Solar FAQ

Solar energy is supplied directly from sunlight in the form of either heat or electricity. It is arguably the best type of renewable energy available due to its versatility, consistency, and seemingly endless supply. Solar energy is absolutely free and readily available.

It can be. Depending on your energy needs, the cost of a complete solar PV system can range anywhere from 6,000 to 30,000 USD. Solar thermal systems tend to be a lot cheaper, but a complete split solar thermal system can still cost up to 4000 USD. However, one must bear in mind that the energy is FREE and you are really prepaying your future energy bills by investing in the solar energy system. Also, many countries have adopted different formats of feed-in tariff (FIT) for grid-tie PV systems. These FITs are basically buy-backs of electricity from grid-tie PV systems to the utility grid and can mean substantial savings on energy bill. Similarly, solar thermal systems also have other forms of subsidies like cash rebates. The details of these incentive programs will influence the payback period of your investment. Please check with your local installers or utility company for more information regarding renewable energy incentives.

Clearly the location of your site and the local climate are the most important factors to consider. Are you getting enough sun? Do you experience subzero temperature in winters? These ambient conditions are important in determining the performance of your solar system. If you are concerned about finance, you should also find out if your country offers any feed-in tariff or other incentives for solar energy systems. Most importantly, make sure you hire experienced installers who fully understand your energy needs so they can design an efficient system.

The amount of sunlight (insolation) is generally expressed as kWh/m2/day. Basically it measures the amount of solar energy that falls on a square meter of earth’s surface in a single day. For most parts of the world an annual solar insolation value of 5~6 is considered very high. For a complete list of global insolation values please see here for more information.

Photovoltaic modules are typically made up of crystalline silicon cells and they also contain small quantities of other atoms, usually boron and phosphorous, to create silicon layers of opposite electrical properties. The positive and negative silicon layers, upon exposure to sunlight, will create and separate the electrical field between the layers. This will give rise to voltage difference, creating electrical current flow. The produced direct current can be either stored in a battery bank for off-grid PV systems, or be sent back to utility for grid-tie PV systems, provided that loads are satisfied.

There are 3 main types of solar PV systems: Grid-Tied Solar Systems, Off-Grid Solar Systems and Hybrid Solar Systems. Grid-tied solar systems generate electricity from solar panels and via DC/AC inverters, supply power directly to loads and local utility grid. The difference between grid-tied and off-grid solar systems is that off-grid systems do not supply electricity to grid but instead store energy in battery banks. However, for those who wish to stay off-grid but still want to enjoy the benefits of guaranteed power supply from utility, hybrid solar systems would be the best solution.

Small off-grid PV systems usually carry a system voltage of 12, but some can carry 24V. It is common for larger PV systems (larger than 3KW) to have 48V. As a general rule of thumb, the most efficient way to run an electrical circuit is to keep your voltage high and your current low. Higher voltages will ensure the loss of energy in cables to a minimum. This is also financially beneficial as higher voltages allow you to use cables of smaller diameters, which can mean substantial savings in cable cost.

You will need to determine the personal energy requirement first and see if this requirement can be met by installing a financially-affordable solar PV system. Environmental factors such as location and E.S.H. (equivalent sun hours) of the site are also important considerations. The process of assessing a suitable solar PV system is best done by qualified and experienced solar installers as they will need to do a detailed survey of the site and also understand the energy requirement before a sound recommendation can be made.

It is not very difficult to calculate the payback period on a solar PV system, but one can only do best approximation as it is impossible to predict economic factors such as inflation and future cost of electricity. The simplest way to summarize this is by first finding out the net energy saving per month (in currency) after you installed the PV system. For off-grid PV systems this is easier to do as you do not need to consider factors like FIT in a grid-tied system. By dividing the cost of the PV system by the net monthly energy saving you will get the approximate payback period on your system. One thing to keep in mind is that energy bills are likely to escalate with time so adjustment may be necessary.

Without going into too much detail, a grid-tied system generally consists of PV modules, a PV combiner box, an inverter, cables, and a DC disconnect/isolator. A typical off-grid system, in addition to these components, would also include a solar charge controller and battery banks.

The most common PV modules available commercially nowadays include amorphous PV modules, polycrystalline PV modules and monocrystalline PV modules. Amorphous modules are the cheapest to manufacture but also are the least efficient of the three. Monocrystalline modules are made from multiple smaller solar cells, each made from a single wafer of silicon crystal. These are the most efficient PV modules available today, with efficiency between 14 to 20%. Polycrystalline are similar in production to monocrystalline modules, except that each cell is made from wafers of silicon crystals. Their efficiency typically ranges from 12 to 16% and are usually about 20 to 30% cheaper than monocrystalline. The choice over which module to use is really a personal one but for most applications, polycrystalline modules offer the best package with good performance at reasonable cost.

It is strongly recommended that for solar applications, deep cycle lead-acid batteries are used. These batteries are very durable and can sustain many cycles of battery discharge. One must pay attention to the DOD (depth of discharge) when using batteries. Deep cycle batteries typically have 80% DOD, though it is recommended to use a lower DOD value as this will prolong battery life. When selecting a deep cycle battery, it is better to choose a type that is maintenance-free. We carry AGM/gel batteries that are maintenance-free. Please contact us if you would like additional information.

Modified sine wave inverters are the most common (and cheapest) type of power inverters on market, and the squared power wave they produce are generally suitable for most devices. However when using certain specialized equipment such as fax machines, laser printers, and electric shavers, the squared wave form due to incompatibility may cause the equipment to function incorrectly. True (or pure) sine wave inverters are those that produce a perfect, smooth sine wave under an oscilloscope and will not have incompatibility issues with equipment. True sine wave inverters are also more expensive than the modified sine wave inverters, usually by 50 to 100%

For off-grid applications, solar charge controllers are needed because electricity generated from PV panels needs to be regulated and managed before they get stored in battery bank. The main functions of solar charge controllers include charging the batteries, protecting PV module from reverse battery current at night, protecting batteries from overcharging/over-discharging etc. Some solar charge controllers are more sophisticated in design and may include light control and data-logging functions and MPPT (maximum power point) tracking capabilities.

Unfortunately, solar PV systems are critically limited by the efficiency of the solar panels as the best panels available commercially now are only about 20% in efficiency. While there are new technologies that are constantly being introduced – such as CPV (concentrated photovoltaics – they tend to be quite expensive and therefore difficult to adopt. The total system efficiency is calculated by multiplying the efficiency of each individual component like inverters, cables, controllers, and batteries. Nonetheless, the current silicon PV technology is the best available and a well-designed PV system can still do a great job in meeting your energy requirement without much difficulty.

Yes. All of our products are CE certified.  While CE is mainly regarded as a European standard, many countries also have standards which are similar to it that involve the same sets of testing in the areas such as EMC (electromagnetic compatibility). These are necessary to ensure the safety of equipment during operation.  On our line of Grid Tie inverters, where country specific regulations are required in order to connect to local grid, our products has additional certification such as VDE0126-1, G83, etc.