PV (photovoltaic) solar panels, installations, and installers

Learn about PV (photovoltaic) solar panels in the UK's climate that benefits for decades to come. Today, you can install an on-grid photovoltaic system with or without storage options. PV with battery storage, water storage, and possibly car charging is perfect for this crazy 21st century.

In a nutshell:

Depending on cloud density, generation can occur passively. With denser cloud cover, not so much. A single 1 kW Photovoltaic Monocrystalline array generates around 900 kWh/year. Domestic instllations range from 1-5 kW. A 3-4 kW arrays are commonly installed. PV systems are a 'solid-state' conversion process with no moving parts.

The science bit.

Photons of light strike the electrons in the p-n junction and energize them, knocking them free of their atoms. These electrons are attracted to the positive charge in the n-type silicon and repelled by the negative charge in the p-type silicon. Electrons align into the circuitry to create a current:

• The Inverter switches electrons from a DC to AC.
• The power gets dispersed around the home, off-grid storage, or export.
• Output data is correlated.

Photovoltaic solar panels.

Common questions about PV systems

Are PV solar panels financially worth it?

The UK absorbs around 50-60% of The Sun's radiation compared to the equator. Add your annual energy/fuel costs x 30 years (panel lifespan.) Add inflationary pressures = your approx future energy costs. Now compare this figure to the cost of installing a PV system.

PV solar panels (modules) are an invaluable partnership whose benefits increase year-on-year. Geographical and orientation variables apply.

What happens to surplus?

Modern inverters can be used to optimise self-consumption, stored in batteries for future use or fed into the public grid. If not stored, it automatically feeds the National Grid, and payment comes via an export tariff. Any deficit in power generation automatically draws from your electricity supplier as per usual.

Micro-Inverter or String Inverters?

Both inverter types have positive and negative attributes.

String Inverters are the original way of altering Direct Current to a more useful Alternating Current. Micro-Inverters are additions added to each panel on the roof.

Mico-Inverters are more complicated to install and typically add about 20% more to the cost of installations. The simpler String-Inverter makes PV more affordable to more people and easier to access for maintenance.

Micro-Inverters get recommended if shading is an issue, such as a split-roof configuration. Micro's offer a negligible increase in performance, but from a longer-term maintenance point of view, they're difficult and costly to replace if required. Any performance advantage may be negligible.

Unless there is a specific reason for doing so, I advocate keeping it simple by installing a traditional String Inverter and keeping costs to a minimum.

Myth busted.

In reality, photovoltaic cells work more efficiently in cooler temperatures. Panel degradation occurs much quicker in hotter climates, just like redlining a car engine will reduce the lifespan and efficiency of a car engine.

Can PV heat water?

PV-to-hot water converters heat immersion-based tanks with solar-generated electricity directed to the heating coil. This device eliminates the requirement for boiler usage most of the year.

How much roof space?

Depending on the size of the array, PV solar panels take up a lot of roof space, but most homes in the UK are suitable. Additionally, they can be ground-mounted A-frames if garden space or land allows.

Do I need planning permission?

No planning permission is required unless listed or conservation area.

Do solar panels work on cloudy days?

This answer depends on the density of the cloud. A solar-powered calculator will work fine outside in most daylight hours. A PV system works on cloudy days, just not at peak performance.

How long does a PV system last?

Photovoltaics installed in the 1960s are still working today. Degradation is minimal consideration when choosing a system. Monocrystalline solar panels still have an 80% generation capacity after 20 years.

Many of the earliest PV adopters may be experiencing reduced performance due to the inverter's end of working life. Therefore, I recommend upgrading your inverter to enable storage in the latter half of a system's life.

DIY solar panels and self-installing?

Yes, but only off-grid systems alongside battery storage as a DIY installation. On-grid or grid-tied systems require an accredited installer to be safe and legal.

DIY PV solar kits are popular with Part P accreditated tradespeople. Electricians can install solar panels but must be legally accredited by MCS to receive an export tariff. No export incentives are available for self-installs.

What about solar panel cleaning?

Photovoltaic solar panels have microscopic layers of titanium dioxide during manufacturing. When ultraviolet light falls on the glass, the coating reacts with organic matter to break it down. However, a periodic cleaning using de-ionised water will ensure the best performance.

Stuart Lovatt
Power My Home Solar Panels
Sundial House, Panton Road, Chester CH2 3HX.
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