Lucy Siegle has written a weekly ethical living column for The Observer since 2004, and two books, Green Living in the Urban Jungle and To Die For. She contributes to various television and radio programmes, a number of magazines, and is a reporter for BBC One’s The One Show.

Agamemnon Otero is the local energy entrepreneur behind the regeneration of some of London’s most deprived estates. Lucy Siegle goes in search of him in Homerton.

Early morning on the Banister House estate in Homerton and the sky is that intense shade of grey that only East London can conjure up. If we were talking Farrow & Ball paint colours – and given the pace of gentrification around here, that might happen – the shade would be Hackney Gloom: in short, a challenging day to generate solar energy.

But Agamemnon Otero, chair of Repowering London, who recently masterminded the installation of solar panels on 18 buildings here, remains ebullient, his default setting. He bounds through the estate, carrying a cup of hot water (he has cut sugar, meat and caffeine out of his diet on the grounds that, like his photovoltaic panels, he needs to be at peak energy to work 14-hour days on Repowering’s ambitious plans), offering cheery salutations to fellow early risers.

We take a very small lift to the top floor of one of the Banister blocks. Despite wearing suit trousers and relatively formal shoes, Otero shimmies up a metal ladder and disappears from view on to the roof as if this were Man On Wire. Then he shouts down instructions about how I might best follow. Not a chance. My vertigo is already kicking in, just looking out of the window.

As I’m too chicken to climb up to see the panels, I tour the estate’s fuse cupboard. It’s strangely exciting to watch numbers flicker across the display of the energy meters as the estate wakes up. And yes, despite the gloom, the photovoltaic panels on the roof are doing their thing. But every bit of power generated is being used on site. No power is being exported back to the grid.

Otero sees this as a victory. When most people talk about solar panels they obsess about how much they can export and sell back to the grid. But the big six energy companies buy this exported solar power at a wholesale rate, then sell it back to the estate later at three or four times the cost. Lesson one: it’s remarkably easy to get shortchanged in the renewable energy game.

Otero has a different plan. In the 379 flats of Banister House, the average income is just £11,000 a year, which has traditionally trapped residents in pre-paid or other higher-rate energy tariffs from the big six. The way Otero sees it, every kWh of community solar means a step away from this dependency and out of endemic fuel poverty.

With Afsheen Kabir Rashid, a fellow leading light in community empowerment (Rashid also helped set up the Muslim Women’s Collective in Tower Hamlets) Otero set up Repowering London four years ago. So far, they have completed three groundbreaking projects in South London, working with the local authority and the community to deliver Brixton Energy Solar, the UK’s first inner-city community-owned renewable energy projects, on three social housing estates.

Lesson two: Otero and team (there are six full-time Repowering staff) are not renewable energy anoraks high-fiving every time they reach 1000kWh of electricity generation (if you are interested in that sort of thing, the panels on Banister House are projected to generate 82,000 kWh of electricity in the first year). Instead, Otero’s first love is for participatory communities. Renewable energy is the hook, the device: it is the power station on the roof that gets people to buy in to the other benefits. Repowering projects set up a Community Benefit Society, and then give residents the opportunity to buy shares from £50. They are asked to view their investment as long-term, for 20 years.

Although Otero lives off the estate – actually on an old North Sea fishing boat in Vauxhall that he has painstakingly refurbished – he has spent hours on London’s biggest estates. ‘In the past, residents here have been promised the moon on a stick, but nobody really delivers,’ he says, ‘so we show that we’re committed. We spend six months going door to door, having conversations.’ Unemployment, fuel poverty and a lack of opportunity for young people were the three issues that everyone talked about and it is those that Repowering tackles.

While London’s social housing estates have spent decades prefixed by epithets like ‘crime-ridden’, Otero sees them as the jewels in the capital’s crown. He also thinks they are under siege as never before. As local authorities abstain from building new social housing, the private developers move in. Where estates border a sought-after amenity like a park, they are sitting ducks for a takeover, he says, and social housing all but disappears. Imagine, Otero says, the effect this has on young people. ‘There’s a myth that communities on estates want to leave, that everyone wants to get out of London. Actually, they often love their estate, but young people on inner city estates are seeing them sold off to the highest bidder. They are growing up with the notion that they’re not wealthy enough to deserve to remain in their own homes.’ Why would you invest in somewhere you don’t believe you’re entitled to stay?

Banister House – like the Roupell Park estate, one of the Brixton Energy Solar projects – was considered so ‘bad’ that squeamish developers gave it a wide berth. Repowering has seized the oppor­tunity to create a programme for young people that gives them an investment in the future.

Central to the Repowering model is an education programme to turn the estate’s young people and unemployed residents into experts who can service and promote renew­able energy in their community. A fifth of the return is put into a Community Fund, supporting a 30-week paid internship programme that teaches young people from the estate about the energy market, including how to switch; and training them in energy efficiency education and installation, in the maintenance of solar panels (they also build their own in workshops), and communication. ‘Look, there are rooms in these flats that are unused because they’re too expensive to heat,’ Otero says, ‘if a young person you’ve known all your life offers to install insulation or show you how to get out of fuel poverty or switch suppliers, you’re more inclined to give them access than some stranger.’

Agamemnon Otero WITH SOLAR ENERGY TRAINEE HABIB HAJO

Otero, who was born in Uruguay and grew up in New York, has survived cancer twice, once at the age of 18 and once at 26. Perhaps as a response, he has crammed in an astonishing range of experiences and qualifications, from pre-medicine, maths and architecture to a relatively successful career as an artist in the US. He is not yet 40.

I ask why he believes so strongly in this recipe for community energy and his answer spans three generations, as many continents, and includes a grandfather who regenerated the New York police department. He wears a huge ring awarded to his grandfather by the department in the 1960s, which is topped with a diamond. The kids on the estate like this bit of bling. They’re inclined to call Otero ‘Mega Man’ (the Nintendo combat robot who has an adversary, Ring Man).

While Repowering seems to have reached an accord with London’s local authorities, not that long ago the same authorities were trying to ban Otero from accessing certain roofs. It would also be disingenuous to pretend that renewables are having a great time. On the day I visit another Repowering project, at Dalston station, the government announced cuts to the Feed-in-Tariff, which many are concerned might kill off solar. One of Otero’s colleagues actually put on her trainers and ran to Westminster to deliver a petition demanding that the drastic digression (cutting) of the tariff be halted, especially for community solar.

Repowering projects make some other community energy projects in the UK (there are now over 5000) look a bit, well, light on actual community: power-to-the-people schemes that don’t give residents any power. Otero is frankly bemused by the UK’s renewable scene, which he describes as being dominated by ‘55-year-old white guys from the countryside’. In a social housing context this makes absolutely no sense.

So, critically, the four directors of each Repowering project live in the community, and it seems they nearly always include at least one estate matriarch. ‘On every social housing estate, there are these women of outstanding character capable of running the show,’ he says reeling off their names to me as if I would know of them, like other people might name-drop a Kardashian: Fay Gordon on the Loughborough Estate, Mary Simpson at Rouple Park and here at Banister House, Ann Canaii and Leila Fortunato, whose children Aisha and Jalil have also gone through the Repowering paid internship programme. ‘Dynamic amazing women make shit happen when others can’t,’ says Otero. Lesson three.