Types of Property
Many off-grid properties are remote farm houses or cottages which are simply too far from mains utility services for economic grid connection. Some of these may have been unused for many years but are now being renovated for holiday accommodation as part of farm diversification initiatives. Other locations may be holiday lodges, static caravans, stables or even mountain huts
Electricity is the basis for all services including lighting, water disinfection, communications and heating where oil or LPG space and water heating is used. Electrical appliances like washing machines, kettles and toasters, and our computers and mobile technology are essential to our modern lives.
Matching the generation of electricity from renewable sources to the demand for electricity in the property is very difficult without battery storage. There will also be periods when the renewable energy sources are unable to supply sufficient power to meet the demand and a petrol or diesel powered standby generator is required.
Renewable Energy Sources
Solar PV is the most common and also the easiest to install and control. A small wind turbine is often used in conjunction with solar PV. Small scale hydro is best suited to locations where there is almost continuous occupation. Controlling the output of hydro can be more complex when dump loads have to be used to shed unwanted electricity generation when demand is low and the batteries are fully charged.
Storage batteries used in off-grid locations are quite different to those commonly used on our cars and trucks. They are referred to as "deep cycle" batteries and are designed for frequent discharging and recharging on a daily basis. The lifetime of the batteries will depend on the total number of discharge and recharge cycles and the depth to which the battery is discharged on each cycle. The batteries are commonly assembled in series to provide a 24V or 48V bank. Flooded Lead Acid (FLA) batteries are most commonly used. Lithium Ion batteries are so far not generally recommended for off-grid projects.
Batteries store electricity as DC whilst all of the services we want to power require AC. On the load side the inverter creates a local AC "grid" at 230V AC and 50Hz to which all of the services are connected whilst being connected to the battery pack and generator on the other side. The inverter monitors the state of charge of the battery pack and will automatically start and stop the generator as required to prevent the batteries discharging below a pre-set level.
Designing an off-grid system correctly is critical to its success and starts with a detailed electricity demand calculation for the property over a 12 month period. Understanding the 24 hour demand in kWh and the peak demand in kW throughout the year enables us to propose a system with correctly sized and matched batteries, energy sources, generator and inverter. Minimising generator run-time and fuel costs whilst maximising renewable energy generation all within a cost effective budget is our goal on every project.
If you have a property in need of a reliable power supply or an existing off grid installation which requires upgrading or even just some tender loving care to keep it running then call and tell us about it. It's our passion.