Anyone know of a good online calculator? Or a method I could use to estimate what energy we might be able to generate? We're getting quotes, but I suspect the sellers' optimism might be exaggerated :)

Our house is 11 degrees 58 minutes north; our roof is a typical pointed affair, approx 30 degrees angle, approx 80 m2 roof space. One house gable points due north, the other due south, meaning we get full sun on the east facing roof in the morning, and sun on the west facing roof later in the day. We get no sun after approx 3 pm winter, 6 pm summer due to nearby trees.

We apparently get 1700 - 1800 hours of sunshine per year.

Apparently we should be able to fit approx 40 no. 400 W panels on our roof.

You might find useful info here.
https://www.leonics.com/support/article2_12j/articles2_12j_en.php

And

https://joint-research-centre.ec.europa.eu/pvgis-photovoltaic-geographical-information-system_en

It is not a 5 minute job working it all out.

16 Kw is a lot of output what can happen if not careful is you won't be able to use it all you can add battery which will help but depending on your DNO, you will be restricted to 3680 w export so you could apply to send more which will cost. Come winter time you will be see the benefit of a big array. If you got 3 phase at your property you can send 16Amps per phase.

8 kwp on each pitch would give you a nice spread of generation over the day. With a bit of shading on the west face it might be worth considering optimisers or micro inverters.

16 kwp isnt going to be cheap, more so if youre adding optimisers and or batteries.

Youll need permission from your DNO if connecting more than 3680kw. One thing to be aware of is DNOs consider total connected generation as the most youll export even though your 16kw is split 50/50 180degrees apart and will never generate anything like 16kw. If you want 16kw and the grid cant take it, youll likely need an export limitation device or pay for grid upgrade!!

PVGIS should give you a fair generation estimate but I m not sure if it will handle a split array?? It should do but Im not sure.

Oops - er - 58 degrees 42 minutes is the latitude ...

Thank you all for the links. According to PVGIS, I'd only have to pay four months of the year ... (I have/will uploaded their file and our usage)

Posted By: minisaurus According to PVGIS, I'd only have to pay four months of the year

Unfortunately unless you only use exactly whats being generated youre unlikely to avoid grid draw for more than a short period, unless youve got storage. Without storage, as soon as the sun goes in youll be drawing on the grid having exported loads the day before, if it was sunny!

Posted By: philedgeUnfortunately unless you only use exactly whats being generated youre unlikely to avoid grid draw for more than a short period, unless youve got storage. Without storage, as soon as the sun goes in youll be drawing on the grid having exported loads the day before, if it was sunny!

Depends upon the contract with the supplier as to how you view for what you are paying.
Over here we are on annual reconciliation which means your export and import is reconciled annually so over production in the summer can balance shortfall in the winter to get net zero. However at the end of this year the system changes to monthly reconciliation for new entrants - IMO not such a good deal !! (for the consumer, probably better for the supplier).

djh.
400w panels are there (sorry about the language)
Fotovoltaikus napelem JUST 450W/24V IP68
https://www.lampak.hu/fotovoltaikus-napelem-just-450w-24v-ip68/?gclid=EAIaIQobChMI9PHkiLGy9gIV0wSiAx1-JgBLEAQYASABEgKnqvD_BwE
But when I have looked at high wattage panels before they get the higher output by being physically bigger i.e watts / m2 output is much the same.

From a few years ago:

"While in the past, sites were using mostly 60-cell p-type multi panels (ratings 240-260W), the industry is now moving to 72-cell p-type mono PERC panels with bifacial capability. This allows for 370-400W panels, with trackers and bifacial generation. This is a massive driver in compensating for the lack of subsidies today."

https://www.solarpowerportal.co.uk/news/uk_large_scale_solar_pipeline_tops_5gw_as_project_developers_return_to_acti

Leading to:
"the pipeline of large-scale solar farms shot up from a few gigawatts at the time subsidies ended a few years ago to a staggering 37GW at the start of 2022"

https://www.solarpowerportal.co.uk/news/meteoric_growth_in_new_solar_farm_planning_in_uk_sees_pipeline_reach_a_stag

I was dimly aware that something incredible and unreported was happening in UK offshore wind, but seems like utility-scale solar farms are doing the same!

No, that's generally not the case - appearances are deceptive! A modern agricultural field is almost a sterile environment, nothing grows/lives there except the crop - hence disastrous crash in UK insects and birds. A solar farm with rough grass below panels, is far more biodiverse, and even more so if the developer is made to plant some hedges or wildflowers.

Don't get me started on polytunnels, though!

Good point Will - I hadn't connected those dots, will look at em in a new way.

Still ugly tho. Geometric purity can contrast with and nicely set off land-forms, but I hate the way these rows are carelessly smeared and tilted up and down the contours to a ragged edge, without thought to visual effect. If each panel was strictly level, a crystaline array, then the varying height-steps would chart and express the ground's shape. Rooftop arrays are usually OK in this respect.

And doesn't maintenance etc require that it's kept mown or even weed-killed as shortish grass, so other 'rough' growth, bracken, brambles, sallow etc, don't get a chance? Are the fragile structures compatible with dartmoor ponies or other stewardship-agreed animals?

Peter, where would you say the rain that falls onto the panels, would end up? :-)

See eg https://scitechdaily.com/ten-ways-to-ensure-pollinators-benefit-from-the-solar-power-boom/

Developers in the UK have to demonstrate "Biodiversity Net Gain (BNG)' eg
https://cieem.net/wp-content/uploads/2020/08/BNG-case-study-28.pdf

"Figure 28.1 shows results from a single solar farm included in this study, which had been re-sown with a
wild flower meadow, whereby the number of:
„„ plant species was significantly higher in the solar farm than the control (an arable field)
„„ bumblebee species was similar between solar farm and control but the abundance on the solar farm
was significantly higher
„„ species of breeding birds was marginally higher in the solar farm and abundance was greater."

Posted By: WillInAberdeenPeter, where would you say the rain that falls onto the panels, would end up? :-)

Dumped on the ground at the down side edge of the panel from where it would be either soaked into the ground or go as run off either way it will be of little benefit to anything growing in the middle of the panel shadow.

How economic is tracking? Big maintenance, with 100s/1000s of mechanisms?

Imagine the dazzle, coming over the hill on a summer evening, fried by acres of glass reflecting the low sun behind me. Reagan's Star Wars!

Lots of the issues there which are usually trotted out by the anti-renewables lobby, often they have a fear of the unknown? But if you drive off the A30 and go and look at one up close, you'll be better informed than them

- stuff grows under them, as you can see below
- they don't spray herbicide in the UK (maybe in Hungary?), so that's an improvement on the previous agricultural field which will usually have been sprayed/fertilised/ploughed to suppress native plants in favour of crop plants
- their planning consent is conditional on them not dazzling people on roads or in houses etc, easy to calculate angles during design. And on having a credible biodiversity gain plan, which becomes part of the consent.

Here's some pics to whet your appetite:

Posted By: WillInAberdeenthey don't spray herbicide in the UK

I'd have thought that too, but there are lots of firms advertising precisely that service?

<blockquote><cite>Posted By: fostertom</cite>Also, t.............
Tracking won't increase that, as they'll shade each other as they come more vertical.</blockquote>



That shouldn't present a problem if the designers have done their calcs correctly. They would of course need to be more widely spaced with more natural pasture between which may aid biodiversity.
They MAY also fulfil a bit of aesthetics too, rather than the serried rows of ground mounts. Almost a bit of installation art even.