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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 Siemens Solar 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 20th century – to hopefully change to efficiency in the 21st) went up, we then added more of them! We now have 21x 48 watt Siemens Solar 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. so 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. (See photo on RHS)
You can clearly see the different construction methods of the two technologies here. Single crystal sawn cells, verses 'sprayed-on' amorphous technology using 1/300th 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
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.
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 used (SW3024E - 3kW, 24VDC input, 230VAC @ 50Hz output. It is the large white rectangle box on the wall in the photo on the RHS).
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 2nd 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
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.
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.
Freedom From Running Ugly Power Lines To Your Rural Property / LifeStyle Block...
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? First come and visit us here at the solar energy house in Auckland. If you are not coming up to Auckland then contact us and we probably know of a local in your area (within NZ) who can offer good advice, and also take the time now to learn about the individual companies we used to make the solar energy house a pleasure to live and work in! These companies typically have representatives or branches in a town near you. If you are overseas, then contact us as a number of my old business associates in the renewable energy field regularly travel overseas to provide consulting and project work.
Continuing The Story About Our System At Our Old House in Mt Roskill, Auckland...
Solar Energy House C/- Simon & Kristina Cope | 19 Manapau Street, Meadowbank, Auckland 1072 | New Zealand | Contact us now to arrange your tour
We were the first NZ users of Solahart's integral 'gas booster' technology. It fitted like a test-tube into the core of the cylinder on the roof in place of the traditional electric element booster.
We were 110% happy with the Solahart system on our place! In fact so happy that when we moved we had it put on my parents Sam & Robin's roof in Kohimarama where it continues to provide oodles of hot water for them every day of the year :-)
4 PC controllers on the wall, with Trace Engineering SW3024E inverter. A beautiful piece of machinery!
How The Grid Intertie System All Goes Together...
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.
Click here to continue reading more about our original solar powered house in Mt Roskill, Auckland where we lived from 1990 to 2004...