Kicked Some Solar Butt Today....

[NY_Rob]

Hey guys.. We are embarking on building our home from a blank slate...

Wanted to know how you would recommend to incorporate solar into the build? Any good resources you would recommend?

A southern exposure roof(s) is very desirable, if not possible- you need a split east/west panel layout like I had to do (costs a little more for the same production).

I would take a look at Tesla's solar roof.. supposedly they dropped the price a lot and they do look beautiful. If they're competitively priced with a conventional panel system with similar output I'd give it serious consideration. Not everyone loves the look of solar panels on their roof.

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[ajdelange]

that will go up once we get our truck.

Apparently the average American drives 30 mi/day. And it seems the RiT uses about half a kWh to go a mile so that means 15 kWh/da for Rivian traction. To that, we are finding, must be added about 2 kWh for phantom drain making a total of 17 kWh/da. I charge with a 13 kW (AC) system so that means 17/13 = 1.3 hours FSE to take care of the R1T. In Dec I only have 2.5 - 3 hrs for everything so it's marginal near the winter solstice (but I don't drive that much). Clearly the story would be more dramatic in a 5 kW system.

 

[ajdelange]

I would take a look at Tesla's solar roof.. supposedly they dropped the price a lot

I intentionally did not mention the Tesla Solar Roof even though I think it looks great. The reason I did not is because it is more difficult to install and thus more expensive but the real reason is that it is hard to work with Tesla. Their history in this (solar) sector has not been great. There are horror stories going around about people who have had their old roofs stripped off, the protenctive underlay installled and then received an e-mail from Tesla to the effect that their project is delayed indefinitely because of supply.

This is not to say there aren't horror stories to be heard about other suppliers. I can tell some.

 

[sub]

Is there a way to integrate EV chargers into a solar setup so that it only charges the cars when you are generating more than you are using, and have it set the max EV charge rate to match the real time excess solar capacity.

It would be even better if it talked to the car, and you could set up additional logic like if charge state is below 40% bring the car up to 40% ASAP using grid power if needed, and after that only charge when you have excess solar. But that is probably impossible since I don't think cars tell the charger what their state of charge is.

Would also be cool if you could send the solar DC directly to the car without first converting it to AC and then having the car convert it back to DC. But that's another one that I suspect is not possible.

 

[ajdelange]

Is there a way to integrate EV chargers into a solar setup so that it only charges the cars when you are generating more than you are using, and have it set the max EV charge rate to match the real time excess solar capacity.

Yes, and, in a real battery system you want to do this so that all the energy going to the vehicle comes from the PV array and none comes from the battery, This avoids the round trip losses associated with charging and discharging the battery. Unfortunately, the only way to do this now (that I know of) is manually i.e. you sit there and look at the energy draw and solar production and manually control the vehicle charge rate to keep the former lower than the latter. I do this using the real time display of a eGauge energy monitor. It has as API. The Tesla cars have an API. Clearly a skilled programmer could write something to automate the process.

Tesla has a wee bit of this sort of thing built into their "system". I once saw a message on the car screen that indicated charging was being limited because I was charging from a Powerwall whole SoC was low.

 

[guernsej]

A southern exposure roof(s) is very desirable, if not possible- you need a split east/west panel layout like I had to do (costs a little more for the same production).

Depending on where you live, if your local energy company uses net metering with time of use pricing then a west facing system can be just as effective as an equivalent kWh south facing system despite less production. For me in San Diego, energy produced during peak hours can be worth 1.5 to 6 times the value of equivalent production during off and super off peak hours depending on the pricing plan.

 

[ajdelange]

Would also be cool if you could send the solar DC directly to the car without first converting it to AC and then having the car convert it back to DC. But that's another one that I suspect is not possible.

It's quite possible but not practically doable, The PV panels typically produce 10's of volts in full sun (and less in less than full sun). This is converted to a higher DC voltage which then runs an inverter producing 240 60 Hz. In a direct to vehicle battery system that inverter would produce a higher voltage at 10's of kHz which would then be rectified to voltage levels suitable for charging the vehicle battery. This would require mods to the PV inverters and what would be effectively a mini DCFC system. lots of engineeering/small demand.

 

[emoore]

Wow I’m jealous of these huge solar systems. I out as many labels on my roof as possible but only produce 10,000 kWh a year. If I ever move I’d want a house with a lot of south and west facing area.

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