ENERGY EFFICIENCY AND ENERGY GENERATION DESIGN GUIDE
Independent Power Generation Systems for New Zealand Rural Homes
Energy Efficiency and Generation Design Guidelines for Solar, Wind and Hydro Electric Power Generation
(Source: Cellpower NZ Ltd)
Is Generating Your Own Power Cost Effective?
Yes, using renewable energies. Solar modules (PV), wind turbines, micro-hydro generators or a hybrid system
is cost effective in the right location. By this we mean where the connection to utility power lines are a major cost factor. If you’re building a new house and you don’t already have power on site get a quote from your
local power company for connection and comparison to off-grid options available through Cellpower NZ Ltd
If you are on grid power then disconnecting to generate your own electricity is
not a cost effective move at present.
Utility (grid) power is cheaper than converting to alternative generation in the short and medium term. However, when we begin to pay for effects of low lake levels, increasing national demand from air conditioners and heat pumps, carbon taxes on burning coal etc., we will see power costs increase. This is happening now. We
believe, over the working life of a renewable energy system, it can very well be a cost effective move even if grid power is available. It all depends on the real price increase of commercial electricity in 2, 5, 10 and more years. And for many people, money isn’t the only reason for wishing to be independent with your power generation.
Lifestyle choice is a major factor
However there is also the option of generating your own electricity while still
being grid-connected and selling electricity back to your power company.
Imagine, the sun is shining; you’re at work and your house. which is using next to no power at this time of the day. is pumping electricity back into the grid. At the end of the month you are going to send a power bill to your power company. Cellpower is a New Zealand agent for SMA inverters and Suntech and Sharp PV panels.
SMA have developed a grid-tie inverter which allows electricity to flow back into the national grid. Suntech produce a wide range of grid-tie solar panels. There are also grid compatible wind turbines so there are a huge range of possibilities of developing a system just right for your situation.
Energy Efficiency and the Whole Home Approach
When considering energy efficiency, it is important to consider the home as a system where decisions in one area impact on another. For example: a well insulated house requires not only less heating and cooling, but also less energy to distribute and circulate this conditioned air. Correctly placed windows not only heat the home, but
can also contribute a great deal of natural light, thus reducing both heating and lighting requirements. The home that is designed from the ground up with energy efficiency in mind will cost less to operate, either from grid power or from your own renewable based power system. Trying to use renewable energy to power the conventional New Zealand home with its conventional appliances and patterns of usage is an unnecessarily expensive project. Looking closely at these costs has prompted most customers to look first at energy efficiency to reduce their loads. This is a cost effective move even for those staying on grid power and can be facilitated in part by ensuring complete insulation (ceiling, floors, and windows) and adopting the use of energy efficient appliances. Real-time energy use can be monitored by installing a .Cent-a-Meter. . by making energy efficiency visible, this is a great tool
for understanding and reducing your total household energy consumption. Energy efficiency results in an immediate reduction in power costs and for those going to a renewable energy resource, reducing load can mean a much smaller and less expensive system.
Most houses powered by on-site generation do not appear to be noticeably different from conventional houses in terms of comfort and convenience. Some people do decide to adapt their lifestyle when producing their own energy, and most of these changes have to do with simply being more conscious of shutting off loads not in use.
The largest change when producing your own power is the responsibility that it entails. Almost without exception, homeowners cite the increased independence that this decision brings as a great source of satisfaction.
Solar vs. Wind vs. Hydro Power
How do the various alternative power sources compare with each other?
Solar Modules generate electricity from sunlight. They are unobtrusive and require little maintenance.
Wind Turbines require a good, steady wind resource to be effective. It is important to have this resource measured, not guessed, as it makes a significant impact on the power produced. Modern wind turbines are reliable, but the tower and background noise can be an issue in some locations.
Hydroelectric Generators are another option. These small generators can operate with a wide combination of head and flow, and can form a part of a larger system or be a complete AC power resource in their own right.
Every site is slightly different, and there isn’t a universal answer for which is best.
