Solar - Where to start?

[DazRave]

(For those short of time there's a TL:DR at bottom)

We've just started a large house extension (side and rear across two floors).

We're on a hill and get a fair amount of Sun because if the angle (there's even a solar farm less than a mile away). The house is south facing and due to an comment the missus made years ago about solar being ugly, we've never considered it. However, we're going to need a new roof anyway and I've just found out she doesn't mind the integrated/flush panels! Rejoice!

But, where the hell do I even start? I'm not afraid of a bit of google-fu but there's so many options, brands, suppliers, installers and so, so, so much regurgitated sales pitch jargon I'm a bit lost with it all.

Below are my requirements as well as what I think I know. I can imagine there's something else I've not thought of that's quite crucial or better for me:

 

• Doesn't have to be attached to the grid (I hear that means I can get it done a little cheaper - see my next point)
• I'd prefer my builder and his team to install it while the roof is being installed by them anyway (I'm assuming this means I need a 'plug-and-play' system)
• It seems the integrated/built-in part is just the tray that the panels are installed into, therefore other than the trays there's nothing else fancy that needs to be done
• I believe having a south facing roof as well as a slightly south west facing side roof, both of which nowhere near anything that overshadows them, is the most ideal position for all day solar generation? 
• We've been with Octopus energy for quite some time and so certainly want to capitalise on cheaper evening electricity
• Top end, we use around 10kwh a day (but this is expected to come down once the 35 year old kitchen is replaced!)
• Batteries seem to take up the majority of the cost (side question: Does a 'solar battery' differ from a normal house mounted battery?? or are they one of the same?)
• I've zero understanding on the budget I need to allow for all the materials or where to even start in order to cost it (I'll deal with labour costs once I understand what it is I need installing)

 

Quite literally everything else to do with this build I've relentlessly researched over the last 5 years, but with the unexpected green light from the misses and the fact the roof is expected to be installed in a couple of months time, I could really do with a head start getting all my ducks in a row!

TL:DR - Where do I even start if I want to install some integrated solar (and a battery) onto my new roof. What questions should I be asking and is it feasible/cheaper for my builder to install it or am I really better off getting the experts in?


Any help at all would be highly appreciated. 

Cheers,
Darren

 

Edited July 3, 2023 by DazRave

[JohnMo]

A few things to consider

 

If you wish to sell the electric generated the whole install needs to be done by a MCS installer. You pay more, but you can sell the electric for 5 to 10p kWh.

 

Not MCS, means you source everything yourself and just about anyone can install. But ideally the electric hook up would be done by an electrician. Plenty of companies are out there that provide full kits.

 

Batteries, if you are installing 3.6kW array, you can self consume everything you produce, so battery benefit in my view is questionable.

 

Roof integrated requires no tiles below the the solar panels, so saving are made there. Pretty straightforward once you get your head around it.

 

Basically the PV panels connect together, go to a DC isolator into an inverter, to an AC isolation switch and then to your consumer unit. It's never plug and play, so don't let anyone convince you otherwise. But it shouldn't be complex.

 

I am in the process of installing a ground mount array of 3.6kW for a total cost under £2000. I have a combination of new and used parts. This is not a MCS install, if it was it would cost 3 to 4 times more.

[SteamyTea]

https://midsummerenergy.co.uk/

 

Look at the GSE in roof system.

[Simon R]

36 minutes ago, JohnMo said:

Batteries, if you are installing 3.6kW array, you can self consume everything you produce, so battery benefit in my view is questionable.

I could not operate our 3.6kW PV effectively without a battery as we gather energy during the day and then use it overnight.  With a 9.5kWh battery I'm still exporting energy despite having A2A cooling and an EV (which has been running on sunshine for the last couple of months).

[JohnMo]

4 minutes ago, Simon R said:

I could not operate our 3.6kW PV effectively without a battery as we gather energy during the day and then use it overnight.  With a 9.5kWh battery I'm still exporting energy despite having A2A cooling and an EV (which has been running on sunshine for the last couple of months).

