Compare Technologies

Sustainable Homes Info

A quick reference overview of all the renewable technologies that we offer.

For more detailed information on a given technology please click on the links in the top row and you will be taken to the relevant section of our website.

	Solar PV (electricity)	Solar Thermal (hot water)	Heat Pumps (ground source and air source)	Biomass	Micro Combined Heat and Power (Micro-CHP)
Type of energy produced	Electricity	Heat	Heat	Heat	Heat and Electricity
Headlines!	Typically provides 65% of domestic electricity consumption. 10% plus returns on investment available over 25 years, thanks to the Feed-In Tariff. Save up to 2 tonnes of CO₂ on a standard domestic install. More on a large commercial install. Non-domestic installs: Loans available to make the investment entirely self-financing.	Provides up to 60% of hot water requirement. Fantastic investment for non-domestic installs, achieving financial savings in the thousands every year. Return on Investment of 15% plus with the Renewable Heat Incentive Makes total financial sense for swimming pools. Not so lucrative for standard domestic installations. Phase II of the RHI in October 2012 could make it more worthwhile.	Provides 100% of hot water and space heating requirement. A must have for every new build, as it will be much cheaper to run than oil or gas. Also no new properties on mains gas can be built from 2016. Big CO₂savings Big financial savings also available if retro-fitting to houses using either oil or electric storage heaters.	Provides 100% of hot water and space heating requirement. Significantly lower cost per kWh than oil or gas (about half the cost of oil). Also no new properties on mains gas can be built from 2016 Big CO₂savings Big financial savings also available if retro-fitting to houses using either oil or electric storage heaters. Easier to retro-fit than a heat pump because heat distribution system won't need to be upgraded.	Provides 100% of space heating and hot water and up to 30-40% of electricity as well. Feed-in Tariff payable in respect of electricity. 8% return on investment when compared to standard boiler replacement.
How does the technology work?	Light energy hits solar panels and creates a direct current. This is converted to alternating current by an inverter.	Solar energy is absorbed by a solar collector and used to heat a fluid. Heat energy is transferred via a heat exchanger to the hot water tank.	Heat pumps draw heat from outside (air or ground), boost the temperature by compression and release the heat into the property (either into the air or into the water based heating system).	Biomass boilers: Like a conventional boiler except it runs on biomass fuel, usually wood pellets, wood chips or logs. Can run on agricultural, industrial or food waste. Biomass stoves are also available, used to heat a single room.	Waste heat produced from the gas boiler is used to drive a turbine to generate electricity.
Typical application	Provides approx 65% of typical home's electricity requirement. No storage of electricity in most cases so house is a net exporter of electricity to grid in summer and net importer in winter. Works well with a heat pump as it will provide a % of the electricity required to run the pump.	Usually used to provide hot water, but can also be used for space heating. Typically provides around 60% of annual hot water requirement (30% in winter, 95% in summer).	Can provide 100% of the space heating AND hot water requirement. Can be combined with another heat source eg Solar hot water, PV Thermal or a boiler (oil/gas-fired or biomass).	Can provide 100% of the space heating AND hot water requirement. Can be combined with another heat source e.g. Solar hot water.	Provides 100% of the space heating and hot water requirement. Produces electricity as a by-product this can be used around the house or exported back to the grid.
kWh produced per annum	Produces around 800kWh per kWp installed capacity. 4kWp domestic system typically produces 3200kWh a year. 50kWp commercial system produces around 40,000kWh a year.	Each 10 tube collector produces around produces around 700kWh of heat energy a year so a typical 30 tube system will produce about 2100kWh a year.	A heat pump for a large 4-5 bedrooms home will output around 30,000kWh of heat energy. It will use around 9000kWh of electricity. So the 'net output' is about 21000kWh.	A biomass boiler for a large 4-5 bedroom home will output around 30,000kWh of heat energy.	Production is highly dependent on how the system is run and controlled by the homeowner. Typically produces at least 15,000-20,000kWh of heat energy each year. The annual electricity production would be between 2,000-3,000kWh.
Main system components	An array of 5 or more 250W PV panels mounted on the roof (or on a ground mount) and an inverter, to convert d.c. electricity to a.c. Output is measured by a generation meter.	A minimum of one or two flat plate or vacuum tube collectors mounted on the roof (or on a ground mount). Pump and pipework to transfer heat to a solar cylinder.	Heat pump, usually mounted on an external wall (air source) or extracting heat from the ground (ground source). Usually requires a special / enlarged cylinder. 'Retro-fits' may require enlarged radiators.	A biomass boiler or stove. Accessories include a hopper / storage silo for the fuel, a buffer tank or thermal store, and a chimney lining or new stainless steel flue.	Boiler, similar to standard gas boiler.
