricity that can be used in the building or fed back into the Grid. Depending on the size of your PV system there will be at least 1 inverters and potentially as many as there are PV panels. The inverters need somewhere to live for the 20-25 years the PV system will be operational where they won’t get damaged, where they won’t get too hot and where they can be accessed for occasional maintenance. A good place to look for is either somewhere near to the panels or somewhere near to the final electrical connection of the building. Usually a good sized loft area is a good place, or a plant room with some spare wall or floor space would be good, but a store room or similar should be suitable as well.

The main thing that the inverters need is ventilation, and for there to be a way to get cables from the PV panels down from the roof, and then to be able to get a cable from the inverters to an electrical distribution point that big enough to handle the energy they generate. A general rule of thumb is that 200PV panels (330m2) is around 50kWp of PV which will take a wall approximately 4.1m long to mount the inverters on, which will then need a 63A three phase connection point reasonably close by. A good installer or consultant will be able to give you more advice if you need to be more specific.

As mentioned above you’ll want to find somewhere to plug the whole system into and the bigger the existing electrical infrastructure you have the bigger the PV system you will be able to install without expensive electrical upgrades. A lot of office buildings use predominantly domestic standard electrical equipment (Computers, lights, kettles etc) sometimes with some bigger air handling units, air conditioning or heaters. It’s fairly common the electrical systems of office type buildings to have electrical systems that match reasonably well with the size of PV system that you could conceivable fit onto the outside of them, as a coincidence of building occupancy design as much as any other reason, but if your building only has 100A single phase fuses by the meter that look the same as the ones on your house you’re unlikely to be able to install a large PV system easily.

You’ll also want to have a reasonably low building ideally. The reason for this is the cost of scaffolding or other access equipment. Your installer will be sending people up onto your roof and using it as a working environment and they have a duty to ensure that their people will be safe up there whilst they’re working. That usually means scaffolding, and the higher the scaffolding needs to be the more expensive it will be plus the more time the installers will need to spend lifting PV panel onto the roof. There is also the issue of wind loading, and the higher the roof is heavier and more expensive the PV module mounting system will need to be to handle the higher wind loadings on higher roofs. PV panel can be like big kites in string winds and you want to make sure they’re well attached.

There are other things that make PV systems more favourable or easier to install of course, but these are the key things that make them worth considering.

Things you don’t want to find

There are few things found in any building that can’t be overcome one way or another to allow solar PV to be installed on it, however, the more complex an install is the more expensive it will inevitably be and it follows that the PV system will be less likely to stack up financially or environmentally if you have to go to huge lengths to be able to install it in the first place. Some of the key things that could make it very difficult to install a solar PV system are:-

Small or very cluttered roof areas essentially mean that there is nowhere simple to put the solar PV panels. Small roof’s usually go hand in hand with small buildings, meaning that not being able to install a large PV system isn’t so bad and is likely proportional to smaller energy demands. A very cluttered roof is a different story and depends what is up there. Lots of roof lights can be problematic as it’s inadvisable to cover them with PV panels and can reduce the number of panels you’ll be able to fit, but they’ll be reducing your electricity needs anyway. If there is a lot of plant on your roof then you’ll likely be using electricity to run it which could be being generated by solar PV. In a similar way to with fragile roof’s it is possible to install frameworks that will support the solar PV above on roof obstacles, but they come at a cost and may have planning implications.

The presence of asbestos in key places in the building – the main one here is if the roof is made of asbestos. This can be hugely costly and disruptive to remedy. More often than not these days’ people will either just seal an asbestos roof and leave it in place, or just cover it over with a more modern roof like a sheet metal roof. The problem here is that for roof’s of asbestos (Or fibre cement) construction, it’s necessary to drill through the sheet to fix to the structure beneath and that can only be done by a specialist contractor which will be costly. However, if you’re considering getting the roof removed or recovered with a sheet metal roof then solar PV is likely to be relatively cheap and you may be able to share costs with the roofing contractor making it even more cost effective.

Fragile roofs of other kinds cause serious problems for solar PV installers for similar reasons to asbestos roofs. Essentially, it isn’t possible to work on a fragile roof safely, and often they won’t even take the additional weight of the PV panels anyway. There are ways of mounting the panels so that they span the roof and only load the walls, or again, of having the roof replaced, but this is likely to be very costly as well.

Poor condition roof coverings cause issues because if you install a solar PV system into a roof that’s in poor condition, it may case additional leaks because of the mounting system which will often penetrate the roof. This is not a problem with a roof that is in good condition, but can be unavoidable if the roof is not sound already. It is also very easy to cause un-noticed damage to roofs that are in poor condition (For example cracked slates) which only become apparent after everyone has gone away and may not be quick to fix afterwards however conscientious your installer may be. Another consequence of installing solar PV into a poor condition roof is that there is a strong possibility that it will need to be replaced within the 20 year lifespan of the solar PV system. This will mean that you’ll need to foot the bill for having the PV system removed whilst the work is done and the re-instated afterwards. This can cost a significant fraction of the original price of installing the PV system as a lot of the cost is in labour and access equipment. We would strongly recommend that you have the condition of your roof assessed professionally before commissioning a solar PV system and if necessary having it replaced first. You should be able to share access equipment between the solar installer and the roofer, and it’s perfectly possible that the same contractor will offer both services.

Old or undersized electrics can cause headaches primarily because solar PV is an electrical technology and needs somewhere to connect to in the existing electrical system in order to work properly. If your electrical system is particularly old or otherwise problematic it’s often more difficult to install the solar PV system. There is usually a way to bypass problematic electrics, but that may mean longer cable runs and additional switchgear which comes at a price. The only serious showstopper for electrical reasons is if the local distributed network operator (DNO) says that you’re not allowed to export any electricity to the Grid. That can often mean very expensive and time consuming upgrades to the electricity network outside your building. There are ways to get past this as well but not only do they cost money, they also reduce the efficiency of the solar PV system.

Is your building is listed or in a conservation area then you’ll almost certainly need planning permission to install solar PV onto it, which is not often withheld, but it nonetheless time consuming and potentially costly to acquire. If you’re installing complicated mounting systems to bypass any of the other problems above then you may also need planning permission as permitted development regulations have some fairly specific restrictions within them.

If your building has a very low EPC rating already then even if there are no other problems associated with installing a solar system, you’ll probably only receive a very low rate of Feed in Tariff for the energy generated because it is tied to your EPC rating. You must have a rating of D or better to get the highest FiT rate and some older buildings will struggle to achieve that. This is a conscious strategy on behalf of OFGEM however, and is intended to motivate you to install other, more cost effective energy saving measures before solar PV, such as insulation and energy efficient lighting. Again, it’s possible that you PV installer will offer some of these technologies or will otherwise be able to advise you on this issue.

In summary

Office buildings come in huge variety and require individual attention by an experienced installer or consultant to be able to design a suitable solar PV system. It’s normally worth engaging a consultant early on when you’re just thinking about getting solar to advise you properly before you spend a lot of money finding out that you can’t sensibly install anything on your building. Most problems there might be can be solved, but there will be a bottom line to that solution and may just make the solar financially infeasible. However, your building may very well be ideal for solar and some good advice may smooth the way to a cost effective and simply installed solar PV system that will generate free electricity and provide a steady income for 20 years or more.

Still, if you have any questions that aren’t covered here then feel free to get in touch and we’ll help however we can.

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