It has been 1 month since I had 12 solar panels installed on my house in West Sussex. After receiving various quotes and generation projections from different installers, I decided to share my experience and discuss the returns I am seeing so far.
13 months ago, after the UK government removed VAT from solar installations, I signed up with E.on Solar for an installation of 12 solar panels on my south-facing roof. Using E.on was a bad choice though — I waited 11 months with no progress, and evenutally cancelled the order in March.
I then signed up with a local solar company, who set up the survey, and the panels & battery were installed within a month.
The actual installation took about 5 hours. The scaffolding was put up the day before, and taken down a few days later, all very straightforward.
My solar system consists of:
- 12x 390W JA Solar panels
- Solis 6kWp inverter
- Pylontech US5000 4.8kWh battery
It’s still early days, but everything seems to be running smoothly.
The SolisCloud app is ok for monitoring the system, but you can’t change any settings for the inverter within the app. Also the monitoring data updates only every 5mins which is a little slow for a data geek!
In one month (5 April–4 May 2023), the 12 panels generated 482 kWh of power, resulting in £153 savings on my current Octopus Energy tariff. Not too bad for one quite cloudy month.
The battery has been crucial in maximising utilization, storing and discharging 97.4 kWh of solar-only electricity. Coupled with the off-peak savings gained by topping it up overnight on Octopus Go, we’ve saved about £70 purely from having the battery on the system.
With 2 people working from home full time, 2 EVs, and an air source heat pump, our electricity usage is high.
I don’t have a solar wall charger (like the Zappi) for the cars, and I’m not sure it would be a worthwhile investment as it seems there would only be enough excess solar to make it worthwhile in summer. However I have topped up roughly 50 miles of fuel for the cars just through plugging in a granny cable on sunny days.
I opted out of installing an iBoost+ to use excess solar to heat our water tank, as I thought it would take too long get the £500 back in savings.
Even with our high usage, on the best day so far (26kWh) we still exported 3.3kWh to the grid after topping up the car, heating the immersion tank and running the washing machine a few times.
Return on Investment
Using the HomeAnalytics project, I set up a Python script that pulls daily generation data from the Solis Cloud API, and uploads them to BigQuery so I can use Looker Studio to analyze how the system is performing.
As the screengrab shows below, the savings so far have been pretty decent despite inconsistent weather:
I am already thinking about getting another battery — the Pylontech batteries are modular, so it’s easy to add capacity. Assuming savings of ~£50 p/m, a 4.8kWh battery would pay for itself in less than 3 years on today’s energy prices which is pretty decent.
Now that HomeAnalytics is humming along nicely picking up the daily stats (and adding current solar generation to my Pi display), I’m thinking of building my own DIY iBoost+, to hit the ‘Heat now’ button on the Ecodan heat pump whenever there’s excess solar.