Here to Help Businesses Use Solar Energy to Save Money

Callidus was established with the vision to help businesses enjoy the many benefits of clean, green, solar energy whilst preserving their capital for use within their core business.

We manage and develop commercial electricity generating solar PV systems across the UK in partnership with our institutional investors.

Our experienced team have been working in the solar industry since 2011. They bring together the unique blend of financial, technical and commercial skills required to develop institutional quality electricity generating renewable energy assets.

At Callidus we help businesses generate their own solar electricity to reduce energy costs and carbon emissions, at no capital cost.

“Why pay for a solar PV system when you can simply pay for the electricity you use?”

Underpinned by long-term, proactive operation and maintenance activities, we ensure every system performs in line with expectations and delivers the forecasted savings not just today, but for at least the next 25 years.

How It Works

• You agree to lease the airspace above your roof for 25 years and enter into a Power Purchase Agreement (PPA).

• We install a solar PV system on your roof, free of charge.

• You pay a low rate per unit of solar electricity you consume.

• We monitor, maintain and insure the system for 25 years, at no cost to you.

How You Benefit

Free solar PV system
The solar PV system is fully funded by our Capital Investment Partners who have an investment portfolio of over £680m within the UK.

Immediate savings on electricity bills
Solar electricity you consume is purchased at a significantly cheaper rate than is available from any current energy provider.

Zero cost ‘green’ credentials
A zero capital route to improving your company’s environmental responsibility, enhancing relations with green thinking customers, supply chains and staff.

No maintenance or insurance costs
We proactively manage the system under a long term operation and maintenance contract, including the provision of insurance cover, all at no cost to you.

Long term protection against energy markets
The unit price you pay for electricity generated by the solar PV system will only rise in line with RPI, allowing you to budget more effectively.

Fully transferable
The PPA can be transferred to new occupants of the property should you move to new premises.

Typical savings you can expect to achieve

Our Capital Investment Partners fully funds the entire installation of the solar PV system and you benefit by consuming the discounted solar electricity which is generated. After 25 years, ownership of the system transfers to you and you enjoy free solar electricity for the remaining life of the system (c. 10 years).

Immediate bottom line savings on energy costs and carbon emission reductions

Year 1Over 25 Years
Electricity bill savings£12,350£835,177
Carbon reductions83.50 tonnes CO2e2,087.50 tonnes CO2e

Cumulative costs:

Do nothing vs. Power Purchase Tariff

*Based on a 250kWp system, 100% on-site usage, 14.2p/kWh electricity tariff, 9.0p/kWh PPA tariff, 2.5% RPI and 5.04% electricity price inflation.

Keeping the process simple, transparent and hassle-free

  • We assess the potential of your roof and gather data regarding your current electricity usage and pricing

  • We provide you with a proposal demonstrating the financial savings and carbon reduction forecasts

  • You agree to lease the airspace above your roof to us and enter into a Power Purchase Agreement (PPA)

  • We install the solar PV system with minimal disruption to your business

  • You enjoy reduced electricity bills for c.25 years with no maintenance costs and worry-free operation of the system

  • After 25 years, ownership of the system transfers to you to enjoy free solar PV electricity for the remainder of the system life – c. another 10 years

Can your business take advantage of a PPA?

To achieve the maximum electricity bill savings and carbon emission reductions, your business should:

  • Own a building† with an unshaded roof which is structurally sound and in a good state of repair (pitched and flat roofs are suitable; pitched roofs facing between south east and south west are ideal)

  • Purchase a minimum of 80,000kWh of electricity per annum which is consumed in a regular daily pattern

  • Be financially stable with a strong credit rating

†PPAs are also available for ground mounted and even floating solar PV systems.

Building Footprint*Building Footprint*# of PanelsSystem Size
1,400 m215,100 ft2385100 kWp
3,500 m237,700 ft2962250 kWp
7,000 m275,300 ft21,923500 kWp
14,000 m2150,700 ft23,8461,000 kWp

*For pitched or flat roofs

Typical solar PV systems installed under our scheme are sized between 100 kilowatts (kWp) and 1 megawatt (MWp), equating to the installation of 385 to 3,846 solar PV panels. Use the building sizing guide to estimate the potential capacity of your building.

