The PV blog

Having recently been on a journey installing Photovoltaics (PV) we have learned much and I thought I’d write this to make the next person’s life a little easier - hope you find it helpful! I’ve tried to split down my thoughts by sub headings for you in case you want to skip or refer back.

Supplier
Trying to find a supplier can be a challenge. It’s a busy market at the moment with energy price rises 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.

There were a large number of PV installation companies, back in those heady days of the Feed In Tarriff, sadly many disappeared very quickly when the tariff was taken away so 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 Minell immediately impressed me with the speed of their first reply. No guarantees of course but their responsiveness and support/direction is a chunk 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 a check on the energy efficiency (the peak generation you will get) of the panels proposed as panels are not all the same.

Lifespan
Nothing lasts forever but check what warranty you get for your installed system from your supplier 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 but we did explore the possibility of more panels to our eastern elevation as this had the potential of adding additional panels, one friend has with a detached house went to three sides including the west- 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 but definitely worth exploring.

Peaks and troughs
Don’t imagine you’ll always get peak capacity, our generation is generally a nice bell curve as the sun does it’s job but cloud obviously drops that value straight down so this can often look more like monument valley or one of those random resistance patterns when training at the gym in profile.

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 the week days and thus for most of the year only really use significant electricity after dark. If you have an EV(Electric Vehicle) obviously this can help with battery storage but obviously that’s often not plugged in either during the daylight hours. Even with a good tarriff 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 exporting 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 think you can put them inside your occupied rooms.

Planning
Yes - you are correct, 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, as we found out that 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. Having found out quite late in the day about this it added stress to things as the 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. 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 the outcome is that’s it’s fine. The panels have a weight (obviously) but are also subject to wind load. For us our calculations showed we needed fixings at closer centres due to this uplift than the supplier would have done “as standard”

Pigeons
An extra to include for in your budgeting. Your budget is the 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 scaffold again this is a must!

Scaffolding
My understanding is this is now essential for roof works for the protection of the team that do the work for you. Minell 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 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. It has been a step change in understanding in our house not just in electricity 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, 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 come to change them plus the new readings once installed (yes I know this should be zero but I did get asked and you are better to have 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), you will also need one to connect from your DB to your battery. These are sizeable armoured cables (ours were in conduit about 5cmx5cm and it’s worth thinking through and agreeing with your supplier the route this will take and how the electrician will access the full route of the cable so you can clear this for when they arrive.

What else do you want to do?
Minell were willing to replace the tiles that broke during their work (ours are clay tiles and these do get more fragile as they age so is to be expected) but we also decided to make the most of having the scaffolding there to sort other things around the roof gutters etc. This added complexity of programming as we needed to time the scaffold (by the PV company) then the roofer and know that they would be clear before the PV installation team arrived.. Also worth double checking the roofer is on track to arrive when they say they will because if they are late you could have a frustrated PV installer on your hands!

Following on
We are still working through the tarriff process which is a little frustrating but will get there. Check out the tariffs out there as you shop around we found Octopus helpful in our case. You also will need the test certificates for your electrical installation and to apply to your supplier for permission to export so check up with them first as this is more online forms to complete. Again hopefully your installer will sort this all 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 in your own PV installation journey.