The current scramble for solar generation and storage has seen some pushback against the ‘obvious’ justifications

<p id="9103" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">I am, after years of debating &mdash; and saving &mdash; finally having solar panels fitted to the roof of my house, combined with a home battery pack. The soaring costs of gas and electricity in the UK have finally tipped the balance to make this financially justifiable &mdash; the &lsquo;payback period&rsquo;, after which the electricity saved and produced pays back the cost of installing them, has gone down from 10 years to 6. I&rsquo;m hoping that in a year&rsquo;s time, the performance of my panels will be just as good as&nbsp;<em class="nl">The New Climate&rsquo;s&nbsp;</em>Frank Parker&rsquo;s&mdash;<a class="af mm" href="https://medium.com/the-new-climate/how-i-saved-over-1-2k-in-a-year-after-installing-solar-pv-on-my-roof-f5c366db4f6b" rel="noopener">which he wrote about here</a>.</p>
<h2 class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj"><strong>The debate around solar</strong></h2>
<p id="be75" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">But what of the environmental justification? This, as an environmental writer, seems obvious: solar is clean, green, renewable energy. By installing it, I will be generating a substantial part of my electricity from the sun alone. Also by doing so, I am taking less electricity from the national grid, reducing overall demand &mdash; and in peak months, when I can&rsquo;t use all I produce, I will be adding some renewable energy back to the grid (albeit at a very low rate for me, and a very good rate for them. The feed-in-tariffs that used to guarantee payment for all electricity generated and exported for 20 years, were scrapped in 2019. The FIT <a class="af mm" href="https://www.which.co.uk/reviews/feed-in-tariffs/article/feed-in-tariffs/what-was-the-feed-in-tariff-aAsa36S95iJy" target="_blank" rel="noopener ugc nofollow">was as high as 54p/kWh</a>&nbsp;for electricity generated in 2011; now I can&nbsp;<a class="af mm" href="https://octopus.energy/help-and-faqs/articles/seg-tariff/" target="_blank" rel="noopener ugc nofollow">expect 4.1p/kWh</a>, and only for power I export).</p>
<p id="5d6f" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">However, as the whole world struggles with rising energy costs, the current&nbsp;<a class="af mm" href="https://www.businessgreen.com/news/4076504/solar-industry-celebrates-spectacular-surge-rooftop-installations" target="_blank" rel="noopener ugc nofollow">scramble for solar</a> generation and storage has seen some pushback against the &lsquo;obvious&rsquo; justifications above. This <a href="https://twitter.com/LionHirth/status/1627597886484582401?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1627597886484582401%7Ctwgr%5Ef9dea32e1d1680d1cb6ba61741925d933c7ed970%7Ctwcon%5Es1_c10&amp;ref_url=https%3A%2F%2Fcdn.embedly.com%2Fwidgets%2Fmedia.html%3Ftype%3Dtext2Fhtmlkey%3Da19fcc184b9711e1b4764040d3dc5c07schema%3Dtwitterurl%3Dhttps3A%2F%2Ftwitter.com%2FLionHirth%2Fstatus%2F16275978864845824013Fs3D20image%3Dhttps3A%2F%2Fi.embed.ly%2F1%2Fimage3Furl3Dhttps253A252F252Fabs.twimg.com252Ferrors252Flogo46x38.png26key3Da19fcc184b9711e1b4764040d3dc5c07" target="_blank" rel="noopener">tweet</a> from Lion Hirth, Professor at Hertie School and an expert on energy markets, caught my eye.</p>
<p id="82bc" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">Most of the replies were along the lines of this one from&nbsp;<a class="af mm" href="https://twitter.com/robert_ferry" target="_blank" rel="noopener ugc nofollow">Robert Ferry</a>, Co-founder of&nbsp;<a class="af mm" href="https://twitter.com/poweredbyart" target="_blank" rel="noopener ugc nofollow">@poweredbyart</a>:</p>
<blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">&ldquo;It will be nearly impossible to fully decarbonize without them. The promise of grid-connected smart homes may finally be coming to pass.&rdquo;</p>
</blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">i.e., private solar and battery packs = good. (FWIW, my own reply to Hirth was &ldquo;Surely they reduce the household(s) demand on the grid, which is good for the centralized system/society?&rdquo;)</p>
