Planning for another EV - Charging /EVSE question

[TonyWilliams]

I produce about 1.2 MWh per month, and I need to add more solar. I just sent a $361 check to SDG&E for my annual "true up", plus we are now operating two Rav4 EV's (the last oil burner goes to the leasing gods July 16).

With a total of about 3500 miles per month driven, and 0.400kWh per mile, equals 1.4MWh per month for transport.

I will use more electricity for transport than home use, meaning I need to almost double my solar system.

My Solar City / Tesla 10kWh solar backup battery comes next month !!!!

 

[agleung]

Thanks everyone for your valuable input. Yes I am in Orange County. I will re-read every post again this weekend when my mind is a little more fresh. In a way I am glad I got the RAV4 EV 4 before ordering the solar panels. The LG 300W solar panels that I was looking into are back ordered and I will have some time to get this figured out.

 

[drmanny3]

Before you actually order and have installed a solar panel system take a look at what you can get via lease. SolarCity has as good a plan as most. Currently, I believe they are leasing for a 20 year time period. They use thick film solar panels so the efficiency is up there requiring fewer panels. They do an excellent job of design as well as getting all the permits etcetera. They will do it for zero down and then a monthly payment that goes up every year. The best way is to get a one time lease payment. It is generally cheaper than you can get buying on your own (unless you do the install) and SolarCity will maintain the system for the 20 years. It is the best of both worlds. You can transfer the lease without any cost being born by either you or the new home owner. While we did ours about 4 years ago, our lease payment was $10,414. We could have purchased the system at about $16,539 (after State and Fed rebates) but then we would have been responsible for it (beyond the labor warranty) from that point on.
Manny

 

[agleung]

Interesting. I wonder what the economics of leasing vs buying for solar panels is. I wonder if there more tax credit for leasing than buying in the system, somewhat akin to the RAV4 EV now.

 

[drmanny3]

The rebates occur whether you lease or buy. Of course if you buy you need to have the income to benefit from the rebates. I choose the lease because they cover all the maintenance for the life of the lease. With technology changing as rapidly as it is, leasing is a good way to go. At the end of the lease SolarCity gives you three choices. One, upgrade the system and re lease it. Two, they will remove the system at their cost. Three, they will walk away and you can keep and be responsible for it. I am betting on Three, as it is the cheapest for them and a good deal for me. Of course we hopefully will have moved back to Santa Barbara long before.
Manny

 

[fooljoe]

Interesting. I wonder what the economics of leasing vs buying for solar panels is. I wonder if there more tax credit for leasing than buying in the system, somewhat akin to the RAV4 EV now.

If you buy you get the rebates/credits; if you lease SolarCity (or whatever company you choose) gets them, but (hopefully) passes the savings along to you. I believe the big difference is that commercial installers like SC get additional savings by being able to write off depreciation of the system, which you as a homeowner can't do - that's why a 20+ year prepaid lease can be cheaper than buying.

What that difference is will vary from installer to installer, however. SC aggressively pushes the lease option, and so they probably inflate their purchase prices a bit to dissuade people from going that route. In my case the bottom line was pretty much the same (leasing was a tad cheaper but only by ~$500), and I opted to buy instead because of the uncertainty about what happens when the 20 years are up and what might happen if I decide to sell the house (it should be fine, but it's just one more complication.)

With the Rav, the issue is completely different. Toyota is making these cars solely to earn CARB compliance credits, and they only get those if the car's registered in California. With a lease they can restrict lessees to being CA residents only, but with purchases it's easier for people to take the cars out of state. Curiously, when I got my Rav last year it was the reverse situation; purchasing was a way better deal than leasing. I guess it just took Toyota a little while to catch on.

 

[smkettner]

My Solar City purchase came with a 20 year warranty including inverter. Also includes 20yr performance guaranty.
Lease seemed like more in SC's pocket. Sales pitch preferred the lease as I assume that is more profitable for them.
Accepted payment through PayPal. Easy to put on a credit card for points and payment flexibility.

 

[miimura]

Solar City actually pushes Power Purchase Agreement, not a straight lease. I got a bid from Cobalt Power Systems that was a true lease through SunPower. Big difference. The Prepaid Lease looked very attractive. I ended up buying the system outright from Solar Universe. I really needed the tax credit for 2012 and the RAV4 got me a 2013 tax credit. I think my 2014 taxes are going to be painful with no big credits.

 

[agleung]

My home usage was 9000 kWh for last 12 months. I estimate up to 400 kWh per month for the EV, if I charge at home only. So my estimate future usage would be anywhere from 9000 to 13800 kWh. I will take the mean arbitrarily, i.e. 11,400 kWh.

I was quoted a 6 kW system (300W x 20 panels) that estimate production of 8723 kWh. This would correspond to 97% to 63% coverage of usage. More specifically 76.5% coverage of usage for 11,400 kWh. % bill offset is much harder for me to estimate. I will have to decide on TOU or separate meter depending on how much I charge at home vs at work. I am guessing my south facing roof can only support a max of 22-24 panels, i.e. 6.6 - 7.2 kW system. Would anyone recommend trying to squeeze in any more panels than 20?

