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What questions should you ask when comparing solar PV quotes?

Posted by Tasha Kosviner on 30 March 2015 at 9:55 am

You’ve got a stack of quotes for solar PV but without the technical know-how it can be very hard to figure out which one is best. Following on from our blog about what should be included in your quote, we’ve come up with a list of questions you can ask to help you to sort the wheat from the chaff.

Don’t be afraid to grill your installer: the more information you have the better able you are to judge which is best for you. You’re spending a lot of money and you have the right to expect a good job. The more questions you ask and the more open the responses you get, the better you’ll be able to judge whether this is the kind of outfit you can trust to be up on your roof!

1. Why have you recommended this particular system?
It may seem like a simple one but different installers will recommend different systems based on their assessments of your particular requirements and setting. See this blog for an example of how this can happen.

Once you have all the quotes in, make sure you quiz each installer on why they’ve recommended their particular system. Are they affiliated to just one manufacturer or do they sell multiple brands? Ask to talk directly to an engineer rather than to a salesperson and ask them whether they considered, and why they rejected, systems recommended by other installers.

2. What is the total cost of the installation?
Obviously! But equally obviously, remember cheaper often doesn’t mean better. Low price should only be used as a deal sealer once you are satisfied that the proposed system and the installer are right for you. More pertinently, you should perhaps ask why a quote differs from another seemingly similar quote.

A larger installer may just be operating with economies of scale but look for costs that may not have been obviously included such as VAT, the cost of obtaining any permissions needed, after care service, the cost of ‘making good’ the property after installation and so on. Particularly look for roof fixing to be included and evidence that they have included the cost of employing a structural engineer to assess your roof and it’s ability to take the weight.

3. How much energy will the proposed system generate?
Different systems will generate different amounts of energy or kilowatts (kWh). The higher the annual kWh figure the more energy your system is predicted to generate and the more you will be paid in feed-in tariffs. All installers are required to calculate the performance of your system based on MCS standards

4. Has the energy calculation taken into account all the possible variables?
When undertaking an energy calculation, the installer must take into account all the possible factors that will affect your installation’s output. This includes kWp, orientation, pitch, shade factor, geographic zone and Kk (kWh/kWp) value. If the installer has not included all these things in the calculation, then be cautious.

5. What is the predicted feed-in tariff income over the next 20 years?
The feed-in tariff total you receive is calculated according to how much energy your system will produce. You will be paid one amount for that total, and another amount that assumes you are feeding half of that total back into the grid (this is regardless of how much you are actually using onsite.

Your installer should have calculated the likely income from your system based on its predicted output. This will be affected not only by the size of your installation but also by its orientation, shading and geographical location. Your installer should be able to confidently talk you through the calculations they made in order to arrive at their predictions.

6. What guarantees cover the installation?
What protection is your installer offering should something go wrong? You should expect to have separate guarantees for the panels, the inverter and the workmanship. These should be in the region of panels: 10 years for manufacturing, 25 years for performance; Inverters 5 to 10 years; and workmanship 5 to 10 years.

Some installers offer a replacement inverter as part of their quote. A well-installed inverter, with surge suppression to guard against lightning for example, should last 10 to 15 years so you will need a new one at some point and they can cost around £1000. If you think your installer will still be in business at that stage, by all means accept this extra sweetener. Some manufacturers may offer a 25 year panel warranty but be wary of making a decision based on this. Unless they are a well-established company, how likely are they to be around in 25 years’ time?

7. What happens to my guarantees if you go out of business?
At this point you want them to confidently answer that all the guarantees are insurance backed and that should they go out of business and something goes wrong, you will have recourse to the insurers. Ask for documentary proof – it’s not enough just to say this is the case.

8. What is your accreditation body?
You cannot claim feed-in tariffs unless your installer is a member of the Microgeneration Certification Scheme (MCS). Ask which certification body they are with and check it. Electricians should be registered with NECEIC, Napit or the Electrical Contractors Association and the two main roofing bodies are Confederation of Roofing Contractors and the National Federation of Roofing Contractors.

9. Are you a member of the Renewable Energy Consumer Code (RECC)?
Your installer cannot be MCS-certified unless they are signatories of the RECC. Installers who are members of the Renewable Energy Consumer Code are required to abide by high standards of training and service. The Code has a strict complaints procedure and should be able to help you seek redress should things go wrong. Confirming their RECC membership is just another check you can make on their credibility.

10. Will you be carrying out the work?
Chris Roberts, technical specialist at the Solar Trade Association, warns that you should be wary of using a sales company who then subcontracts, even if it is to an MCS-installer. Even if the sales company is a RECC member, using a different installer exposes you to problems contractually, for example who to blame if things go wrong or if sales information is inaccurate. For this reason MCS requires that the certified contractor must contract directly with the customer and not through a sales intermediary.

11. Can I talk to some of your other clients?
Your installer should have a long list of other satisfied clients who are willing to talk to you independently about their experiences including satisfaction with both the process of installation, the after care and the performance of their panels. Take up the references both recent and from two or three years ago so you can get an idea of satisfaction levels over time.

Photo: SuperHomes

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1 comments - read them below or add one


jevbanComment left on: 7 April 2015 at 10:21 am

Tasha if only RECC and the MCS body who regulates the installer could ensure that the installer complied with the rules, all would be good. Unfortunately rogue installers continue to flout RECC and the courts, so it really is a matter of interrogating the installers prior to starting the job and ensuring they have a solid electrical or electrical engineering background. I speak from experience as having spoken with previous customers , found out to my chagrin that they were carefully selected. 

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