Managing Energy

We have an alternative energy power system installed in our place and every now and then people ask questions about it. This page answers some of the questions we get asked. Please send any questions you might have. If I’m unsure of the answer, I know how to find the answer.

Solar Panels

Is the system commercially installed?

Connection to the grid and to household wiring needed to be done by a licensed electrician. The rest we did ourselves.

Where did you buy the system?

We used a local solar power electrician for the grid connect and the other system components we bought on online auctions.

Did you have a plan to design the system?

The design evolved over time based on the outcomes of what we experienced with the system. We achieved this by keeping a log of the outcomes of the system. Compared to other off grid systems, we believe we have done better. I think this is because of less polution where we are, high elevation and cold climate (solar panels work best in the cold.) Designing this systems was something I felt capable as I have a background in electronics. Others may need to hire a consultant to help design the system. Don’t be afraid to ask for help!

You have more space because you live on a farm, so how would it go on an urban house?

Your local council will help you with the development rules which will guide you on how many panels you can put up. If grid connected, your local power supplier might place limits on the maximum you can feed back into the grid. A professional solar consultant can give you assistance in doing this.

How does grid connection work? Do I need to hire a professional electrician to connect it up?

Yes, all work involved in connecting your system to your house and the grid needs to be done by an electrician. Also you will need a contract to supply electricity to your electricity supplier. It’s best to hire a professional solar consultant to see if they can do a deal for you.

How do you receive a power rebate or at least a reduction in your bill? Is it based on your power meter reading?

When you connect a solar system to the grid, they install a special meter that measures what you consume minus what you sell to the grid. Off grid power is not counted by the meter. Our freezer is powered by a separate inverter. Connecting your system to the grid is the cheapest method but we decided to have both a grid connect and independent system. Many farms have generators as a back up too. Some local farmers aren’t even connected to the grid. The grid was only built to our area in 1975 and many had off grid systems in place before then.

How much battery storage do you need per panel you install?

You need to do research on this. You need to measure how much power you need, a good starting point is to take power meter readings daily. Plus work out the consumption of each appliance in your house. There are cheap meters that can measure one power point that can be used for individual appliances. To have enough capacity, plan to have three days storage at a minimum. This will carry you through cloudy days. Our freezer consumes 1.5 kWh each day to keep our goods frozen during summer days. So you need 400 ampere-hour of storage to get the freezer through three days.

Now we need to work out how many panels we need to maintain charge in the battery, not just for night time use but also to last through three cloudy days. There are many factors affecting this, the angle your panels are pointed at, the distance you are from the equator, trees, clouds and smog. My 380 W of panels makes 2.5 kWh on sunny days during the summer at 860 m elevation, in the country and panels pointed to the north. It would take two days to recharge the battery without turning on the freezer. From these facts, more panels will be included in the system in the future. Also during extended periods of cloudiness, we’ll turn off less useful loads.

How are your appliances connected to your battery?

We have two inverters set up. One is a pure sine wave inverter for running our electronics in our office and the other is a less expensive modified sine wave inverter for power tools. When we use power in the shed, we just use an extension cord.