Solar Power and Zero Energy Balance in NZ

Last week I had a look at whether using a grid connected PV system for generating solar power is viable for NZ homeowners. The short answer is yes. Five years ago I had a look at some of this in a post called How to Survive Peak Oil by Acting Locally – 7 ways.

Back then in 2007 I noted that Germany had achieved great success in renewables and especially solar.

“There are now 250,000 jobs in Germany in the renewables energy sector. Asbeck expects the number of jobs in solar power alone to double to 90,000 over the next five years and hit 200,000 in 2020.”

Compare this with actual results in Nov 2012 – from 250,000 jobs in ’07 to 382,000 now is impressive.

“Germany’s boom in renewables created a growing industry that has a $16.9 billion annual turnover and employs 382,000 people, many of them in the economically depressed, rural former East. Investment in renewable energy plants reached an all-time high of $31.2 billion in 2011.

Since the production of wind and solar power is largely free of costs once initial investments in infrastructure have been made, one day Germany will have rock-bottom energy prices compared to economies still addicted to fossil fuels and nuclear energy. With “peak oil” days already behind us, and an expected subsequent rise in fossil fuel costs as supply dwindles, this day of comparative advantage may come sooner rather than later.

In addition, Fell claims the energy transition has helped Germany weather the recent economic crises so well. The renewables boom benefited not just major industries like steel, but actors along the value chain: craftsmen, planning offices, financial firms, mutual funds, farmers, and engineering and construction companies, among others. The key to its success is not government subsidies or central planning, but rather a small surcharge tacked onto consumers’ energy bills. This feed-in tariff model is, for Fell, essential to combating climate change.”

In comparative terms NZ and Australia have a lot more sunshine than Germany and most parts of Europe. We don’t have the visionary legislative framework or quite the same incentives since we have been lucky so far with hydro as a source of renewable power generation but that can’t last.

Come on NZ policy makers – we need to do much better on encouraging clean and green technologies especially ones which improve our net energy capability. I wonder if solar, wind and tidal power generation might be some of the innovation drivers which can power the NZ economy in the next century or so?

While updating the NZ situation I came across the ZEH – zero energy house project which shows clearly that New Zealand policy makers need to be thinking about energy use for future buildings.

The ZEH project looks at the total energy balance in the home and shows how in practical terms design changes can be made in the building process to minimise energy usage for heating and lighting and then electing optimised systems to then generate power to minimise drawdown from external electricity sources.

Here are 3 of the big changes they have made.

  1. Building envelope design. The shape and construction methods used will eliminate the need for any heating. This normally accounts for around 30% of a standard home’s energy use (and bill).
  2. Solar hot water heating. Most of the hot water needs are provided by a roof mounted solar system. The system being used is made in New Zealand and reduces energy needs by a further 25%.
  3. Solar photovoltaic (PV) panels. It’s not unusual to see a solar panel bolted onto roof tiles in New Zealand. What’s unique about the panels being used on this house is that they are the roof tiles. 88 of them laid out on the north-facing side of the roof will provide the remaining 45% of energy.

Here is the graphic. They make an excellent point that in the UK by 2016 every new home built will be required to incorporate principles that are being used in building this house…


To read the full post go here

If you are building a new house your designers, engineers and architects should be across at least some of this.

If you have an existing house then to get a more specific evaluation of what can be done at you place it looks like. This is an actual paid service for NZ $195 that you can get now.

SunAudit on-site inspection and report – Not sure how much power your roof could generate?

What details do you need to consider in terms of roof mounts, council approvals, wiring and integration?  How can you reduce your current power bill?  Get all the answers with an on-site* SunAudit.  We will come to your property to assess your roof potential, wiring layout, energy usage from power bills and device auditing and produce the following documents:

  • SMA SunnyDesign or EnaSolar compatibility report
  • Solar Pathfinder shading analysis
  • Payback estimate and consumption model (before and after)

As a result of these post I have come across two other very good questions about the PV technology.

1.What is the energy payback for photovoltaics? – that is – how much energy is used in producing the panels and at what point do they start to pay back that energy balance.

“Energy payback estimates for rooftop PV systems are 4, 3, 2, and 1 years: 4 years for systems using current multi-crystalline-silicon PV modules, 3 years for current thin-film modules, 2 years for anticipated multi-crystalline modules, and 1 year for anticipated thin-film modules (see Figure 1). With energy paybacks of 1 to 4 years and assumed life expectancies of 30 years, 87% to 97% of the energy that PV systems generate won’t be plagued by pollution, greenhouse gases, and depletion of resources.

Based on models and real data, the idea that PV cannot pay back its energy investment is simply a myth. Indeed, research has found that PV-systems fabrication and fossil-fuel energy production have similar energy payback periods (including costs for mining, transportation, refining, and construction).”

2. This question is harder to answer. What about early failure of the PV panels and other delayed waste stream, environmental factors such as disposing of old panels?

From what I’ve learned current PV systems are more reliable than some of the early ones and with PV panel costs having reduced substantially in the last 25 years I’d say manufacturers should be able to cover any warranty claims more easily since replacement costs are cheaper. The technology efficiency is still improving and it does seem that new ways of making PV cells might also improve reliability and lifetime.

Most systems are estimated to last 20-30 years and with payback of 10 years or less then  that should work out. I did have a look at a paper on the end of life waste stream but it was from 1997 and not sure how useful that is now.

Depending on where you live – if your regular power plants are powered by fossil fuels there may also be a carbon saving as well as solar power to the home would reduce the amount of CO2, sulphur and other pollutants from typical power plants.

Maybe there is an argument for carbon credits as an additional benefit for householders.

A New Zealand business in Drury has 68kW system which is the largest grid connected system in NZ. For more detail on that project which is believed to have cost about $250k to install.

Solar power projects in New Zealand include the engineering plant, Hubbards foods and one plant in Queenstown.