 How to design your own solar system- the basics manual
In a quick glance, the illustration above demonstrates the basic components of a simple solar powered - off-grid system. The modules are the power generators. The solar panels create electricity when exposed to sunlight. This is 12v current. The electricity generated is sent to the battery passing firstly through a charge regulator. The regulator makes sure your system is protected from over charging and discharging. Charge regulators comes in various forms and types. For instance with timers, with photocells proving customised jobs for any job needed. However the basic regulator has a job of protecting your system. These also usually have a battery state indicator providing visual information of your battery charge condition. And finally charge regulators almost all have 12v outputs for directly connecting , for example a 12v lamp. It is essentially vital when designing your solar system to specify. A - Your Load and how many hours you intend to use this equipment on a daily basis. This calculation provides us with a total of watt hours used daily. ('load' meaning equipment such as laptop, light bulbs, radio, tv, pump etc) B - How often do you need this power to be available and what autonomy ( backup ) do you need at one single time. Are you going to use the power daily or once a week. These factors have a heavy effect on what system you require. C - Finally the above will allow us to determine a basic overview of your system sizing. What battery bank is needed and what solar panel is need. Sizing a PV system Follow these these by step details to determine your requirements 1. Determine your power consumption demands Make a list of the appliances and loads you are going to run on your pv system. Find out how much power each item consumes while operating. Most appliances have a label on the back listing the wattage. | DC APPLIANCE | WATTS X
| Qty X
| Hrs/Day =
| Wh/Day X
| Days/Wk =
| Wh/Wk | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
|
| | | | TOTAL Wh/Wk
| _____________ |
Print out the table above and work out the following. ( example below ) WATTS X QTY X HRS/DAY = WH/DAY X DAYS/WK = WH/WK (appliance watts x qty x how many hours it will be on for = your total daily watt hour consumption. Then multiply your daily consumption by how many days per week = your watt hours weekly load for the appliance. Do this for all your items appliances and add the final total column. This is your DC power requirement. Please multiply x 1.2 to compensate for system losses during battery charge and discharge cycle. Sizing your battery Bank How much storage do you need? How many days of autonomy do you require from your solar system ? Consider your usage pattern and the criticality of your application. If you are installing the solar system in a weekend home, you might want to consider a larger battery bank because your system will have a full week or 5/6 days to charge and store energy without consumption. Again these are all down to individual needs and what a person wants and how much money you are prepared to spend. Batteries in solar systems should be deep discharge batteries. If not it will result in quick battery life depreciation. Deep discharge batteries can usually withstand a daily discharge rate of 80% the rated capacity. 1. Enter your daily watt hour requirement from your load chart. Divide this by 12. It will equal your Amp Hours Daily Requirement _______________________ 2. Enter the days of autonomy ( days with no sun/ bad weather ) you would like to withstand. ___________________ 3. Multiply the amp hour requirment by the days of autonomy required. This is the total amp hours needed in your battery bank storage. _____________________ 4 Multiply the above line 3 by 1.2 this represents your battery optimal discharge rate. In order to keep your battery above the normal discharge rate. Find out the sun hours in your area - In Malta you can use the guideline of 3 sun hours between November & February and up to 8 sun hours in peak July summertime. 5.5 to 6 sun hours is a good yearly average for Malta. ( these figures are estimates only ) Size your solar array ( panels ) under constructions
Shortly we shall be uploading a calculator for you to work out your energy needs and backup battery and solar module sizing. In the meantime you can email us your request at - david@sunsource.biz or view our demonstration basic solar kits on sale now online. |