Interesting it may the difference in location me being a further North in NE Scotland, has a reduced yield comparatively. Plus we are home all day, to make use of the electric.

 

 

 

 

[DazRave]

2 hours ago, JohnMo said:

A few things to consider

 

I'm certainly not bothered in selling back. I'm wanting to run a few always on home servers etc and so I'll pretty much always try and use all the energy we gain.  So that's great to know, thank you.

 

So is that 3.6Kw a day gained from sun? How many panels/large of a surface area would this be then? £2000 is much lower than expected and if I budget £10k I'm hoping we I can push the numbers higher with battery too. 

 

Really appreciate the small dummies guide to the order of things you did for me there too. It actually clarified a few questions I'd forgotten to ask in my original post.

 

2 hours ago, SteamyTea said:

https://midsummerenergy.co.uk/

 

Look at the GSE in roof system.

 

Boom. Thank you for sharing this link! 

[JohnMo]

The measure of electric are kW that's the power, kWh is the energy usage.

 

So a 3.4kW array is the max power the array can generate. If it generated 3.4kW for an hour, that would 3.4kWh, if it generated for 2 hours that would 6.8kWh and so on.

 

Panels are generally sized in watts (W). Panel sizes carry slightly depending on efficiency. My 340W panels are about 1.7m X 1.0m each. So 10 panels in a line would be 10m long by 1.7m high.

 

Do the maths on pay back, electric is 29p per kWh, so you have a lot of kWh to generate to pay back a £10k spend.

 

Have a play on here to take a look at yield.

https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#api_5.1

 

[SteamyTea]

10 minutes ago, JohnMo said:

The measure of electric are kW that's the power, kWh is the energy usage.

Where did you learn to say that from?

[DazRave]

22 minutes ago, JohnMo said:

 

 

Have a play on here to take a look at yield.

https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#api_5.1

 

I found this a few days ago and could not make any sense out of it. Little too advanced for me to use without fully understanding the basics yet.

[JohnMo]

Move map about find your location mark it with curser.

 

The other boxes where there is a red star click on that it explains what the box is and what you enter 

[SteamyTea]

3 minutes ago, DazRave said:

Little too advanced for me to use without fully understanding the basics yet.

 

This is for a 1 kW_p system in Manchester

 

[JohnMo]

Out of interest NE Scotland with same data inputs - winter production for me is rubbish compared to Manchester 

[DazRave]

9 minutes ago, SteamyTea said:

 

This is for a 1 kW_p system in Manchester

 

Thank you. I've just had another little look on the laptop and managed to actually make it work. The site wasn't very phone friendly that's for sure.

So it reckons "Yearly PV energy production [kWh]: 861.08" - How much degree of change should I expect from that estimate? Considering we intend to stay in this house for well over 15 years and assuming the panels don't work half as good in 10 years time, my loose calculations say a £8-10k system (inc battery) could be really worth it.

[SteamyTea]

5 minutes ago, JohnMo said:

winter production for me is rubbish compared to Manchester 

Penzance

 

[SteamyTea]

4 minutes ago, DazRave said:

How much degree of change should I expect from that estimate?

It shows that

 

So for me, 48/1060 * 100 = 4.5%

 

Huge daily variation though.

Edited July 3, 2023 by SteamyTea

[JohnMo]

After 10 years your performance will drop circa 10 to 15%.

 

Paying loads will not see a return on your spend.

 

4 minutes ago, DazRave said:

So it reckons "Yearly PV energy production [kWh]: 861.08

That's for 1kW installed, so about 3 or 4 panels.

[DazRave]

3 minutes ago, JohnMo said:

After 10 years your performance will drop circa 10 to 15%.

 

Paying loads will not see a return on your spend.

 

That's for 1kW installed, so about 3 or 4 panels.