Talk to Cellpower and we can help evaluate the available technologies and resources at your site to help you make the best decision. It is often found that a combination of systems works the best as when the weather reduces solar output, wind or hydro systems are able to cover the shortfall.
Solar Hot Water Heating
Different solar technologies are often confused. The conversion of sunlight to electricity is termed photovoltaics, and the collection of radiant energy to produce heat is solar thermal. We do not recommended using photovoltaics to create heat, as this is an unnecessarily complex, very indirect and inefficient way to do so. The direct capture of solar radiation by heating a tube collection surface, however, is a very cost effective and efficient way to produce hot water. A solar hot water system is an excellent way of reducing electricity consumption for those on the grid, and for greatly reducing electrical load. and therefore system size and cost. for those off the grid.
Cellpower recommends Solar Peak solar hot water systems, which can also have an element, wetback or gas backup setup installed
The Importance of High Efficiency
If selecting appliances for a new house, bear in mind that they will be with you for many years. Using the best available technologies can save you money by saving energy. Such appliances provide better service than older and less efficient technologies. Newer designs often cost more initially than their less efficient counterparts, but can have impressively short payback times. The importance of high efficiency appliances becomes doubly important for someone providing their own electricity. For example: A high efficiency refrigerator may be run with three 80
watt solar modules, whereas a conventional refrigerator might necessitate an additional six modules and additional battery capacity. This extra generating and storage capacity will cost many times the investment of the more efficient unit. An additional benefit is that more efficiency means less run time and less wear and tear on components. In the case of the refrigerator this can mean a life span twice that of the conventional unit. This has obvious cost advantages for those on-grid as well as those generating their own power. Cellpower supplies low energy Gram upright fridges, freezers and fridge/freezers and low energy Elcold chest freezers.
Phantom Loads
Small loads that are not easily discernible but can consume considerable amounts of power each day are termed .phantom loads.. Examples include TVs and VCRs in stand-by mode, clock radios, clocks in appliances such as microwaves, stoves and VCRs, Ni-Cad battery chargers and cordless telephones. There are two ways to deal
with these troublesome loads:
1. The first, easiest, and most costly method is to accept them. Accept the fact that you pay an ongoing cost for these items every month in your power bill, or that, if you generate your own power, your inverter will never go into standby mode. You will need a larger system size to compensate for this consumption.
2. The second method minimises power consumption. Switch off the appliances that run unnecessarily, turning them truly off and on at the wall when required. Fix that dripping hot tap!
System Components
Systems vary greatly due to variation in size and run times of differing loads. They can use as little as a single twenty-watt module, or tens of large modules. There really is no such thing as an .average. system, even within a single kind of use. However, the basic renewable energy system can be divided into several major components. The overleaf section lists these components and their functions.
Component Function
12, 24 or 48 Volts . System Voltage Selection
The nominal voltage of your system is usually determined by the system size. Small systems, where most loads are DC, or only a few loads are AC through an inverter, lend themselves to 12 volts nicely. Many lights and small appliances can be found at this voltage and efficiencies are acceptable. On the downside, 12 volt suffers from higher line loss problems. The power generators (solar, wind etc) and loads cannot be far from the battery bank. To avoid line losses, the nominal voltage can be increased, thus reducing the amperage of the system. This gives the same useable power, or more, but with higher efficiency. 24-volt systems are suggested, and most commonly used in houses, for medium systems and 48 volts or higher for larger systems. We would recommend higher DC voltages (24 or 48) for most cases due to the improved efficiency, and modern energy efficient lighting and appliances avoid duplication of wiring around the house.
Solar modules
Silicon is abundant, electrically stable, and relatively easy to manufacture, however not all solar modules are created equal. There are currently several different types of technology used in the manufacture of solar modules. The three major technologies are Single Crystal, Poly Crystalline and Thin Film, or Amorphous.
