600 W MPPT Grid Tie Inverter for Solar, Wind Turbine

Introduction

Of all the different kinds of renewable energy available today, solar and wind are the two most popular ones favored by homeowners due to their relatively easy implementation and wide range of suitable sites. However, these green energy sources do not come with a plug to connect to a wall socket (the grid). Even if they do, there are different parameters for each type of renewable energy and interconnecting with the grid would present a challenge.

Fortunately, grid-tie inverters have been invented to solve this interconnection problem. "What is grid-tie inverter?" you asked. A Grid-Tie Inverter is a device that that can transform 12V DC electricity (i.e.: Solar Panels, Wind Turbine, Battery Storage) into 120-240V AC power that can be directly injected into your utility's electricity network (the power grid). However, the down side is, most inverters available in the market today are in the high output (1000W ~ 5000W) category. Their prices range in the thousands and it is just too much of an upfront cost for anyone interested in green energy generation. In addition, because of the high output, a certified electrician will need to be hired to install the equipments and connect the cables

"But I am a small home owner. I would like to start small and test things out and perhaps expand my system in the future if I have the money. I would also like to DIY to cut down on cost and have a project that I would be proud to work on... isn't there an easier and more affordable way to do this?"

Yes, there is. With our latest developed micro grid-tie inverter Grid Power 3 feature the popular plug and play function, you will be connecting your renewable energy sources into the grid and join the green movement in no time. Start small. Think Big. A Greener future awaits.

What's New in the 3rd Generation?

So you ask, "What's new in this third generation?". Well, by reaching the 3rd generation, we have again improved the power output by incorporating Maximum Power Point Tracking (MPPT) technology to harvest more solar energy. The inverter has also utilized better surge protection components to shield against voltage spikes and energy surges. In addition, this inverter will work with our SolarWind Hybrid RX charge controller to allow wind energy input. Here are the high lights:

Maximum Power Point Tracking (MPPT):

What is Maximum Power Point Tracking (MPPT)? MPPT is a techinque we implemented to get the maximum possible power from a solar panel. When trying to characterize the output of a solar panel mathematically, it can be represented by an IV-Curve (shown below). The equation for Power is P = IV. Where I is the Current, V is the Voltage, and P is the possible output Power. Each point on the curve is a possible combination for output power and our goal is to find the best combination to obtain maximum power.

In simple terms, we are trying to get the biggest rectangle to fit under this so called IV-Curve, the bigger rectangle we can fit, the more power we get. Below are graphs to help you understand the idea better. This is a comparison between inverters with and without MPPT on an 85W solar panel. Please note that different solar panels will have slightly different IV-Curves.

No Tracking Vs Tracking

Figure 1 No MPPT, with voltage fixed 17.5V P = 17.5V x 4.6A = 80.5W	Figure 2 With MPPT, amount of current and voltage to draw are calculated P = 17V x 4.95A = 84.15W

As we can see, Figure 2 is able to 84.15W with MPPT while in Figure 1, we can only get 80.5W. This is 4.5% increase in power output. Why do we care? Because solar panels are still quite expensive these days, and the increased power output will directly affect our return on investment (ROI). In addition, depending on weather, time of the day and amount of solar irradiation the panel receives, the IV curve will move along the Y-axis to reflect the possible increase / decrease in potential power output, and cause the maximum power point to shift along as well. Coming up are illustrations to visualize this idea.

IV-Curves Under different weather conditions

		Figure 3. Sunny, Clear Sky days in Summer 600 ~ 1000 W/m2   No MPPT MPPT Power 80.5W 84.15W Color Red & Yellow Yellow& Green Percent N/A +4.5%
		Figure 4. Scattered Clouds or Partly Cloudy days in Summer 300 ~ 600 W/m2   No MPPT MPPT Power 42.0W 46.4W Color Red & Yellow Yellow& Green Percent N/A +10.5%
		Figure 5. Cloudy or fog days, dawn or dusk in Summer 100 ~ 300 W/m2   No MPPT MPPT Power 5.25W 14.25W Color Red & Yellow Yellow& Green Percent N/A +171%

Figure 3 - 5 illustrate the power gain in different weather condition with MPPT compare to a non-tracking inverter that locks voltage at 17.5V. While 17.5V is randomly chosen, it does show what would happen in real life when there is not MPPT. Studies have shown, by making use of MPPT, there will be an average of 30% increase in power production. Since the maximum power point is a variable, we have implemented a tracking algorithm that utilizes the micro processing power of our inverter to calculate the optimum voltage and current to maximize our energy harvest.

Increased Power Rating:

In 2008, when we designed the first generation inverter, what we had in mind was an inexpensive device to allow the public to have a chance to test out renewable energy production and promote the green movement at an affordable price range. As people's environmental awareness increased over the years, the demand for bigger systems also increase. Therefore, once again, the power of this inverter has increased by 50% to 600W.

Compatibility with GreenergyStar SolarWind Hybrid RX Charge Controller:

Want to grid-tie a wind system? Then it is time to get a charge controller. The GreenergyStar SolarWind Hybrid RX is designed to work with our grid-tie inverters for solar and wind applications. It offers the protection needed by inverters against volatile storms and unstable inputs. Compatible with solar panels, 12V AC / DC wind turbines, Southwest Windpower's Air-X, 403, 303 and SunForce's 600W wind turbines.

Enhanced Safety:

In this generation, we have utilized better surge protection components to shield against potential energy surges during connection or disconnection to the grid. Voltage spikes in night time or stormy weathers are eliminated with higher grade electronics. The circuit board has been completely redesigned to accommodate to the UL 1741 Standard and the status of our UL application is currently pending.