Photovoltaic panels for domestic housing - a personal tale

Having recently been on a bit of a journey to instal photovoltaic panels (PV) on my home, I thought I’d share a few of my thoughts and some of the lessons learned. Hopefully it will prove helpful to anyone thinking about doing the same. I’ve tried to split my thoughts into sub-headings in case you want to skip forwards or refer back.

Supplier
Trying to find a supplier can be a challenge. It’s a busy market at the moment with rising energy prices and many of us doing what we can to decarbonise our lives and /or make an investment, so I had several companies not even return my repeated calls or online enquiries.

Back in those heady days of the Feed In Tarriff, there were a large number of PV installation companies. Sadly, many disappeared very quickly when the tariff was taken away - you might want to ask how long the company you are engaging with has been around and how much longer they will be.

Personal recommendation worked for us and the company we chose immediately impressed me with the speed of their first reply. No guarantees of course but their responsiveness and support/direction formed a large part of what we learned through the process.

Panel type
Your manufacturer may only have one panel on offer at any one time as they will have stock that they have purchased and wish to use. It’s worth checking the energy efficiency (the peak generation you will get) of the panels proposed as not all panels are the same.

Lifespan
Nothing lasts forever but check what warranty you will get from your supplier on the installed system and whether you can extend this.

Panel number and orientation
The panels themselves are relatively cheap in proportion to your overall setup - so the more the merrier in many ways (subject to loading and geometry limits). Our main roof is south facing which is ideal. We did explore the possibility of adding additional panels to our eastern elevation - partly inspired by a friend who has installed panels on three sides of their detached house (including the west). This is less efficient than south facing but worth thinking about. During the initial pre-installation survey we were informed that there was a minimum of four in a group which sadly didn’t work for our east elevation.

Peaks and troughs
Don’t imagine you’ll always get peak capacity. Our generation is generally showing a nice bell curve as the sun does it’s job, but cloud cover obviously causes that value to drop sharply - causing the generation profile to look more like Monument Valley or one of those random resistance patterns when training at the gym.

To battery or not to battery?
That is the question. For me the only answer was yes. As most people in this country, we work during the sunniest period of week days and thus for most of the year only use significant electricity after dark. If you have an electric vehicle (EV) this can obviously help with battery storage but that’s often not plugged in during daylight hours either. Even with a good tariff, it will generally be more cost effective on a kW by kW basis to use what you have generated yourself. Also with batteries further options emerge with smart technologies and tariffs that will allow you to store from the grid overnight and even export it back at peak times. Batteries generally come in sets of 5kWh capacity so it’s worth thinking through the balance of cost and what you will typically generate or use in a day.

For us we were offered an economy of scale and went for 15kWh which is around the maximum of what we can generate in one day and about double what we typically consume. The hope is to have the capacity to link with an air source heat pump when we take that next step. Batteries do take up space and you need to plan where you put them. We found some wall space in the garage which fitted the bill as I don't think you can put them inside your occupied rooms.

Planning

In most cases - and there are many exceptions - conventional roof mounted PV panels are covered by something called permitted development which means you can install without the trouble of a planning application. Big warning to you though: if you are ever planning to sell your home, it has become standard practice during legal checks to require the production of a certificate from the planners to confirm that the installation was indeed permitted by them. The only way we could access such a certificate was to go through the planning process and the planning portal including having to prepare plans, elevations and application forms. We found out about this quite late in the day and it added quite a bit of stress to our lives - the application process takes time (from memory it was 6 or 7 weeks) and certainly for us it would have been double the cost after the fact. It's also key to include the statement (assuming it’s true of course) that the panels will not project more than 0.2m above the roof plane - we had to update our drawings and resubmit because I had not covered this the first time around.

Calculations and condition survey
Similar to the planning certificate, you are highly likely to need these even if they raise no issues. The panels have a weight (obviously) but are also subject to wind load. Due to this uplift, our calculations showed that we needed fixings at closer centres than the supplier would have done 'as standard'.

Pigeons
An unexpected element to include in your budget is pigeon screening. PV panels form a nice warm, safe environment for pigeons because most are set a convenient distance above the roof tiles. If you don’t want to have to go back and pay for scaffolding again, this is a must!

Scaffolding
My understanding is that this is now essential for any roof works in order to offer protection to the team doing the installation. Our supplier arranged this for us and had specific requirements to suit their way of working so be careful you understand these if you intend to arrange for scaffolding separately.

Smart metering
There are potential concerns about remote monitoring of these but others are better placed than I to judge. To export to the grid with the tariff I was going to use and to interface with the batteries, I needed a smart meter. This has led to a step-change in our house in terms of understanding not just our electricity use but also our gas use and has helped us spot accidental use and waste that we were just not aware of. I’d therefore recommend a smart meter, but with a dose of caution, as there are times we’d rather put the monitor in the cupboard and forget about it! If you are changing meter, remember to take a photo of your existing meter readings on the day they are changed plus the new readings once installed (I know this should be zero but I did get asked and you are better off having the record!)

Plugging it all in
It sounds obvious but you will need a cable to run from the PV panels to your electrical distribution board (DB), plus another to connect from your DB to your battery. These are sizeable armoured cables - ours were about 5cmx5cm in conduit. It is worth thinking this through and agreeing with your supplier as to the route this will take and how the electrician will access the full route of the cable prior to installation.

What else do you want to do?
Our supplier was willing to replace the tiles that broke during the installation (clay tiles do get more fragile as they age so was to be expected) but we also decided to make the most of having the scaffolding in place to fix other things around the roof gutters etc. This added some complexity to the programming of work as we needed to align the installation of the scaffold (by the PV company) with the arrival of the roofer and know that they would be finished before the PV installation team arrived. It's also worth double-checking that the roofer is on track to arrive when they say they will - if they are late you could have a frustrated PV installer on your hands!

Following on
We are still working through the tariff process which is a little frustrating but we will get there. Check out the tariffs that are available as there is some variation. You also will need the test certificates for your electrical installation and to apply to your supplier for permission to export - check this with your supplier first as this will require more online forms to complete. Again your installer will hopefully sort this all out for you but worth knowing to look out and ask for.

I hope this has been some small use to you if you are going on your own PV installation journey.