ABOUT OUR HOUSE

Where we currently live and work (part-time anyway). Our house is unique in that we generate all our own electricity on site with solar electric modules, (PV's). From March 1994 to until March 1999, we were completely self sufficient (electrically that is), and stored the generated power in a large battery bank to use when required. In March 1999, we 'grid intertied' which means we now spin our electricity meter backwards, and get credits from the Power Company when we have excess power. (More about this on the following pages).
If only I had known I was going to do this....how different the house construction would be when I built it in 1990....

It would be made out of earth - adobe/rammed, the entire house would be facing true North, and would have the roof pitch at 60 degrees so the PV wouldn't look soooo ugly!

What's the Excitement About?

Why on earth did we do this? [ TOP ]

Many of you wonder if there is a real commercial market for grid-tie solar.

The remote power market has grown steadily over the last 20 years. Remote consumers often have no other access to power, it is prohibitively expensive to run utility lines to provide power, and the use of a generator is inconvenient. These reasons compel them to choose alternative energy. On the other hand, the grid-tied domestic markets, commercial and residential, normally have constant, reliable, and convenient access to power. Why then would they choose an alternative energy system?

Utility interactive systems are available both with and without battery systems. Which system is right for the consumer depends on the application. Those systems designed to run directly from the sun may not require battery backup. However, people with systems deployed where off-hour or backup power is required should consider investing in a battery backup system.

A number of reasons compel energy users to choose solar for grid-connected power. First, there are economic reasons. If an area suffers from high-energy costs associated with peak utility hour charges, solar energy produces most of its power during those peak hours. Peak power requirement hours can be supplemented by solar, this is called peak shaving. Utilities forgo building more generation facilities by installing solar in their territory to offset peak hour power needs.

Reliable backup or standby power is another strong economic reason for buying a utility-interactive system. From the very small user, such as a home office, to a large user such a bank, hotel or gas station, individuals and companies depend on reliable power 24 hours a day, 7 days a week.

People who were in Auckland central during the power outages that occurred in 1999 went up to 14 days without power. In this age of global commerce, 14 days without a fax machine or computer could destroy even the smallest company. With the onslaught of utility restructuring, the government and utilities predict a greater frequency of outages. An alternative energy backup power system provides a real economic benefit to consumers and businesses that put value on reliable power. A NZD$2000 to $7500 system can provide low cost insurance to avoid costly downtime due to power loss. A NZD$10,000 to $75,000 system can provide long term to endless power supply. The addition of solar panels and batteries to utility interactive systems serves to enhance the economic gain of a fully integrated system.

Non-economic based decisions also drive commercial and residential consumers to choose solar. These reasons are not as tangible, but are equally if not more compelling, and could be referred to as "doing the right thing".

Hardened alternative energy professionals often claim the grid-tie market will not be a reality until power produced competes dollar-per-dollar with utility power. Commercial examples from other industries contradict this.

Consumers do not buy Nike’s or Reeboks because they are economically comparable to other generic sneakers. They do not buy 4x4 Vehicles, Porsches, Mercedes or Volvo’s because they cost the same as a Ford or Hyundai. Consumers buy Rolex’s when they could just as easily buy a watch from their local Deka. Evian water, which costs more per litre than petrol, is purchased and consumed instead of tap water.
The examples could continue on and on; it’s about perceived value. Solar and other renewables are associated with positive value: uniqueness, positive public relations, non-polluting, greenness, technology appeal, independence, and so on. Schools, commercial companies & institutions, have all put solar on their roofs here in New Zealand. These were not economically based decisions.

Time and time again, solar and other alternative energy technologies rank the highest on opinion polls. People think solar is great; it’s green; it’s cool. Maybe you too should look at it more closely. Start slowly – replace those old appliances (incandescent light bulbs at less than 5% efficient should be illegal to make, let alone purchase!!) with more energy efficient models. Install solar hot water, and between doing this step alone, you have probably reduced your power bill by 40-60% already. Contact us at Sunpower Co to learn more.