 

[miimura]

A good solar installer will be able to estimate how much bill offset you will achieve based on your usage history, your planned off-peak EV charging, and the various rate plans available in your area. I would use that information to decide how many panels to install.

Most utilities will only let you use net metering on a single meter, not spread across meters. A second meter is only useful if you don't have solar or your solar system can only offset your household usage bill. My general advice is that if you are going to get solar, don't get a second meter for EV charging.

 

[smkettner]

My home usage was 9000 kWh for last 12 months. I estimate up to 400 kWh per month for the EV, if I charge at home only. So my estimate future usage would be anywhere from 9000 to 13800 kWh. I will take the mean arbitrarily, i.e. 11,400 kWh.

I was quoted a 6 kW system (300W x 20 panels) that estimate production of 8723 kWh. This would correspond to 97% to 63% coverage of usage. More specifically 76.5% coverage of usage for 11,400 kWh. % bill offset is much harder for me to estimate. I will have to decide on TOU or separate meter depending on how much I charge at home vs at work. I am guessing my south facing roof can only support a max of 22-24 panels, i.e. 6.6 - 7.2 kW system. Would anyone recommend trying to squeeze in any more panels than 20?

The TOU rate will tend to give advantage as you are selling at on-peak rates. I would error a bit on the low side. 4 to 6 kW is fine. Usually the biggest savings is offsetting the top 2/3rds if you have tired rates. Completely zeroing out the bill is overrated IMO.

 

[drmanny3]

When we got our system SolarCity used thin film technology panels that looked really good but were lower in efficiency. Often thin film is used for commercial applications because there is a lot of roof area. I mention this because even maxing out three locations on our roof with a total of 68 panels we only covered 70%. I was concerned but found that the process of going solar also makes you think about waste. So over the years we have replaced any standard bulbs with led and replaced appliances, etcetera with energy efficient options. So in the end the 70% coverage worked pretty well. When we got the Leaf (which had not been planned for) we ended up going with the TOC Time of Use from SCE. That made charging the car almost free. We are home everyday and thus have adjusted our life styles to adapt to the TOU schedule. If that is an issue then the only way out is to put in more panels. So if you are home during the day that can add to the energy usage especially with TOC. A lot also depends on how efficient your home is. Is the insulation in the attic appropriate? It is relatively cheap and makes a big difference. Do you have duel pain windows? You can also add film to the inside of the windows and deflect a lot of heat. So look holistically at your home. If you can squeeze in a few more panels then I would recommend you do so. Make sure you compare one quote to another by considering the brand of panel and its efficiency. You electricity generation will be maximum during the spring summer fall and then fall during the winter months. It will be greater than 100% on some months and less than 50% on others. That is why you want to maximize your energy efficiency in the home itself. We have duel air conditioning condensers that are fairly high in efficiency. Yet I also installed room fans in almost every room. That insures that you get the most bang for your buck. Our usage was about 12000 kwh per year for a 4000 sqft house . We have significantly changed how we do things. I have our instant hot water on a timer and I also have a timer for the hot water circulation (gas fired). You want to save as much energy as possible whether it is gas or electric. Our two refrigerators are side by side and not as energy efficient as other configurations, however they are still pretty decent. Refrigerators use a lot of juice. I have a lot of electronics running continuously, so I could do better. Hope that helps

 

[fooljoe]

Most utilities will only let you use net metering on a single meter, not spread across meters. A second meter is only useful if you don't have solar or your solar system can only offset your household usage bill. My general advice is that if you are going to get solar, don't get a second meter for EV charging.

+1. Especially with SCE's TOU rates, an EV and solar together on the same meter work out great. I guess if you use a lot of air conditioning or otherwise have very large on-peak usage that might throw things off, though.

 

[Dsinned]

My home usage was 9000 kWh for last 12 months. I estimate up to 400 kWh per month for the EV, if I charge at home only. So my estimate future usage would be anywhere from 9000 to 13800 kWh. I will take the mean arbitrarily, i.e. 11,400 kWh.

I was quoted a 6 kW system (300W x 20 panels) that estimate production of 8723 kWh. This would correspond to 97% to 63% coverage of usage. More specifically 76.5% coverage of usage for 11,400 kWh. % bill offset is much harder for me to estimate. I will have to decide on TOU or separate meter depending on how much I charge at home vs at work. I am guessing my south facing roof can only support a max of 22-24 panels, i.e. 6.6 - 7.2 kW system. Would anyone recommend trying to squeeze in any more panels than 20?

A consideration for the question of "how many panels?" is whether or not, you will need modifications to your main service panel entrance and/or the grid's infrastructure. Older homes may not have sufficient capacity "as-is" and require a substantial investment in those type of modifications. Thus, pushing out the ROI payback and break even threshold on the cost of a larger solar system.

 

[drmanny3]

That is a good point about your current panel, its capacity and also the line that delivers electricity to your home. SolarCity looks at all that and gives you the information you will need. They will include upgrading your panel if it is necessary. I also recall SCE coming out to our home to make sure we could handle the system.
Manny