[photo1902]

Originally Posted by tuccillo

I worked up the numbers in a previous thread. Here is a summary.

I will use energy units (watts-hours) since they make the most sense.

- A new, fully charged 8 x 6-volt battery pack can hold approximately 12000 watt-hours of energy.

- A 260 watt solar panel on a golf cart roof will deliver, on average across the year, 1000 watt-hours of energy per day if the cart is outside all day (and not under a tree). This is according to NREL (National Renewable Energy Lab in Colorado, I taught some classes there) and takes into account our latitude and climatic conditions.

- Therefore, a 50% discharged battery pack would take about 6 days to recharge if left outside all day and not driven (6 days times 1000 watt-hours per day equals 6000 watt-hours or 50% of the capacity). Estimations for smaller capacity battery packs and different percentages of discharge are easy.

- A 1000 watt-hours of energy costs about 13 cents from SECO. Therefore, you can save a maximum of 13 cents per day with the solar panel on the roof of the golf cart or about $47 per year. If the cart is not outside all day and/or if you don't actually consume 1000 watt-hours of energy (approximately 6 miles of driving) then the cost saving will be less.

-An electric golf cart consumes approximately 150-200 watt-hours per mile. It depends on your driving style and where you are going. The reason many people see 60+ miles of range with their golf cart is because 60 miles times 150-200 watt-hours per mile is about the capacity of many battery packs (12000 watt-hours for a 8x6-volt pack). Of course, you are always better off not fully discharging your battery pack.

- In terms of extending the range of the golf cart, if the cart is outside all day then the range can be extended about 6 miles. In other words, energy will flow into the battery pack from the solar panel and will also flow out of the battery pack to power the motor and the battery pack will discharge more slowly than without the solar panel. 6 miles times 150-200 watt-hours per mile equates to the 1000 watt-hours per day of energy you can obtain from the solar panel if the golf cart is left outside all day.

Thanks, Tucillo. I'll stick with my Yamaha Gas Cart. Maybe 10 years from now when Im ready to trade it in/sell it, electric technology will improve.