Commonly asked questions

Who should consider a wind turbine or PowerCrate?

Anyone in rural New Zealand who has poor energy security, in particular those who live in a moderately windy site and:

a. who want to live off-grid.
b. for whom establishing a grid connection is impossible or too costly (e.g. >$45,000)
c. for whom current electricity quality is poor or supply is insecure.
d. who may have solar panels but still find a strong undesirable reliance on diesel in the winter.
e. who put a premium on independent energy security.

How much energy is generated?

Our electricity is generated from wind only (Thinair™ 102 turbine) or from wind and sun (PowerCrate®). The power generated by the wind turbine is location specific. While rated at 2kW, the annual energy generated depends on the local capacity factor (CF). The power generated at any instant depends strongly on wind speed and wind velocity is stochastic. The CF is a location dependent scaling factor that captures the average availability of a resource over time. When multiplied by the rated power one gets the expected power generated in any location. For reasonable locations in NZ the CF for wind can vary from 0.09 to 0.35.

Similarly photovoltaic panels even when ideally oriented cannot always produce at their peak power (because of night and overcast days). Solar capacity factors generally increase from south to north but are dependent on cloud cover. Typical ranges in NZ are 0.12 to 0.16.

For a 2kW turbine at 0.15 CF annual power production would be:
8760 x 2 x 0.15 = 2628 kWh per annum
For a 4kWp PV panels at 0.15 CF annual power production would be:
8760 x 4 x 0.15 x 5256 kWh per annum

So a PowerCrate operating with CF=0.15 would be capable of 7884 kWh per annum. The lower bound energy generation would be 5,800 kWh and up to 11,700 kwh is conceivable.

An average house in NZ requires ~ 7260 kWh per annum. Whether supply meets demand requires a more detailed calculation to forecast daily generation vs daily load across all seasons and ideally using a wind dataset from measurement or modelling. Daily load can be estimated from power bills. We discuss the generation calculation in more detail below.

We won’t be connected to the grid. How much power is generated by wind v solar? Which one is better?

We prefer to think of wind and solar as complementary generation assets. By having diverse generation you are boosting energy security while lessening your reliance on diesel. There is a mild counter-correlation between solar and wind . The wind turbine can continue to generate on overcast days and in the night. The wind turbine is also able to generate energy on a smaller areal footprint.

To estimate resources in your area  we use the wind record from NIWA climate stations to get a fair prediction where possible. When there isn’t a data record, as is the case for many rural regions, we use the Global Wind Atlas. Similarly, one can also estimate local insolation using NIWA’s Solarview calculator.

Estimate of wind resources in Waimakariri basin using Global Wind Atlas:

What is best for me? Wind turbine or PowerCrate?

The Thinair wind turbine was built in order to give rural NZ another generation option. It is, however, only a single component of a comprehensive and diverse off grid energy strategy. The PowerCrate on the other hand is a complete system containing all the necessary components for “plug and play” power . It offers diverse energy harvesting with both PV panels and wind turbine, but removes much of the stress of integrating a patchwork of parts.

If you already have solar panels but want to increase the diversity of energy generation, a Thinair turbine may be a good option. It is best suited for off-grid systems but needs a battery to store the intermittent energy.

If you simply want no fuss power, especially for a new house build, or remote projects, consider the PowerCrate which contains all the needed equipment including the pre-mounted wind turbine.
What are the benefits of a PowerCrate versus one of your single turbines?

The table below highlights some of the key differences. The Thin Air turbine is a single component and costs less than the PowerCrate complete renewable energy system. However, PowerCrate generates at 6kWp versus 2kW for a single turbine. Importantly the PowerCrate contains all necessary components making installation a snap. Its simply deliver and deploy – typically a 2-3hr process. This “time saving” also transfers to the planning and consenting process. If PowerCrate does not suit your needs we can remove it or we can reposition it. This is not possible with a single turbine.

