Frequently Asked Questions for Solar

Solar Basics

Here you will find a set of Solar Basic FAQs.

Can the Sharp SHS Small Home System power my ceiling fan?

In a good day, the Sharp Small Home System can generate about 400Wh under direct sunlight. If your ceiling fan is 55W, it can run for about 6 – 7 hours.

Will solar work in my location?

Solar is universal and will work virtually anywhere, however some locations are better than others.

Irradiance is a measure of the sun’s power available at the surface of the earth and it averages about 1000 watts per square meter. With typical crystalline solar cell efficiencies around 14-16%, that means we can expect to generate about 140-160W per square meter of solar cells placed in full sun.

Insolation is a measure of the available energy from the sun and is expressed in terms of “full sun hours” (i.e. 4 full sun hours = 4 hours of sunlight at an irradiance level of 1000 watts per square meter). Do not base your solar product based on e.g. 6am in the morning to 6pm in the evening since production varies. We use sun hours as an average.

Obviously different parts of the world receive more sunlight from others, so they will have more “full sun hours” per day. There are also other deciding factors on site including the amount of shading the area is in.

What is Kilowatt-hour? How is it different from Kilowatts?

Kilowatts (kW) is a measurement of power requirements of an appliance. Kilowatt-hour (kWh) is a measurement of power usage in terms of kilowatts per hour. For example, a computer might have power requirements of 400W. Every hour that it is running will use up 400 watt-hour. That is 400Wh. If the system is left running for 5 hours, the total power usage is 400W x 5h = 2000Wh or 2kWh. This is also how the power utility company calculate your monthly electricity usage and bills you accordingly.

What components do I need?

There are many components that make up a complete solar system, but the 4 main items are: solar modules, charge controller(s), batteries and inverter(s). The solar modules are physically mounted on a mount structure ( and the DC power they produce is wired through a charge controller before it goes on to the battery bank where it is stored. The two main functions of a charge controller are to prevent the battery from being overcharged and eliminate any reverse current flow from the batteries back to the solar modules at night. The battery bank stores the energy produced by the solar array during the day for use at anytime of day or night. Batteries come in many sizes and grades. The inverter takes the DC energy stored in the battery bank and converts it to 230 VAC to run your AC appliances

How do I know how much power my applicance may need?

Power is measured in watts (W).  Power = Voltage (V) x Currrent (I) = VI

For applicances at home, its power ratings are normally in watts (W) or kilowatts (kW). Look at the labels of your appliance. Furthermore, check if it is a household running on alternate current (AC) or direct current (DC) power.

If your appliance do not have any labelling that tells you its power rating, do check out any  manuals, specifications or instructions that came with the appliance.

Can I use PV to heat water or for space heating?

No. Photovoltaics converts the sun’s energy into DC electricity at a relatively low efficiency level (14-16%), so trying to operate a high power electric heating element from PV would be very inefficient and expensive. Solar thermal (or passive solar) is the direct heating of air or water from the heat of the sun and is much more efficient for heating applications than photovoltaics.

Do I really save money if I install a solar electric system in my house?

No. Unlike US or other European countries, Singapore does not have rebates or any incentives program in place. The reason homeowners overseas can break even is because their governent offer up to 50% off the initial cost of a solar system. For example, for a 1kW system that costs US$12,000, the government subsidises $6000. The homeowner only pays $6000.

Therefore it is not feasible to consider installing a solar electric system to save money off your power bills. It is just not possible to get payback even after 20 years.

Still Clueless?

We recommend the following resources for your reference.

Renewable Energy Solutions
5 Book Deal – 1. Build A Wind Generator 2. Biodiesel 3. Install Solar Panels 4. Build Your Own Home 5. Renewable Energy Solutions For Home, Car And Business. Click here

Solar Power Design Manual
Teach Yourself All About Solar Power. Comprehensive Manual By Genuine Expert. Spreadsheet Included. Click here

Alternative Energy Resources
Offers An E-book Titled Understanding And Installing Your Own Solar Electric System. Includes Worksheets,& Resources. Click here

Build A Solar Pool Heater For Under $100.
Highly Popular Project. Click here

Solar Power Secrets.
Everything You Need To Know About Harnessing Solar Power To Save Money…and The Planet. Click here

How important is the solar panel efficiency?

It is not important at all! Contrary to what most consumers are led to believe, solar panel efficiency does not affects the power output from the solar panel. A more ‘efficient’ panel does not produce less power than a less efficient panel. We normally see efficiencies of 12-14% for crystalline solar panels and less than 10% for amorphous solar panels. However, this efficiency refers to how efficient sunlight is converted to electricity, this only affects the size or surface area of the solar panel.

Power output, on the other hand, tells you how much actual power is produced. For example, a 80W rated polycrystalline solar panel will give you the same power as a 80W rated monocrystalline solar panel. It is as simple as that. To a lightbulb, it does not matter whether the solar panel is 10% or 100% efficient. The lightbulb will work as long as 80 watts output is supplied to it, no matter what effeciency of the solar panel is producing it.

How can I justify myself using solar?

You want to install solar power systems not because you want to save money. But because you have a place or item that is located remotely and has no access to power grids. Or your region has power failures, blackouts or brownouts. You want a power source that is self-sustainable. Or you want to contribute towards zero CO2 emissions power consumption or you are an advocate of green and renewable energy.

How long will my solar system last?

A: Most solar panels come with a 25 year power output guarantee and are expected to last at least twice that long.  The power output guarantee on the solar panels in provided by the manufacturer of the panels and states that at the end of the 25th year, the solar panel will still produce a minimum of 80% of their original power output.

How big are solar panels?

Solar panels can come in all shapes and sizes. However, solar panels are normally rectangular or squarish in shape. For example, a 20W solar panel measures 650mm x 250mm. A 80W panel measures 1200mm x 530mm. Thickness is around 30mm. As a rough guide, solar panels take up areas of 1 square metre for every 120W.

What's the effect of rain and fog?

A: In fog,  the system will still produce about 25 – 30% of the normal production. A steady rain can cut production slightly but is great for cleaning your panels.

What is an inverter?

An inverter converts the DC (direct current) power produced by solar panels to common household AC (alternating current) power.

How will the weather affect the solar electric system?

Solar electric systems are designed to withstand most weather conditions. Lightning, wind up to 80 miles per hour, and extreme temperatures are all things your solar system can handle. However, these conditions may temporarily reduce its energy production.

What is solar?

Well, solar is the latin world for Sol which means Sun.