Sorry, I never meant to suggest paying loads would. I just plucked a budget of 10k out of my head and so knowing that 3 or 4 panels could generate roughly 850kWh a year... it's looking pretty promising over a 10+ year period.

 

6 minutes ago, SteamyTea said:

It shows that

 

So for me, 48/1060 * 100 = 4.5%

 

Huge daily variation though.

How accurate is this tool, was actually what I was getting at. As in, how close is it's prediction compared to reality if you were to input the exact specifications (not that I have these, but curious how good the tool is)

[SteamyTea]

12 minutes ago, DazRave said:

How accurate is this tool, was actually what I was getting at. As in, how close is it's prediction compared to reality if you were to input the exact specifications (not that I have these, but curious how good the tool is)

Pretty good, most people find it under estimates a bit, maybe 3 to 5%.

Some of that will be down to quality of modules (the real term for panels).

This is because, to offer a guaranteed output in a decade of say 80% performance, the manufactures actually supply higher powered modules, but marked up as lower powered ones i.e. 320W modules but marked as 305W.

 

Edited July 3, 2023 by SteamyTea

[DazRave]

6 minutes ago, SteamyTea said:

Pretty good, most people find it under estimates a bit, maybe 3 to 5%.

Some of that will be down to quality of modules (the real term for panels.

This is because, to offer a guaranteed output in a decade of say 80% performance, the manufactures actually supply higher powered modules, but marked up as lower powered ones i.e. 320W modules but marked as 305W.

 

Thank you. Extremely interesting and already given me lots to think about. I'm quite the realist and always under estimate when planning things such as cost vs reward for anything. So it's good to know the tool is also already doing that.

[SteamyTea]

2 minutes ago, DazRave said:

Extremely interesting and already given me lots to think about

What is hard to put a price on is the satisfaction that you are are generation clean energy at source.  You can make a game out of planning when the washing is going to be done, and for a lot of the year your hot water will be solar heated.

Storing the PV energy in a cylinder as hot water is the cheapest type of storage, way cheaper than batteries.

 

[DazRave]

1 minute ago, SteamyTea said:

What is hard to put a price on is the satisfaction that you are are generation clean energy at source.  You can make a game out of planning when the washing is going to be done, and for a lot of the year your hot water will be solar heated.

Storing the PV energy in a cylinder as hot water is the cheapest type of storage, way cheaper than batteries.

 

 

I'm quite big on my home automation so this is music to my ears.

As for heating water, we're going to keep the gas boiler as it's not very old but I hadn't thought about a solar system that could aid this too.

[JohnMo]

You need a solar diverter. Good in summer not that good in winter. As the amount of solar irradiance is low.

[SteamyTea]

1 minute ago, DazRave said:

As for heating water, we're going to keep the gas boiler as it's not very old but I hadn't thought about a solar system that could aid this too.

You can get 'diverters' that sense when the system is exporting power to the grid and turn on the water heater, or battery charger.

 

The thing to remember is that PV is not a constant power, or even a normally distributed power curve.  It is very variable.

If you can find a local WeatherUnderground station that has a solar meter on it, you will see how, even on a sunny day, there is often a lot of variation.

 

Two very very rare days in a row.

 

3-6-23

 

4-6-23

 

5-6-23

 

6-6-23

[Dave Jones]

9 hours ago, SteamyTea said:

What is hard to put a price on is the satisfaction that you are are generation clean energy at source.  You can make a game out of planning when the washing is going to be done, and for a lot of the year your hot water will be solar heated.

Storing the PV energy in a cylinder as hot water is the cheapest type of storage, way cheaper than batteries.

 

 

hard to run the tv off the hot water tank though lol

 

Battery is a given to do the solar job properly.

[SteamyTea]

2 minutes ago, Dave Jones said:

hard to run the tv off the hot water tank though lol

Hard to wash in a TV.

Now stop being a twat.