Photovoltaic (PV) in Manchester: It’s so grey, Is Solar Really Worth It?

Solar energy is an exciting prospect for homeowners looking to reduce their carbon footprint and save money on energy bills. But when it comes to Manchester, with its characteristic weather and location, does installing photovoltaic (PV) panels make sense? Let’s dive into the facts, crunch the numbers, and decide once and for all whether solar energy is a worthwhile investment for the typical Manchester household.

Why Photovoltaic (PV) Systems Shine

Photovoltaic panels convert sunlight into electricity, making them a renewable energy source with significant environmental benefits. Solar energy plays a crucial role in helping the UK achieve its ambitious climate goals, including the legally binding target of net-zero carbon emissions by 2050. Solar energy contributes to lowering greenhouse gas emissions by reducing our reliance on fossil fuels, which is essential in combating global warming and limiting temperature increases to 1.5°C above pre-industrial levels as per the Paris Agreement. Unlike energy production with fossil fuels, solar energy production doesn’t emit carbon dioxide, making it a key player in global efforts to mitigate climate change. Its widespread adoption is seen as a critical element is the mosaic for limiting global temperature rises and transitioning towards a more sustainable energy system that prioritises environmental health and the reduction of carbon footprints worldwide. Here’s why many households are turning to solar:

• Energy Independence: By generating your own electricity, you become less reliant on grid electricity and its rising costs. This independence contributes to energy security, ensuring a steady supply of power regardless of market fluctuations or energy shortages. It also enhances resilience during energy crises, as you are less vulnerable to grid outages and price spikes, which have become increasingly common in today’s volatile energy markets.
• Long-term Savings: Over time, solar panels can pay for themselves, especially with consistent use and favourable conditions. The profitability is one topic this blog will delve deeper into, providing a thorough analysis of how solar compares with other investments in energy efficiency and renewable technologies.
• Eco-Friendly: Each kWh generated by solar reduces dependence on fossil fuels. The Carbon Trust claims on average, every kWh of solar electricity offsets approximately 0.233 kg of CO₂ emissions in the UK . For a 1,089 kWh/year system, this equates to about 254 kg of CO₂ avoided annually. Over the typical 25-year lifespan of a system, this adds up to 6,350 kg (or 6.35 metric tons) of avoided emissions. These reductions contribute significantly to the UK’s climate goals, including achieving net-zero carbon emissions by 2050, and align with global efforts to mitigate the effects of climate change by limiting warming to 1.5°C above pre-industrial levels. You can see the UK carbon intensity of electricity in the UK at any given moment at carbonintensity.org.

Carbon Emissions Comparison: Solar vs. Other Power Sources in the UK

What Manchester Homeowners Should Know about PV

While solar energy has clear benefits, its feasibility is not universal. Let’s outline some concerns and we can quantify them and compare later:

1. Energy Output (kW)vs. Cost(£)

Solar panels generate electricity based on the sunlight they receive. In Manchester, where sunny days are fewer than in southern parts of the UK, not only can total energy generated be low, but the power output can be low. This raises questions about whether the electricity generated justifies the initial investment.

2. Cost per kWh Over the Lifespan

Solar panels have an average lifespan of 25-30 years, a critical factor when calculating the long-term cost per kWh and overall return on investment. This durability means they can provide decades of energy production, but it also requires careful consideration of efficiency degradation over time and potential maintenance costs. Factoring in installation and maintenance costs, it’s important to calculate the cost per kWh generated and compare it with alternatives.

3. Carbon Footprint of Solar Panels and System Components

While solar panels themselves generate clean energy, their production and installation require energy, which contributes to a carbon footprint. The embodied carbon of a solar power system includes emissions from the manufacturing of the panels, inverters, optimizers, mounting systems, and other components. These emissions are important to consider when evaluating the true environmental impact of a solar energy system. The carbon payback period refers to the time it takes for a solar system to offset the carbon emissions from its manufacturing.

Components of a Solar System and Their Embodied Carbon

The following table breaks down the carbon footprint of each major component in a solar power system:

How the Carbon Debt Is Repaid

Let us consider a 16m2 array to have 1000kg of CO2 embodied also known as carbon footprint. Which means there was 1000kg of CO2 released to into the atmosphere to; mine the materials, manufacture the parts, assemble and install the solar array. Once installed, the system generates renewable energy that displaces electricity generated from fossil fuels, which has a carbon footprint. The first amount of energy generated by the system goes toward repaying the emissions that resulted from producing the system’s components. This “carbon debt” is repaid quickly due to the high efficiency and sustainability of solar energy production.

After the carbon payback period is reached, the system continues to generate carbon-free electricity, contributing to a reduction in overall emissions for the remainder of its operational life (typically 25 years or more).

