If you want to rely on an off-grid power system working 24/7 whatever the weather then selecting the right components is key. Quality is king - there's no room for cost cutting. Here are some of the common mistakes we've seen.
Solar PV
The cheaper production methods of polycrystalline solar panels mean that these are often selected over monocrystalline as they are a cheaper alternative. But in small off-grid power systems where space is limited we recommend monocrystalline panels.
They have the highest efficiency rates because they are made out of the highest-grade silicon. Efficiency rates for monocrystalline panels are typically 15-20% compared to 13-16% for polycrystalline. The monocrystalline solar panels provide higher output at low light levels such as during light cloud cover or at both ends of the day. They also perform better at higher temperatures and bearing in mind the dark surface of panel can easily get to >50oC during a sunny day this is an important consideration.
Batteries
The daily rhythm of charge during the day and discharge at night means that deep-cycle batteries are a must. A deep-cycle battery is designed to discharge between 45% and 75% of its capacity depending on the manufacturer and the construction of the battery; generally lead acid batteries are the most cost effective with industrial grade deep cycle batteries from companies such as Trojan or Rolls being popular.
It is important to size up the battery bank correctly. Although deep cycle batteries can be discharged by 80% of their rated capacity (80% Depth Of Discharge) a system that is designed for less than 50% gives a much longer overall battery life.
Overcharging a battery raises the temperature of the electrolyte causing excessive gassing loss of distilled water and eventually damage to the plates. Consequently use of a suitable charge regulator such as our DL-300 or the Tristar 45a Diversion Charge Controller is necessary to limit the charging current as the battery voltage rises. Conversely excessive discharge of a battery can also lead to permanent damage.
Wind turbine
Cheap Chinese turbines have flooded the market in recent years but generally speaking they don't stand the test of time. It's not unusual for us to hear stories of Chinese turbines literally falling to pieces within a few years. Our wind turbines are precision engineered and manufactured in the UK to the ISO 9001:2008 quality standard and come with a design life of 20 years. The tail fin on the upwind LE-300 is integral to the aluminium chassis the blades are made from tried and tested glass-reinforced nylon.
A small wind turbine on an off-grid system is often required to provide power in the winter months when solar PV is at its weakest. It also helps with the life span of your deep cycle batteries as the 24/7 availability of the wind makes your batteries less liable to the daily charge / discharge pattern of solar PV only systems. Of course a wind turbine is a mechanical beast that could potentially be spinning 24 hours a day 7 days a week so it's important that a high quality wind turbine such as our range is employed in your off-grid system.
If you are looking for an off-grid power system that you can rely on 24/7 to generate power then contact us.
