Charging from Small Solar Station

T

Tradesmith

New Member
Hello, I am wondering if it is possible to charge a battery system from a small solar panel over time and then charging my EV truck off that battery? Buying a big solar system in my area is cost prohibitive and would then make it more expensive to drive and charge my truck then just a regular ICE truck. So I'm wondering about just buying several small solar panels that would slowly store up energy in a battery over several days so that I would be able to get maybe 1 charge a week out of it? I'm new to the game and know really nothing about this. I considered buying a Powerwall for this purpose with 4 400W solar panels to charge it.
 
I don’t have a specific answer but I do charge my EV directly from my solar panels. The inverter for my rooftop solar panels has an outlet on it for a 240 volt power cable. It takes about 5 hours to charge my car from 20 to 80% using a combo of direct solar and AC electric power. I would think any battery that is charged by even a small solar system could be used to charge an EV but even a small solar setup would use a inverter and power directly from that inverter can slowly charge the car if it had the right AC outlet, thus bypassing the need for a battery.


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Have you looked into a grid tied system for your area? Many electric utilities will pay you for the surplus, then that's the most cost effective way to use solar. For the same money as 1600 W plus powerwall you can get a lot more solar and a grid tied inverter.
I have 4.4 kw solar and its enuf for me to be net zero annually, including EV. (But I do live in a sunny area)
 
+1 on comments above, I have had rooftop solar (39 panels with two DC-AC inverters grid tied) and several EV's, both since 2018. To your question and very interesting idea @Tradesmith. You are correct that solar panels do produce DC current, the tricky part is that solar panel voltage varies. My inverter voltage readouts vary at different times of day as the solar panels power up and down and with sunlight. An EV battery voltage also varies at different states of charge. To charge safely it would need some type of DC-DC inverter between the solar panels and EV battery to match the varying voltages.

Don't know if there are any units on the market now that do that. I did see an article from earlier this year where a startup, called Enteligent, introduced a DC-DC charger with a built-in inverter to charge an EV directly from solar. So I was curious and looked up the Enteligent website. They show a Hybrid DC Bi-Directional Fast EV Charger and indicate 'coming Fall 2023'. However, there is no mention of price. Based on the other info on the website like claims of up to 24 kW output, and connections to the home AC system and/or a battery system, I have a feeling that their unit with a battery will be a lot more than a few solar panels and a DC-AC inverter.
 
bwilson4web said:
One caution, there are reports that some EVs require at least 8 A to charge.

Bob Wilson
Click to expand...

J1772 has a minimum current specification of 6A. Minimum voltage is likely 85V. At that power level, there will a significant loss to parasitic charging demands. Fans, cooling etc. My Mini has several hundred watts of parasitic loss. Considering this, you should consider having an inverter of at least a few kW.

A grid tied net metered system effectively uses the grid as a battery. When your truck isn't plugged in, the panels 'charge' the grid.
 
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