Solar modules from a westly angle. They are facing true north at a fixed angle of 60 degrees to the horizontal. This is ideal for winter conditions to maximise solar input. Winter is when we use the most electricity, and the least sun shines, therefore, the entire system is designed around this time of the year. Hence the reasons why we have such a large battery bank. Now that we are grid-intertied, we do not need a large battery bank, nor do should we cater for the winter months. We ideally should now change the angle of the modules for summer (~18 degrees to the horizontal), and make electricity (hay?) while the sun shines, and gain a large ‘credit’ in the summer months, and then draw off this credit in winter…

We will do all that when we build our next house…..(‘if it isn’t broke, don’t fix it’ comes to mind).
We have two different technology solar electric modules on our roof. We chose the Siemens Solar Industries single crystalline modules (in the foreground with the individual square cells), over the other current brands on the market at the time due to their superior performance under 'normal' operating conditions. We initially started with 12 x 48 watt modules (576 peak watts). It soon became apparent, that we needed more, and the beauty of the system is that it is very modular, so as we added more appliances (& people) and consumption (such a great word for the 20^th century – to hopefully change to efficiency in the 21^st) went up, we then added more of them! We now have 21x 48 watt modules
When the Canon (UniSolar in the USA) brand was launched on the market, we were one of the first countries to get these modules (our modules have serial numbers like 120, 121, etc). This technology was & is still unbeatable by all competing manufacturers (cheaper to make, better performance in normal operating conditions, flexible, light weight etc. we jumped at them. Want to know more? , So we added 6x Canon 32 watt amphorous modules, and managed to squeeze 4x of their 48 watt modules on the roof also. We have run out of room to put anymore!
This gives us a grand total of 1,400 peak watts per hour, which generates ~7kW in summer per day, and ~5kW in winter per day for us. Heaps of power.

Close up of the solar electric modules. You can clearly see the different construction methods of the two technologies here. Single crystal sawn cells, verses 'sprayed-on' amorphous technology using 1/300^th of amount of silicon to do the same job.
You can also see the fantastic Solahart solar hot-water system also. This is 100% separate from the solar electricity system.

Introduction to solar hot water [ TOP ]

The shallow water of a lake is usually warmer than the deep water. That's because the sunlight can heat the lake bottom in the shallow areas, which in turn, heats the water. It's nature's way of solar water heating. The sun can be used in basically the same way to heat water used in buildings and swimming pools.
Most solar water heating systems for buildings have two main parts: a solar collector and a storage tank. The most common collector is called a flat-plate collector. Mounted on the roof, it consists of a thin, flat, rectangular box with a transparent cover that faces the sun. Small tubes run through the box and carry the fluid – either water or other fluid, such as an antifreeze solution – to be heated. The tubes are attached to an absorber plate, which is painted black to absorb the heat. As heat builds up in the collector, it heats the fluid passing through the tubes.
The storage tank then holds the hot liquid. It can be just a modified water heater, but it is usually larger and very well-insulated. Systems that use fluids other than water usually heat the water by passing it through a coil of tubing in the tank, which is full of hot fluid.
Solar water heating systems can be either active or passive, but the most common are active systems. Active systems rely on pumps to move the liquid between the collector and the storage tank, while passive systems rely on gravity and the tendency for water to naturally circulate as it is heated.
Swimming pool systems are simpler. The pool's filter pump is used to pump the water through a solar collector, which is usually made of black plastic or rubber. And of course, the pool stores the hot water. Interested in more information?
Our particular system is a passive one, with a gas booster built into the end of the storage tank.

Sunpower Co...Urban solar powered house [ TOP ]

Our view is perfect for solar gain and generation. Un-impeded views of Auckland city. We get the early morning sun rise on the east side of the house to gently wake us in the morning, through to full sun during the day to slowly warm the house, to the west sun as it falls to give pleasant afternoons and early evenings on the deck to enjoy the day-end. We have now grown wisteria on the pergola which loses all it leaves in winter to allow the low intensity sun into the house, and is in full flourish in summer to block the high-noon sun from overheating the inside of the house.

