Home   /   Frequently Asked Questions

+ How much electricity will my solar PV system generate?


The Government has provided a recommended method for calculating the amount of energy produced annually by a solar PV system. It is known as the Standard Assessment Procedure (SAP).

The equation is:
Predicted Generation (kWh/year) = Irradiance x Shading factor x kWhp x 0.8.

It’s important to note, however, the amount of energy produced can vary over the course of a year, with more energy being produced in the summer months than the winter months, This is due to the longer days and more sunlight in the summer. The Nene Valley Eco Home Improvements solar PV team will work this out for you and show you the results on an easy to read printout.


+ Will I need to maintain the PV Panels and equipment?


A Nene Valley Eco Home Improvements solar PV system needs little maintenance as there are no moving parts.  The panels are designed to be self cleaning but a build up of debris can affect performance, therefore, we recommend the panels should be cleaned on a yearly basis.  This work should be carried out by personnel who are suitably qualified to work at height, or with equipment which would enable the cleaning to be carried out from ground level. 

The inverter, which transforms the current produced by the solar panels into useable electricity may need to be replaced within 25 years.   Nene Valley Eco Home Improvements provide an extended 10 year inverter warranty, you can increase this to 25 years if required.


+ How long will the installation take?


During installation of solar PV roof systems, scaffolding is required.  This will take about half a day to erect and the same to remove. The scaffolding team will usually arrive a couple of days before the Nene Valley Eco Home Improvements Solar PV installation team and will be removed a few days after completion. Installations of your Nene Valley Eco Home Improvements solar PV system usually takes 1- 2 days depending on the size of the installation, with minimal disruption. For larger commercial PV installations, we can work within required deadlines as necessary.


+ What is the Feed-In Tariff scheme and how much will I be paid?

  The Government launched the Feed-in Tariff on 1st April 2010, this provides the householder with a payment for every unit of electricity that is generated by small solar pv systems.  
Size of installation      Feed-In Tariff (p/kWh)
Less than 4 kWp (new build or retro fit) 14.90p
4-10kWp    13.50p

The Feed-in Tariff is tax free for domestic households (as long as you live in the property and don’t rent it out) and index linked to inflation for both commercial and domestic installations.

The Feed-In Tariff is available for businesses as well as homes.  The amount you will receive depends on the size of your system.

The Government has confirmed 15.44p will remain in place until 1st May 2013:

15.44p per unit for systems up to 4kWh (retrofit and new build)
13.99p for systems 4 - 10kWh

An additional 4.77p bonus will be awarded for every unit of electricity exported, however if you do not have a smart metre then your export amount will be presumed to be 50% of the electricity generated.

This Feed-In Tariff will be paid for 20 years. It will increase each year in line with inflation (Retail Price Index). The FIT will be subject to reviews by the Government for new installations.

From April 2012, the Government is has introduced energy performance requirments which will be linked to the Tariffs. Your building will have to achieve an EPC rating of band D or above to be paid the maximum FIT tariff.


+ Who is eleigible to receive the Feed-In Tariff?


All PV installations under 5MW, domestic and commercial are eligible. 


+ How will the Feed-InTariff be implemented?


Ofgem administer the Feed-in Tariff. Energy suppliers are responsible for paying the reward to their customers.


+ How do I get the Feed-In tariff?


As an MCS Installer, Nene Valley Eco Home Improvements are required to input details of all installations into a central MCS Database.  The database generates an MCS Certificate with a unique certificate number that is sent direct to the customer.  The customer will require this certificate to gain access to the Feed-in Tariff. Nene Valley Eco Home Improvements will help you fill in all of the required paperwork.


+ Is VAT payable?


VAT at 5% is payable on domestic installations.  New builds are often VAT exempt, commercial buildings will pay standard VAT rates at 20%. 


+ How are PV panels fitted?


Photovoltaic panels can be mounted on a roof or ground mounted. Ideally the roof will be south facing, near to an angle of 30 degrees with the horizontal for optimum performance. The panels produce DC electricity, so an inverter will be fitted inside the house, generally in the loft, to change the DC into AC (used in all normal homes and the Grid).


+ How many solar panels are needed?


