61-Watt Solar-Powered PC: Storage Batteries Operation in the Dark

We measured the energy consumption of our complete system, including the monitor, keyboard and mouse using the Voltech PM3000A, a high-end power measurement device.

At a level of around 62 Watt-hours for a one-hour usage period, energy consumption for our solar-powered PC is sensationally low. Those who want to work all day long without plugging into the power grid, must purchase solar cells that can generate 1.5 kWh.

When the weather is bad solar cells deliver little power, at night they don’t produce anything. Providing power during such periods requires a storage battery. During the day, when the sun is shining, the solar cells provide energy for the PC, but also charge the storage batteries as well.

Because solar cells can only deliver energy during roughly half of each day, the batteries must be able to power the PC for at around 12 hours (the other half of the day). We therefore determined that we would need storage capacity of around 1.5 kWh from our battery. It operates at 12 Volts, which requires a capacity of 130 Ah at 1.5 kWh. We also took into account that transporting energy over a distance as short as 50 feet (15 meters) requires incredibly thick power cables to avoid excessive power losses.

In the next installment of this article series, we provide a step-by-step description of how we built our solar-powered energy collection and storage system.