Calculate Solar Power Needs
Follow the Off Grid Project and learn how to calculate your own solar energy requirements. The following article will guide you step by step through calculating how many solar panels you need, how large a battery bank, what sized power inverter and what size solar charge controller. This website will be constantly updated as the project continues, so check back often.
Making your own solar panels is the first step. The next step is to calculate just how much power you really need. You can always make more solar panels as your energy consumption increases. When you start out off the grid, there will be a lot of changes in your household. One of these is watching your power use.
In the Off Grid Project, You will learn how much energy the average household appliance consumes. Learn how to make the calculations needed to figure out your total household energy requirements. Then learn how to put it all together.
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Solar panel output is actually lower than the manufacturer rated numbers under normal circumstances. Unless you have a sun tracker, an MPPT controller and the best of materials in your homemade solar panels, you can figure on about 30% of the rated performance. The Off Grid Project will show you how to increase those numbers.
For now, calculate 30% of your homemade solar panel's rating. This takes into consideration the cheaper glass or plexiglass used in DIY panels, heating of the panels and lack of expensive electronics. For example if your solar panel is rated at 100 watts, figure on about 30 watts output. Do not panic, we will raise these numbers later. But when you first install a homamade solar panel, do not be surprised at a much lower charging current than you had expected.
This also allows for clouds and partially sunny conditions. The sun does not shine 24-7. The sun is also not shining directly on your solar panels at all times. Depending on where you live and where you have the solar panels installed, you will get varying hours of direct sunlight. In the setting of The Off Grid Project the sun rises just after 5am in the summer, but is not hitting the solar panels until about 9:30 am due to mountains and trees in the way. The same goes for sunset. The sun sets around 8:45 but has already left the solar panels after 5:45 pm. That gives about 8 hours of full sunlight on the panels.
You can use the Free Solar Panel Requirements Calculator to calculate how many solar panels and what equipment you will need. Take note that this calculator shows the full manufacturers rated solar panel output. The link opens up to The Do It Yourself World in a new window.
Feel free to ask any questions or get help with your project on The Do It Yourself World Support Forum.