Windsor Road, Swindon

Solar Together installation, PV with 3kWh battery, December 2022. Six 390W panels facing south-west, 3 facing south-east. The chart (second picture) shows the performance over the first full year.

Our Energy Supply: 

• Central heating and hot water is GAS (two-thirds of total energy consumption)
• ELECTRICITY used for cooking, appliances, auxiliary heating, lighting, etc.

Scheme Used: Solar Together (https://solartogether.co.uk)

ST work with Local Authorities (LAs), who surveys residents and collect names.

Then ST:

• carry out an initial consultation for each customer
• carry out a tender exercise to find a suitable supplier
• negotiate bulk purchase of equipment (savings) => lower cost to customer
• oversee the proces

Then selected installer carries out installation and commissions system.

Installer Used: Infinity Renewables (https://infinity-renewables.com). Handover pack supplied on completion.

Export Tariff: 

Your electricity company should have an export tariff – this will be much lower per kWh than the price at which you buy (e.g. 12p vs. 30p).  

Equipment: 

Panels: JA Solar (Japan) (https://www.jasolar.com/html/en/)

• 9 x 390W (products will be different now)
• 3 on SE-facing roof slope, 6 on SW

Inverter & Battery: Growatt (China) (https://www.ginverter.com)

• Battery 3 kWh
• Inverter SPH 3000-6000TL BL-UP – 3-6 kW

Cost: £11.3k including installation.

Return visits were made later to install:

• bird netting around panels (to stop nesting underneath)
• emergency power sockets (intended to supply power from solar units if the main grid fails)

 Performance - Good.

Generated (first year): approx 2,500 kWh = approx the same as our annual electricity usage

Owing to seasonality (more generated in summer, when usage is lower) we only used about 50% of this, and exported the rest.

Therefore our electricity consumption from the grid fell by half.

We have tried to use more electricity when available, e.g. using dishwasher rather than hot water (gas), and (in spring and autumn) using auxiliary electrical heating with central heating turned down.

Estimated Savings

• reduced electricity consumption
• income from exported electricity
• slightly reduced gas use

Total for first year about £660

At this rate the payback time will be about 17 y – although energy prices are likely to rise over time, making the payback time shorter.

CO2e saving in first y: about 280 kg.

 Tips

• Look for an energy supplier who offers a good feed-in price
• If you have a hot water tank or electric car, surplus solar can increase your savings
• if you have an old gas boiler, consider replacing it with a new one – savings can be significant.