Which properties work best?	Work best on south facing unshaded sloping roof. But any orientation from east through south to west will work well, as will flat roofs. Can be ground mounted if sufficient unshaded space available. Grid connected systems are cheapest as they don't require batteries.	Work best on south facing unshaded sloping roof. But any orientation from east through south to west will work well, as will flat roofs. Can be ground mounted if sufficient unshaded space available.	Great for new builds and renovations. Can be retro-fitted to well insulated (post 1980s) properties. Great savings when replacing oil-fired boilers. Heat pumps produce 'low temperature' heat and therefore work best with low temperature heat distribution systems i.e. underfloor heating. Also need good insulation to limit heat loss.	Works very well on new builds or to replace expensive oil fired systems. Better than a heat pump on retro-fits as the heat distribution system won't need to be upgraded. Works particularly well if there is a cheap source of fuel nearby - e.g. wood pellets or logs.	Best suited to larger, older properties. Or locations with significant and consistent heating and hot water demand The units are small and can often fit in the space vacated by existing boilers.
Planning requirements	Planning unlikely to be required for domestic systems on a sloping roof, unless the building is listed or in a World Heritage area. All non-domestic systems and all domestic systems on a flat roof require planning.	Planning unlikely to be required for domestic systems on a sloping roof, unless the building is listed or in a World Heritage area. All non-domestic systems and all domestic systems on a flat roof require planning.	Planning not usually required for domestic ground source heat pump (except for listed buildings or properties in conservation areas). The installation of a SINGLE air source heat pump on domestic property does not require planning, provided ALL the limits and conditions listed on this link are met. Primarily pump unit must be more than 1m from any boundary and the compressor unit must have a volume less than 0.6m3. Must not be wall mounted above ground storey level, or on a wall that fronts a highway.	Planning permission is not normally needed when installing a biomass system in a house if the work is all internal. If the installation requires a flue outside, however, it will normally be permitted development if it is on the rear or side elevation of the building and not more than 1 metre above the highest point of the roof. Check if it's a listed building or in a World Heritage Site or conservation area.	There are no planning obstacles to overcome as the units are wall-mounted in domestic properties or installed in adjacent garages.
Key project hurdles / timescale	Standard domestic (<4kWp) installs have a 4-6 week lead time and take 2-3 days to install. Roof mounted systems need a structural survey. Roof may need strengthening. For large domestic and non-domestic installs: If planning required, allow 10-11 weeks (see above). Systems over 3.68kWp need an application to connect to the grid prior to installation. Allow 6 weeks. Roof mounted systems need a structural survey. Roof may need strengthening.	Standard domestic installs have a 4-6 week lead time and take 2-3 days to install. For large domestic and non-domestic installs: If planning required, allow 10-11 weeks (see above). Roof mounted systems need a structural survey. Roof may need strengthening.	As long as planning permission not required, lead time is 4-6 weeks. Typical domestic install takes a week. Upgrade of the heat distribution system, for example with the installation of underfloor heating, may increase installation time and extend the project duration.	Lead time is 4-6 weeks. Typical domestic install takes a week. The addition of a fuel store or boiler house will also add to the installation time.	We can usually arrange for a installation within two weeks from the order being placed. We understand that boiler replacement is sometimes an expected necessity. For urgent cases (especially in the winter months) we may be able to get the unit installed and running within 4days of confirmed order.
Cost	Systems start from £6000. Typical domestic system prices are £2500 - £3000 per kWp, falling to £1750 per kWp for larger non domestic systems.	Domestic systems cost between £4000 and £7000. Good economies of scale on larger systems.	Domestic systems typically cost between £9000 and £14000 for the heat pump and cylinder. There may be an additional cost on 'retro-fit' installations for upgrades to the heat distribution system (radiators).	Domestic biomass boiler systems typically cost between £11,000 and £14,000 for the complete installation including flue/ chimney lining. Standalone pellet stoves are typically around £4,500 including installation and flue.	A simple installation, which does not need any accompanying plumbing upgrades, will start from £7,500.
Carbon Savings (CO₂emissions cut per annum)	0.45 tonnes / kWp installed (1.8 tonnes for a 4kWp system on a south facing roof).	Typical domestic system replacing heat from oil fired boiler saves 0.5 tonnes a year.	Domestic system saves 2-4 tonnes of CO₂ per year if replacing oil. 1 tonne saving if replacing gas. These are 'net' savings, taking account of the emissions produced by the electricity used to run the pump. If this electricity comes from PV the savings will be much bigger.	Domestic system saves 3 tonnes of CO2 per year if replacing gas, more if replacing LPG or oil. Up to 7.5 tonnes per year if replacing electricity.	The amount of carbon savings depends largely on how the system is run and how much electricity demand is displaced. As a rough comparison. Micro-CHP units produce 0.8 fewer tonnes of CO₂ than the Band-A efficiency standard boilers.
