## Blog

### How to Set Up a Small Solar Power Generator

1 Decide how much power you need.

To do so, determine which electronic devices you would like to use, then find out how much power they use. Most devices have wattage ratings, which can then be multiplied by the number of hours of use to produce Watt-hours (Wh), which is a unit of power consumption. For example, if you intend to use a 15W device for 2 hours a day, that is 15W x 2h = 30Wh. Note, however, that ratings are usually higher than the actual power consumption. To determine how much a device actually draws, you can use a meter like the Kill-a-Watt. Once you have all the Watt-hours, add them up. If the total exceeds 1000Wh (or 1 Kilowatt-hour), this How to may not be suitable for you.

2 Determine how much-unobstructed sunlight you receive in the location you intend to set up solar panels.

Unobstructed literally means that there are no shadows. If a tree, neighboring building, or anything else casts a shadow in that particular spot, do not count the time during which a shadow exists. So, if you get 12 hours of sunlight, but the sun is beyond the fence for 2 hours in the morning, then behind a tree for an hour at noon, then shadowed by your neighbors barn for 2 hours before sunset, you only get to count 7 hours. Note also that days are shorter in Winter. If you intend to use your set up in Winter, use your Winter hours.

3 Divide your total power consumption from Step 1 by the number of hours you came up with in Step 2.

If you decide you need 600Wh and that you get 6h of sunlight, that is 600Wh / 6h = 100W. This is the amount of power you need to generate per hour of sunlight to meet your needs. To be safe, multiply that by at least 2 or more. This is to account for the fact that solar panels only generate their rated output when pointed directly at the sun, and if your solar panels are fixed, they we not be facing directly at the sun most of the time. After various inefficiencies, you may lose another 20% or more of the power generated. If you expect regular and sustained cloud coverage, you may need to multiply by 5 or more or simply reduce consumption to live within your means

4 Buy solar panels.

Broadly speaking, there are 3 types of solar panels, strictly speaking, photovoltaic cells amorphous silicon, polycrystalline, and monocrystalline. Amorphous silicon panels are relatively inexpensive, relatively unaffected by small shadows, but are very inefficient in terms of space (for the same power rating, amorphous silicon panels will be larger and heavier). Polycrystalline panels are more efficient, cheaper than monocrystalline, but also less efficient. Monocrystalline panels are the most efficient, but also the most expensive. The output from mono- and polycrystalline panels can be halved or less by even a tiny shadow because of the way individual cells are wired.

5 Consider “B-grade” panels which are significantly cheaper, yet come with reasonable warranties.

While some people want their panels to last 25 years, the reality is that the cost of PV cells are coming down so rapidly that replacing or augmenting your panels in another 5-10 years may actually be cheaper than paying more now for ones that last longer. If the solar panels are more expensive than your budget allows, consider lowering your power consumption. Turning off or forgoing some devices not kill you and if it will, this How to is not for you.Calculate the amount of battery capacity you need. To do this, take the power consumption estimated in Step 1, then double it, because only about half the batteries capacity should be considered useful to avoid over-discharge. Then, multiply by the number of days reserve you would like. For instance, if you want to use 600Wh, you need 1200Wh (or 1.2kWh) of capacity, so if you had 3.6kWh, you will be good for a few days even if the sun disappears (though you may have other problems at that point). Since most batteries have capacities in Amp-hours, it may be best to convert Wh to Ah. To do so, divide the capacity you calculated by the batterys voltage, so 3600Wh / 12V = 300Ah (divide by 6 for 6V batteries).