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Off-grid case history

Today’s Installation Cost £46,000+vat (excluding existing wind turbine, 4kw tracker and diesel generator)
Property Type South Cheshire family farm not connected to the grid (Off-Grid)
Installation Type  10Kw Solar PV and 33.6kWh Battery Storage
Location South Cheshire
Installation Date Nov-2015
Equipment New PV : Solar World 38 x 270w Mono Panels, 2 SMA 5000TL inverters, 2 x SMA Sunny Island SI 8.0 battery inverters, Sunny Webbox, Sunny Remote Control, Load shedding contactor, invertor by-pass switch, 9kw Proportional power dump controller, 28 x 1.2kw Sony Olivine batteries, 2 x Sony BMU’s, 1 Sony Comm’s Hub


This was an unusual case where an existing undersized, failing 8 year old Off-Grid system with 18kwh Lead acid batteries, existing 6kw Proven wind turbine, 4kw PV tracker and16kw generator. All needed rethinking and upgrading. With an average daily 20kwh load and failing lead acid batteries the diesel generator was costing a small fortune to run.

The owners wanted a long term 20 year solution that would meet the majority of their electrical loads from renewable energy (PV & Wind) with minimal use of their diesel generator.

System Specification

Sony LiFePO4 Olivine batteries were chosen for their market leading reliability, 20 year+ service life, deep depth of discharge and fast charging abilities to capture Renewable energy from the existing 6kw WT, 4kw Tracker and new 10kw roof mounted PV when it was available. To meet farm loads two new Sunny Islands giving a constant 12kw load ability were selected along with full Sunny Portal on-line monitoring. To make use of surplus Renewable energy after the batteries were charged and farm loads met the UK’s first Off-Grid Proportional Power dump to a large an existing thermal store was brought in from Germany. Although the system was complex to set up it is proving to be simple to run and monitor.


The customer now has a state of the art system that is already demonstrating its reliability, ease of use, minimum diesel generator run time and no power cuts. FIT income will help pay for the system along with savings on diesel costs.

Both we and the customer can monitor the system on-line 24/7and look for more ways to utilize useful free summer excess solar power while being comfortable that power will always be available when its needed.

10kw Solar Pv