Glints Of Light 💡 Rooftop Solar Potentials 💡 Part 2

People And Nature ☭ Written by Simon Pirani.

24-April-2025

Rooftop solar panels and other decentralised technologies (solar water heaters, small windmills, biomass generators, and so on) produce electricity near the point of use, and so reduce the flow of electricity through the grid – and potentially, therefore, reduce fossil fuel burning in power stations and associated greenhouse gas emissions.

Trainees in India fabricating a solar converter box.
Photo from the Vikalp Sangam web site

Capital’s drive to expand its economy always threatens to nullify this potential, as the system by its nature seeks out the most profitable ways to invest, relentlessly reversing the savings made, prolonging and even expanding fossil fuel use.

Nevertheless, assessing and using solar’s decarbonisation potential is surely part of our common fight against capitalism, for social justice and climate action.

Decentralised electricity technologies (distributed energy resources, in the industry language) have another, related potential: because they are small-scale and versatile, they can be controlled and operated by communities and individuals more easily than nuclear, coal- or gas-fired power stations, where corporations and states do their utmost to prevent even highly-skilled workforces from gaining any hint of control.

In Part 1, I documented capital’s efforts to keep control of decentralised resources, to fence them off, to stop them falling into society’s hands. In this part, I propose that these efforts can be confounded and defeated.

Technological potentials

Here is my (non-engineer’s) summary of the potentials of (1) technologies that reduce dependence on grids; (2) changes that reduce throughput and pressure on grids; and (3) network modernisation.

There is an important issue of framing: I rely on research by engineers and others who mostly assume that technologies will change, but economic and social relations will not – and, specifically, assume that electricity will remain a paid-for commodity. This conditions not only their views of progress, but also the language used: electricity throughput will be cut by “demand reduction”, technologies will become more efficient via “competition”, and so on.[1] In my view, technologies’ potentials will only be fully realised in the fight to decommodify electricity. But anyway, we should pay attention to what the engineers can tell us.

1. Solar technologies that reduce dependence on grids

People do not need electricity. They need things that electricity can provide: light, heat, energy to power motors, the ability to use household appliances, charge mobile phones, and so on.[2] Solar PV technology puts into people’s hands not only solar panels, but a much wider array of devices, including many that work without connecting even to a low-voltage local network. Outside the rich world, this has current practical relevance.

Solar-powered water pumps are the most widespread such technology in India, a report by three development organisations[3] stated. It listed other technologies coming into use, including: small solar refrigerators, milk chillers and other types of cold storage; solar dryers for agricultural products; solar-powered charkhas (domestic spinning wheels), looms and silk reeling machines; and grain milling machines.

The report’s authors pose the question: why develop such off-grid technologies, rather than solarising existing, grid-connected devices?

Most off-the-shelf livelihood technologies, they answer, “are not energy-efficient, as they are designed to run with a grid supply that is often subsidised, creating limited incentives for customers to demand energy-efficient solutions”.

A solar water pump.
Photo from India Mart

Such technologies are “often over-designed to take care of the unreliable supply, enabling a day’s worth of throughput in a few hours when electricity is available”. This in turn means they need bigger solar systems, or battery back-ups.

The energy researchers Neelakshi Joshi and Ashish Kothari have shown that in Ladakh, an autonomous region of north-east India with limited grid access, small-scale and solar technologies have been combined e.g. in earth buildings adapted with Trombe wall systems to keep them warm, parabolic reflectors for cooking and off-grid solar for schools and water pumps.[4]

A proposal by the Indian prime minister, Narendra Modi, to spent $1 billion on a 13 GW wind and solar electricity generation project could disrupt, rather than enhance, this existing aggregation of technologies.

Millions of people with no, or limited, grid access see solar devices as “a form of ‘pre-electricity’” or a “stepping stone” to full electrification, Ankit Kumar and his colleagues have shown.[5] But Manabi Majumdar and Parthasarathi Majumdar, who work in development organisations promoting household solar technologies, argue that, with currently available technologies, such distinctions will fade. They advocate and practice education in the operation of solar and electrical equipment, including non-grid-dependent devices.[6]

Rooftop solar also works without a grid connection in many contexts, but is more useful and versatile with one.