Below we will calculate what that payback period you might expect in Manchester.

4. Could Your Manchester Home Benefit More Without PV?

Before committing to solar, consider other energy-saving investments that could compete with the 3 questions listed above. These would include but are not limited to; insulation, heat pumps, double-glazing, MVHR, or appliance upgrades all might offer better cost-to-savings ratios, initially and also over their lifespan. There are many variables to consider, so for the purpose of the discussion we have created a sample Manchester house to unpick.

PV for a typical Manchester Terrace

For the purpose of answering the hypothetical question, Is solar worth it in Manchester?, we have assumed a house to consider for the upgrade. This house has the following properties to help begin our discussion:
The house has a floor area of 100m² and a dual-pitch roof with a 22-degree angle, 196-degrees from due north which is 16 degree azimuth (from due south). These are fairly ideal conditions for the array, and we can fit 8 panels (16m2) on the 25m² roof. There is also no shading nor inefficiency dirt on the panels or degradation of the panel efficiency over time. This may be comparable to a larger terraced property. The panel we will install will be modern 440W panels. This means, in optimum conditions the panel can produce 440 Watts at any moment.

Budgeting for Solar: Small PV Arrays in Manchester

What can Photovoltaics Power in Manchester

In theory the maximum power that can be generated is 8 times 440w which is 3520W. Making this a 3.5kW system. However, considering the non-perfect conditions. Such as the non-optimal roof angle, the varying trajectory of the sun across the sky. This power will likely reach highs of 3kW at midday in the middle of summer. Meaning that the solar panel could power several appliances at that moment directly.

500W Freezer + 700W Fridge +1800W Dishwasher = 3000Watt power demand

This seems undeniably useful, but it must be remembered that this will not be possible year-round. Investing in a battery system would help utilise the potential of the system. But we should explore the annual generation for more clarity on its financial effectiveness in the form of an investment.

Annual energy generation for PV in Manchester

Estimated annual output = kW_p x Kk x SF (kWh)

Where kW_p is the installed capacity = 3.52kWh

SF is a shade factor which in our case is 1 as there is no shading.

Kk is a factor taken from the MCS energy design tables (Microgeneration Certification Scheme is the independent government-backed scheme that certifies microgeneration products such as photovoltaic panels)

Tables of kWh/kW_p described as (Kk)  provide generation values for each postcode zone of the UK. For each location in question 1° variations of inclination(pitch) and 5° variations of orientation are provided.

In our case the equation is as follows:

3.52 kW x 837h x 1 = 2946 kWh each year.

Monetising Solar Energy

The value can simply be calculated by multiplying the cost per kWh to purchase energy by the amount generated. This is a key indication; however, in reality, the full amount of energy generated is rarely used in the home. The export value is a fraction of the import cost of electricity, and therefore, its value is dependent on the usage profile of the home in question, as well as the tariffs the homeowner is using.

We should consider the two opposite ends of the spectrum, and then the potential variation between them. Scenario A is a 4-bedroom home and has an annual electricity consumption of 3,900 kWh and uses all the energy generated because the occupiers were in the house all day. Maybe the occupier is running a business from their home or charging their electric car all day. This would be ideal, and the value of the electricity would be the highest, but it must be made clear this is an unlikely scenario and the difference between the consumption and generation must still be purchased.

In this instance, the annual value of that electricity is 2,946kWh x 0.25p/kWh = £737.

Scenario B, however, has the same consumption but no one was at home during the generation hours and the home had no battery, then the electricity would be exported to the grid. This rate is variable depending on the supplier and tariff. Let’s assume it is 10p export price, which would generate a lower income for the household. The occupiers would still need to purchase electricity in the evening to carry out daily life tasks.

In this instance, the annual value of that electricity is 2,946kWh x 0.10p/kWh = £295.

We can consider the value in two ways. Firstly, consider the net present value of each scenario given the 25 years of the solar panel’s life generating energy. This method has 3 distinct pros.

1. Realistic and widely accepted in financial modelling.
2. Allows for comparison with other investment opportunities.
3. Captures the impact of long-term opportunity costs

NPV=∑ C_t÷(1+r)^t​​

Where:

• C_t is the cash inflow in year t (savings from solar energy).
• r is the discount rate (4% or 0.04). Typically used in financial prediction and considers such things as, risk, economic climate, and desired return on investment.
• t is the year number (from 0 to 24).
• The formula sums the discounted cash inflows for each year from year 1 to year 25.

Scenario A = £11,966

Scenario B = £4,786

The second NPV calculation, could consider a scenario where the value is discounted less because the value of energy generated will increase and should be penalised less. I could consider a 2% discount rate.

