We have many enquires come through where customers ask us if it's possible to connect wind turbines to our PV series solar energy storage batteries and which wind turbine controllers are best suited for DCS batteries?
The beautiful thing about the DCS PV series batteries is that they feature a very advanced battery management system (BMS) and you can directly connect a wind turbine to our batteries.
One of our customers (we will call him Doug), recently installed a wind turbine at his property and connected a DCS PV Series battery. We were invited along to see how easy the installation was.
First things first. Doug had to choose which wind turbine to install. After contacting some of the larger local Australian suppliers of 48V nominal wind turbines, Doug was astonished to learn how difficult it was to find the correct information not to mention the ambitious pricing on low wattage 400W, 900W and 1000W turbines. So he purchased an American built and engineered 1.0kW turbine for the same price (even after including the freight costs from the USA) as he could source a 400W turbine from local suppliers.
The important thing for our customers to note here is that it pays to do your research with wind turbines. As they are still a relatively new technology there is a lot of misinformation out there about what you need and don’t need. Be sure to check with your local council for restrictions on placement and wind turbine heights and whether your particular system requires fitting by a qualified electrician or not.
Doug purchased a KT5 48VDC 1kW turbine along with optimised blades for his property, the blades are designed to operate in an area with low/medium wind speed averages of 4.4 to 5.6 m/s and greater (Zone 3-4). This turbine is capable of providing around 189 kWh per month (2,299kWh year) OR 6.3 kWh per day with 5.6 m/s average wind speeds.
Wind Zone 1 - 0.0 ~ 4.4 m/s
Wind Zone 2 - 4.4 ~ 5.1 m/s
Wind Zone 3 - 5.1 ~ 5.6 m/s
Wind Zone 4 - 5.6 ~ 6.0 m/s
Wind Zone 5 - 6.0 ~ 6.4 m/s
Wind Zone 6 - 6.4 ~ 7.0 m/s
Wind Zone 7 - 7.0 ~ 9.4 m/s
Doug informed us that the wind turbine arrived quickly and was easily assembled and he didn't even need to read the instructions, we must admit it’s a very nicely built turbine, stripped of all the bells and whistles to provide the best possible ROI.
All Permanent Magnet Alternators (PMA)'s produce a 3-phase alternating current (AC), you'll note Doug ordered a 48VDC - direct current PMA which means it simply features a device called a rectifier that outputs single phase direct current (DC). This full wave rectified DC is not a clean DC waveform it's known as a wild or modified DC waveform. The DCS BMS boards are designed to handle the charging currents from this type of DC waveform.
Now onto the installation and optimum location for the wind turbine. To achieve the best possible return on the wind turbine it should ideally be installed above the nearest tree line or a good distance away from it to be exposed to non-turbulent winds. Doug picked a suitable location at his site and assembled a 13m mast for the turbine to sit on. From a local steel supplier he purchased 2 x 6.5m lengths of 50mm steel tube (mast), 2 x 1m lengths of U-Channel (footing) and 2 x 600mm lengths of square hollow to use for joining the 2 pipe sections to create one long 13m mast. Other materials included saddles, rivets, 3mm stainless steel rigging wire, turn buckles and eye plates, bolts, washers and locknuts.
First Doug dug a hole deep enough to position the U-Channels as they would form the footing for the mast, and filled this with 80KG of concrete and allowed to settle for the day.
Assembled the mast and drilled and riveted saddles to the mast for the anchoring/stabilisation points. Pulled through a 20m length of twin 6mm DC cable through the mast and assembled the turbine on top of the mast - ready to be winched into place.
The next step was to locate the mast and turbine onto the footing (using a simple pivot pin type bolt, nut and washers) and then used a snatch block and the winch on a 4WD to winch the mast into place.
Once everything was in place it was time to do the connections. What is most important to note is that if you’re going to sustain any damage to any equipment it's going to be during a major storm. During high wind speeds the turbines RPM's can climb very high and get out of control and create very high voltages. So to connect this specific turbine directly to our DCS batteries you must connect a 10Amp circuit breaker. If the voltages from the PMA climb to say 100V x 10A (circuit breaker) = 1kW the circuit breaker would open circuit protecting the batteries. If the batteries reach full charge at any point the BMS will automatically open circuit the batteries to protect the lithium iron phosphate cells should there be no loads on the house.
So like Doug you must have 2 protection devices to protect the DCS batteries during storms and any other equipment connected to them;
1. A 10Amp circuit breaker (note this must be an AC circuit breaker as in this instance we are dealing with a rectified AC waveform from the wind turbine. DC isolators are not going to provide you with any protection).
2. The DCS BMS will always provide protection to under or over voltage situations.
3. Should the above 2 safety mechanisms both fail, the DCS batteries have mechanical fuses between the BMS and lithium battery cell circuits that will open circuit as a last resort to protect the battery cells.
4. Should the lithium cells themselves be subject to extremely high internal pressures due to excessive temperatures such as those that could be exerted on the battery packs when installed in bush fire hazard zones such as BAL-FZ (flame zone). In the event of a engulfing fire the lithium cells will degas and feature a fire retardant electrode and will not physically combust therefore not adding any further fuel to the fire.
After having powered through 2 major storms since the day of commissioning (without tripping the circuit breaker). Doug informs us the wind turbine is averaging between 3-5kWh of power per day, and has been able to make around 8-9kWh on very windy days. He gets asked all the time how noisy the turbine is. He says in fact it’s so quiet that he never hears it. It’s surprisingly quiet even during major wind speeds, it's positioned well above the house so as the blades cut through the air the noise is quickly dissipated before it reaches occupants at ground level.
Combined with the existing 5kW hybrid solar system the wind turbine is a great addition as the sun doesn't shine at night. The overall energy output is a very consistent power source, the nice part is that your wind turbine's will make power all night on those long and cold winter nights and that's when turbines really start adding up the Watts when added to a solar system. It won't take long to get a return on this tidy little setup.