2. Changes that reduce throughput and pressure on the grid

Once rooftop solar, or other decentralised electricity generation, is connected to electricity grids in sufficient quantities, it reduces the amount of electricity transported through those grids. This has implications for infrastructure development: fewer centralised power stations, and fewer transmission (long-distance, high-voltage) and distribution (local) wires may be needed.

Obviously, each kilowatt-hour of solar electricity produced and used locally, in a household or community network, reduces the need for a kilowatt-hour (plus the electricity used in transportation) to be produced at a nearby power station.

But this is by no means the only saving. The more that decentralised generation is coupled with batteries or other storage operated at local level, the more significant are the potential savings from “peak shaving”, i.e. reducing the amount of electricity generation needed at the busiest times. Locally-produced electricity can be stored for use during “peaks”, as well as electricity use being rearranged (see below).

In rich countries, electricity companies have since the mid-20th century built sufficient (mostly fossil-fuelled) power stations to meet estimated peak demand (e.g. the level of demand on a cold winter’s evening).

This was partly a response to the physical fact that it was difficult (and more expensive than it is now) to store electricity. But it also reflected the material-heavy, infrastructure-centred ideology of mid-20th-century capitalism, the target of vituperative critique by environmentalists of the 1970s.[7]

The expansion of renewable electricity generation over the past two decades means that such overbuild of infrastructure is now regarded as out of date by mainstream energy researchers, too.

For example, a group of engineering researchers, headed by Christopher Clack, estimated that 20-25% of generation capacity on the US grid, i.e. 300-350 GW, covers only around 3% of electricity use, i.e. it is unused most of the time. Decentralised generation could “shave the peak” by an average of 17% nationwide, and reduce demand for 80% of the hours of the year, they found.[8]

Research by the Rocky Mountain Institute, which prioritises energy efficiency and conservation, estimates even greater potential impacts, including 24% lower peak demand net of renewables.[9]

This “peak shaving” means that 20-25% of power station capacity, that is only used during “peaks”, could be shut down; a more level demand curve (i.e. less variation of levels of demand over time) means that all generators on the system would run more consistently; transmission assets can be used more efficiently. Decentralised technologies offer the network the option to shift demand to meet variable supply, instead of always forcing it to shift supply to meet demand. The conclusion: decentralisation versus utility-scale renewables is a false dichotomy. Both are needed.[10]

Much engineering research now considers electricity generation and storage, and technologies that use electricity, as a single integrated system.

There is a body of research into how decentralised electricity generation can work together with energy conservation (e.g. insulating homes and other building efficiencies, mechanical improvements to heating systems, and so on), household-level storage (e.g. in electric vehicle batteries), and with the management of electricity use (e.g. running more electricity-intensive equipment at non-peak times).[11] In China, engineers have devised a system of integrating solar PV, energy storage, distribution and flexibility technologies in new buildings, that they say will reduce their peak electricity demand by 50%.[12]

In mainstream literature, management of electricity use is usually called “demand response”: companies that sell electricity to households encourage them to shift times of use with financial incentives, or even compel them, with restrictions. But existing technologies could perfectly well be used and controlled by communities and households themselves, without companies, in the context of economic relationships that treat electricity as a service, not a commodity.

The growth of rooftop solar has also renewed researchers’ interest in the potentially transformative role of direct current (DC). Solar panels produce DC, which is transformed to alternating current (AC) by inverters. For most household equipment, and devices containing semiconductors, it is usually converted back to DC again at the point of use. Each transformation uses up to 10% of the supply.

Nearly 20 years ago, when solar’s share of electricity generation was tiny, a US research institute published a detailed argument that DC power systems would eliminate multiple conversions and potentially avoid energy losses of “up to 35%”.[13]

Engineering researchers have also looked specifically at how DC microgrids could raise the efficiency of solar PV. One estimate was that, by eliminating system losses, household systems’ energy efficiency would increase from the current 70-75%, to 85-92%.[14] Another project examined the potential for DC microgrids supplying groups of households.[15]

Given electricity corporations’ dominant role in supporting and financing engineering research, and the substantial threat all this poses to their business model – of producing electricity in large power stations and selling it – no conspiracy theories are needed to explain why the testing and implementation of these ideas has been so slow.