Any number of PV panels can be connected based on available space to provide as much electricity output as required. A basic 2kWp solar panel installation will generate around 1500 kWh per year and will require about 8 solar PV panels.


+ Will it supply all my electricity?


The average household consumption is 3300 kWh per year. The 2kWp system would supply nearly 50% of annual consumption. A 4 kWp system could provide most of your electricity needs depending on consumption for the average household. Recent advice by the Energy Savings Trust (August 2011) has shown that some houses are only able to use 25% of what they generate, this depends on usage of appliances and occupancy during the day. Please remember solar PV systems do not produce energy at night and unless they are installed to batteries they cannot store any excess power.


+ What is a Grid connected system?


Photovoltaic panels can be connected to the Grid through the local electricity supplier. Surplus electricity can be sold back to the supplier.


+ Is planning permission required?


Most domestic properties in England and Scotland do not require planning permission before installation of photovoltaic solar panels. Those in Conservation areas, listed buildings and Areas of Outstanding Natural Beauty or World Heritage Areas must consult local planning departments. 


+ How does a photovoltaic cell actually work?


Solar PV systems consist of modular panels made of silicon, which react directly to sunlight by generating electric current. An inverter changes the DC (direct current) generated by the panels into AC (alternating current).


+ What is the Installation process - what do I need to do?


For a domestic system we supply, install and test all of the equipment, we arrange the scaffolding, notify your network operator and will provide you with all the warranties and certifications you require to receive the Feed-In Tariff. All you will need to do is contact your electricity supplier and ask for a microgeneration pack and then relax whilst we do the rest. Once installed, we will help you fill in your pack and send back to your supplier to receive your Feed-In Tariff.


+ Is tax payable on my income?


HMRC announced in December 2009 that tax will not be payable on income from the Feed-In Tariff for domestic solar PV installations. Commercial installations will pay tax at the applicable rate.


+ Do PV Panels work in the UK?


Generally temperatures above room temperature reduce the efficiency of PV solar panels, making the UK a good climate for photovoltaic technology.  The panels require ambient light rather than direct sunlight to generate electricity so they work even on overcast days.


+ Choosing your Solar PV installer and avoiding the rogue traders


We suggest asking the following questions to ensure that you are getting a good deal, a good price and a good service:

- Always ask to see a copy of the MCS certification and check whose name is on the certificate and if they will be installing your system.
- Ensure that you can deal directly with the company that will be installing your panels and you are not being passed to a third party.
- Check who is accountable for the work, including the insurance and warranty for electrical and installation work, along with panel product and performance warranty and inverter warranty.
- Confirm that the solar panels and inverter on the quote are MCS accredited and are a recognised label with good customer services that can handle warranty issues. 
- Is the company an REA member and adheres to the REAL Consumer Code of Conduct, protecting the rights of the customer - this covers the integrity of the information provided, through to keeping your deposit safe and ensuring you are never misled or mis-sold solar PV


+ Which solar panels should you choose?


Nene Valley Eco Home Improvements only uses top manufacturers for all our products, including panels, inverters and meters. This gives our customers confidence in the quality of the product and also the warranties behind the products.  We have a wide range of products to choose from.


+ Is my roof suitable for solar panels?


Nene Valley Eco Home Improvements will come and survey your property to see if it is suitable to fit solar panels.  We will advise on the size of system you could have, what sort of returns you could expect from the Feed-In Tariff and, of course, how much it is likely to cost should you want to get a solar system installed.

Ideally a south facing roof provides good returns, however, you can actually generate very good returns from roofs facing anywhere from an east/west split right through to south facing.


+ Where can I go for more information?


The following websites can provide you with further information about solar PV systems: www.energysavingtrust.org.uk, or www.ofgem.gov.uk


Contact us for a quote, email info@nenevalleyeco.co.uk or call now 01536 303300.

49 Northampton Road
Northamptonshire. NN14 1NR
01536 303300
  © Nene Valley Eco Ltd.  
  Company Number 07781687  
  VAT Number GB 122 6800 43  
  REAL Assurance Scheme Number: 00050187  
  MCS Number: NAP 18175  
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