Arrh, the heart of the system, the inverter and control gear. A very good 'jack-of-all-trades' is the Trace inverter we use (SW3024E - 3kW, 24VDC input, 230VAC @ 50Hz output). We started off with many other brands, and eventually wound up with this beast. At first it provided us with that all important near sine shaped waveform, that is vital for efficient running appliances, with no harmonics to interfere with your motors, radio stations etc. As it is an inverter-generator, which means that in the middle of winter when we occasionally ran out of power (I remember one particular September in 1997 when it just rained and rained and rained. By the end of the 2^nd week, we had nearly run out of power, so by running a power cord to our friendly neighbours, giving them literally NZD$2-3 dollars, we 100% topped up our batteries again. Trouble was, it was still raining, and continued to rain for the rest of the month. Batteries nearly flat again….back to the neighbours again. NIWA (our weather monitoring people here in NZ), announced that it was the rainiest /wettest September in recorded history - well, I could have told them that!) it becomes a big battery charger when you attach a petrol/diesel generator to it.
No small battery bank either. It takes up one end of the garage – the width of Kristina’s 4x4, and from floor to ceiling in height! I.e. 48x 2volt lead-acid cells - each one ~600 AH in capacity, and weigh 62kg each to give us an available capacity of 2,400Ah (57,600 watts of stored power), which is approximately 2 weeks worth of daily power usage. This is for the 24VDC system to supply the inverter. We also have a separate 12VDC-system power from 2x 48 watt Canon amphorous modules, feeding into 6x 2 volt cells (same model as the main battery bank). This powers all those 12-volt appliances we would normally power from ‘Plug-packs’ (cube blocks, or whatever you call them in your country) – the 2 cordless phones, the cellphone charger(s), the doorbell, burglar alarm, and the kitchen TV.
Then once we tied the Power Company in knots and introduced Grid-intertie systems to NZ, it became connected to the grid, and sells and buys power from the grid as and when required.
Grid intertie is the best of both worlds - if you already have the luxury of electricity coming to your house.

Solar Grid-Tie Operations [ TOP ]

A happy marriage of solar power (wind or hydro) and the utility power lines, "grid-tie operation" utilising an inverter is a relatively new phenomenon – world-wide. Grid-tie systems are common in areas where grid power is normally available. Grid-tie allows the user to rely on a sine wave inverter system as the primary means of electricity, and to fall back on utility (grid) power on an as-needed basis. Although the initial cash layout can be pricey, ecologically-minded consumers take great pride in protecting the environment by generating some, if not all, of their own power from renewable sources. Here is a glossary important terms related to line (grid)-tie: Time-of-day metering: Utility customers are charged more dollars/kilowatt during the day than at night. Users can avoid the higher rates by making their own power during the daytime and buying utility power at night - or by using a Trace Engineering inverter to power loads during the day and to charge up their batteries at night. Load shedding: Turning off power to selected loads in order to maintain high-quality power for critical ones. Peak shaving: Providing short-term power boosts in order to maintain high-quality power. Power point tracking: Electronically tracking a solar module's output power and adjusting it for optimum performance. Power conditioning: Filtering and conditioning poor quality power in order to provide clean, high-quality power to loads. Dispatchability: The ability to provide an instant power increase based on load demand. Peak metering: The highest (or peak) amount of energy used over a short period. Line-tie systems generally fall into one of three categories: Small battery storage line tie:Two to four car-sized batteries are required. The advantages are low cost, small footprint, limited short-term back-up, peak metering (in minutes), limited but expandable dispatchability, and power conditioning capabilities. On the down side, small battery storage line-tie requires space, parts, and battery replacement (which, over 5 to 10 years could run to several hundred dollars); it has limited power storage capacity and no time-of-day metering. Large storage battery bank line tie: These systems use medium to large industrial type batteries. These systems are able to run as a utility back-up for hours, days, or indefinitely; they offer time-of-day metering, load shedding during peak periods, and peak shaving. Such systems are ideal for homes, offices, clinics, and small to medium commercial systems. The costs to the end-users are greater than those for small small-battery systems. The large-battery system is also more complex and requires more space, both for the system itself and for the required ventilation (for non-sealed batteries, especially). Capacitor system line tie: Capacitor systems are low cost (no batteries required), simple, require very little space, have a long life (up to 10 years), and offer maximum power-point tracking. The limitations include no un-interruptible power supply ability, no time-of-day metering, and no load shaving or power conditioning capabilities. When I first put the PV's on the roof, grid-intertie did not exist in NZ (nor many other places in the world infact). The majority of systems (& are still today) are designed for rural ‘life-style block’ customers, who have typically purchased a piece of land in the middle of nowhere, for the view, silence and beauty the property offers them. Not like the old farmhouse, they don’t want the house down at the road with all of the other amenities - but rather up the back of the section away from the ever increasing noise of city sprawl. This is when they get the quote from the now privatised power company who starts to say figures of NZD$8,000+ to get electricity to their proposed site….. This is where a renewable energy designed home comes into the fore! Want to know more about this?

