Show HN: Helios – what plug-in solar could generate for any address in Britain

helios.southlondonscientific.com

86 points by ruaraidh 8 hours ago

Plug-in solar panels (no electrician needed) have just become legal in the UK and will go on sale soon. Helios estimates how much electricity a typical installation could generate at a given address and what that's worth against your tariff.

It uses UK government LIDAR data to reflect the actual skyline, so it knows whether there's a building or a hill blocking the sun.

Caveats: - Outside LIDAR coverage (most of Scotland and Wales) it falls back to a synthetic horizon (less accurate). - Trees and recent developments (post-2022 or so) may not be in the data, and some address placements could be off (geocoding via OSM).

Feedback on the shading model especially welcome.

ltrg - 6 hours ago

Really cool stuff. Nitpick: it failed to grab an OSM ID for my house and fell back to postcode centroid, but then still reported LIDAR-derived shading at quite high precision.

I'm wondering if it should fall back to a more general shading approach when no OSM building footprint is available, to avoid false precision? My street has a gap in the houses on the other side from mine, so picking the right location matters for the calculation.

You could also try Inspire Index polygons instead of OSM? These correspond to actual lease/freehold boundaries.

ruaraidh - 6 hours ago

Thanks - I didn't know about Inspire Index, I'll check it out. I tend to agree about false precision. My first instinct was to use the synthetic horizon for addresses in that group, but I think that's over positive. A range might be better (if a bit more complex)?

ifh-hn - 4 hours ago

> Worth it. The kit pays for itself in 7.1 years; over 20 years it's good for about £1,095 net.

This is my issue with this sort of thing. Am I going to have this kit in 7 years? Or would I upgrade to better stuff at the technology improves?

pjc50 - 3 hours ago

Why would you replace it if doing so is uneconomic?
Panel lifetime is very high. The scope for efficiency improvement is not huge (unless there is a cost breakthrough in multi band photon capture). It's not a car, phone, or computer. It's more like the rest of the house electric infrastructure.
I had my rooftop solar over 10 years ago and basically intend to leave it until some maintenance issue forces action.
(Also, the kit secondhand value is hard to determine but far from zero; 30-50% maybe?)
brk - 2 hours ago

These calculations often fail to account for present vs future value of money.
If you’re financing the system you have no big cash outlay, but returns are further out, possibly never when accounting for the useful like of the system.
With cash up front all the returns are yours, but they are much lower than what that cash would net you in an average investment.
The financial math on small solar systems can be complex. If the system is sufficient to provide power to major appliances in a power outage (assuming you have a power outage risk in your area), it can make more sense to tie money up in these systems.
IshKebab - 3 hours ago

The technology is unlikely to improve meaningfully in 7 years. And you'd only upgrade if it was a financial improvement so it makes complete sense to give an estimate based on keeping it for 20 years.
I don't see what your issue is.
toomuchtodo - 4 hours ago

Depends on your energy requirements and future technology and energy costs. At the moment, one should value this outlay as a fixed income equivalent investment [1].
The panels have a ~25 year warranty though [2] (at which point, they should still produce ~80% of rated output), so it’s entirely possible to just leave them in place. At a certain age (~55-60), these are the last PV panels you’ll need to buy, as they’ll potentially outlive you (assuming developed country life expectancy).
[1] https://magnifina.com/articles/rooftop-solar-yield/
[2] https://www.energysage.com/solar/solar-panel-warranties/
ErroneousBosh - 2 hours ago

I got the exact same values.
I'd like it if it would actually show me how much sun it thinks I'd get at the postcode I put in. I've got about a third of an acre of garden in a 6 acre field to play with, before I start having to dig up roads. I can afford to be quite free and easy with placement ;-)

redfloatplane - 7 hours ago

Huh, TIL about the National LIDAR Programme: https://www.data.gov.uk/dataset/f0db0249-f17b-4036-9e65-3091...

Very interesting stuff and quite a large undertaking! I'm often impressed by the quality of the UK's open data.

cowsandmilk - an hour ago

> I'm often impressed by the quality of the UK's open data.
The ordnance survey not being open data is a bad look though.
- danw1979 - 26 minutes ago
  
  I’ll add the UKHO Admiralty marine charts to this list too.
kilroy123 - 6 hours ago

I noticed this as well! Very interesting.

GordonS - 7 hours ago

This is really nice! Would be great if it could handle regular rooftop solar calculations too.

ruaraidh - 7 hours ago

Thanks! Should be doable, I just got excited by the new shiny thing first.

overfits_ai - an hour ago

This is a really interesting project! The use of LIDAR data to account for actual building shadows is a clever approach. I'd be curious to see how this compares to commercial solar assessment tools in terms of accuracy. The UK's move to legalize plug-in solar is great for residential adoption.

pinkgolem - an hour ago

I am just surprised about the cost?

Kits in Germany are 300€ without a battery.

gib444 - an hour ago

Surprised which way? Too cheap? Too expensive? Surprised things differ in price by country?

realty_geek - 5 hours ago

Nice. I'm working on a project called homestocompare to help people house-hunting in the UK.

Would be nice to add this as an extra data point when comparing. Are you open to collaborating at all?

ruaraidh - 5 hours ago

Absolutely! I have some other datasets that might be useful too (e.g. air quality). Drop me a line: ruaraidh[at]southlondonscientific.com :)
- realty_geek - 2 hours ago
  
  Great, thanks - I'll drop you a line.
simonjgreen - 4 hours ago

Let me know if you’d like access to alt net availability data
- realty_geek - 2 hours ago
  
  Sorry, not sure what you mean by "alt net availability"

dnlzro - 3 hours ago

This is a great use of open data!

Please consider making the source code available. I’d love to make something similar for your friends across the pond (in Canada).

domh - 4 hours ago

Would be good to be able to select multiple points on the compass and have it tell me the best place for it (front and back garden)

ruaraidh - 4 hours ago

Good idea. I want to add specific options for different mounting locations (sheds etc) as well.

ErroneousBosh - 2 hours ago

"Any address in Britain"

"Caveats: - Outside LIDAR coverage (most of Scotland and Wales) it falls back to a synthetic horizon (less accurate)"

So, "any address in the most of the southern half of Britain"?

IshKebab - 3 hours ago

What if I already have solar, can I add this?

Also do you actually need a balcony or can you hang these out of a window somehow? Very few houses in the UK have balconies.

jimnotgym - 2 hours ago

You can put it on the ground if you like

toomuchtodo - 4 hours ago

Great work. Is it possible to use this dataset to calculate total plug in solar potential within the geographic constraint?

ruaraidh - 3 hours ago

Oh, that's such a good idea! I suppose the challenge is knowing where there are installable surfaces are (or at least making defensible guesses). I'm going to have a go at this...