Earth Notes: KEHS talk: Why Do Solar? (2024)

Updated 2024-05-24 14:02 GMT.
By Damon Hart-Davis.
Kingston Efficient Homes Show 2024 small talk by Mark H.
KEHS2024 4 RBK
Mark H delivering one of the "small talks" at KEHS 2024, inspiring the audience to consider installing solar PV at home in Kingston!

Many thanks to Mark H for the slides and for delivering the talk!

1178s "KEHS2024 why do solar" (captions) Uploaded . Downloads:
Transcript:
[00:00]

Okay, good morning everybody, thank you for coming along. I want to try and inspire you to go solar,

[00:08]

but equally give you a few lessons and what to watch out for, especially on sales tactics and

[00:17]

what lessons I've learned. So basically we've got two technologies, one is based around thermal

[00:27]

for water, or photovoltaic generating electricity. Slightly different technologies, we're definitely

[00:35]

going down the photovoltaic route. So benefits of it, meeting your electrical needs for quite a bit

[00:44]

of the year and a little bit for other parts. Storage of power and a battery, so if you go

[00:51]

for electric vehicle ... for example, or just generally meeting your overnight demands for

[00:59]

electricity most of the year. Then otherwise excess energy gets fed into the grid and you can even,

[01:10]

depending on the power you're generating etc, use it for immersion heaters and so on.

[01:20]

First thing to consider is the quality of your roof - it needs to be in fairly good

[01:28]

nick, not going to struggle under the weight of panels. And you may have 8, you may have 12,

[01:40]

you may have 16 panels. But hopefully, whoever you choose to come and do the installation will very quickly identify if there are any things to be concerned about.  Optimum pitch (the angle of of the roof) 36 degrees - but don't let that put you off at all.  Direction of the roof facing optimum is south again but

[02:08]

it will produce almost any direction it's facing. Going back to the pitch, if you have to use a flat

[02:15]

roof for all, you can do. One thing is that a lot of installations are done with panels in

[02:24]

series and so you may have (say) seven panels on a string. If a shadow gets onto one of those

[02:33]

panels it's the weakest link in principle that applies. There are ways round that don't worry. So this is to

[02:43]

give you a quick idea of what your panel productivity may be reduced by based on the

[02:53]

direction and tilt etc. My roof is actually west facing so I get about four fifths of what I might get if it were due south.

[03:03]

Somethings you can do something about it, others you can't. But don't let that deter

[03:10]

is the reason I've put that on. As I mentioned, shadows are something to be wary of, but if predominantly

[03:21]

you have none during the 10 'til 4, you've really nothing to greatly worry about. Technology can actually

[03:33]

get around as a problem. You can have what are called panel level optimisers. So basically that's

[03:43]

super duper technology which up at the panel level optimises and then sends the direct current down to your

[03:52]

inverter device. An inverter device is a fairly chunky piece of metal that you will have typically in a

[04:01]

garage, that you might have elsewhere; what I don't recommend is the roof. Microinverters:

[04:09]

a little bit more sophisticated because they don't actually have, you don't need to have the

[04:15]

inverter in the garage or elsewhere. The inversion to AC is actually done at the panel level and

[04:23]

there's further technology; smart panels but that's going well beyond what any of us would need.

[04:31]

Good news on the weight side, just in case you do have any qualms on that. There is

[04:38]

a lightweight panel coming now through the Dutch firm that invented them, that is also made of

[04:47]

recycled material. They are introducing something for commercial installations already,

[04:55]

and a residential premise installation is planned for next year. But only if you need to worry about

[05:04]

the weight of your panels would that be of any interest. So you'll find the last two

[05:12]

slides here that there are a raft of Web sites. They are brilliant for going and doing your own

[05:20]

homework.  Read through it at your own pace rather than trying to absorb it all from people like me,

[05:26]

or especially salesmen trying to push things. First things first, check if you're

[05:33]

likely to need any planning permission, but generally speaking that's unlikely to get in the

[05:39]

way. If there are any people who happen to be on Universal Credit or Pension Credit, there are

[05:48]

significant grants available under what's called ECO4. Otherwise though [you'll] be struggling to get any

[05:59]

grant support for it. Another very important thing is the installation. Make sure that you're

[06:08]

using a Microgeneration Certification Scheme accredited installer. I mean deep difficulty

[06:17]

trying to get any of the benefits you can get if you haven't got an accredited installer. Another lesson:

[06:26]

do due diligence - word of mouth - do a bit of research [of] the installers you choose.