Single Crystal: Single crystal silicon solar cells are made by melting purified chunks of silicon in a crystal growing furnace, and slowly solidifying the silicon into a large cylindrical crystal. In this process the atoms of silicon are aligned, and individual round wafers are then sawed from the cylindrical crystal. And are the most efficient
Polycrystalline Silicon: Advanced cell-processing technology and automated production facilities produce highly efficient multi-crystal photovoltaic modules. To protect the cells from the most severe environmental conditions, they are encapsulated between a tempered glass cover and an EVA The entire laminate is installed in an anodized aluminium frame for structural strength and ease of installation. The newly developed treatment method processes multicrystalline silicon cells in order to produce a surface texture that minimizes surface reflectance and maximizes output. The result is maximum conversion efficiency close to single crystal modules
Thin Film Amorphous Silicon: Over the past years, great progress has been made in manufacturing solar modules by depositing extremely thin films of semiconductors onto glass or metal substrates. The semiconductor layers are only a few hundred atoms thick, and the entire module is made as a unit. The atomic structure of the thin
film is not totally ordered and efficiencies of mass produced thin film modules is currently around 8%.
Shading
PV modules are very sensitive to shading. Unlike a solar thermal panel, which can tolerate some shading, many brands of PV modules cannot even be shaded by a branch of a leafless tree. Once a solar cell, or a portion of a cell, is shaded it becomes a load and draws power instead of producing it. Some solar modules offer
protection from partial shading, which includes a diode between cells, aiding in reducing partial shading problems. Another rule of thumb. make sure no shading occurs between 9am and 3pm. Shading outside these hours is not much of a problem because these are low power producing hours anyway.
Reverse Current Protection
PV modules will leak power back from your batteries during no sun periods if not protected. This leakage is very small, but over long no-sun periods this loss can accumulate. To prevent this install a diode, or protecting circuitry in a battery controller. Most modern solar panels already have these installed, but check or ask to be sure.
Module Mounting
Solar modules perform best when perpendicular to the sun’s rays, and would normally be mounted facing due north. Because the sun’s position in the sky varies throughout the year, it is a good idea to provide for seasonal adjustment. Latitude plus 20º angle in winter and latitude minus 20º angle in summer is optimum.
A minimum angle of 15º is recommended which allows for natural self-cleaning of the module by rainfall. If you wish to permanently mount the modules and not seasonally adjust the structure, consider fixing your mount at an optimised winter angle. This is when sunlight is limited, days are shorter, and you want the system maximizing the
available power.
Wind Turbines
Is wind generation for you?
Electricity produced by wind generation can be used directly, as in water pumping applications, or it can be stored in batteries for household usage. Wind generators can be used alone, or they may be used as part of a hybrid system, where their output is combined with that of solar module and/or a fossil fuel generator. Hybrid
systems are especially useful for winter backup of home systems where cloudy weather and windy conditions occur simultaneously. The most important decision when considering wind power is determining whether or not your chosen site has enough wind to generate the power for your needs, whether it is available consistently, and if it is available in the season when you need it. Impact on neighbours should also be considered. The power available from the wind varies as the cube of the wind speed. If the wind speed doubles, the power of the wind increases eight times. For example, a 10 kilometre per hour wind has one-eighth the power of a 20 kilometre per hour wind
(10x10x10=1,000 versus 20x20x20=8,000). This is important as it also shows how over estimating the speed of the wind will greatly over estimate the power produced from a given site.
