Building integrated photovoltaics | Archive Titles

Table 1: PV technology guide
	Hybrid (mix of monocrystalline & amorphous)	Monocrystalline	Standard polycrystalline	Silicon film & ribbon polycrystalline	Thin film amorphous
Typical applications	Modules, especially where space is limited.	Modules, rain screen cladding. Also laminated in glass.	Modules, tiles,slates. Also laminated in glass.	Facades, decorative cladding.	Modules, rain screen, tiles, slates, large roof areas or facades.
Conversion efficiency at standard test conditions*	17% to 18.5%	14% to 16%	11% to 13%	9% to 10%	7% to 8%
Area needed (m²) per kWp in UK	6·5 to 7	8 to 10	11	12	15 to 18
Performance in low or diffuse light conditions	Excellent	Good	Good	Very good	Excellent
***Installed cost £/kWp	5000 to 8000	5000 to 13000	5000 to 13000	5000 to 8000	4000 to 8000
***Installed cost £/m²	850 to 1250	850 to 1300	500 to 1200	500 to 700	300 to 450
**Approximate annual BIPV energy generated (kWh/m²)	120 to 130	75 to 90	65 to 70	65	50 to 60
Value of annual BIPV generation (£/m² @ 5p/kWh)	6 to 6·5	3·75 to 4·5	3·25 to 3·5	3·25	2·5 to 3
**Approximate CO₂ savings Kg/m²/year	84 to 91	53 to 63	46 to 49	46	35 to 39
Environmental impact – embodied energy payback period (years)	Approximately 4	4 to 5	Approximately 4	2 to 3	0·5 to 2
*Standard test conditions are: 25°C, light intensity 1000 W/m²
**Estimates based on south-facing installation inclined at 30° to the horizontal.
***Cost varies widely according to application and installation size. Mass produced modules cost the least, and bespoke laminated glazing the most. Tiles and slates come in between the two extremes, and overall system costs may be reduced depending on any offset due to conventional materials displacement. Economies of scale are generally achieved above 5 kWp.

Table 2: BIPV project costs
Total Capital cost of pv installation	£361 000
Total cost per m²	£241
Total cost per kWp	£3540
DTI grant	£270 000
Operation and maintenance (estimated at £5 per kWp)	£500 pa
Project costs breakdown
PV panels	£238 260
Inverters	£28 880
Cabling, connections, switchgear	£18 050
Framing for pv panels	£21 660
Installation	£54 150
Project savings
Value of energy generated (80 MWh * 5p/kWh)	£4000 pa
Value of savings through awareness (5% of total)	£150 pa
Value of ROCs, sold to electricity supplier	£4000 pa
CO₂ saved by bipv generation	56 tonnes pa
Note: excludes inflation beyond third quarter 2002; incoming mains electrical service; builder’s work in connection with services; main contractor’s overheads; profit and attendances; main contract preliminaries; professional and prescribed fees; contingencies and design reserve; tax allowances and vat.