Solar Panel Charging

[geoffarias]

Was looking at solar panels at harbor freight the other day when I stopped in for a TV bracket and started thinking about why not mount some on the roof of my EZ GO TXT and have some charge rate when it sits outside for hours on end in the South Florida sun when we are out and about?

What I dont know is how to calculate the wattage of the solar panel into charge rate and determine how much charge I am putting into the battery bank over a given period of time?

Ex: If I mount 2 panels that are 100 watts each, and connect to my 48 V bank (6-8v batteries if it matters), what does that look like? Do I need a charging controller/converter between the panels and the bank? And if so, lets say that the panels are in direct full sunlight for an hour, how much charge does that put into my batteries? am I adding 5% of the bank total?

Really learning to not just get an answer but understand how to calculate this type of thing going forward.

[cgtech]

You will need panels with about 60v OCV, then a regulator won't be necessary. Otherwise, any converter will waste most of the energy. Or 4x 12v panels would work. 100w at 48v would be just a little over 2 amps into the battery. That's 2ah into a pack that's rated at least 160ah, not a whole lot of power.

[OttyFields]

They are making all kinds of them already.
Golf Cart Solar Panels

[geoffarias]

Originally Posted by cgtech

You will need panels with about 60v OCV, then a regulator won't be necessary. Otherwise, any converter will waste most of the energy. Or 4x 12v panels would work. 100w at 48v would be just a little over 2 amps into the battery. That's 2ah into a pack that's rated at least 160ah, not a whole lot of power.

Is that 2 AH in one hour? And that doesnt account for any random cloud cover etc. So hypothetically in 8 hours in perfect conditions Id be adding 10% of the bank capacity back in? so another way of saying is if my range is 15 miles and I drive the 2 miles to my in laws Id have to let it sit for 8 hours in perfect conditions to recover that lost charge? Def not worth it.

Guess that answers my question why these Teslas don't have solar roof options lol.

[coosa]

Originally Posted by geoffarias

Is that 2 AH in one hour? And that doesnt account for any random cloud cover etc. So hypothetically in 8 hours in perfect conditions Id be adding 10% of the bank capacity back in? so another way of saying is if my range is 15 miles and I drive the 2 miles to my in laws Id have to let it sit for 8 hours in perfect conditions to recover that lost charge? Def not worth it.

Guess that answers my question why these Teslas don't have solar roof options lol.

You have a good idea, but the technology just isn't there yet to make it practical.

But maybe it will happen eventually. When I bought my first panels, I bought 4 of them at 15 watts each to give me 60 watts going into the pack at ideal conditions. I have my pack wired to produce 12 volts and run the lights at that voltage, and have an inverter for everything else. That was in 2007 and the system cost about $400 with the controller.

I got another panel a couple of years ago and added it in. It is the same size as the other panels, but produces 60 watts by itself, and it only cost $100. That is a lot of improvement in 10 years, so who knows where solar panel technology will be in another 10?

Still, I doubt that solar is ever gonna be a real good way to charge a cart. You need to charge a cart in a relative hurry compared to solar for a home. I'm not sure it's possible, at least not any time soon.

Solar seems to be a good way to make a pack last a long time. I have a couple of 12 volt marine batteries added on to the pack that I pull off for farm work, then hook them back into the pack to charge when I leave. I didn't know how well that would work, but those 2 batteries are now 8 years old and seem to still have full power.

[Dwalls]

If you try do it make sure that you get a MPPT Charge controller they do better than the old PWM charge controller.

I have 2 of the 100w renogy solar panels at the shop and want to try them with the golf cart and see how they do but don't have a 48v charge controller.

I currently use 4 of the old 6v batteries out of our motorhome and have them hooked up series parallel to have a 12v battery bank and the 200w of solar keeps them charged up enough to run the stereo and small hand tools while I am up there.

Maybe one day I'll run across a 48v charge controller and see what it can do for the cart.

You can get something like this for about the same price as I paid for the 2 100w solar panels.

https://www.solarpanelstore.com/prod...yABEgIQSvD_BwE

Good luck and keep us posted

[coosa]

Originally Posted by geoffarias

Was looking at solar panels at harbor freight the other day when I stopped in for a TV bracket and started thinking about why not mount some on the roof of my EZ GO TXT and have some charge rate when it sits outside for hours on end in the South Florida sun when we are out and about?

What I dont know is how to calculate the wattage of the solar panel into charge rate and determine how much charge I am putting into the battery bank over a given period of time?

Ex: If I mount 2 panels that are 100 watts each, and connect to my 48 V bank (6-8v batteries if it matters), what does that look like? Do I need a charging controller/converter between the panels and the bank? And if so, lets say that the panels are in direct full sunlight for an hour, how much charge does that put into my batteries? am I adding 5% of the bank total?

Really learning to not just get an answer but understand how to calculate this type of thing going forward.

I've had a solar powered cabin for 12 years and use a golf cart battery pack as storage. My cabin is far from the grid and that is the only reason that I use solar. I don't think that one of these kits for a cart would ever pay for itself, and you are much better off with a regular charger. Even living off the grid, I charge my cart with a generator when I have it at the cabin.

Solar at this level of investment works ok for a cabin that is used a few days per month. The battery pack will slowly charge when I am gone and be ready by the next trip, but I don't want to wait a week to run my cart.

Still, you must have a charge controller to shut off the charging once the pack is charged. Good luck with it.

[geoffarias]

Ya I wasnt looking at it solely for a ROI. It was more so to have a project and have some charge going into my golf cart. Im in South florida and the cart will sit on a black top driveway for 6-8 hours at time in direct sunlight when Im a friends or family house in the neighborhood. If you go outside in August, you will feel the energy that is just beaming off the driveway in form of heat and just made me curious as to feasibility and benefit of any such system.

[WalterM6]

Here is the only way to charge a golf cart with solar power. And it is not that reliable. It doesn't work that well on cloudy and rainy days. It charges a bank of 9, 8v batteries. Which in turn powers a convert to run my DPI charger. One advantage to these is that when my cart batteries aren't good enough to run my cart I can still use them for my solar array. BTW it's 1500 watts but I'm lucky to get 1100 out on a good day.The only thing the cart mounted systems are good for is "Show and Tell" at the Country Club.

[BobBoyce]

When I lived in S Florida, I used solar power to charge my cart. I never had to use the cart charger over a period of years. I mounted the panels, stacked side by side, held together with galvanized angle iron full of holes from Home Depot, as a solar roof. It worked quite well. The solar roof was one panel longer and a little wider than the cart, but it was not an issue when divided evenly front to back. The mounting holes in the panels lined up really close to where the angles bolted nicely to the original roof supports.