One of the effects of the cube rule is that a site which has an average wind speed reflecting wide swings from very low to very high velocity, may have twice or more the energy potential of a site with the same average wind speed but experiencing little variation. This is because the occasional high wind packs a lot of power into a
short period of time. Of course, it is important that this occasional high wind comes often enough to keep your batteries charged. If you are trying to provide smaller amounts of power consistently, you should use a generator that operates effectively at slower wind velocities. Installation of wind generators should be close to the battery bank to minimise line loss, and be six metres higher than obstructions within 160 metres. The tower should be well earthed. Operating a nominal voltage of 24 or 48 volts will help with transmission losses between the turbine and the battery bank. Wind is commonly used in New Zealand, but not suitable in most sites
Hydro Electric Generators
Small hydro electric turbines are available to produce either 230 VAC power at 50 Hz, or 12, 24 or 48 VDC to charge a battery bank. It is possible to use a very wide range of head and flow combinations to make useable power, and even power outputs of 100 or 200 watts continuously can add up to make a significant
contribution to daily power needs for an off grid house. To get an indication of the viability of your resource, take the available flow rate of the stream in litres per second, multiply it by the available .head. or fall in meters, and
then by 5 and this will give you an estimated power output in watts. For example, if you have 10 litres per second, and a 30 meter head, then you could generate 10 x 30 x 5 = 1500 watts, or 1.5 kW 10 litres per second and 150 m head could yield 10 x 150 x 5 = 7.5 kW An AC turbine can provide power without needing batteries or an inverter, but a smaller DC turbine will still need a charge controller, batteries and an inverter before it can provide AC power to your location.
Charge Controllers / Regulators
Why you need a controller
The main function of a charge controller or regulator is to fully charge a battery without permitting overcharge. If a renewable energy system is connected to lead acid batteries with no overcharge protection, battery life will be reduced as at times the battery will be overcharged, or sometimes over discharged. Simple controllers
contain a relay that opens the charging circuit, terminating the charge at a pre-set high voltage and, once a pre-set low voltage is reached, close the circuit allowing charging to continue. More sophisticated controllers have several stages and charging sequences to assure the battery is being fully charged.
How controllers work and available options
The circuitry in a controller reads the voltage of the batteries to determine the state of charge. Designs and circuits vary, but most controllers read voltage to reduce the amount of power flowing into the battery as the battery nears full charge. Features that can be included with controllers are:
Reverse Current Leakage Protection: by disconnecting the solar array or using a blocking diode to prevent current loss into the solar modules at night.
Low-Voltage Load Disconnect (LVD): reduces damage to batteries by avoiding deep discharge.
System Monitoring: analogue/digital meters, indicator lights and/or warning alarms.
Overcurrent Protection: with fuses and/or circuit breakers.
Mounting Options: flush mounting, wall mounting, indoor or outdoor enclosures.
System Control: control of other components in the system; standby generator or auxiliary charging systems, diverting array power once batteries are charged, transfer to secondary batteries.
Load Control: automatic control of secondary loads, or control of lights, water pumps or other loads with timers or switches.
Temperature Compensation: utilised whenever batteries are placed in a non-climate controlled space. The charging voltage is adjusted to the temperature.
Central Wiring: providing terminals to interconnect system wiring. Some systems require all of these functions; others require only one or a certain combination.
Sizing a Controller
Charge controllers are rated and sized to the systems they protect by the array current and voltage. Most common are 12, 24 and 48-volt controllers. Amperage ratings run from 1 amp to over 100. For example, if one solar module in your 12-volt system produces 3.5 amps, and four modules are used, then 14 amps of current at a nominal 12 volts is produced. Because of light reflection and the edge of cloud effect, sporadically increased current levels are not uncommon. For this reason, we increase the size of controller’s amperage by a minimum of 25%, bringing our
minimum controller’s amperage up to 17.5. Looking through the products available we find a 20 amp controller as close a match as possible. There is no problem with going to a 30 amp or larger controller, besides additional cost. If you think the system may increase in size in the future, then consider buying a charge controller that can cover your future needs as well.
Inverters
Inverters convert DC power to AC power. An inverter is necessary for on-site generation systems that power AC loads. Common standalone inverters operate at 12, 24 or 48 volts DC and create 240 volts AC. The rated power of an inverter indicates the wattage it can supply continuously. Your inverter should be sized to 125% of the AC loads that will run simultaneously. The extra 25% capacity will protect your inverter from being overloaded and provide you with the ability to expand. The three most common types of inverters are square wave, modified sine
wave and pure sine wave. The output waveform depends on the electronic conversion and filtering methods used to create the AC power. Modified sine wave inverters are capable of running household appliances including televisions, VCRs, power tools, microwave ovens, washing machines and many personal computers.