[06:33]

And while some Web sites say three quotes I would recommend five. If you have a good idea

[06:43]

and you perhaps don't necessarily go for the cheapest one, the next one you have to judge

[06:49]

the quality of the individuals that come along. A pleasant surprise for me. I had mine

[07:00]

installed in 2010, and I thought four percent decrease per annum productivity of the

[07:10]

panels. It is nothing like as severe as that. You may find that between a quarter of a percent and one

[07:18]

percent with a certain type would be the decreasing productivity, to quash that. And duration... lovely

[07:29]

story. It's the AMSAT-OSCAR 7. That lost communication in 1981, about seven years after;

[07:39]

corrosion, went open the circuit in 2002, suddenly communicating again. And here you are,

[07:47]

2023 it is still functioning. IE the best part of 50 years getting panels still working.

[07:55]

What is it? Is it some space thing? Yes, low orbit satellite. But there are plenty of stories

[08:02]

of people who have got PV which has been working 40 years after it has gone up, so it's not

[08:08]

out on a limb. No, that sort of message is - it is probably not likely we are going to

[08:16]

get into issues, and productivity is pretty good. So typically say the inverter would

[08:27]

be housed in the garage as I mentioned, or a utility room, and not the loft. But the reliability of the inverter - I was very much warned [that] after 6 or 7 years I would need to get a replacement, but that's not the general experience now. And many come with a decade plus or even a 25 year

[08:49]

guarantee with some of them I believe. ... . Something you are generally

[08:59]

not warned about are pigeons, and they can be a real nuisance. Certainly, once they find they can

[09:08]

get under and nest there you will be bothered by them. And a couple of images on the top as to what they can

[09:17]

do to your panels over time. Common remedies for this. Make sure you install some very robust sturdy

[09:31]

wire. I've just had to have mine replaced and the firm that did it has given me a 15 year guarantee and I trust them.

[09:39]

Make sure it's sturdy stuff. Spikes: most Web sites say to put spikes, and spikes work.  They don't!

[09:50]

At least two people in the profession I have spoken with, say it's common knowledge and

[09:58]

there's a lot of people in the trade. You will find hundreds of sites that say they do.

[10:04]

Under that "the customer is often confused as to why the spikes they've paid someone else to put

[10:11]

on the roof didn't keep the pigeons away. The answer is actually pretty simple. Those bird

[10:16]

spike strips don't move and they can't cover the entire roof. Therefore it just didn't work."

[10:24]

So like I said, get some sturdy wire. The other thing, early sales tactics,

[10:33]

nice lovely rectangles if it's all level and you benefit all year: you don't. One day in summer

[10:42]

you'll produce as much panelling as you would in about two months.

[10:48]

So I said to people eight / nine months of the year you will find that you'll generally get

[10:56]

self-sufficiency of the amount of energy you produce from your panels but not 12 months of the year.

[11:02]

And to give you an example right, the top one is based on about 12 years of metrics. The bottom

[11:16]

one which is a direct south facing is about five years. Obviously it's a sizeable investment to be

[11:31]

interested in what you can do to recover the the outlay. And savings on energy bills obviously

[11:40]

fluctuate according to prices, and that can and your usage profile, so you can save anything from

[11:48]

£160 to £350 a year.

[12:02]

Well the utilisation of the panels and what they produce is generally 20 - 25 percent.

[12:12]

The savings depend on the size of the panels and the productivity you get.

[12:18]

The other thing is what's called the Smart Export Guarantee.

