We are always getting asked questions about how solar panels are actually integrated into the home to supplement your electricity usage or to replace your energy provider.
Here are a few typical questions and our answers.
Question: Why are commercially available panels so expensive?
There are lots of reasons but principally it's because the market is still quite small and there isn't yet a really competitive marketplace. Government solar rebates help reduce costs.
Question: How do I connect my panel into my home wiring?
Unfortunately it's not quite that simple. Never attempt to connect the solar panel into your home wiring yourself unless you are a currently registered electrician. The solar panel is part of a system consisting of a controller, batteries and an inverter.
You are generally allowed to wire up everything to the batteries but an electrician is needed for the rest.
Question: What do I need a controller, batteries and an inverter for?
A solar panel generates direct current not the alternating current used in your home. Further, the level of current generated varies in accordance with the amount of energy being converted by the photovoltaic cells in the panel. The controller regulates the power from the solar panel to the batteries so as to increase battery life or damage.
The batteries are the storage medium. You store energy during peak periods of sun light and consume the electricity from the batteries as you require 24 x 7.
The inverter is required to convert the direct current from the battery into alternating current at the correct voltage for use in your home.
Question: What does the controller really do?
The controller's job is to control the amount of energy going into your batteries so they don't over-charge or over-discharge. It's just like the voltage regulator in your car. As the battery approaches full charge, the controller slows down the rate of charge and significantly increases battery life. Without one you will need to manually watch the voltage on your batteries and connect and disconnect them from the solar panel manually.
Controllers are reasonably cheap to buy and there are plenty of DIY panel designs on the web. Just Google solar panel controller.
A basic controller simply monitors the battery voltage and opens the circuit and stops the charge when the battery voltage reaches a certain level. More complex controllers control the power applied to the batteries as the batteries get closer to full charge, so extending battery life. They can keep batteries in a fully charged state indefinitely.
The controller can also detect when no energy is coming from the solar panels and disconnect the panels to stop reverse current flow.
Question: Why do I need batteries?
Basically, they are the storage device to store energy from your solar panel until you actually need it. As the amount of energy converted by the solar panel varies during the day and night, the battery input charge varies. But the power stored in the battery is available to be used at any time, 24 x 7.
Question: Do I need special batteries?
Yes. Most solar panels require 12 or 24 volt batteries similar to what you find in cars.
You need batteries which can handle the deep cycle from fully charge to heavily discharge repeatedly over a short period of time. Car batteries are easily damaged if they discharge too deeply as they are designed to deliver a quick burst of power to start the engine. There are plenty of deep cycle batteries available on the market AND if your eligible for a solar power rebate, you may be able to include them as well.
Question: Why do I need an inverter?
Your home uses 110v (or 240v) alternating current. Remember this from your school days?
Appliances won't run off a battery as it is direct current. The inverter does the conversion for you.
Inverters are readily available on the web. Google solar panel inverter.
The inverter is powered by the battery as well but they are very efficient devices these days.
It is illegal for you to connect an inverter to you house wiring unless you are a currently registered electrician. And, your inverter must be an approved device so we don't recommend you make your own.
Question: Can I sell my excess electricity back to the electricity company?
The short answer is yes. The electricity company will change your power meter for a two way device which measures electricity being used by you as well as any electricity being sent to the grid.
But, we suggest you concentrate on reducing you consumption and saving yourself money that way.
There are some issues with selling back to the electricity company. They sell to you at retail prices but buy back at wholesale. So don't expect high prices. AND, the electricity you sell back must meet their standards which mean you may need special inverters and switchgear.
If you have any further questions check out our FREE newsletter on solar panels and building your own solar panels. We've done the research and our information is free - no catches!
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