Monday, 24 March 2014

Tones Of A Winter - Inverter Sizing

Tones of A Winter – Inverter Sizing

Continuous Thought

Deanna had called for me from the Sierra’s and asked me whether I liked the photographs of the Solar Energy System she had sent me, “Doesn’t it look pretty sitting on top of the tiled roof?”
Once the conversation began, it never stops for both of us and she had just stopped short of asking me that critical question, whether I was monetarily doing well in my country now. “There is a depression around these parts and more so when one goes to the consumer market.”

I could sense this urgency in her to tell me something,
it was her boyfriend back in Reno and I waited for more, though she spoke more eagerly about the Solar Energy System.  Here life was going through a crisis today, it was obvious, and to me as somebody who had always relied on her for advice this was a abberation, I had grown to like her a lot in those early days of friendship, till it had evolved into a peer bond that was ever lasting.  I laughed at the irony of things, after all I was just a country boy compared to her sophistication, and had never occurred to me that she was herself human and not super being.

“I want you here with me,” she had spoken urgently, there had never been a hunger for money in me, it was always the love of people that had driven my life and she had told me to live the life that I thought was mine.  So I started thinking on these lines soon as I put the phone down, whatever I was doing here, I could very easily do there and her voice with all the connotations and tones always had me sensitive to her point of view, especially so today.

Those days I would sit on the balcony of the house which had its north side built in concrete and pretty windows on the South side and sip cups of tea, it had been a beautiful winter, especially when the Sun shone on the snow covered plains, suddenly those floods of the past seemed to have come back to her and as human beings we are borne to believe that the illusion would last forever, probably she was more aware than anybody else that nothing seemed to last forever.

“I am game,” I said eagerly, anybody overhearing this conversation might have thought of it as pillow talk; these were just two friends talking about a future that could be mutually beneficial to each other.  It was the symbiotic relation between the Sun and the Solar Equipment, when they exchanged roles to understand each other and learned from the mutual intensities.

“Sometimes She Was Me, but Mostly I Was Her.”

The Surge of Memories

Deanna’s house was ready and the specifications were as below, what was the rating of the inverter we would have to install in the system to handle existing watts and surges in equipment especially when they start:

Inverter Sizing

There are two ways to tie an inverter, off grid with a battery and grid tie without the battery.

Off Grid

For Off Grid Inverters, simply add up the Loads, Base Loads of
equipment and add  cumulative Surge Load values.  In our previous example as seen in the table to the right, the Load Watts were 675 watts.

Design criteria for the Inverter include:

1.     -Surge Load which could include Clothes Washer, Refrigerator or other such equipment, remember not all household equipment surge
2.     -Surge requirement is calculated by simply multiplying the Total Watts of the equipment by 3
3.     -Also compare the surge rating of an inverter with the surge requirement of an equipment
4.     -Match the inverter input voltage with the nominal battery voltage, while choosing the desired AC volts at 120VAC or 240VAC

So from our example of above, the Total Load Values for the inverter can be defined as follows:

Final Inverter Ratings

Minimum Inverter Continuous Rating
675 Watts Total AC Loads
You could round this to 700 Watts or two inverters with 350 Watt rating

Minimum Surge Rating
(250W refrigerator) x 3 + 100W Base load = 850 W Surge Rating

Desired AC Output
120 VAC

The Inverter model chosen should also have input voltage of 24 VDC to match the nominal voltage of the battery banks of our example.

            “Did You Think Of Me at all, or Just Let Your Dreams Fly”