We’ve listed some questions below that we feel any reputable solar installation company should be able to answer. If they can’t or won’t, think about whether or not you want to give them your hard earned money.
Choosing the right size system
- What size system should I install?
This depends on several factors including:
- Your budget – Systems range in price from £3,500 for a 5 panel 1kW system up to around £6,000 – £10,000 for a 20 panel 5kW system.
- How many panels you can fit on your roof – The smallest system most companies will install is a 1kW 5 panel system. Panels measure on average 1.7m x 0.9m – give or take.
- How many people occupy the house – Generally, the more people in the house, the bigger the system you’ll require and the higher financial return on that system.
- If you own the property – If you rent the property, it’s probably not worth installing a system unless you plan on staying there for longer than 5 years or you have a generous landlord.
- How long you intend to occupy the property – Systems generally take at least 6-8 years to pay themselves.
- Do I want to reduce my bill or totally wipe it out? What size system will I need to do either?
This depends also on your budget and many other factors. Have the installer go through the different scenarios with you BEFORE making any decisions.
- How much is the feed-in tariff and how much extra do I receive from my electricity retailer?
This changes over time and you can access up-to-date info here.
- How long will it take to pay off my system?
This depends on:
- The size of system you install
- The direction the panels face
- The percentage of that production that you’ll use yourself and the percentage you’ll export to the grid
- The feed-in tariff available, and;
- The amount you initially paid for the system.
Any reputable installer will be able to go through these numbers with you, explain how the calculations work and also provide the raw data to back up their calculations.
- Can you show me what affect the system will have on my bill?
As above, this depends on many factors so ask this installer to give you his best estimate, compare these results across the different installers and if there’s discrepancies, ask why.
- Is shading going to affect my production? If so, by how much?
Generally, shading outside of the hours of 8am and 4pm won’t be a problem. Shading on one small area of the system does disproportionally affect production so consider positioning on the roof and whether or not pruning trees is worth it. If you think the trees will need cutting periodically, factor this expense in to your calculations.
- Is roof pitch an issue?
This isn’t a big issue and not really worth worrying about. A 25 degree pitch is optimal and you’ll lose 1% production with every 5 degree deviation. This means that the difference between a flat roof and the average roof is 5% production. Generally not worth the extra cost of installing tilt frames.
- Can you produce a roof plan to show me where my panels will be placed?
This is essential as you’ll be looking at the system for many years to come; you definitely want it laid out in a way that looks good. Make sure you agree on the location with the salesperson and also that the installer on the day has that same plan and that you agree to the plan on the day. Plenty of times, a plan will be done but the installer will install wherever they like.
- What direction will the panels face and what affect will this have on production?
South gets the most sun during the day. However, due to the changes in Feed in Tariffs which mean that you’re better off using the power generated yourself, installing on east or west roofs could mean that you use your own power from your system when you’re home in the morning and afternoon. This is worth discussing with the installers who contact you and asking for multiple opinions.
- Can the inverter take more panels if I’d like to increase the system size in the future? How many extra panels could I fit?
Remember that you can always add another inverter in the future if you want to expand at a later date. If you don’t plan on adding panels in the near future to your existing over-sized inverter, you may not be able to get the same panels which could mean that you’ve wasted money paying for a larger inverter that you can’t utilise in the future.
Choosing the right components
- What brand of panels and inverter will I receive? Can you point me to 3rd party reviews or tests of them?
Make sure that you receive documentation outlining what panels and inverter you’ll receive. Check this on the day of install as well to make sure you’re getting what you paid for.
- Where are the components made?
About 80% of panels and 50% of inverters are made in Asia, the rest generally in Europe. Country of origin isn’t a problem in itself. Who services the warranties if a panel or inverter fails is more important. Make sure you ask the installer this question.
- Do the panels have a negative or positive power tolerance?
A 5% positive power tolerance means that a 100W panel will produce between 100W and 105W. A 5%+/- power tolerance means that the panel will produce between 95W and 105W. Better quality panels have a positive power tolerance. No solar cell manufacturer can produce cells to the exact specification so therefore, the higher quality manufacturers will pay more for the cells with positive tolerance while the rest with +/- will go to lower quality manufacturers.
- Do the panel and inverter manufacturers have an office in the UK?
This is important. If the installation company isn’t around in 10 years, you don’t want to be having to call the manufacturer in China or Europe, so you can realistically kiss your warranty good bye.
- If the panels are installed on different roof areas facing slightly different directions, will you use an inverter with an input for each different facing section?
This is a must, otherwise all panels will produce only as much as the weakest panel at all times, greatly reducing production.
- What maintenance is involved with the system?
This generally involves cleaning the panels with soapy water once or twice a year depending on rainfall. A car cleaning hose will do the job nicely. Be aware of companies who make you sign up for a yearly maintenance programme. If you check the fine print, they’ll demand you pay for this or else you’ll void your warranty. This is a ploy to reduce their obligations into the future and may be illegal under consumer law. This is a sign of a dishonest company.
- Does the inverter have communication software?
Communication software which links wirelessly to your computer allows you to keep an eye on production and spot any problems quickly and easily. If you have the option for this, we would definitely recommend it.
- Will I be able to add an off-grid storage battery to this system in the future? If so, can you manage this for me and what is involved [time and cost]?
The short answer is ‘yes’. A new battery/power source will need to be interfaced with your current system. The supplier that installs the system will be able to simply check the specs and both the system and on the new power source before providing you with a time and price quote for interfacing them. This should not take longer than a few hours.
Choosing the right installer
- How long has your company been around?
The solar industry is relatively new and few companies will be older than 5 years old but still ask the question and try to find out a bit about the company’s history.
- How many systems have you installed?
Go for companies who can demonstrate that they’ve installed a good number of systems in your area.
- Do you have a physical office I can visit?
Visiting the company can be worthwhile and will give you a better insight in to how the company is run.
- Can you provide me with references in my area?
Any good company should be able to point to systems they’ve installed in your area and provide references.
- Do you handle all the rebate paperwork for me so I just have to pay the difference?
Generally, the installer will take care of the rebate so all you pay is the difference. Ask the question though.
- What documentation will I receive both before and after the install?
Make sure you receive a written quote outlining all of the components that go into the system and the terms and conditions of the contract. If a company won’t give you this, it’s not a good sign.
- Am I responsible for organising connection to the grid?
Generally, the installer will organise this but definitely ask the question.
- If so do you provide the paperwork and instructions?
- How much will I be charged and how do I pay this?
Ask the installer and get confirmation in writing as some companies will include the meter expense in the price and others won’t.
- How much is a new meter?
This varies by supplier so ask your installer.