3. Network modernisation

In countries with a high share of decentralised generation, electricity networks are being compelled to modernise. The previous generation of technologies, which carried electricity from large, centralised power stations to consumers, is being superceded by networks that can manage flows from much larger numbers of smaller generators, whether, wind, solar (including utility-scale solar, much of which is still far smaller than fossil-fuelled power stations), or other types.

Engineers are confident that the growing share of decentralised generation will make grids more robust.[16] The principal obstructions to network development are not technological but social and economic: corporations that produce and transport electricity fear losing control of the process, and are loathe to make infrastructure investments that could take networks in that direction. Their resistance to change is epitomised by the many years’ wait faced by companies in many rich countries that wish to build solar or wind farms.

An important aspect of network development is microgrids, i.e. grids, low-voltage and potentially DC, covering a discrete area, that produce and store electricity, and can feed it to the grid, or offtake it from the grid, but can also “island”, i.e. operate autonomously. Rooftop solar will typically play a big part in these. Corporations outside the rich world (see e.g. Part 1, India, above), are investing in microgrids; in rich countries, they are supporting research on the subject.[17]

Decentralised electricity generation and transformed networks are key to a vision of a future in which electricity is treated as a service not a commodity, in my view. In this vision, economic arrangements serve people, not capital, and energy systems are transformed in line with the need to avert dangerous climate change.

Any doubts about the technological potential for such networks have been overcome in the last couple of decades.[18] The obstructions are the power relations and hierarchies through which capital rules over society. These can be changed.

Social potentials

Transforming the economy to avoid dangerous climate change, and transforming social relations to meet human need instead of profit, are social and political challenges. These things can not be done by rooftop solar or any other technology. Nevertheless, due to its potential to be used by people, outside big capital’s control, rooftop solar is better suited to play a role in such transformations than other technologies.

The claim made by intergovernmental organisations and the most powerful governments, that an “energy transition” is underway to forestall global heating, is false. After more than 30 years of international climate talks, even feeble, voluntary measures to restrain fossil fuel production are being junked. Hundreds of billions of dollars of state subsidies continue to pour into fossil fuel production and consumption. The juggernaut of lopsided economic expansion drives on, supercharged by “growth” dogma. Renewable electricity generation takes its place in this ineffective “transition” alongside fraudulent “solutions” such as carbon removal and hydrogen fuel.

The alternatives that dominate public discussion are also fundamentally technocratic, such as the “100 per cent renewables” research by Mark Jacobson and his colleagues. While they claim to show that renewable technologies have the theoretical capacity to substitute for the world’s entire fossil fuel supply, there is a gaping hole in their research: they present the conclusions as “policy advice”, and discuss only in the most general terms what social forces obstruct technological change, how technological change relates to social change, or how social relations shape the use of technologies.[19]

There is a significant technocratic strand in socialist writing about the climate crisis, too. A recent example is Overshoot, by Andreas Malm and Wim Carton. They take Jacobson’s work as a starting point, ignore the substantial critique of his conclusions by other energy researchers, and portray renewable technologies not as technological grounds on which battles between social forces are being fought, but as a sort of extra-societal lever that could bring about explosive, but unspecified, social change. (See “Technology and Society. How not to use Karl Marx”, on People & Nature this week.)

Instead, I propose a view that takes human society as the crucial factor of change; whether technologies can help us depends a great deal on who controls them and in whose interests they are developed. Technologies do not work outside of social contexts.

This applies to rooftop solar and other renewable electricity generation: in capital’s hands, it can be used to reinforce the system that dominates us now. Under our control, it can help us. To understand how, we need to proceed from an assessment of its social role.

Among researchers who have considered solar’s social potential, K. Rahul Sharma and Parth Bhatia argue that it “offers an opportunity to fundamentally disrupt the political, financial and institutional arrangements associated with the existing system”. In India, such disruptions have included “attracting high-paying industrial consumers away from the grid, allowing new players (individuals, co-operatives, high-risk fast capital) to compete for energy ownership, and shifting the federal balance of power as the centre’s monopoly over coal loses salience”.

