Would you do it again?

rugbyleague

Further update

20 panels can be placed on roof south facing no shading, roof good condition, installation straight forward. Can have a 5.5kw system if I ask for permission, or straight fit of 4.5kw system.

Ian

tunnel

If 20 panels will fit then why not go with 20 x 285Wp for a 5.7kWp system. DNO approval should be included in any price you get too.
With the fixed costs that Mart mentioned the bigger the better as it should bring down the cost per kWp giving a better return. Suppose it depends now what you can afford?

Martyn1981

rugbyleague wrote: »

I'm loving this!

Postcode LA11 Roof pitch 30 degrees.

Glad you're having fun. It's not all boring.

I stuck random pins in LA11 and got generation estimates from 3,500 to 3,700. [Edit: for a 4kWp system. M.] So looks like your figure is correct. So long as you don't have any bad shading, that should be a very solid figure to use for your income calculations.

rugbyleague wrote: »

We talked about going larger than 4kw (have to get permission from the electricity board), different panel types and batteries (interesting lifestyle consideration here i.e when do you use your electricity?)

&

rugbyleague wrote: »

20 panels can be placed on roof south facing no shading, roof good condition, installation straight forward. Can have a 5.5kw system if I ask for permission, or straight fit of 4.5kw system.

Just want to be clear. You don't need DNO permission to go bigger, only to have an inverter that can export more than 3.68kW. To put it simply, the DNO doesn't really care about kWp (panels on roof), they only care about kW's exported (or potentially exported) to the local grid. Only the FiT scheme cares about kWp, and that's why the obsession used to be 4kWp, as the FiT rated dropped for 4-10kWp systems, but now they've been combined into a single 0-10kWp banding.

I suspect your later post is confirming that (hope I'm not reading too much into it) but possibly the installer is suggesting a 4.5kWp system is fine, as in via a 3.68kW cap, but for 5.5kWp he'd want to use a bigger inverter and therefore get (or at least try to get) DNO permission.

Sounds like he knows what he's talking about. Good news.


Obviously this all comes down to money, but you can no longer apply for FiT on extensions, so certainly worth exploring the options of going bigger now. And also, whilst I'm a bit negative on batts, making sure the system is upgradeable / batt friendly for the future. Fingers crossed there could be economic systems available in the next 5 years.

Mart.

rugbyleague

Thank you for continuing to help with this, really making a difference. Both local companies stated installation fine on my house.

Agreeing with you that 20 panels would be favourable (understand advantages to be had when generation is limited). Not sure about DNO Application so going to research

"I suspect your later post is confirming that (hope I'm not reading too much into it) but possibly the installer is suggesting a 4.5kWp system is fine, as in via a 3.68kW cap, but for 5.5kWp he'd want to use a bigger inverter and therefore get (or at least try to get) DNO permission"exactly right sir!

Martyn1981

rugbyleague wrote: »

Not sure about DNO Application so going to research

Probably would have been helpful to have explained this, rather than drone on about it.

The DNO (Distribution Network Operator) is your local grid supplier. National Grid manage the big cables and high voltage, the DNO's run the local grid.

You are allowed to install SSEG's (small scale electricity generators) and connect to the grid, so long as they are limited to 3.68kW (16 amps at a nominal 230V), and you (the installer) notifies the DNO withing 28 days of the install.

To have a system that can potentially export more than 3.68kW, you need to ask permission in advance. Whether or not you get it will depend on local issues, as the local grid can't send leccy backwards past the sub station, so they have to make sure everything is up to the job, even down to the cabling that reaches your house, and whether you are connected singularly, or via a cable that also supplies one or two other houses.

The cost for this is quite low, and the installer will probably chuck it in. You can ask your DNO for advice, and if like mine, they might be very helpful, explain, and even do a site visit to say if they'd be minded to approve or not. However, only an accredited electrician can actually apply, and get an 'actual' approval.

You can actually connect a stupid amount of PV to a 3.68kW capped inverter, as it only 'takes' as much leccy as it needs from the panels. However, the bigger you go, the more capping you'll see, and therefore the greater your losses, which will start to negate the extra investment.

If the DNO says "NO", then 4.5kWp via 3.68kW is absolutely fine. the system will rarely exceed 90%, due to panel temps pulling down efficiency, and on a long hot summers day, will be running at 80%, so next to no capping on those occasions.

If this is helpful, great, but if I'm throwing too much at you, too soon, then just tell me to calm down.

Mart.

rugbyleague

Your not droning on! You have a skill which makes some of the detail easily understood.........last man or lady due to quote in 15 mins. ....

EricMears

Martyn1981 wrote: »

Whether or not you get it will depend on local issues, as the local grid can't send leccy backwards past the sub station, so they have to make sure everything is up to the job, even down to the cabling that reaches your house, and whether you are connected singularly, or via a cable that also supplies one or two other houses.

I'm not sure that's strictly true.

WP recently recabled our house but for the first four years of having SPs, we were fed by a dedicated transformer on the nearby 11kV power line. Our installer did apply for permission to install the full 4kWp which was granted (and I'm pretty sure he said there was no charge for applying). Our panels continued to generate at or near their max even when we weren't using anywhere near all of it so we must have been exporting. Since no other houses used the same transformer our exports must have been transformed up to 11kV and fed back along HT line.

Granted, a sub-station is a tad more complicated than a simple transformer but the principle is the same.

rugbyleague

Ok last quoting person hasn't turned up........national company,made 1 appointment, changed it and hasn't shown up or advised......brilliant.

Have been left some information by two of the installers and actually from first impressions they all appear very genuine.

Now need to really think about what would work for me as from what I have been told my house is very suitable for an installation 16 or 20 panels with no shading, South facing and a 30 degree sloping roof.

A bit about the occupants me and my wife in full time 9 to 5 daytime employment, son 18 , our retirement 25 years away.....out of the house during the day apart from weekends and holidays.

Will buy system from savings, plan to stay here for a good few years (got some nuclear Submarines to build!) Initial cost not too much of an issue but important, we like the thought we can directly influence how we use electricity.

I like my tech, would be fascinated looking at generation figures.....may choose electric car in future, don't think a battery is right thing to do yet but my view could be changed.

Aesthetics of the panels not important (nobody will see them) not sure which panels are best......

Typing it in like this makes me think I should go for 20*285s (are there bigger ones, would I need them?). Which inverter? (10 year warranty would be nice).

Have a combi hot water system with gas central heating doesn't really fit with solar power I think.

How could I maximise benefits of generation ie is there other gadgets that help...?

Typing it like this helps me understand!

Martyn1981

EricMears wrote: »

I'm not sure that's strictly true.

Granted, a sub-station is a tad more complicated than a simple transformer but the principle is the same.

Maybe you're correct, each house in our street now has an individual connection, via a small grey transformer(?). However, my understanding is that the larger sub stations, those 10ft by 10ft green structures (or is that just me), can't run backwards.

Maybe someone knows for certain, and can advise.

Mart.

EricMears

A transformer ought to work in either direction. All that is happening is that voltage in one set of windings create a magnetic field & the MF creates voltage in the other. AFAIK, it's not normal to incorporate some sort of diode to prevent it working 'backwards'.