Pure sine wave inverters produce power that is comparable to grid power. Using sine wave inverters will increase AC motor efficiency and life. Other important parameters include power conversion efficiency and surge capacity.
The power conversion efficiency is the percentage of the battery power delivered to the AC load by the inverter. Surge capacity allows inverters to exceed their rated power for limited periods of time in order to start AC appliances that require several times their operating power when starting.
Battery Chargers
Many of today’s inverters incorporate battery-charging circuitry. This is easily and economically accomplished because of the design of most inverters. Inverters step up low voltage and change DC power to AC power. Battery chargers do the reverse of this. Additional circuitry is all that is required to add a whole second function and
economically create an Inverter/Charger. Transfer switches are also incorporated into these inverter/chargers so that the AC loads can be powered directly from the generator when the battery charger is operating. From a reliability, performance and economical standpoint, built-in battery chargers are the way to go.
Inverter to Battery Cabling
Because of the high current required on low voltage circuits, this cable is large, commonly 35mm2 to 107mm2. Smaller cables than required are unsafe and will not allow inverter to perform to its full rating. Don’t skimp on small cables!
DC Input Disconnect and Overcurrent Protection
It is important to have a safe installation with a properly sized DC rated, disconnect. Typically a disconnect works in conjunction with an overcurrent protection device such as a fuse or breaker.
Shunts
Shunts are used to read the amperage flowing between the battery and inverter and are installed in the negative cable line.
Batteries 
Although the idea and usage of a battery is very simple, if batteries are neglected, degradation can occur at a fast pace. As someone in the industry once put it, .few batteries die a natural death, most are murdered..
The following information is designed to tell you how to get the longest life possible from your battery bank. (This information applies only to flooded, lead-acid batteries).
Cycling. Deep versus Shallow
A cycle in a battery occurs when you discharge a battery and then charge the battery back up to the same level. The battery is designed to absorb and give up electricity by a reversible electrochemical reaction. How deep a battery is discharged is termed .depth of discharge..
A shallow cycle occurs when the top 20% or less of the battery’s power is discharged and then recharged. Some batteries, like automotive starting batteries, are designed for this type of cycling only. The plates of active material are thin with large overall surface area. This design can give up lots of power in a very short time, and also be
recharged very rapidly. The second type of cycle is a deep cycle where up to 80% of the battery capacity is
discharged and recharged. Batteries designed for deep cycling are built with thicker plates of active material that have less overall surface area. Because of their A renewable energy system is made up of a number of components and, of these, none needs as much attention as the batteries. lessened availability of surface area for chemical reaction, these batteries yield just as much power relative to their size, but do so over a longer period of time. This type of battery design is preferred for a solar power system because discharging a battery
to a deeper level is normal during extended cloudy weather. The depth of cycling has a good deal to do with determining a battery’s useful life. Even batteries designed for deep cycling are used up faster as the depth of
discharge is increased. It is common practice for a system to be designed with deep cycle batteries even though the daily average discharge amounts to a relatively shallow depth of discharge.
Temperature Effects
The speed of the chemical reaction occurring in a lead-acid battery is determined by temperature. The colder the temperature, the slower the reaction. The warmer the temperature, the faster the reaction and the more quickly the charge can be drawn from the battery. A battery’s full rated capacity is available at 25ºC, but at 0ºC only
around 65% of capacity is available. The optimum operating temperature for a lead-acid battery is around 25ºC. For this reason we recommend that the batteries be placed indoors or in a heated and ventilated space to maintain them between 18ºC and 25ºC. If installed in an unheated place, battery capacity must be increased to compensate for this de-rating. High temperatures can also drastically shorten the life of a battery and should be avoided.