But, they argue, the rise of renewables also offers opportunities to link choices of energy technologies to broader goals of social justice. They warn that “whether the ultimate beneficiary of a renewables-based society is the common energy user, instead of the elite, will be contingent on how new energy infrastructures are specifically structured, and will not be simply determined by the choice of technology”.[20]

(Sharma and Bhatia highlight the distinction between “energy democracy”, a concept widely shared by social movements in the global north, and “energy justice” as understood in the global south, an idea that is “dominated by the challenge of access [to electricity], which is not a major concern in developed countries”. This resonates with points made in Part 1 about the social role of rooftop solar.)

How might solar technologies move from disrupting current arrangements, to becoming instruments of, or helping to achieve, deeper-going social changes? Could they, in the right hands, facilitate a permanent move away from grids based on central power stations, away from fossil-fuel-centred technological systems, and help usher in systems of energy production and use free of capital’s domination?

Part of the answer to these questions depends on ownership and control. Electricity companies use renewables, including rooftop solar, to retain control of their markets and commodified economic relationships. State ownership under capitalism is a double-edged sword: Chinese households and communities apparently have little or no control over the millions of panels sited on their roofs by China’s state-sector electricity companies. They are hardly less alienated from those instruments of production than Indian households suffering the consequences of living near a Tata-owned solar farm.

Public ownership of both large-scale wind and solar farms, and of decentralised generation such as rooftop solar, is a key demand of many electricity workers’ unions internationally, and has been championed over many years by Trade Unions for Energy Democracy (TUED).

The Trade Union Programme for a Public, Low-Carbon Energy Future, initiated by TUED and supported by many unions, calls for energy resources and technologies to be “publicly owned and managed in a manner consistent with a global public goods approach”, and for “workers and users” to be involved in “democratic decision-making processes”.[21] This may serve as a basis for discussion of how forms of social ownership might take shape.

Such a discussion should also consider individual household ownership of solar panels (about which some socialist writers have, in my view mistakenly, been dismissive).

Balcony solar, now spreading in Germany.
Photo from Namkoo Solar web site

Households use these panels as tools to produce electricity. Where they retain ownership and control of them, they can use the electricity they need, and sell the rest on the market – to neighbours if technically possible, or, more likely, to electricity suppliers present on the grid.

Economically, these households are in the same position as hundreds of millions of subsistence farmers who produce most of the world’s food. Their panels are tools, no more or less than a construction worker’s toolbox or a computer programmer’s laptop. While ownership of panels is perceived to be, and to a large extent still is, a privilege of wealthy or better-off households, that need not be true forever. At one time, the same could have been said of cars, or personal computers.

The relatively small scale of rooftop solar, and the ease with which it can be integrated into the grid, makes it well suited not only e.g. to state ownership at municipal level, but also to other forms of social ownership, including co-operatives. These can magnify the power of individual households with solar panels, just as a trade union magnifies the power of individuals in a workplace.

Microgrids, which are now being built under capital’s control (see above, Network modernisation), could instead be owned and controlled by co-ops. Linking multiple microgrids to share electricity, and to enhance the stability of larger grids, is also straightforward with existing technologies.[22]

The US-based socialist writer RK Upadhya has assessed the strengths and weaknesses of the rural electricity cooperatives that manage electricity distribution for about 40 million people. These were set up in a top-down manner during the New Deal of the 1930s, and are mostly run as businesses.

He argues, citing examples of recent challenges to the status quo by community activists in several of the co-ops, that “co-ops should be seen as potential weapons of class struggle. […] Local power production should be seen as not just a way to save money and decarbonise, but also as a means of cultivating local jobs and distributed knowledge in renewable energy.”[23]

Once electricity is seen as a common good, not a commodity, and manifold ways are found for society to take its production and use into its own hands, independently of, and against, corporations and governments, then the true potential of rooftop solar, and other technologies, will begin to be realised.