ALL appliances must be energy efficient to maximise the energy that has been made on site! As stated on our first page, the sun produces 95% of our energy needs. We still need to use LPG gas to run the oven, and we have opted to use LPG to also heat the house. If I known of a free source of firewood (that is easy to gather and cut), then I would have put in a wetback on a fireplace. However, I had not identified this 'source' until after the fact, and so, LPG it is. We pay on average ~NZD$10- (USD$4-) a month for gas to run the oven & outdoor barbeque (everyone has a 'barbie' in NZ! Like flame-grilled to you people in the USA) all-year round, & run the heaters & boost the solar hotwater in winter for 1 hour a day, for ~3 months of the year. The dishwasher, refrigerator, and the chest freezer are European in origin. Sadly NZ made ones are not energy efficient enough. (By a factor of 3-5 depending on which model and brand). This is critical for the success of your system, that these appliances are the best at the day you go to purchase them. It just is not efficient to use electricity to heat resistive loads (electric hot water, bar heater, electric stove etc), it is just convenient – one power bill from one company that is all. In fact it is incredibly in efficient, in some cases, some of the electric appliances we use. The incandescent light bulb for example! It is a better heater than a light bulb! When was the last time you touched a light (?) bulb and burnt yourself – its meant to put out light – not heat!

We, as inhabitants and custodians of this planet, took a minuscule step towards ensuring our planet's future. Each one kilowatt PV array will save putting one metric ton (2,200 pounds) of carbon dioxide into our atmosphere each year. Each 1 KW array, each year. Over the next twenty years, this small system will displace 20 metric tons of CO2 that would have been produced to make the same quantity of electricity. A small step to be sure, but a step in the right direction.

The local utility Power Company gained another power source. A power source that is radically different from any they previously had. This power source runs on sunshine. It produces no pollution, no CO2, no acid rain, and no waste. This power source produces electricity during peak consumption hours, when we need it the most. It's a power source bought and installed without using a single cent of Power Company capital. A power source that brings energy close to where it is used, saving us the losses, expenses, and environmental damages of long distance power lines. The energy from this source is donated to us by God, and we can sell it to our Power Company (I love it!).

We, as the installers of the system, gained experience in utility-intertied solar energy. We learned something that we will want to do again and again - it just felt right. Our biggest reward is watching the utility meter recording the 5-7 kWh of solar energy that the system pumps onto the grid each day. Even better is when we get a credit from the Power Company at the end of the month!

Grid Tie with Backup Power (battery based)
Grid tie systems may also include batteries, providing back-up power during grid outages. A battery-based inverter allows you to send power back to the utility and protects your home or business against power outages! The additional cost of a battery based system offers reliable power during a grid power outage.

The following illustration shows how the typical solar electrical system is configured to send power to the grid

Note: The illustration is a general schematic only and does not include fusing, breakers or any of the components required for code complianceThis system consists of a solar array, a charge controller, a battery bank and the inverter. All other items, the main service entrance to the building and the net kWh meter are already installed on existing buildings if utility power is present. Some battery-based inverters, such as the Trace SW series also offer energy management opportunities to reduce your electrical charges during the time of day when electricity is the most expensive. Peak load shaving is important when the utility time of use (TOU) metering may be overcome by using a battery-based inverter for storing energy during the low cost power hours and consuming the battery energy during high cost power hours. Plus, with a battery-based system, you can tap into other features of the inverter, such as programming operation periods, automatically starting a back-up generator, and many other load management measures.

Some Pros and Cons of a Battery-based Utility Interconnected System are:
Pros	Cons
Provides Uninterruptible Back-up Power	Batteries are an Additional Cost
Reduces Energy Costs for TOU metering	Additional Efficiency Loss in Charging Batteries
Offers Power Management Opportunities	More Components to Install

Photovoltaic (or PV) systems convert light energy into electricity. The term "photo" is a stem from the Greek "phos," which means "light." "Volt" is named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. "Photo-voltaics," then, could literally mean "light-electricity." Most commonly known as "solar cells," PV systems are already an important part of our lives. The simplest systems power many of the small calculators and wrist watches we use every day. More complicated systems provide electricity for pumping water, powering communications equipment, and even lighting our homes and running our appliances. In a surprising number of cases, PV power is the cheapest form of electricity for performing these tasks.

Why Use PV? [ TOP ]

PV-generated power offers advantages over diesel generators, primary (one-time use) batteries, and even conventional utility power. These benefits make PV the power of choice in more and more cases every day:

High Reliability
Low Operating Costs
Environmental Benefits
Modularity
Low Construction Costs
Case Studies

High Reliability.
PV cells were originally developed for use in space, where repair is extremely expensive, if not impossible. PV still powers nearly every satellite circling the earth because it operates reliably for long periods of time with virtually no maintenance.