<p id="504d" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">But what of Hirth&rsquo;s point &mdash; might this&nbsp;<em class="nl">not&nbsp;</em>good be for society? I am of course in a privileged position to be able to afford and install domestic solar panels (albeit, by the skin of my teeth). Despite my seeing this as an environmentally altruistic choice, is it in fact the opposite? In a world with finite materials, would they be better used for centralised infrastructure and mega-solar farms? Am I, in some ways (and there is no worse crime in English culture) <em class="nl">jumping the queue</em>?</p>
<h2 class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj"><strong>The evidence</strong></h2>
<p id="2b13" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">Turns out, a team of researchers already posed this question in a <em class="nl"><a href="https://www.nature.com/articles/s41467-021-25720-2" target="_blank" rel="noopener">Nature</a> </em>paper in 2021.</p>
<p id="d37f" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">The authors estimate that the total surface area of all the rooftops in the entire world is around 0.2 million square kilometres &mdash; similar to the size of the UK. And you wouldn&rsquo;t need to plaster them all with solar panels to meet the world&rsquo;s current electricity needs: in fact, only half of them would suffice. Amazingly, the study led by Siddharth Joshi of the SFI Research Centre for Energy, Climate and the Marine (MaREI), Ireland,&nbsp;<a class="af mm" href="https://www.nature.com/articles/s41467-021-25720-2" target="_blank" rel="noopener ugc nofollow">found that</a> between 2006 and 2018 the installed capacity of rooftop solar had grown from 2.5 GW to 213 GW &mdash; an 85-fold increase globally. It accounted for 40% of all solar PV globally and nearly one-fourth of the total renewable capacity additions in 2018. And despite the pandemic, the growth has continued to snowball, with&nbsp;<a class="af mm" href="https://www.iea.org/reports/approximately-100-million-households-rely-on-rooftop-solar-pv-by-2030" target="_blank" rel="noopener ugc nofollow">the IEA forecasting</a>&nbsp;that at least 190 GW will be installed each year from 2022 onwards.</p>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph=""><img style="display: block; margin-left: auto; margin-right: auto;" src="https://illuminem.b-cdn.net/articlebody/880c56f92cf330ecf827cd94b02f0257529be56f.jpg?" alt="Evolution of annual solar PV installations" /></p>
<p id="521e" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">In a subsequent interview, Joshi&nbsp;<a class="af mm" href="https://www.forbes.com/sites/davidrvetter/2021/10/11/could-rooftop-solar-really-provide-enough-electricity-for-the-entire-world/?sh=6098694022ee" target="_blank" rel="noopener ugc nofollow">told&nbsp;<em class="nl">Forbes</em></a>,</p>
<blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">&ldquo;Rooftop solar has two unique attributes that set it apart from other forms of renewable energy generation: fast deployment, and decentralised citizen-driven uptake. These attributes lend it specific advantages over other renewable generation technologies&rdquo;,</p>
</blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">adding that rooftop solar</p>
<blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">&ldquo;brings significant advantages in terms of broad participation of society in the energy transition to a low carbon future.&rdquo;</p>
</blockquote>
<p id="6f17" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">In particular, India and China have a sizable potential for rooftop solar photovoltaics, along with the lowest cost for the deployment of these technologies &mdash; considering the latter manufactures most of the world&rsquo;s solar PV.</p>
<h2 class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj"><strong>Challenges of solar</strong></h2>
<p id="378b" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">The IEA outlines the challenges of solar, namely that upfront costs remain a significant obstacle and multi-family buildings and apartment blocks make the split of production and billing among different tenants remains a complex issue. But in summary, <a class="af mm" href="https://www.iea.org/reports/approximately-100-million-households-rely-on-rooftop-solar-pv-by-2030" target="_blank" rel="noopener ugc nofollow">said the IEA</a>, the</p>
<blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">&ldquo;barriers are social, financial, psychological, and regulatory rather than technical.&nbsp;<strong class="mp fx">The technology has reached such a level of maturity that it can be deployed easily everywhere</strong>&rdquo;.</p>
</blockquote>
<p id="8770" data-selectable-paragraph="">Similarly, opposition to industrial-sized solar farms in the countryside is growing. I&rsquo;m not anti-solar farms by any means &mdash; especially when <a href="https://www.perchenergy.com/blog/industry/what-is-agrivoltaics-solar-agriculture-farming" target="_blank" rel="noopener ugc nofollow">combined with sheep grazing</a>&nbsp;and&nbsp;<a href="https://www.euronews.com/green/2021/12/14/planting-wildflowers-around-solar-panels-could-make-them-a-home-for-bees" target="_blank" rel="noopener ugc nofollow">wildflowers for insects</a>.&nbsp;But existing rooftops are, by definition, already brownfield sites.&nbsp;Why build on greenfield sites unless we really need to? CPRE, the countryside charity,&nbsp;<a href="https://www.cpre.org.uk/news/unleash-rooftop-solar-to-tackle-energy-crisis-we-urge-chancellor/" target="_blank" rel="noopener ugc nofollow">points out that</a>,</p>
<blockquote>
<p data-selectable-paragraph="">&ldquo;Germany has focused on rooftops first, with 80% of its solar power coming from panels that generate little public opposition&rdquo;.</p>
</blockquote>
<p data-selectable-paragraph="">CPRE is calling on the government to &ldquo;adopt a renewables strategy that prioritises rooftops, surface car parks and brownfield sites&rdquo;.</p>
<p data-selectable-paragraph="">If implemented quickly, they say,&nbsp; &ldquo;the policy could drastically reduce energy bills during the cost-of-living crisis and speed up the transition to net zero&rdquo;.</p>
<h2><strong>What then?</strong></h2>
<p id="c923" class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">The&nbsp;<em class="nl">Nature&nbsp;</em>authors say that the global electricity supply cannot rely on a single source of generation. So no, rooftop solar isn&rsquo;t about to power the world. The equipment required to store solar power is still <a class="af mm" href="https://www.igs.com/energy-resource-center/energy-101/solar-panel-batteries" target="_blank" rel="noopener ugc nofollow">expensive</a>, while solar panels can&rsquo;t deliver power for heavy industry, which requires very large currents. That said,&nbsp;<a class="af mm" href="https://theconversation.com/solar-panels-on-half-the-worlds-roofs-could-meet-its-entire-electricity-demand-new-research-169302" target="_blank" rel="noopener ugc nofollow">they write</a>,</p>
<blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">&ldquo;Despite this, rooftop solar has huge potential to alleviate energy poverty and put clean, pollution-free power back in the hands of consumers worldwide. If the costs of solar power continue to&nbsp;<a class="af mm" href="https://www.woodmac.com/press-releases/solar-power-now-cheapest-way-to-add-electricity-in-many-markets---and-getting-cheaper/#:%7E:text=The%20cost%20of%20solar%20power,China%2C%20and%2014%20other%20nations." target="_blank" rel="noopener ugc nofollow">decrease</a>, rooftop panels could be one of the best tools yet to decarbonise our electricity supply&rdquo;.</p>
</blockquote>
<p class="pw-post-body-paragraph mn mo fw mp b mq mr ms mt mu mv mw mx my mz na nb nc nd ne nf ng nh ni nj nk fp bj" data-selectable-paragraph="">Well, that&rsquo;s me sold (which is just as well, because I&rsquo;ve already bought them).</p>
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<p><em>This article is also published on the <a href="https://medium.com/the-new-climate/could-the-whole-world-be-powered-by-rooftop-solar-444a14046f1d" target="_blank" rel="noopener">author's blog</a>. illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability &amp; Energy writers, their opinions do not necessarily represent those of illuminem.</em></p>
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Tim Smedley

Tim Smedley

Could the whole world be powered by rooftop solar?

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