Determining the power requirements of your home is the first step in the planning phase for a new home solar system. It is important to install a system large enough to take care of your needs, but if your system is too large, you are wasting money since the power company may only issue credit up to the amount of your annual usage. Of course, if you live on the grid, you can just look at your utility bill and find out how many kilowatt hours of electricity you used for the month and divide by number of days to get your daily usage. I suggest you go a little further than that because you are making a big investment in time and money to get this project done. Most people have never taken the time to analyze their usage, and generally waste a lot of electricity. You really must look at ways to save energy because it may be possible to significantly reduce the size of your solar system.
Save Energy and Money by Installing the Right Size System.
Now is the time to analyze each appliance and your lighting to see if you could improve your usage numbers. Your refrigerator may be older and not an Energy Star version. Is your air conditioner or dryer older? It would be cost effective to replace these and not plan for their current energy use. You might even consider switching some of your appliances to natural gas since this is a much cheaper source of energy. Have you switched your lighting to the new compact fluorescent bulbs and put your televisions and other electronic equipment on power strips so they are not always drawing power. Contact your Power Company and see if they can help you with an energy audit. Most utilities are only too willing to help since they can avoid the capital investment in new plants if they can help customers save electricity usage.
Calculate Watt Hours Usage for Your Home.
If you are planning a battery back-up or off grid system, you must tighten up your planning even more because the additional cost of battery systems makes it even more important not to over build your solar system. The best way to do this is to make a table listing all electrical items in your house, the number of hours of usage and the watts per hour consumed for each item. Thus you can calculate the watt hours of energy consumed for each item and find the total watt hours required for your house for a day. Building this list will also help you in your energy audit since it will highlight exactly where you are using electricity so you may make some additional changes to your usage.
Once you have arrived at the final figure for watt hours usage, you must adjust it for the inefficiency of a solar system. since batteries will only operate at 95% efficiency, and inverters operate at a 90% efficiency. Once these adjustments are made, we are ready to go to the next step which is to calculate how many watts of power your solar system will produce in your location.