The debate

Delegates at the workshop not only discussed the problems that each of the ETSU studies threw up, but proffered solutions of their own. Naturally, the alternative solutions were relatively back-of-envelope calculations, but often differed only marginally from the conclusions of the real design teams.

The important issues and problems became clear through repetition. These were the prohibitive costs of photovoltaics, the importance of material offset calculations, exporting excess generation to the grid, and the general paucity of design advice for those wishing to use photovoltaics.

A major issue is the capital investment required for pvs, and recognition of the nonsensical payback periods. Prices are falling, at around 7%/y according to popular consensus, but BP Solar, for example, quotes £340/m² for a standard laminate photovoltaic, with glass modules costing around £450/m².

Competitive prices are difficult to obtain – both Bucknell Austin and Buro Happold reported difficulty in getting accurate quotes. This is due, they say, to increasing volume and evolving construction techniques.

There was widespread consensus that photovoltaics will remain a fringe technology while clients feel they are signing blank cheques to their design teams. "Clients," said Duncan Price of Whitby Bird, "have to make a leap of faith that their European funding application will come off. They have to want it to happen and take risks to ensure that it does." There was much debate on the potential for offsetting the cost of building materials. Thin film laminate photovoltaics are cheaper than glass modules, but the offset cost for building materials is not as great. It also depends where on the building the material is being used. The Sheffield ArtSpace project demonstrated that while standard laminate modules provide the cheapest solution, they only substitute a very small part of the existing building fabric when designed for use on roofs.

‘Clients have to make a leap of faith that their European funding application will come off’ – Duncan Price

The workshop agreed that the UK electricity supply industry, as currently regulated, represents a considerable barrier to the use of building integrated photovoltaics. Connection, harmonisation and monitoring charges levied by local electricity companies can make exporting to the grid a costly exercise. The ArtSpace building, for example, would need to generate a couple of thousand kWh/y simply to cover connection charges.

It clearly depends on who you talk to. At Haileybury, Eastern Electricity was happy to credit pv-generated electricity not used by the boarding house against the electricity used elsewhere on the estate. By contrast, Yorkshire Electricity scared the ArtSpace design team off a grid connection by a purchase price of 1.83 p/kWh, and fixed and annual charges for billing and inspections amounting to £2000/y.

If, as Feilden Clegg's David Saxby pointed out, electricity companies purchased energy produced by photovoltaic generation at their supply cost, then there would be a benefit in producing as much pv-generated power as possible.

The problem, as Arup's Chris Twinn said, is the lack of incentives for the National Grid or the electricity supply industry to get their power from renewable energy. "In Holland there is a voluntary agreement between generators and the government that 10% of delivered energy should be from a sustainable source. On that basis, the energy company provides photovoltaics for your [sic] building. There is a golden opportunity here for the UK government," he concluded.

‘I would like to see a planning audit that asks designers to show how pvs might be retrofitted to the buildings they are designing’ – Steven Costello

Consulting engineer Whitby Bird is involved on a solar housing scheme at Kensal Green for the Peabody Trust. In trying to make pvs stack up, Whitby's Duncan Price concluded that a site-wide scheme using a local electricity network could allow renewable energy to be fed to other buildings. Thus removing the need for export to the grid. This network could either be owned by the local electricity authority or by the Trust.

Broadway Malyan architect Steven Costello, designer for Morn Hill, said that clients should be more aware of the "intangible value" of photovoltaics. "The big corporations know that their net assets are four thousand times what they actually own in terms of capital plant, and the good feeling [a company's] environmental initiatives radiate to the public vastly outweigh the capital cost issues of kit like photovoltaics," he said.

"It is quite wrong for buildings today to be constructed without passive solar elements," he said. "Even if the case for photovoltaics doesn't stack up, the buildings we put up today are going to be standing a long time. I would like to see a planning audit that asks designers to show how pvs might be retrofitted to the buildings they are designing." There was a big debate on the degree to which solar aspect should be maximised to satisfy the effectiveness of photovoltaics, and whether, at the end of the day, the design time could be better spent on better massing, improving ventilation effectiveness and fabric detailing. The bottom line must be that technical solutions, be they photovoltaics or any other, more mainstream, technology, can never be a substitute for an inherently robust energy efficient building.