## What does it take to solar power my home

Producing electricity by photovoltaic cells is fairly expensive compared to other types of generation. However, when considering the "cost" of solar energy, figure in all of the carbon emissions that you aren't producing, and the toxic waste that you aren't making.

We now know that solar cells can be used to generate electricity, but the problem is getting it in a form that we can use in our homes. Sure, it is possible to run a few simple bulbs from a DC supply, but to run most of our household appliances, we need to generate electricity in a form that is suitable for themâ€”AC.

You will notice that the output from all of our solar cells is "direct current" (see Figure 10-39). The voltage is always a fixed polarity with reference to 0 V. We can couple solar cells in series to produce a higher voltage, or in parallel to produce

Solar Power for Your Home

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Figure 10-40 Alternating current.

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Figure 10-39 Direct current.

Figure 10-40 Alternating current.

a higher current, but we are always going to end up with DC.

By contrast, in our homes, our appliances and devices require "alternating current," AC (Figure 10-40). We see how the AC waveform differs dramatically from the steady DC line. In the United States, the frequency of this AC supply is 60 Hz, in the U.K. it is 50 Hz, it is also at a higher voltage (120 V in the U.S.A., and 230 V in the U.K.).

So, how can we take the power from our photovoltaic cells, and turn it from "DC low voltage"

into "AC high voltage"? The answer is that we use an "inverter."

An inverter is a piece of electronics (Figure 10-41), which takes the DC supply from our solar cell and generates an AC waveform at the correct voltage and frequency for our items of mains equipment.

We need some extra devices for safety reasons, you will see in the setup that there is a mains isolator switch (as shown in Figure 10-42). This allows us to disconnect the mains from the inverter u

Figure 10-41 A typical inverter setup.
Figure 10-42 Mains isolator switch.

in the event that we need to carry out work or maintenance.

We also need to include a mains circuit breaker to protect against overcurrents or surges, which could be potentially damaging and dangerous. A circuit breaker is shown in Figure 10-43.

And in addition, we need to be able to isolate the DC supply coming from our solar array. A DC isolator switch is shown in Figure 10-44.

It is also interesting to see how much energy our solar array is producing. This can be useful for accounting purposes, say if we are selling the solar energy back to the grid, or simply to benchmark the performance of our solar system and see if it is in line with our design predictions. A watt hour meter is shown in Figure 10-45.

Figure 10-43 Mains circuit breaker.

Figure 10-44 Solar DC isolator switch.

Figure 10-44 Solar DC isolator switch.

Figure 10-45 Watt hour meter.

Figure 10-45 Watt hour meter.

Figure 10-45 Awelamentawe school solar display. Image courtesy Dulas.

Of course, if we have a solar array in a public area, it is also nice to promote solar technology to others, and our solar array is a powerful tool to educate others with. At this school in Wales, in Awelamentawe (Figure 10-46), a display is prominently mounted in the main reception, to show visitors, and help educate children about, how much energy the school's solar array is producing.

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## Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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