Self Discharge
Due to impurities in the chemicals used for battery construction, batteries will lose power to local action, an internal reaction that occurs whether you are using your battery or not. This slow discharge is termed self-discharge. Self-discharge rates vary greatly among battery types and with temperature. The rate also increases with the age of a battery, so much so that an old battery may require a significant amount of charging just to stay even. Even new batteries may lose 1-2% of charge per month.
Battery Connections
The connections from battery to battery and on to the charging and load circuits are critical. Terminals should be greased to prevent corrosion, interconnects should be clean and fastening hardware should be tight. Tightening all bolts equally avoids variations in resistance. This is also the reason it is preferable to minimise the number of parallel strings in the bank. Higher resistance values on one string of batteries results in less charge to that string and consequently shorter life. The main negative and positive connections should be made on opposing corners for the same reason. The goal is to keep the variation of resistance from one cell to another to a minimum.
Battery Enclosures
Install your batteries in a warm, dry location. 18-25ºC is the optimum temperature range. Lower or higher than this and performance diminishes significantly. Because batteries produce a potentially explosive mixture of hydrogen and oxygen, venting is needed to prevent a build-up. Since hydrogen is lighter than air it has a tendency to rise. If venting is placed at the top of the battery enclosure and the air is Shallow cycle your deep cycle battery for the most cycles brought in from the bottom, the gas will move up and out of the battery area. When possible, power venting of the battery enclosure to the outside is a wise move. Keeping the batteries simultaneously warm and adequately vented can be challenging, yet with proper planning is not that difficult. Hydrogen sulphide is also corrosive and does not smell nice. The amounts released are small, and only when the battery is .gassing, however it is wise not to install batteries in a confined space with other sensitive electronics that may corrode over
time. Vent them to the outside and avoid the potential for problems.
Overcurrent Protection
Batteries have the potential to discharge incredible amounts of power over a very short period of time, melting conductors and possibly starting a fire, which is why so much time and energy is spent on overcurrent protection. It is not so much the solar module that you need to protect against, but the batteries. Solar modules are current
limited, which reduces the danger, yet modules and their cabling also require protection. The idea of a fuse or breaker is to include a .weak link. in each circuit that will open if the current exceeds that which the cable can safely handle. In a typical solar system, we deal with both AC and DC power. Standard components purchased from an electrical supplier are typically rated for AC use. These are fine for inverter output circuit protection. DC overcurrent devices required between the battery, inverter, controller and modules are much more specialised. They are generally heavier duty and more costly. Of primary importance is to place a current limited fuse and disconnect on the main battery cable and assure that all components on the DC side are rated for DC use. If you are installing your own system, please obtain a copy of your Local Electrical Code, work with your inspector and be safe.
Monitors
Proper monitoring of a system should not be overlooked. Typically you will want to know how much power is coming into the system from its charging sources and the state of charge of the battery bank at any point in time. A third and equally important value is how much power the system’s loads are using.
Instantaneous and Cumulative Information
Common meters report current flow or battery state of charge (voltage) at a single point in time. the present. This type of metering is termed instantaneous. Devices that report instantaneous information are less complex and less expensive and can give a general idea of what’s happening. Cumulative type monitors, such as the Bogart TM2020 and Trace TM500A, usually include instantaneous information but go a step further by recording the power over
time. With this information, termed amp hours or watt hours, you can see just how much power was generated yesterday or last month and how much power was consumed and, with much greater accuracy, determine battery state of charge.
Lightening Protection
Lightening presents a potential hazard for systems with exposed cables and aluminium framing mounted on rooftops or adjacent to a building. Direct or close-in strikes can damage sensitive electronic circuitry through the presence of static charges and electromagnetic fields. These forces can induce voltage surges and may damage the system’s wiring and components, particularly if your system is not properly grounded and protected.
While no lightening protection system is foolproof, practical counter-measures are available and include a lightening rod at the solar module source, adequate system grounding, and surge protection on the incoming DC wires and the secondary AC wiring.