Comparison of PowerCrate and Thin Air features:

	Thinair 102	PowerCrate
Specs & Features
Power	2kW rated wind only	6kW rated •2kW wind •4kW solar
Batteries	no	28kWh
Inverters	no	10kW
Charge controllers	yes	yes
Turbine controller	yes	yes
Integrated  data display	no	Web interface and physical touchscreen
Cost	~$20k	~$85k
User Preparations
Planning	Integration consultation and project management	“Plug and play”
Site Prep	Levelled concrete pad (12 sqm footprint, 3.2 cu m of concrete)	Level ground (32.5 sqm footprint)
Cabling	Trenched cable to user’s controller/battery enclosure	Trenched cable to house
Deployment time	1-2 days	2-3 hrs
Consent risks	Permanent	Easily relocated

 

Can I order a wind turbine or PowerCrate now?

We will not be selling  single turbines separately in 2023. PowerCrate is, however, available now, with a lead time of approximately 2 months.

Do you rent PowerCrates?

If you are interested in renting a PowerCrate, please call us to discuss possibilities.

How are PowerCrates or turbines delivered?

PowerCrates are shipped as a fully contained unit (20 ft container form) and once sited the solar panels are folded out and the turbine is folded up.

Currently nationwide transport of PowerCrates is by a curtain side truck with the last miles delivery by HIAB trucks (flatbeds with a crane). The PowerCrate frame has also forklift holes if this preferred for loading or unloading.
The turbine and tower segments are lighter structures that are delivered by standard freight.

Can PowerCrates be customised?

PowerCrates for residential use are not typically customised, except for options for battery storage capacity.

PowerCrates may be customised for commercial clients to meet industry requirements. For example telecommunications companies will already have an industry standard for their hardware or may require N+1 redundancy . In this case we can work with other energy storage module suppliers to provide options.

Will the wind turbine (by itself or on the PowerCrate) stand up to the high winds in our vicinity?

Yes. It is designed for very high wind speeds. The turbine revolves on its main tower bearing so that its hub is always downwind of the approaching wind (see Thinair for imagery). It cuts in at about 2.5 m/s and cuts out at 18 m/s. It will furl automatically on its patented teetering hub to horizontal, protecting the blade from high wind. The tower itself has been designed to withstand winds in excess of 60 m/s (216 km/h).

What is the warranty period for the equipment?

We currently use high quality lithium iron phosphate batteries and Victron inverter technology. The batteries and inverters in our system have a 5 year warranty. The solar panels have a 12 year warranty. The turbine has a 3 year warranty although we expect its life time to be 15-20 years. Powerhouse Wind will comply with requirements of the 1993 Consumer Guarantees Act.

Do I have visibility of the system performance?

For the PowerCrate (only) we currently use the Victron web application to give the consumer a graphical display of real time performance as well as the ability to access historical data. At Powerhouse Wind we can also monitor the system performance and be proactive in the rare event that we see anomalous performance. The electronics enclosure also has a physical touchscreen interface.

We already have, or want to have, solar panels on the roof of the house. Can we still install a wind turbine?

Yes. It is always possible to integrate a wind turbine with existing installations however this may require extra cost, design and field work to connect a wind turbine to what might be a patchwork of hardware.

We recommend contacting us for options as early as possible in your planning process. Note that the Thinair turbine will not be available separately until mid-2024.

Is there a diesel or petrol generator option available?

Solar and wind power generation is weather dependent and so it is always advisable to have a standby generator to maximise energy security. Key is optimising a system so that diesel usage and required battery capacity are minimized. Sometimes clients have their own generator already. In other cases you may want us to configure a generator for you.

The price estimate for a 6 kW diesel generator with autonomous start is ~$10,000. It is possible to have a manual start generator but we feel a generator under the control of the inverter is ideal. Petrol generators are typically cheaper for the same kW rating. However, generally the diesel generator is considered more robust and has better long-term reliability and efficiency. Diesel works out cheaper than petrol (on a $/kWhr produced) because of both the efficiency of the generator and lack of fuel excise tax. In the long run the increased reliability and lower operational costs will likely trump the initial low capital cost of the petrol generator.