In the last NPV calculation, I could not discount them at all if I do not consider the investment risky at all. I have no ambitions for optimising investment return, it simply assumes that today’s value of energy will remain constant in real time.

Scenario A = £18,413

Scenario B = £7,365

These values are all considerably different and as you can imagine result in considerably different payback periods and therefore worth of the solar panel system. We can plot all these on a graph along with a 50:50 energy used and energy sold to the grid (scenario C) option for a visual representation.

Although the future economic outlook is difficult to predict there is one clear distinction in the graph. Regardless of inflation, the discounted cost assessed by risk or opportunity cost etc. You can see that the most influential factor is using the energy that is generated in your home. This is because the cost to purchase energy is so much more than the export value to the homeowner. In Manchester, it is likely that most homes with solar arrays would sell a significant amount back to the grid as it cannot all be used. When trying to decide if solar is right for you and money is a consideration, you need to assess how much energy you will be directly using in your own property. This makes all the difference. To help increase this energy consumption, people also purchase battery storage capacity to save the energy for later in the evening. Yes, this does increase the initial cost (in effect lifting the red line on the graph). But it should significantly steepen your personal accumulative value line till it looks more like Scenario A. Alternatively, the energy can be used to heat water, which is a good way of benefiting from the energy in the home. Water is a great storer of energy and the infrastructure for doing so is already in everyone’s home, making it a more economical option. This reduces the energy needed to be imported to heat your hot water tank.

Considering a 2% discount rate the best-case scenario is clear. A NPV of £14,667 and a break-even point in year 9 after the installation.  Although a more realist example would be to take Scenario C (50:50) £10,267 and a break-even point in years 13-14.

The ROI (Return on Investment) For Manchester Homeowners

Let us consider our realistic case, Scenario C with 50% of the energy going to the grid whilst 50% is used in the home. We will use the 2% discount rate as we are very confident in our investment, the market and government policies that will continue to favour the investment. We can calculate annualised ROI as an alternative way to compare the investment. It is often the critical figure when considering financial investments.

ROI= Annual saving ÷ Initial Cost ​×100

The average annual saving is the NPV divided by the years in operation of the solar array.

£10,200 ÷ 24years= £425

ROI=£425 ÷ £6,013 ×100= 0.0707

ROI = 7%

The Solar Verdict: What We Learned About PV in Manchester

You can see that even in Scenario A, the payback period for the array between 8 and 10 years, although a more realistic example would be to take Scenario C a break-even point in years 13-14. The total cost of each kWh generated by the solar array is calculated as:

Scenario A: total cost ÷ total generation = £6,013 ÷ 73650kWh = £0.0816/kWh

Realistic scenario: £11,555.5 ÷ 73650kWh = £0.1569/kWh

This is 8.1p per kWh in the best scenario. This helps compare solar energy costs with grid electricity rates or alternative investments. This is markedly cheaper than the current cost of electricity at 25p highlighting again the savings that could be made. In our realistic scenario C not all the energy is used so the cost would increase to 15.7p per kWh generated.

Financially, detailed calculation and a home use survey has to be done of the home, an energy management system may need to be utilised this comes as an additional cost (£600-£2,500) and in some cases a battery which will significantly add to costs (£6,000-£15,000) and squeeze the ROI. I will investigate the use of batteries to maximise own power consumption and the financial implications in a following blog post likely titled ‘PV and battery storage in Manchester’.

We can also estimate the time required to pay back the embodied carbon of the system. The system has an embodied carbon of 1000 kg CO₂. Generating 2946 kWh of electricity with solar produces 0kg CO₂, while generating the same amount of energy with non-renewable such as gas can be estimated at:

394g × 2946kWh = 1160kg of CO₂.

This means the solar array offsets its carbon footprint within 1 year of installation.

All in all, there are several variables that tip the scales for the viability of solar panel on any roof. A professional should be considered in each and every case.

Alternative Investments: Weighing Solar vs. Other Options in Manchester

While investing in a solar array is undeniably a great choice from an environmental perspective. Only those with excessive financial means should invest with little hesitation Slashing their carbon footprint and reducing energy costs. However, for individuals without the necessary funds readily available, financing the system could lead to significantly higher costs, depending on the interest rates, financing mechanisms, and repayment periods. This would push the financial break-even point further away, making the investment less appealing. See the table below and visit our previous blog on government grants and finance for guidance on whether you are eligible for an upfront cost reduction.

Solar PV prices for 4kW systems = £4,000 – £6,000 for an installation on an average pitched roof at time of writing.​

Solar Investment Timeline: It’s key to always factor in a long-term investment horizon, typically 15-25 years, for solar projects.