Your roof in safe hands

When we install a solar PV system, we recognise we are being trusted with one of our client’s major business assets; the roof on their building.

As an accredited partner of the Capital Investment Fund, we have significant experience installing solar PV systems and represent the very best the UK has to offer.

We have designed, then installed high performance solar PV systems in all environments, on all roof types, across a wide range of public and private sector buildings within the UK.

On behalf of the investors, we are responsible for our solar PV systems for at least 25 years, so we only install high quality products and components.

All the equipment is supported by robust product warranties and performance guarantees provided by leading manufacturers.

Start Saving Today

Government data indicates that average electricity prices in the industrial sector are rising by 5.04%* per annum. That equates to your bill doubling every 14 years.

As fossil fuels become harder to source and with an ageing UK electricity infrastructure requiring significant expenditure to meet the country’s future needs, even the most conservative observers do not expect this trend to improve in the future.

You could join over 23,000 businesses in the UK who have already taken a stand against rising energy prices by generating their own zero-carbon electricity with solar PV.


I am a commercial landlord and have tenants in my building. Can I still take advantage of Callidus’s scheme?2019-04-25T14:36:43+00:00

Yes. However, you will normally require approval from your tenant beforehand. If you are happy to share the benefit of the cheaper, clean, green electricity with your tenant, then there is little reason for them to object. Specific circumstances will apply and you should contact us for further information.

Does my building need to meet a certain energy efficiency requirement?2019-04-25T14:36:20+00:00

Normally your building must achieve an Energy Performance Rating of D or higher, although certain exclusions do apply. If required, we will we able to arrange this for you but the solar PV system we install cannot be included in this initial assessment.

By 2018 it will be illegal to lease a property with a rating lower than E, so we recommend all property owners start to consider how they can improve the performance of their buildings and a solar PV system would be one such improvement.

What happens if the solar PV system breaks down or develops a fault?2019-04-25T14:35:44+00:00

Our remote monitoring equipment will alert us to a fault immediately and it is our responsibility to resolve the problem through our long term operations and maintenance contract. To minimise the risk of any such issues, we only specify and install high quality equipment supported by long term warranties and guarantees.

What is the cost of electricity produced by the solar PV system and does it increase?2019-04-25T14:35:19+00:00

Typically we are able to achieve savings of 10-30% against a client’s grid electricity tariff. The starting tariff (in pence per kWh) is adjusted annually by reference to Retail Price Index (RPI).

If I wish to re-develop my building can I terminate the lease and have the solar PV system removed?2019-04-25T14:34:50+00:00

It is permitted to terminate the lease at any time during the course of the 25 year term, subject to the payment of an agreed compensation, details of which are calculated on an individual basis for each property and are included in each lease from the outset.

Can I buy the system from you during the 25 year term?2019-04-25T14:33:08+00:00

Yes. You will have the option to break the lease and buy the solar PV system from us to receive free electricity and the Feed-in Tariff at any point throughout the term. The price for doing so is set out in the lease and will typically deliver an attractive return on investment no matter when you decide to buy the solar PV system.

What happens if we move or sell our property?2019-04-25T14:32:46+00:00

If you move or sell your property within the 25-year term, the lease of the roof space and the Power Purchase Agreement are transferred to the new building owner and they will then continue to enjoy the benefits of the discounted clean, green electricity the system generates.

There is a mortgage or other charge on the property. Do I have to tell the lender and will they approve the installation?2019-04-25T14:32:20+00:00

Yes. Before leasing your roof space we will seek consent from any lender who has a legal restriction over the property on your behalf. We have direct experience with most banks and as they are familiar with these schemes it is extremely rare for them to object.

What happens if we need to repair our roof during the term of the lease?2019-04-25T14:23:01+00:00

If your repair necessitates the removal of part or all of the solar PV system, we will arrange the removal and reinstatement at our cost. The repair work to your roof is undertaken by you at your expense unless it has been caused by the solar PV system itself, in which case we would be responsible for all work and costs.

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