My personal experiences of solar panels – my first year of living with PV

Author: 28/05/2015

Our Communications Manager, David Dean, reports on his first year living with solar panels, and how being an independent electricity generator has changed the way he and his family view and use energy.

It’s 12 months since I had solar panels fitted onto the roof of my house – so (following my first and second blogs) now is a good time to assess how they’ve changed how we live our daily lives and what impact they’ve had on my electricity bills.

My 3.6kW system was predicted to generate 3,496kWh of electricity a year. The actual figure in its first year was 3,815, an over-generation of 9.1%. The system has outperformed its predictions during all but one of its first 12 months (with an under-generation of 3.4%) and the positive months varying between 2.6% and 51%. So, that makes for a good first year.

FiTs

As a result, my FiT payments have been slightly higher than expected. In addition, my experience of the FiT process has been a good one. My energy company dealt with the initial paperwork very efficiently and I now receive an email a few weeks before the end of each quarter to remind me to provide my generation meter readings. Having done that, I receive a confirmation email, followed by a letter summarising my payment and the money is in my nominated bank account by about six weeks after the end of the quarter.

The post-installation customer care I received from the installer was also very good. I didn’t actually have any problems but I did have a few questions, all of which were answered very competently by my (very dedicated) Account Manager. These included a query I sent him on a Saturday afternoon, which he dealt with within minutes!

Reducing costs

Measuring the impact on my electricity bills has been a bit unscientific – largely because:

  • I had switched energy supplier not long before I had the panels installed.
  • Having moved, I no longer have access to the information held in my online account with my previous supplier – although I do have some hard copy bills.
  • My energy tariff has changed during the last year.
  • My energy company has been able to reduce its prices twice over the last 12 months.
  • A few months before installation, I undertook some DIY energy efficiency measures such as installing LED bulbs and radiator reflectors.

We were never big users of electricity in our house so the opportunity to reduce our bills was always going to be quite limited. Having said that, we have noticed our bills go down – by between 20% and 50% each month, depending on the time of year. A good example is a month in April/May 2015 when I was charged £20.12 for the electricity element of my energy bill, and that included VAT and £7.40 of standing charges – not bad for that time of the year!

Overall, I reckon I’ve saved about £150 per year on electricity charges. Although this is less than predicted, the combination of FiT (generation and export) payments and the savings on my bills still mean that the pay-back period on the total cost of the system is within the six to seven years I originally calculated.

Behaviour change

The savings on my bills have, in part, come from changes to the way we use electricity on a daily basis. My app/online monitoring system tells me exactly how much electricity we’re using and how much my panels are generating – in real time. It also provides the associated costs. This means that I can assess the best time to run our high energy use items such as the oven, vacuum cleaner, washing machine, dish washer and tumble drier. The app has also made me and my family more conscientious about turning off appliances when they’re not needed – to the extent that I’m now amazed when I visit friends or relatives and the lights in their house are blazing away (even though many of the rooms aren’t being used) and the TV has been left on with no-one watching it!

I’ve also become more conscious of when to use our Economy 7 as it can sometimes be cheaper to use night-time electricity than that produced by my solar panels - for example, when I want to use the tumble drier but my solar panels aren’t generating enough electricity to completely cover the running costs of the appliance. In this kind of scenario, my panels might be generating some electricity but it might cost me (say) 10p per kWh to run the drier. When this is the case, it’s better to leave drying the clothes until Economy 7 is available, in which case it’ll cost less than 7p per kWh. Better still, I ought to look at the weather forecast and see if it’s going to be sunny the following day!

Useful tips and advice

  • My system has a notional generating capacity of 3.6kW so I assumed it would reach that output level whenever the conditions were good enough. However, my system is fitted with a 3.0kW inverter so it only ever reaches a maximum generation of 3.0kW. In the UK, installers design and fit systems with inverters that are less powerful than the maximum potential capacity of the panels. This undersizing allows the inverter to maximise power generation at the lower light levels we get in the UK. The theory is that conditions in the UK will only occasionally reach above the maximum capacity of the inverter and, when it does, it will only be for relatively short periods of time - so the 'losses' will be relatively small. Where this does happen for any length of time, that day’s graph will plateau at certain points. So, although you lose out at the top end, you get the benefit of the inverter working better at lower levels, which more than compensates for the top-end losses.
  • To get the maximum effect from having solar panels, install some other energy efficiency measures as well – for example, replace your bulbs with LEDs.
  • When we had our panels installed, we were also given the option to have a device fitted that makes use of some of the unused PV-generated electricity by diverting it to an emersion heater, for example. A number of these devices are available and they cost around £400 to buy and have fitted. Although I opted not to have one (based on my personal circumstances and the amount of energy it would save versus the pay-back period) they should be given serious consideration as they reduce the use of both the central heating pump and the boiler.
  • Join the Generaytor website. This is a community of solar panel owners and can be a useful source of tips and information. It also allows you to compare the performance of your PV system with others that are either anywhere in the country or with a similar specification.

So, at the end of my first year of living with solar panels, I’ve generated 3.8MWh of clean, renewable electricity and I’m very happy. I’ve had no problems and no nasty surprises. On top of that, there’s a great deal of satisfaction in being an independent energy generator, doing my bit for the environment and partly freeing myself from the big energy suppliers.