Economics
To Calculate the economics of a home Solar-Electric System,
you need to be aware of the amount of electricity per day you will need,
which is expressed in kilowatt hours per day (KWH/day).
You can calculate this information from the power needs of the lights and
appliances you have in a home or cabin, or, take your monthly electric bill and divide
the number of kilowatt hours consumed by the number of days in the month
to get the average daily usage for that month.
Electricity consumption does vary during the year. It would be best to add up a years worth of electricity used and divide the total hours by 365.
The average cost of a Solar-Electric system is determined NOT by the KWH/day produced by the system, but by the hourly capacity the Solar-Electric System can produce. Most Solar-Electric Systems in the Africa have an hourly capacity of approximately 2KW.
That means the system will produce 2 KWH for every hour of sunlight it receives. Assuming a minimum of five hours of Sun light, that’s 10 KWH/day or about a third of the electricity needed for the average home.
For most Solar-Electric Systems, pricing works out to be about $4 per watt, or $4000 per kilowatt of capacity. Depending on your system configuration, you may need batteries, controllers, and labor to install the system. These needs add around $5 per kilowatt for an approximate total of $9000 per kilowatt of capacity installed. Note that battery storage for these multi-kilowatt systems would add approximately 50% to the system cost.
Therefore a 2KW Solar-Electric System without batteries would cost about $9000, and a larger 4 KW system would cost around $16000. Now the addition of battery storage will increase the cost to about $18000 for a 2KW Solar-electric System, and the larger 4KW system would cost about $36000.
Next, calculate the approximate cost per kilowatt hour. Multiply the system’s minimum daily output (not its hourly capacity) by 365 to find its yearly output. Then multiply by 25 to find the output over the warranted life of the system. Divide the result into the systems total cost. So a 2KW and a 4KW solar-electric system would cost about 16.5 cents per kilowatt hour. If the system will receive more than 5 hours of sunlight a day, the system could cost around 12 cents per kilowatt.
For businesses, the economics will be especially cost effective when you figure the peak demand usage rates. A solar-electric system produces its maximum capacity during peak usage which would drastically lower energy consumption from your utility company.