This PV-powered water-level monitor will operate reliably for several years with little or no maintenance.
Like many of the lighthouses around the coast of NZ (solar modules supplied by Cope's previous company, C+I Solar), they are only visited on a yearly basis, and therefore must be reliable!

Low Operating Costs.
PV cells use the energy from sunlight to produce electricity—the fuel is free. With no moving parts, the cells require little upkeep. These low-maintenance, cost-effective PV systems are ideal for supplying power to communications stations on mountain tops, navigational buoys at sea, or homes far from utility power lines.
Once installed, PV power systems can operate continuously with little upkeep and minimal operating costs—a great benefit for this telecommunications station.
NZ Police has a dedicated telecommunication system that runs from one length of the country to the other. Designed for use in any emergency - able to operate at anytime - day or night, any time of the year - winter or summer. Absolutely no local power in some of the extremely remote places Cope has helped them install these in.

Environmental Benefits.

Because they burn no fuel and have no moving parts, PV systems are clean and silent. This is especially important where the main alternatives for obtaining power and light are from diesel generators and kerosene lanterns. As we become more aware of "greenhouse gases" and their detrimental effects on our planet, clean energy alternatives like PV become more important than ever.

Energy for our children's children's children [ TOP ]

What will the world's energy use be like in the future? Well, we can be pretty certain that electricity use will grow world-wide. The World Bank projects that the world's electricity use will increase to 5 million megawatts by the year 2020, up from about 2.9 million in 1995. However, the world supplies of fossil fuels – our current main source of electricity – will start to run out from the years 2020 to 2060, according to the petroleum industry's best analysts. How will we meet those electricity needs? Our best answer could be renewable energy. Shell International predicts that renewable energy will supply 60% of the world's energy by 2060. The World Bank estimates that the global market for solar electricity will reach $4 trillion in about 30 years. Biomass fuels could also replace gasoline. It is estimated that the United States could produce 190 billion gallons per year of ethanol using available biomass resources that exist already in that country. And unlike fossil fuels, renewable energy sources are sustainable. They will never run out. According to the World Commission on Environment and Development, sustainability is the concept of meeting "the needs of the present without compromising the ability of future generations to meet their own needs." That means our actions today to use renewable energy technologies will not only benefit us now, but will benefit many generations to come.

As we begin to realise and respect the fragility of our planet's ecosystem, clean power choices like PV become extremely important. (Photo: NASA)
Modularity.
A PV system can be constructed to any size based on energy requirements. Furthermore, the owner of a PV system can enlarge or move it if his or her energy needs change. For instance, homeowners can add modules every few years as their energy usage and financial resources grow. Ranchers can use mobile trailer-mounted pumping systems to water cattle as the cattle are rotated to different fields.

The Florida Solar Energy Centre (FSEC) demonstrated the modular benefits of PV
after Hurricane Andrew in 1993. FSEC employees deployed this PV emergency power system right at the point where it was needed after the hurricane. (Photo: FSEC

Low Construction Costs.
PV systems are usually placed close to where the electricity is used, requiring much shorter power lines than if power is brought in from the utility grid. In addition, using PV eliminates the need for a step-down transformer from the utility line. Less wiring means lower costs, shorter construction time, and reduced permitting paperwork, particularly in urban areas.

What does clean energy have to do with me?

As a homeowner?
By using renewable energy and energy-efficient technologies in your home and automobile, you'll help the environment and typically save more money in the long run.
As a small business owner?
You can reduce your utility bills and impact on the environment by using renewable energy and energy-efficient technologies. There are also small business opportunities in clean energy.
As a student or teacher?
You can benefit from learning about renewable energy and energy-efficient technologies, and how they can help our environment and replace fossil fuels, which are being depleted.
As an electricity provider?
There are many renewable energy technologies available for electricity production, as well ways you and your customers can save money through energy efficiency.
As an inventor?
There are many opportunities available to inventors of renewable energy or energy-efficient technologies.

Quotable

[ TOP ]

Thomas Edison once said of time, "that you never have enough, you can't replace it, and you can't spend it too wisely." The same can be said of energy. We, your humble servants at Sunpower Co, believe we're doing our part toward an energy conscious world. We're always open to a better way...let us know.

Home	Write to: 60 Ernie Pinches St, Auckland Phone 64 9 6272 089 Fax 64 9 6272 087
© Copyright 2000 Sunpower Co & Venice Trust, except where noted. All rights reserved.

-Last revised-Wednesday, 23 May 2001

S & R Cope design