We recently looked into installing a solar power system and found the option to be riddled with limitations. That’s not to say we are turned off (LOL) but we are certainly having to make some compromises. Here are a few things we have found out that make installing photo voltaic panels.
Solar panels are an inefficient way of heating water. Photo voltaic panels vary in their output but in conversion of energy for heating water they are less efficient than a water-circulating solar water heater. In the photo voltaic panels solar energy is converted into direct current that is then converted into alternating current that we can use in our normal appliances and lighting. A solar water heater has water in pipes that are directly heated by the sun or reflection. The hot water is pumped or rises to the water tank and is replaced by cold water. The water circulates becoming hotter and hotter the longer sunshine is hitting the pipes somewhere on the heater. Unlike solar voltaic panels a solar water heater can work even if the sun is hitting the water pipes at a low angle. Solar voltaic panels need direct sun or at no less than 30 degree angle.
Location and position are everything. Living on a hill in Golden Bay, which has high sunshine hours and no pollution, we should be ideal for solar panels. Not only do we have no large trees shading the roof, we also have the bonus of a large body of reflective water to up the ante. Unfortunately in the middle of winter our sun is obscured by a slight hill until about 10am. This is when we would really want some input. However, not all is lost, because at the height of the day one roof would be receiving full on sunshine and the other, at a slight westerly angle, would receive sunshine at lesser levels. So position-wise we would be fine. Except that the size of the panels is such that we cannot fit enough of them to cover what we are currently using in electricity.
On-the-grid options. If we go ahead with solar we can supplement our power from the power supplier. This means that during times when sunshine is not enough to meet our requirements we can use and be charged by the power supply for the power we use. Conversely, when our solar panels and producing more than we need we can give back to the grid (and store up credits for power we later use). Sounds ideal! But it doesn’t guarantee us continuous power. If the power supply goes down, and it is known to do so in our rural retreat, we lose power even if our solar panels are producing it at the time. The reason is that power company workers will assume they are working with dead lines, and if we’re busily feeding back into the grid – zappo chappo. So the minute the grid goes down our solar energy generation stops too.
Off-the-grid options. Ah ha! So what if we went off the grid completely? First, the installation costs are more expensive and we would have to install a large bank of batteries to store enough energy to maintain our household systems when the direct solar input is not enough – at night and on wintery days, of course. From an ecological point of view batteries are not okay. They last about 10 years before they need to be replaced. Then they and their destructive fluids have to be disposed of safely.
So now we are looking at:
- Ways to reduce our current energy use so that panels would cover our power consumption
- Ways to combine a solar water heater with voltaic panels for other power
- Whether to change our stove to an all gas model (LPG has its own green issues)
- Whether to add a wetback option to our wonderful Metro fire that has considerably reduced our winter power use (we use it for slow cooking and boiling the kettle)
Just watch this space as we explore the options further
A good site to check out is the NZ Government’s energy website: http://www.eecabusiness.govt.nz/renewable-energy/solar
A further update:
We decided to go ahead and get some quotes for installing solar water heating. (See Post: Solar water heating gets the thumbs up).
One was for mounting on the roof and the other for mounting on a frame in the garden below the deck so it didn’t obscure the view. They were both going to take the best part of $NZ6000. Then we decided to take a look at the Consumer Magazine website report on solar energy.
Wow! Did that force us to take a second look at what and why we were planning to use solar energy!
There were several issues that Consumer’s report investigated. So sum up:
- The cost of installation may not be recouped before the solar energy system itself broke down and needed costly repair.
- Power/cost savings have been vastly overstated in many cases.
- The altruistic belief that by going solar you will have less impact on the environment from using fossil fuels is based on false assumptions.
The high-use times for energy, when coal and gas fired generation plants are used, occur in the evening and during winter (i.e. bad weather). These are times when solar panels are not gathering solar energy. And in New Zealand, at least, the predominance of water power generation means we have a low impact on the environment (if you exclude the social/environmental costs of flooded river valleys).
Ouch! All my arguments for using solar energy cut off at the knees.
Consumer actually recommended looking at other alternatives, e.g. installing a wet back on your clean-air burning wood stove. We have already installed such a wood fire and find it so efficient we use no power heating at all during winter. It’s not as instant, and we do have to buy and stack wood each year, but as that is already happening, adding a wet-back water-heating system to our existing fire seemed a good option.
On talking to the supplier of our original fire the cost of retro-fitting a wetback was $NZ335 plus the cost of plumbing. When I inquired of our local council I found that we didn’t even need to apply for a permit. The heat output loss on our 20kw fire will be about 3kw, which will not be significant as we often have to open doors to cool down the space. If your wood stove had a lower heat output (10-12kw) the heat loss would be a more significant percentage.
Solar is free energy. If we were off-the-grid we would definitely use it. But in the meantime we’re going to further investigate the wonders of a wetback. If you would like to see the Consumer report (it’s a pdf document) Click Here.