What is an on-grid or grid-tied inverter?

An on-grid solar photovoltaic system refers to a system, which is only connected to a utility grid.
When solar energy is available, the system will sell the energy which generated by the sun back to the utility grid.




What is an off-grid inverter?

A standalone photovoltaic system refers to a system, which is not connected to the utility grid.
The electricity you consume comes solely from energy generated via PV arrays. These types of systems store the surplus of energy in batteries.




What is an hybrid inverter?

A hybrid solar photovoltaic system is a combination of solar & grid power technology to take the most advantage.
If the energy produced via PV arrays is enough for household consumption, the inverter will use PV energy and charge the surplus to the battery.
Likewise, if consumption exceeds PV energy, the inverter will take extra energy from the utility grid.
In absence of sun, the inverter will, depending on energy consumption, use energy solely from batteries or take energy from the utility grid.




What type of system do I need?

To put it simple, it depends on your situation:

- Situation one: "My house doesn't have access to the national grid and I want electricity for my kids to have light to study at night."

In this situation, we would recommend you to get an off-grid Inverter with battery packs for sustained electricity at night.


- Situation two: "I have access to the grid but I don't want to depend on it in most time, since it's too expensive, meantime, the power backup system is also required."

In this situation, a Hybrid Inverter is recommended. On sunny days, you will consume the energy produced via PV arrays. This inverter also connect with batteries for power backup. PV will charge batteries as well.
Low PV power or at night, the inverter will switch it's input power source to the utility grid.


- Situation three: "Solar energy is most green solution, I want to use it to support my daily electricity, beside, the surplus solar energy can feed into utility grid for benefit.

In this situation, we strongly recommend our On-Grid inverters, because it can efficiently transfer PV power to utility power (0.96~0.99%).
During high-peak hours, the inverter will transfer solar DC power to AC grid power for daily electricity, meantime, the surplus solar power will be used to get compensated from local government or related benefit authority.
During off-peak hours, the inverter will come to sleep mode before the sun light appear.



What is MPPT?

MPPT (Maximum Power Point Tracking) is a key technology to harvest the maximum amount of energy from a solar panel.
As sunlight intensity varies depending on the climate, time of the day, and seasonal change, the output voltage and output current of the solar panel under the sun also changes.

The output power from a solar panel is the mathematical product of its output voltage and output current.

Typically, it takes a sophisticated digital signal processor (DSP) to try, sample, and calculate many operating voltage and current combinations before a maximum power point is identified. This kind of perturb-and observe MPPT algorithm is time-consuming and in many cases, may lock into incorrect operating point. In contrast, OPTI-Solar uses an advanced analog MPPT algorithm. It does rely on conventional perturb-and-observe time-consuming method. It locks in the maximum power point in less than 1000th of a second. With this ultra-fast MPPT algorithm, the solar charger can spend 99.9% of the time charging the battery and harvesting the maximum power possible from the solar panel. It uses only 0.1% of the time updating the present sunlight condition and re-calculate the maximum power point. As illustrated below, solar MPPT can track the maximum power combination of 17.2V and 5.8A(99.7W). Charge controller without MPPT can only obtain power combination of 12V and 6.2A(69.6W).



What is PWM?

Pulse Width Modulation (PWM) is effective means to achieve constant voltage battery charging by switching the solar system controller’s power devices.
When in PWM regulation, the current from the solar array tapers according to the battery’s condition and recharging needs.

When a battery voltage reaches the regulation point, the PWM solar charger slowly reduces the
charging current to avoid heating and gassing of the battery, yet the charging continues to return
the maximum amount of energy to the battery in the shortest time. The result is a higher
charging efficiency, rapid recharging, and a healthy battery at full capacity.

PWM solar charger will benefit you receive more solar energy acceptance and keep your battery longer life span.



Why would I need an external solar charger?

Solar chargers are required for higher charging capacity, max efficiency and customized functions solar systems.
It also regulates the voltage/current sent to the battery to prevent it from overcharging.
Usually use it when you want more solar energy.