Conclusions

There is no question about whether rooftop solar will play a significant part in electricity generation. It is doing so now, and will continue to expand, at least as rapidly as other ways of producing electricity.

This expansion makes too little difference to the continuing, disastrous growth of greenhouse gas emissions, because of the way that governments and companies treat solar as an addition to fossil-fuel-produced energy, not as a replacement. China, while leading the world in solar installations, is also opening new coal- and gas-fired power plants. In Europe and the USA, big capital is investing heavily in gas and hydrogen.

Rooftop solar alone can not stop the juggernaut of capital expansion and the “growth” dogma that justifies it – but we can fight to use it, and control it, alongside fighting for the broader transformation of the economy to cut greenhouse gas emissions.

In a world dominated by big capital, the supply chains for solar panels will inevitably reproduce damaging material and ecological impacts. Moreover, in this world, rooftop solar can often be installed and used in ways that exacerbate social inequalities, as shown in Part 1 above. These are reasons to fight for social control and ownership.

I have argued that, despite the current dominant trajectory, rooftop solar has the potential to develop at least partly outside exploitative, hierarchical economic and social relationships. This depends heavily on ownership. Although most of the world’s rooftop solar is owned by corporations, some of it is not.

Forms of social ownership – public, municipal, co-operative and commuity – are not widespread. But they can proliferate.

Individual households with their own panels, and better still batteries, can both manage their own electricity use and supply electricity to the grid. These households are multiplying. Economically, they are in the same position as the household farms that, using their own tools, produce most of the world’s food. No less than workers employed by energy companies, their interests are pitted against those of big capital.

I have argued here that, potentially, solar can play a part in our collective struggles to avert dangerous global heating and for a socially just society, to supercede capitalism.

The first reason for this is that rooftop solar can perfectly well supply a large share of the electricity that people need, with a minimal level of greenhouse gas emissions. Even now, outside the rich world – and not only in China – rooftop solar is being mobilised by governments to supplement or replace unreliable electricity from fossil-fuelled grids, meeting millions of people’s urgent need.

Nuclear or big coal plants look superior, only if judged using the category of undifferentiated “energy demand”, so beloved of giant corporations – which treats supply e.g. to a house or factory in India as a number, much smaller and therefore less important than the number needed to supply cryptocurrency back-up, a data centre, a luxury hotel or a weapons factory in the rich world.

Secondly, rooftop solar, and technologies such as microgrids that make best use of it, have the technological potential to reduce substantially the amount of electricity flowing through networks, and therefore to make many fossil-fuelled power stations redundant.

Thirdly and most significantly, rooftop solar, like other decentralised (or distributed) energy technologies, is suited by its nature to development and use by communities. Unlike a nuclear power station, it can be operated by any group of people with relatively basic technical knowledge. It can be operated at almost any scale. This raises the prospect of a society in which communities can produce, control, distribute and use electricity with their own tools, free of states and corporations.

These potentials are as yet far from being realised, but they point to some possible ways forward. That is why I call them glints in the darkness.

Part 1 of the article is here. / Download both parts as a PDF here

References

[1] Managing electricity use is routinely described as “demand management”, as though its use can only be imagined as the supply of, and demand for, a commodity. Technologies are judged to be “competitive”, as though the global threat of climate crisis, and the billions of subsidies routinely funnelled to fossil fuels, could never justify subsidies to other technologies. Even the term “energy”, used as though it is some sort of homogenous, exchangeable commodity, is problematic. For a discussion of that, see: Simon Pirani, Larry Lohmann and David Schwartzman, Roads to an Energy Commons, People & Nature, February 2022

[2] In research publications, the distinction is made between these “energy services” and “energy”, this use of the word “services” frequently implying an economic framework in which they are commodified, bought and sold

[3] A. Jain, W. Khalid and S. Jindal, Decentralised Renewable Energy Technologies for Sustainable Livelihoods (Council on Energy, Environment and Water, Villgro and Powering Livelihoods, May 2023)

[4] N. Joshi and A. Kothari, “Autonomy and pluriversal energy futures in Ladakh, India”, Human Geography 1-8 (2024)

[5] Ankit Kumar et al, “Solar energy for all? Understanding the successes and shortfalls through a critical comparative assessment of Bangladesh, Brazil, India, Mozambique, Sri Lanka and South Africa”, Energy Research and Social Science 48 (2019), pp. 166-176

[6] Manabi Majumdar and Parthasarathi Majumdar, “Solar electricity as a democratic question”, Vikalp Sangam web site, 22 June 2024.