Backup Generators
Generators are typically used as a supplement to renewable energy generation when the system is totally off the main grid supply. Generators are used for backup power in situations where seasonal variability is substantial as in cloudy climates, or for systems where occasional use of very large loads are required, such as for intermittent use of large workshop tools. There will be times when there is no sun for an extended period of time, or friends arrive and power consumption doubles for a few days. It is often not worth adding additional solar panels to cover those odd situations, and a backup generator is a valuable backstop for those occasions when necessity demands.
Modern generators with a control panel are able to be started and stopped automatically by the inverter if total demand or low battery levels requires it.
What you can expect from CELLPOWER
Every renewable energy system begins its working life as a pile of equipment. Preparation, planning, and proper installation, are all essential if the system is to be a success. You can do it yourself, or you can get help from us. Here’s what you can expect from us – or what you may miss if you decide to do it yourself.
Load Analysis
Every renewable energy system should begin with a complete, accurate and thorough analysis of the appliances to be used in the system. If the load analysis is not properly done, the system is bound to disappoint its users. If the system’s energy consumption is estimated too low, power shortages and dead batteries will soon follow. If the estimate is too high, the user will be wasting money on unneeded equipment. So who does this analysis. the system’s user or Cellpower? In most cases, both contribute information. The user lists and gathers data about each appliance (don’t leave out even the smallest one, and don’t forget to plan for future appliances). How much and what type of electrical energy does the appliance consume? How long will the appliance run? Cellpower then takes this information and generates an estimate of daily energy consumption. Cellpower will also recommend appliance changes to reduce the system’s energy use. The golden rule is: Money spent on an efficient appliance saves you considerably more money in system components. Cellpower will suggest replacing inefficient appliances (such as incandescent lighting and high energy fridges), with the most efficient types available. We will be trying to save you three to five times the cost of these appliances in solar-electric modules, controls, batteries, wiring and inverters. Sad to say, many systems are purchased without ever doing a load analysis. This risks wasting money, and can result in disappointment with the system. Cellpower will insist that a load analysis be done before selling you a system.
A Budget is NOT a Load Analysis
Don’t buy a system based on preferred budget. Do the load analysis and, if the system needed to power these loads is too expensive, modify the loads. Replace inefficient appliances and, if need be, eliminate appliances until the system is affordable. It is not unusual to go through the load analysis and system design phase three or four times before the right setup is found. This is an essential give and take process. A properly designed system costs what the user can afford to spend on the system, and the load analysis details the energy consumption of each appliance.
Site Survey
A site survey is an analysis of a specific location for its renewable energy potential. Every place is different, but your system is going to be installed in a specific location. You need to determine what types and amounts of energy (solar, wind, water) are available to you. A solar array needs to be located where it will receive the maximum
amount of sunlight. With seasonal variations in the sun’s declination, and possible shading from hills, trees and buildings, finding the best spot for the solar array can be difficult, but Cellpower is well able to do this for you.
Wind is a less easy resource to survey. Local experience is sometimes required, or the installation of a monitoring tower at the proposed site, which then collects data over a year’s period, indicating whether the site is suited for a generator. Checking for vegetation .flagging. and of locally recorded wind data may also be required to establish suitability of the site. NIWA can often provide local wind data at a price, but this is a good investment to ensure that mistakes on anticipated power generation are avoided. We can help with advice on how to proceed.
System Design
Cellpower has much experience regarding what works and what doesn’t. Our engineering experience provides answers to questions such as how many solar panels to use, what kind and size of cables/wires are required, inverter/appliance capability, how tall a wind tower should be, and how the batteries should be configured. Our professional help with your system design pays off with better systems and avoided errors. Every system, regardless of size and without exception, should be safely designed. Once we have a specific list of renewable energy equipment, we can calculate the system’s hardware cost. Our aim is to provide you with an affordable system that works for your unique situation.
Contact Us
For assistance and advice on all aspects of an independent power generation system contact:
Cellpower NZ Ltd
Unit 2, 129 Maraekakaho Road
Stortford Lodge
Hastings
Phone: 06 8782804