[12:26]

Years gone by we had what was called Feed-in tariff. That was a perk / rebate from the government to

[12:35]

encourage people to have it. Now you have to export your excess electricity and you can get

[12:43]

prices. Now the Smart Export Guarantee rates vary greatly. You might get a penny a unit up to

[12:52]

as high as 40 pence. So you need to do a bit of research and find that who're offering schemes

[13:00]

and watch out for some of the terms and conditions often. But if things move to a more Time-of-Use

[13:11]

for charging for electricity, obviously you're likely to gain significantly. So your panels

[13:17]

are producing in the afternoon around the peak time for fair bits of the year. Obviously winter

[13:25]

doesn't make a great deal of energy. The next one, the root point is regarding the

[13:35]

Energy Performance Certificate. Your score will go up for sure, but here we are I think they

[13:45]

created in about 2007. Say four years ago some articles in the paper explaining the government

[13:53]

because metrics and measurements parameters haven't been changed in 15 years. So you had examples

[14:02]

where responsible people were put in batteries and then the score have actually decreased and

[14:11]

heat pumps as well, especially with the high usage of electricity by the heat pumps, there

[14:18]

were some perverse impacts. Lord Deben is still trying to get something satisfactory. So be warned.

[14:29]

I emphasize the MAY increase property value, because if you've got (say) something from the

[14:40]

feed-in tariff and generating a lot of income stream each year that will definitely be a big

[14:47]

appeal and the feed-in tariff is transferable. Smart export isn't, what you can obviously do

[14:54]

it for the next person who can use it and gain it, but you're not quite getting the

[15:00]

guaranteed regular income stream that feed-in tariff gave.

[15:04]

So that's why I said "MAY", you may get 15-20% of what we put on the balance, you may get 50% for demand in the market.

[15:17]

Basically in terms of optimising it, try to adjust your usage patterns in terms of recharging things during the day.

[15:28]

I mentioned immersion heat, so you may want to put that on in the early afternoon when the system is producing heavily.

[15:38]

So a few conditions, as I mentioned, Smart Export Guarantee, you must have the Microgeneration Certification Scheme qualification.

[15:48]

And that also necessitates a smart meter. There are various issues with that technology, and rolling that out, as we know.

[16:00]

As I mentioned with the Energy Performance Certificates, net zero targets for Energy Performance Certificates...

[16:08]

Quite where we're going to head with that in five, ten years' time is difficult to see.

[16:16]

Another thing is it could potentially even affect mortgage rates, maybe incentives going: all sorts of possibilities.

[16:28]

So, indirect benefits: the government has cut VAT on products.

[16:39]

I assure you that a mid-life upgrade of a battery, until recently, ..., you paid 20% VAT on the battery.

[16:51]

That happened to me, but thankfully it has been removed.

[16:55]

Panelling, insulation, all these sorts of things have now been zero VATted, so that's a good incentive.

[17:03]

Obviously from a responsibility perspective, reducing your carbon footprint,

[17:10]

there's some various numbers in terms of the reduced emissions, and generally per kilowatt of your system, you'll get back 900 kilowatt hours per annum.

[17:29]

The thing with panels, of course, they're getting better as the years go by.

[17:36]

For instance [when] my system was installed,

[17:39]

each panel was 285 watts. You will now get the normal 360, around 400 plus watt panels that are available.

[17:50]

The other nice thing is to always consider local employment, depending on who you've select.

[17:58]

The last two slides are some Web sites where you can go and do your own research.

[18:09]

Some very good quality ones. Federation of Master Builders, comprehensive step by step, all the things you need to do.

[18:19]

Centre for Sustainability, sustainable energy, not just solar batteries. There are lots and lots of ideas to make your place greener.

[18:30]

Friends of the Earth, saving on [...]

[18:35]

Here you go. Something about the microinverters and optimisation configurations.

[18:42]

Just to help you with the DC/AC aspects I mentioned earlier, and cost-effectiveness.

[18:49]

It's a bit of a misleading end of that Web site address "free" solar panels!

[18:57]

What I would say is that, don't take up any of these offers where they will install and offer you, bait you with, free electricity: there are pitfalls with that as [folks] in Stoke on Trent and elsewhere have found.

[19:17]

I emphasise the diligence because of the firm Green Energy Together, rather recommended by government,

[19:29]

and they went bust last year, and folded, so you have to do your due diligence.

Show Notes

Recorded with the Zoom H1n, stereo 48ksps, sitting on the desk at the front of the drama room near the speaker.

~2476 words.