Hi everyone, I’m thinking about getting solar panels for my roof with a 10kWh battery storage to charge my EV at night. My plan is to charge the EV with about 8kWh daily, keeping my battery between 20% and 80%. I drive between 50 and 200 km (30 to 100 miles) every day.
Are there any potential downsides to this setup that I should be aware of?
A 10kWh battery should be enough to power your house at night, but you might not have much left over for the car. For a 200km drive, you’ll need around 40kWh. You might need to charge during the weekend while the sun is shining, but in the winter, solar charging might not be as reliable, depending on your location.
@Christopher
That really depends on the house. For some homes, it’s a bit of an overestimate unless you’re running heavy appliances like a heat pump on a cold night. The bigger concern might be in the late afternoon when you’ve still got appliances running and the sun is going down.
8kWh isn’t a huge amount of power. At my house, that would save me about 70 cents per day, assuming you get the full amount daily. On cloudy days in fall or winter, it could be much less, depending on where you live. Also, you’ll likely still need to use grid power for longer drives.
Honestly, a better idea would be to charge your car from the grid at night using cheaper EV rates and use your battery during peak hours for the house. That way, you’re saving more money overall.
Ronald said:
Honestly, a better idea would be to charge your car from the grid at night using cheaper EV rates and use your battery during peak hours for the house. That way, you’re saving more money overall.
Yeah, we plan to use the remaining charge from the battery to zero out our electricity bill at home.
@MAKENA
Yep, and that’s how the wealthy end up getting their electricity bills subsidized by everyone else.
sorphia said:
@MAKENA
Yep, and that’s how the wealthy end up getting their electricity bills subsidized by everyone else.
The rich are already getting subsidized by everyone else through electric bills, at least in the US. Utility companies like Duke and PG&E gouge customers, and that money goes somewhere. So, honestly, this setup spreads the costs a little more evenly.
@abidemi
Electric rates are regulated by the state. If you don’t like the prices, take it up with your elected officials. But let’s be honest, owning a home, an EV, and playing the solar game means you’re doing alright financially. It’s okay to admit that.
@sorphia
How is installing solar panels to be energy independent from the grid impacting anyone else? That logic doesn’t make sense.
Thomas said:
@sorphia
How is installing solar panels to be energy independent from the grid impacting anyone else? That logic doesn’t make sense.
Well, there’s a cost to maintaining the grid and fewer users means higher costs per user. Plus, politicians have allowed energy companies to kick the can down the road when it comes to grid upgrades. Eventually, prices will go up, and only those who can afford alternatives like solar will benefit. So in a way, it’s part of a larger problem, but it’s also about the broken system of how energy is priced and maintained.
@abidemi
In some places, you can’t sell solar energy back at retail rates, which means the energy companies benefit from buying it cheap and selling it high. So it’s not all one-sided. Plus, most solar users still pay a basic delivery fee, so they’re still contributing to grid costs. It’s not as black and white as it seems.
Think about it like this: if your solar battery can power your home at night, you save money by not drawing from the grid. You can then charge the car from the grid during cheaper times. You’re still saving on your overall energy usage.
@Randy
That’s a good point, but we’re trying to be as grid-independent as possible. The problem is the car isn’t at home during the day, and we can’t install more solar panels due to space and weight limits on the roof.
I have a 10kWh battery as well. I use it mostly during peak hours to save on costs and as a backup during power outages. I charge my EV during the cheapest off-peak times. You do have to be mindful of usage, though, since 10kWh is not a lot.
8kWh * 4 mi/kWh = 32 miles of range. That’s for the more efficient EVs, though. You might need to use the grid for longer drives, especially if your car isn’t home during the day to take advantage of solar charging.
If we assume your average daily commute is about 65 miles, you’ll need roughly 18.6kWh to charge. You didn’t mention how big your solar setup will be, but if you’re in a place with good sun, a 13kW system would be a good idea.
What kind of energy plan does your utility company offer? If they have time-of-use rates, a larger home battery might be worth it, but you’d need at least a 20kWh battery to meet your needs.
@Michael
Thanks! Our solar setup will likely be 7.2kWh, but I’m concerned about getting a larger battery, as it might not be used as much in the winter months. We also can’t install more panels because of space and weight limits.
The downside to this plan would be the unnecessary cost. Solar is meant to feed back into the grid, and using a battery just for EV charging could wear it down faster. What’s the advantage you’re hoping for here?
@jabali
Well, where I live, we can trade solar power at spot prices, which can be negative during the day in the summer. This is why a battery setup makes sense for us.