admin answers:

In terms of system design, you need to consider the load imposed on the supply. In your question you mentioned a figure of 1500 kWh per week. This seems very high. It represents an average of 35 amps being drawn from the supply 24/7.

I have a 4 bedroom house occupied by 2 adults and the minimum load, during the night falls to 0.8 Amps and peaks on some days to around 18 Amps for very short periods, the average through the day is about 2 Amps.

One kW represents a load on the supply of about 4 amps for 240 volt supplies and about 8 on 120 volt supplies Understanding the load that is being imposed on the supply will help you to decide the dimensions of the system you need.

For local power generation (micro generation) you can use wind or water turbines dependant upon location, and you can also use peizo electric generation (solar cells), all these are referred to as primary power. In addition to this you will need storage which is in the form of batteries.

To use the battery power you will need an inverter, which generates power at mains voltage from the low voltage batteries. Additionally you will need a regulator, which controls the charge/discharge of the batteries, and is essential for efficient battery use and economical battery life.

If your system is capable of generating power surplus to your requirements, you can sell this to your grid supplier for quite a reasonable return.

admin answers:

Hey Patrick, this concept has been around since about 1998 when it first surfaced in regard to solar panels. There was a lot of complaints that solar panels never earn back their, “Embodied Energy,” which is a phrase referring to how much energy it takes to mine raw materials, ship them to a factory, build the product, ship it to it’s destination and install it. To be honest, it is difficult to put an exact energy price on something like that, there are almost limitless variables, such as which mine was used, where it was shipped, how it is installed and used in the end, and so on. A non profit group called, Solar Energy International finally offered some grants to a few colleges to research this. In the end, they couldn’t come up with an exact timeline, but a range based on the above variables.

First of all, solar panels actually do repay their embodied energy some time between 1.5 and 6 years after they are installed. Virtually all manufacturers warranty their product to last at least 25 years, and typically they operate well beyond this time. Similar work was done later with wind turbines, and the results are very similar. The main difference being the range of payback time is wider, meaning it’s possible for a turbine to repay its embodied energy faster, like in less than a year, but it may take as long as 9 years. This is because shipping a utility sized wind turbine can take a huge bite into its embodied energy budget depending on how far it has to go. Solar panels can fit in the back seat of a good sized car, some wind turbines have specially designed hauling vehicles that might have to drive across the country, or across the street. But when you look deeper down this rabbit hole, you eventually learn that non of this matters, I’ll explain.

Electricity has been around since Thomas Edison nearly burned down his house running high amounts of current through bailing wires inside old mason jars, so it isn’t going away anytime soon. The question becomes, “What is the best way to produce it?” Let’s assume you build a 10 KW wind turbine, and put it alongside an efficient conventional power source, say a natural gas fired turbine 10 KW generator. Which will earn back its embodied energy faster? The answer is the gas generator never does. You have to remember that once you build a natural gas generator, coal plant, or any other non renewable energy based power plant, you now have to feed it fuel for the rest of it’s life. It’s conversion rate will always be something below 100%, so in the end it slowly digs itself a deeper and deeper energy hole that it can never crawl out of. At least the wind turbine has a chance to get even in it’s lifetime. This is the key to what makes renewable energy so great, it’s really the difference between buying a home and renting an apartment, one day the home will be paid off, the apartment never is.

We live in a home that is powered by the wind and sun today. About 12 years ago we started looking into solar and wind when our electricity was constantly going out. It began as a small backup plan, just to run a few lights and some electronics. Over time it became more of a hobby and lifestyle, like growing your own tomatoes instead of buying them at the store, we just grew electrons in our garden. Now our home generates over 90% of its own electricity, and we use the power company as our backup source. Even though it will take years to get even with the power bill, it’s worth it to us, and we’ve turned a lot of heads. Once each year now I am invited to the local schools to teach solar power to the 5th graders, then they run a field trip out to our house to see a working solar and wind powered home. Since then the power companies have been busy building wind farms and looking into solar, geothermal and biomass energy. They even have a methane plant alongside a landfill in the next county. Most people are not aware of these things, but they are happening. They are busy complaining about wind mills never earning back their manufacturing energy, solar being too expensive, or hybrid cars not really saving and gas. There is research on these subjects, and it’s available for the asking if you look for it online. My suggestion is you look into it and become better informed insteading of asking hacks like me online for advice. I’ll include some sources below. Hope this answers your question. Good luck Patrick, and take care, Rudydoo