Electricity Supply — October 2005
October 2005 we bought the house knowing that is was that was off-grid and the alternative power supply was totally inadequate and expensive.
When we arrived at the house in October 2005 all its electricity was supplied by a FG Wilson 16.5KVA diesel generator with a Xantrex SW3024e inverter and 24volts of batteries (Exide Classic Solar OPzS rated at 985AH at C120).
There were no meters to tell what power the house was using so having settled into the house and started to think about power that was the first thing we had fitted (December 2005).
Electricity was fed to the house from the batteries through the Xantrex inverter which converted the 24 volts DC from the batteries to 240 volts AC.
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FG Wilson 16.5 kVA diesel generator |
Xantrex SW3024e inverter |
When the batteries became discharged the Xantrex inverter automatically started the diesel engine to recharge the batteries. That cycle repeated indefinitely. The only intervention necessary was keeping the diesel tank filled up and servicing the diesel engine every 500 hours running time.
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| Exide OpZs 24V battery bank | Xantrex SW3024e inverter Change over switch with MCBs and meter above |
With this set-up and dependent on house load, the diesel generator used to run for three periods of about three hours every day — 9 hours a day. That equates to Over 3000 hours a year. A simple calculation shows how very expensive such a regime is. The engine uses ~2 litres of diesel an hour under partial load, that is about 18 litres a day.
Our first 1000 Litres of red diesel we bought in November 2005 cost 36p per litre, £360 to fill the tank. That meant that running the diesel generator was costing ~£6.50 per day and just over £2,300 per year for a very limited amount of electricity. On top of that there was the cost of servicing the diesel generator six and a half times a year. Fast forward to December 2022 and red diesel cost us £1 per litre, a thousand pounds to fill the tank. With the same set up as in 2005 the limited amount of electricity provided would cost £18 per day and over £6,500 per year!
There were a number of problems with this set up. Firstly the Xantrex could only deliver 3KW. All power to the house was through the Xantrex. So, even when the 16.5KW diesel engine generator was running the house could only draw 3KW. Massively inefficient and bad for the engine, it coked up very quickly. Also the nature of the charging cycle for the batteries meant that there were effectively dead after about three years — badly sulphated.
The electricity board said that they would connect us to mains electricity, probably with a with a buried cable running ~2 Km across the marsh from the Acle Straight, for a mere £115,000. They could not use the cheaper solution of an overhead pole run as Halvergate Marsh is a SSSI and a conservation area.
It appeared we had the worst of all possible worlds! Perhaps buying the house wasn't such a good idea but it was too late now. There had to be a better and more cost-effective solution. Something had to be done.