Subsidies available	Feed-in Tariff payments Dependent on system size. Tariff payable: max 21p per kWh on a sub-4kWp system, falling to 8.5p per kWh on large systems. Payable for 25 years after installation. Inflation linked.	Renewable Heat Incentive Domestic systems: £300 upfront RHP payment for installations Subsidy per kWh expected but not confirmed from Oct 2012 Commercial systems: Inflation linked tariff of 8.5p per kWh payable for every kWth generated by the system for 20 years. This was introduced in Nov 2011.	Renewable Heat Incentive Domestic systems: £850 upfront RHP payment for installations prior to March 31st 2012 in properties without a mains gas connection. Subsidy of 7.5p per kWh expected but not confirmed from Oct 2012 Commercial systems: Ground source: Inflation linked tariff of 3.2p-4.5p per kWh payable for every kWth generated by the system. This was introduced in Nov 2011. Air source: Subsidy of 7.5p per kWh expected but not confirmed from Oct 2012	Renewable Heat Incentive Domestic systems: £950 upfront RHP payment for installations prior to March 31st 2012 in properties without a mains gas connection. Subsidy of 9.0p per kWh expected but not confirmed from Oct 2012 Commercial systems: Inflation linked tariff of 1.9p-7.6p per kWth payable for every kWth generated by the system. Tariff is tiered to avoid excessive/wasteful heat generation. This was introduced in Nov 2011	Feed-in Tariff payments For domestic systems the current feed-in-tariff rate is 11p per kWh of electricity produced. With an additional export income of 3.1p per kWh produced. (Deemed at 50% of electricity production.) A recent government review highlighted the potential of CHP technology. The rate is therefore due to rise to 12.5p per kWh of electricity in October 2012. Export rates to stay the same.
Expected life of technology / guarantees	Expected life: 25 years Defects warranty of 5-10 years on panels and inverters. Performance warranty of 25 years on panels, guaranteeing they will produce at least 80% of year one output after 25 years.	Expected life: 25 years Defects warranty of up to 20 years on collectors and cylinders, depending on manufacturer.	Expected life: 20 years Defects warranty of 3-5 years on most heat pump units.	Expected life: 15 years plus Defects warranty typically 5 years.	Expected life: 15 years plus The expected life is roughly the same as traditional boilers. Its productive life can be prolonged with professional servicing.
Analysis of financial benefits Fuel savings Subsidies	See Guide Prices and Returns for PV Three sources of financial benefit: Generation tariff - Feed in Tariff payable per kWh produced (see above) Fuel savings ‐ each unit used (about 50% of what is produced) being worth around 15p per kWh (i.e. current average cost of electricity) Export tariff - each unit not used (about 50% of what is produced) is exported back to the grid, attracting a further payment of 3.1p per kWh.	Two sources of financial benefit: Fuel savings - each unit produced being around 9p, depending on the fuel replaced and the efficiency of the boiler. Renewable Heat Incentive - payable per kWh produced (see above). Already available at 8.5p per kWh for 20 years for Non-Domestic installations. We expect it will be rolled out to domestic installations in October 2012.	See Guide Prices and Returns for Heat Pumps Two sources of financial benefit: Fuel savings - each unit produced being around 9p, depending on the fuel replaced and the efficiency of the boiler. Renewable Heat Incentive - payable per kWh produced (see above). Already available at 8.5p per kWh for 20 years for Non-Domestic installations. We expect it will be rolled out to domestic installations in October 2012.	Two sources of financial benefit: Fuel savings - each unit produced being around 8.5p, depending on the fuel replaced and the efficiency of the boiler. Renewable Heat Incentive - payable per kWh produced (see above). Already available at 7.6p per kWh for 20 years for Non-Domestic installations. We expect it will be rolled out to domestic installations in October 2012.	Heat energy produced has similar cost to conventional gas boiler. In addition produce FREE electricity which attracts a Feed-in Tariff and Export Tariff.
Typical Return on Investment	Typical IRR over 25 years of 10% plus. Note Feed-in tariff income is inflation linked and non-taxable for individuals.	Non domestic installs: Typical IRR over 20 years of 14% plus. Less lucrative for domestic installs.	Typical IRR of 10% plus over 20 years, even before the Renewable Heat Incentive.	Typical IRR of 10% plus.	If replacing an efficient and well-functioning boiler the IRR would only be around 4%. If the unit is being installed in place of a new boiler. The IRR on the additional expenditure over the base cost of boiler replacement is around 8%.
Funding availability	Yes for non-domestic installations. We work with a partner providing loans / leases for up to 15 years for schools, farms, public sector organisations and businesses with a trading history of more than 3 years. All technologies are self-financing with the savings / cashflows from the technology being sufficient to pay off the loan in full.	Yes for non-domestic installations. We work with a partner providing loans / leases for up to 15 years for schools, farms, public sector organisations and businesses with a trading history of more than 3 years. All technologies are self-financing with the savings / cashflows from the technology being sufficient to pay off the loan in full.	Yes for non-domestic installations. We work with a partner providing loans / leases for up to 15 years for schools, farms, public sector organisations and businesses with a trading history of more than 3 years. All technologies are self-financing with the savings / cashflows from the technology being sufficient to pay off the loan in full.	Yes for non-domestic installations. We work with a partner providing loans / leases for up to 15 years for schools, farms, public sector organisations and businesses with a trading history of more than 3 years. All technologies are self-financing with the savings / cashflows from the technology being sufficient to pay off the loan in full.	Yes for non-domestic installations. We work with a partner providing loans / leases for up to 15 years for schools, farms, public sector organisations and businesses with a trading history of more than 3 years. All technologies are self-financing with the savings / cashflows from the technology being sufficient to pay off the loan in full.