There’s a new video on our channel which follows system designers Off Grid Engineering as they install a 6kW PV ‘Glass Roof’ with 15.36 kWh Lithium storage – and explain their choices.
Interestingly, the overhead power cables of the local electricity grid pass directly over the building site of this new build house, yet the owner – Jim Watt – decided not to connect to the power grid, but to supply his new build house in a Shropshire village, UK, with off-grid electricity.
Close proximity of a power cable doesn’t always mean that connection to the grid will be straightforward or inexpensive. Often in rural locations in the UK there is insufficient capacity to add a new connection to the existing infrastructure – or the transformer is distant and so a cable has to cross someone else’s land, requiring permission, legal agreement and ‘easement’ payments. Cost of connection can escalate to a six-figure sum.
When the quotation for connecting to the national electricity grid takes your breath away it makes it easier to decide to do what you wanted to do all along – go Off-Grid!
Cosmetically Stylish PV roof panels; super-reliable power inverters and chargers; and increasingly durable battery storage technology take all the worry out of that commitment.
Jim plans to use efficient electric domestic appliances – but makes no concessions to the fact he is off-grid: For cooking he uses an Induction Hob; he has an efficient fridge freezer which runs 365 days a year; and his domestic heating is from an Air Source Heat Pump – for every 1kW of electricity it consumes it provides 5kW of heat. Oh, and he has a Hot Tub.
Jim’s installation comprises:
- 22 Veridian roof integrated Solar Panels offering 6kWp
- 2 SmartSolar MPPTs 250/60 maximise the solar harvest
- power is stored in two paralleled BYD Lithium Iron Phosphate batteries with a 48V capacity of 15.36kWh
- Domestic AC power is provided by a Quattro 48/8000/110
- There’s an HRD Generator rated at 4.6kW
- The cross-manufacturer system is controlled, and can be programmed using a Color Control GX
- Off-Grid Engineering can manage and monitor Jim’s system remotely, from Victron’s free-to-use VRM platform
Ian Hewson from Off-Grid Engineering says that in his experience the back up generator will typically be used to provide less than 5% of domestic electricity use …and certainly less that 10%.
In Jim Watt’s installation the generator has been programmed (via the Color Control GX) to start automatically if the battery state-of-charge falls to 20%. The generator will then run until the state-of-charge has reached 45%, when it will stop. A welcome refinement prohibits an automatic generator start from occurring during Jim’s user-defined ‘quiet period’ – overnight.
Another automatic setting has been programmed to conserve stored energy: If ever Jim’s domestic power demand exceeds 5kW for a period of more than twenty seconds the generator will start automatically, and run until the power demand has fallen to below 3.5kW.
Let’s watch the video and see how it all comes together.