Looking after solar panels in Manchester

Cleaning: rain does most of it

For most Manchester roofs, rain is the cleaning service. The Met Office station at Woodford, in Stockport borough, records at least 1 mm of rain on 156 days in an average year. Its yearly total averages 868 mm (Met Office, 1991 to 2020). On a pitched roof that steady rinsing carries off dust, pollen and light grime.

Cleaning becomes worth doing in a few specific cases:

• Low pitches and flat-roof frames. Water runs off slowly at a shallow tilt, so dirt collects along the bottom edge of each panel and moss or lichen can take hold there.
• Bird droppings. Rain moves them slowly, and a heavy patch shades the cells beneath it.
• Trees nearby. Leaves, sap and blossom from street trees and gardens can sit on the glass for weeks.
• A drop you can see in the figures. If output has slipped and the glass looks dull from the ground, cleaning is a reasonable first step.

Do it safely or not at all. Nobody should walk on panels or climb a pitched roof without proper access. Clean from the ground with a soft brush on a water-fed pole, or use a firm with the right access equipment and insurance. Plain water is usually enough. Avoid pressure washers, abrasive pads and strong chemicals, and check the panel warranty first, because some makers set conditions on how their glass is cleaned.

Pigeons and pigeon mesh

Pigeons are the most common nuisance for panels in Manchester. The gap between the panels and the roof is dry, sheltered and warm, which makes it an attractive nesting spot for city birds. Once a pair moves in, the problems follow: droppings on the glass and in the gutters, nesting material packed round cables, noise, and birds that come back every year.

The fix is mesh clipped round the edge of the array, closing the gap without blocking airflow. It is far easier to fit at installation, while the scaffold is up, than to add later. When you compare quotes, ask whether mesh is included and how it is fixed; clips that grip the panel frame avoid drilling into the panels or the roof.

If birds are already nesting, get the nest cleared before mesh goes on, otherwise birds can be trapped inside. Check the mesh from the ground every so often too. Storms and squirrels can open gaps, and a small gap is enough for a pigeon. The installer checklist covers what a quote should itemise, mesh included.

Checking output against PVGIS

The single most useful habit is a monthly look at the inverter app. Most inverters log daily and monthly generation, and a monthly total tells you more than any glance at the roof.

Divide the month's total by the number of kW in your system, and you have a kWh-per-kW number to check against the PVGIS value for that month and your roof's direction (PVGIS 5.3). The table gives three common Manchester cases. The roof yield explorer has every other direction and pitch.

Read the comparison sensibly. One month can easily come in well below the average because it was dull, and well above it because it was bright. What matters is the pattern:

• Several months in a row clearly below the figure for your roof, especially in spring and summer.
• Days with no generation at all in daylight, which usually means the inverter has tripped or lost its connection.
• A step change from one month to the next that the weather does not explain.
• This year's June well below last year's June, with no obvious reason.

Comparing the same month across years cancels out most of the seasonal swing. Keep a simple note of each month's total; after a couple of years you will know your own roof better than any model.

The inverter and the panels' working life

The panels are the long-lived part: the Energy Saving Trust puts their life at 25 years or more, and expects an inverter to need replacing after around 12 years (Energy Saving Trust). So over the life of a typical system, plan for at least one inverter replacement.

The signs of a failing inverter are usually clear: a fault light or error code, the app showing it offline, or zero output on a bright day. Before anything else, check whether it is still under warranty, and call the installer who fitted it.

A replacement is also a decision point. A like-for-like swap keeps the grid arrangement the same. A larger inverter, or a hybrid that adds a battery, can push the total over the 3.68 kW single-phase limit and move the system from G98 to G99. That means applying to SP Electricity North West before it is switched back on. The grid connection guide explains the difference, and the battery guide covers adding storage at the same time.

A yearly look-over, and access for repairs

Once a year, it is worth a proper check, either by the installer or by another competent firm. A sensible look-over covers:

1. The glass and frames, from the ground or with a camera on a pole: cracks, discoloured cells, slipped panels.
2. The roof around the array: slipped slates or tiles near the fixings, and anything blocking the gutters below.
3. Pigeon mesh and the gap beneath the panels.
4. Cables and isolator switches in the loft and at the inverter, for heat marks or damage.
5. The inverter's fault log and the year's generation against the PVGIS figures.
6. The generation meter reading against the app's total, so you know both agree.

When scaffolding is needed again

Most checks need no access to the roof. A real repair often does, and on a terraced street the front scaffold usually stands on the pavement. That needs Manchester City Council's permit again, exactly as at installation. The council charges a £175 administration fee. On top of that comes £90 per four weeks for a scaffold of up to 25 m², or £132 for one of up to 50 m², according to the council's permit page. Each permit runs for 28 days or more, and the council works to a 20-working-day target for replies, so a non-urgent repair needs planning ahead.

Grouping jobs saves repeated access. If the scaffold has to go up for one repair, use it for everything else at the same time: mesh, cleaning, a stack repair or slipped slates. On older slate roofs, the guide to older homes covers what to look for.

The paperwork to keep

Keep one folder, paper or digital, for the life of the system. You will need it for warranty claims, for the export tariff and when you sell the house.

• The MCS certificate. It proves the system was installed to the scheme's standards and is needed for export payments. You can look up the installer on the MCS register if you lose track of them.
• Warranties. The panel maker's product and performance warranties, the inverter warranty and the installer's workmanship warranty, with their start dates.
• Consumer code details. Which code the installer belonged to, such as RECC, and any insurance-backed cover for the workmanship warranty.
• The electrical certificate and the commissioning record.
• The grid paperwork. The G98 notification or the G99 agreement.
• The export tariff contract and the meter details.
• Your monthly output notes. They are the evidence if you ever need to claim that something is underperforming.

If the installing firm has closed, the folder matters even more: a new firm will need the system details before it can help. Common questions on snow, insurance and moving house are answered briefly on the FAQs page.