Diesel is also a much safer fuel to handle and is difficult to combust (e.g diesel engines utilize compression ignition as diesel cannot be ignited by a spark). Gasoline is extremely volatile and flammable. Regarding flammability, the HSNO hazard classifications are 3.1D (low hazard) for diesel and 3.1A (very high hazard) for gasoline. Because of this hazard we do not have a petrol generator option and we recommend a diesel generator from the point of view of safety and operational costs.

What does it cost to increase the battery bank?

Our standard configuration has a 28 kWh battery bank which provides 1.5 to 2 days of energy security. We use  lithium iron phosphate batteries from EV-Lution. Currently prices are ~$NZ 700/kWh upgrade.

Do we need to get consent to install a PowerCrate or Turbine?

This will depend on your particular district. Typically building consent may require adhesion to the “45 degree” rule requiring the turbine to be set back at least 8m from any fence.

Every district will have a resource management plan with strict noise limits within a “notional boundary” typically 20m around any dwelling place. This treats the dwelling place and anything within notional boundaries as a residential space with regard to noise.

How far from the house should the turbine/PowerCrate be?

Typically for unimpeded access and streamlined deployment we would suggest at least 20m (note: the wind turbine hub is approximately 10.4m high).

What noise do you get from the turbine?

Noise from the spinning turbine is quite low and some have compared it to the noise of a heat pump outside fan. Unlike such a fan however the turbine blade is responding to the wind speed and so the noise while low also changes depending on the angular velocity and during cut-in/cut-out. It’s difficult to measure in the field because its level is often comparable to the wind and other ambient noise. From lived experience and client reports, a turbine 15m from the house, is heard usually only in low to moderate winds when the hum from the alternator becomes audible. In higher winds, the noise from the wind or trees is louder than the machine, so it is harder to discern.

Does the PowerCrate or turbine require maintenance? (I’m pretty practical – could I do it, or does it need a specialist?)

PowerCrate solar panels are at ground level and so can easily be cleaned by the user as needed. No regular turbine maintenance is required. We anticipate a bearing change at 10 years. The turbine is designed to be field reparable with either a swap of the entire alternator or a replacement of any of the six stators modules. For Health and Safety reasons we couldn’t recommend maintenance by the client. Although relatively simple, since maintenance on the turbine is rare (i.e. cannot be routinely practised by a user) it is better that we or a trained professional from a distributer complete any maintenance.

Where do we site the turbine or PowerCrate and what site preparations are required

The Thin Air 102 is a downwind turbine that operates at a height of approximately 10m. It exploits the kinetic energy in the wind and so performs best when there is an unimpeded stream tube of wind impeding on the swept area of the turbine blade. The turbine should be located where it will have the clearest possible view of prevailing winds. A rule of thumb is that the turbine should be at least 8-10m above any flow obstructions within 90-150m for complete unimpeded performance.

Generally building consent rules should be followed ( e.g. 45 degree rule and noise guidance)

Site preparations for both a PowerCrate our wind turbine include trenched cable to the house or battery enclosure respectively.

The single turbine tower currently requires a concrete pad for tower mounting, although we are considering new alternatives to minimize work required of clients). The PowerCrate only needs level ground with a gravel or weed-matted surface (no preparation is required for the tower as it is pre-mounted to the PowerCrate frame)

Do you install systems which are permanent rather than in a “Crate”?

Yes. We would need to discuss and work with our electrical contractors. Our preferred method for the deployment is the PowerCrate, but for a permanent system we would essentially unpack components. We can send for instance, details for the concrete mounting panel for the turbine. Beyond portability, two points in favour for the PowerCrate configuration is that the panels are near the ground and thus easily cleaned, and that no concrete pad needs to be poured as the metal frame of the crate is designed to have sufficient ballast.