[7] A classic critique of wasteful electricity infrastructure (but by no means the only one) is: Amory Lovins, The Energy Controversy: soft path questions and answers (Friends of the Earth, 1979)

[8] C. Clack et al, Why Local Solar For All Costs Less: a new roadmap for the lowest cost grid (VCE, 2020)

[9] Demand Flexibility: the Key to Enabling a low-cost, low-carbon grid (Rocky Mountain Institute, February 2018). The institute was founded by, and continues the work of, Amory Lovins

[10] I have based this paragraph on the research paper, and a helpful journalist’s summary: David Roberts, “Rooftop solar and home batteries make a clean grid vastly more affordable”, Volts, May 2021

[11] A technical summary is: The Role of Distributed Energy Resources in Today’s Grid Transition (Gridworks / GridLab August 2018). A summary of mainstream energy policy views is: Energy Transition Commission, Making Mission Possible: delivering a net-zero economy (September 2020)

[12] Embarking on a New Era: Rural Residential Photovoltaics are Driving China’s Rural Revitalisation (Energy Foundation China / Asian Infrastructure Investment Bank, 2024), page 89

[13] Electric Power Research Institute, DC Power Production, Delivery and Utilization. An EPRI White Paper (June 2006)

[14] K. Shenai and K. Shah, “Smart DC micro-grid for efficient utilization of distributed renewable energy”, IEEE 2011 Energy Tech; and D. Magdefrau, T. Taufik, M. Poshtan and M. Muscarella, “Analysis and Review of DC Microgrid Implementations”, International Seminar on Application for Technology of Information and Communication (iSemantic / IEEE Explore), 2016

[15] Brock Glasgo et al, “How much electricity can we save by using direct current circuits in homes? Understanding the potential for electricity savings and assessing the feasability of a transition towards DC powered buildings”, Applied Energy 180 (2016), pp. 66-75. See also V. Vossos et al, “Energy savings from direct-DC in U.S. residential buildings”, Energy and Buildings 68 (2014), pp. 223-231

[16] A good summary is: M.N. Alam, Saikat Chakrabarti and A. Ghosh, “Networked microgrids: state-of-the-art and future prospectives”, IEEE Transactions on Industrial Informatics 15:3, March 2019, pp. 1238-1250

[17] See for example Guidehouse Insights White Paper: How Utilities can enhance our DER energy future (2022); “ABB invests in direct current microgrid”, Digital magazine, 9 March 2023. In November last year, the European Research Council approved €8 million funding for research of grid modernisation. See press release, “We want to make fundamental changes to the way the electricity grid is controlled”, 5 November 2024

[18] I commented on these issues in a previous article: S. Pirani, Wind, Water, Sun and Socialism, People & Nature, September 2023

[19] For a critique of Jacobson’s work, see my book review, “We need social change, not miracles”, The Ecologist, July 2023

[20] K. Rahul Sharma and Parth Bhatia, “How just and democratic is India’s solar energy transition? An analysis of state solar policies in India”, in P. Kashwan (ed.), Climate Justice in India (Cambridge University Press, 2022), pages 50-73

[21] Trade Union Program for a Public, Low-Carbon Energy Future, TUED, 2021, and Launch of the “Trade Union Programme” TUED, November 2021

[22] A group of European researchers have shown how current communication technology can be used to manage electricity as a commons, not a commodity. See, for example: Chris Giotitsas et al, “Energy governance as a commons: engineering alternative socio-technical configurations”, Energy Research & Social Science 84 (2022), 102354, and Vasily Kostakis et al, “From private to public governance: the case for reconfiguring energy systems as a commons”, Energy Research & Social Science 70 (2020)

[23] RK Upadhya, “Co-ops, Climate and Capital”, Science for the People 24:3 (Winter 2021)

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