Tesla Powerwall

[Finlay]

Which utility company is that? I was unaware that any were actually paying money out to customers.

.

I have Xcel energy, and they pay me. They have two programs - one where I get a credit for surplus created, and one where they send me a check.

I pay in a little in the winter, and they pay me in the spring, fall and summer. I won't get rich off of it, but the array will pay for itself long before it fails. Or would, if it wasn't paying for all that delicious beer. Plus, we save money on the shading the array provides to the roof - less heat to pump out of the house.

I would arguably be better off getting the credit - they pay more per KWh for that, but although the credits never expire, I can never transfer them, and I lose them if I ever move. Better to get the cash, in my opinion.

 

[Finlay]

".....At the time of this writing, the installed cost of solar panels was between $7-$9 per watt:

Also, I paid ~5 dollars per watt for the array and installation.

But, that includes the cost of fairly substantial rewiring of the house - increased service from 100 amp to 200, new panels, new meters and all that. Absent those costs, I paid just less than 4 dollars per watt, including financing and interest.

 

[dwh]

I have Xcel energy, and they pay me. They have two programs - one where I get a credit for surplus created, and one where they send me a check.

I pay in a little in the winter, and they pay me in the spring, fall and summer. I won't get rich off of it, but the array will pay for itself long before it fails. Or would, if it wasn't paying for all that delicious beer. Plus, we save money on the shading the array provides to the roof - less heat to pump out of the house.

I would arguably be better off getting the credit - they pay more per KWh for that, but although the credits never expire, I can never transfer them, and I lose them if I ever move. Better to get the cash, in my opinion.

Sweet. Is there a cap? I mean, could you double or quadruple your generating capacity (assuming you had the room for it) and they'd buy that as well, or is there a limit to how much they'll buy from you?

 

[Finlay]

Sweet. Is there a cap? I mean, could you double or quadruple your generating capacity (assuming you had the room for it) and they'd buy that as well, or is there a limit to how much they'll buy from you?

Yeah, Xcel puts the cap at 125% of your average yearly consumption. If you just bought the place, or it's a new build, then they have a square foot calculator that is used to determine the cap.

We could have sized our array much larger (nearly 3x, 6.2KW) according to their calculator, since we just bought the house. It didn't make much sense though, because we buy power at ~12 cents/KWh, but sell our excess at 3. So, our offset is worth 4 times as much, and it would take longer to pay off a larger array. As it stands, we make enough power to fully offset our usage, pay the connection fees and taxes, and still get a check from Xcel. This roughly equals what our payments are for the financing, so for the next 7 years, it's a wash - the system pays for itself. But, the financing eventually gets paid off, and the array should be productive for 20 or more.

I figure we can maybe upgrade later, if we need to (say to add an EV or something) as prices continue to fall. No real reason to go much larger, yet.

 

[dwh]

Yeah, Xcel puts the cap at 125% of your average yearly consumption. If you just bought the place, or it's a new build, then they have a square foot calculator that is used to determine the cap.

We could have sized our array much larger (nearly 3x, 6.2KW) according to their calculator, since we just bought the house. It didn't make much sense though, because we buy power at ~12 cents/KWh, but sell our excess at 3. So, our offset is worth 4 times as much, and it would take longer to pay off a larger array. As it stands, we make enough power to fully offset our usage, pay the connection fees and taxes, and still get a check from Xcel. This roughly equals what our payments are for the financing, so for the next 7 years, it's a wash - the system pays for itself. But, the financing eventually gets paid off, and the array should be productive for 20 or more.

I figure we can maybe upgrade later, if we need to (say to add an EV or something) as prices continue to fall. No real reason to go much larger, yet.

Next question.

Do they have any rules concerning batteries - i.e., allowed/disallowed? I wouldn't think so, if they are buying at 3 and selling at 12, but I'm wondering.

 

[Dan Grec]

Which utility company is that? I was unaware that any were actually paying money out to customers.

They're in Australia.

-Dan

 

[Finlay]

Next question.

Do they have any rules concerning batteries - i.e., allowed/disallowed? I wouldn't think so, if they are buying at 3 and selling at 12, but I'm wondering.

No restrictions, and in fact, I looked at a battery system. Too expensive for too little capacity, and a large footprint besides. The Powerwall is intriguing, because it is much smaller, and 30% of the cost for equivalent storage. I'll be watching it closely. It doesn't make the most sense right now, but in 3-4 years, I suspect the market will be much improved - costs will come down and reliability will go up.