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Solar without powerwall - what to expect

Solar without powerwall - what to expect

Most of the topics here are about people using solar with Powerwalls. I’m wondering if any of you who do not have Powerwalls can share your experience with your solar investment. Are you seeing a significantly reduced bill? How do you deal with the various TOU plans? EV charging?

Passion2Fly | 12 janvier 2020

I’m not sure that we can cover the benefits of solar panels here... they’ve been around for a long time and numerous research is available...

All I can say is that the cost of electricity is around $0.07/kWh from solar taking into account $3/W for the system cost over 20 years and 30% tax benefits...

The rest is simple: how much do you pay for electricity?

There use to be a rule of thumb that if your electricity bill is more than $200 per month, you might want to invest in solar.

Ben in CT | 15 janvier 2020

I have a Power Purchase Agreement (an older type of lease agreement) and have had solar for 4-1/2 years, without Powerwalls. My solar power rate is currently $0.147/kWh compared to a utility rate of $0.2137. So I save about 33% on every kWh my system produces. Since I have had solar, my cumulative savings are about $4400, or around $1000 per year. From my perspective, very worth it. For information, Eversource in CT does not have a tiered TOU rate structure, nor do I have an EV (although an EV would only increase consumption, and thus would have no effect on savings). TOU can definitely complicate things; most utilities only let you offset consumption within the same rate tier.

With Net Metering, one kWh generated via solar is one kWh not generated by fossil fuels -- it doesn't matter whether your EV is charged at night or not. The utility makes it cheaper to charge off-peak, because this helps their generation capacity issues, but it doesn't make any difference from an environmental perspective.

MattV | 16 janvier 2020

It's good for the planet to go solar, now whether it's good for your wallet will depend on how much your utility charges and how much usage you have. All electric house or Electric vehicles AND kwh cost above $0.15, it should work out in the end...

I installed 13.2kw setup a year ago in California, and PGE owes us money at true up time...All electric house + 1 EV + pool. (Second EV added toward the end of the year)

I would have a go on energysage to see what sort of cost you have and then crunch some numbers to see the timeframe for break even. It will depend on your utility, but the tendency with recent changes in tariffs make net energy metering less attractive without any storage (basically your generation is credited mostly off-peak, from 4pm). I'm grand fathered on the original tarif for now, but it made sense to add powerwalls to optimize TOU and get some relief from the preventive power shut off that affected us last year (and are probably here to stay)

Happy to discuss over email further if you're interrested (maffiou (at) gmail.com)

bcmusik | 16 janvier 2020

Thanks everyone for the solid info. My install date is Feb 14th (yes Valentine's Day). We were all set to include a powerwall but missing the Dec install date + needing to do a partial reroof stretched us a little thin. We will revisit adding a powerwall around September based on how things go using solar only.

Some Stats:
We average between 500-900 monthly kWh and we're getting the "small" system which is 3.8 kWh. Burbank Water and Power offers us the TOU plan which isn't bad at all as long as we keep aware of the summer Peak hours (4-7pm). The other times are either 0.16 for "mid peak" or 0.08 during night time off peak. They say that any solar credit is only applied in the same rate tier that is was produced.

Currently we are charged 0.11 for the first 300 kWh used then anything after that 0.16.
We have a model 3 that we plan to charge late night at 0.08
I'm always interested in seeing the type of numbers others are working with.

Passion2Fly | 16 janvier 2020

@bcmusik,
Let's do some simulations assuming 700kWh per month (your average consumption).
Also, let's assume driving your EV 1000 miles/month at 250 Wh/m => 250 kWh/month.

Using the current plan (no EV-TOU), you will pay:
300*0.11+400*0.16+250*0.16 = $137 / month

Using the EV-TOU plan, you will pay (I'm making assumptions here):
500*0.16 (mid peak) + 100*0.24 (on peak) + 100*0.08(off peak) + 250*0.08(EV) = $132 / month

Now, let's assume that you're getting solar and can replace all your mid peak consumption with solar at $0.07/kWh if you purchase the system. A 3.8kW system should produce around 500 kWh/month:
500*0.07(solar) + 100*0.24(on peak) + 100*0.08(off peak) + 250*0.08(EV) = $87 / month (with solar)

Now, if you add a PowerWall, you can shift your on peak price from $0.24 to $0.07, so the math will be:
500*0.07(solar) + 100*0.07(battery) + 100*0.08(off peak) + 250*0.08(EV) = $70 / month (with solar+PW)

To summarize:
$137 / month with the current plan
$132 / month with EV-TOU plan
$87 / month with Solar + EV-TOU plan
$70 / month with Solar + PW + EV-TOU plan

Honestly?? The amounts are so small that it's hard to justify $11k solar + $10k battery...

Passion2Fly | 16 janvier 2020

@bcmusik,

Something very important: DO NOT RENT THE SYSTEM!

At $65/month rent, that's $0.13/kWh for an average production of 500 kWh/month...

500*0.13(solar) + 100*0.24(on peak) + 100*0.08(off peak) + 250*0.08(EV) = $117 / month (with solar rented)

So, your electric bill drops by $15 per month but your new solar monthly payment is $65 per month!!!

infofiles | 17 janvier 2020

it makes sense to go Solar only based on your calcs. Do not rent.

I think of it as an investment. instead of paying Edison monthly, you pay to your investment and at some point 6-8 years you get independence. I would not do powerwall, instead put 30% of powerwall cost into slightly bigger system. Remember Solar will continue past 25 yrs while Batteries who know how good they would be past 10 yrs. Also, no point in going in with big Solar system or batteries as solar is continuing to get more efficient while prices keep dropping, and battery technology will keep changing, currently battery makes sense for some folks.

lets say in 3-5 yrs your energy needs are greater, you simply add onto your system and prices would be lower plus more advanced panels.. Make sure to go with Microinverters as that is easiest way to expand system in future.

bcmusik | 17 janvier 2020

@Passion2Fly

AMAZING !!! Thanks for calculations, super helpful to me and anyone else new who may read this. Really puts it in perspective. Yes we are PURCHASING the system outright and taking advantage of the now .. 26% incentive. Net cost after tax credit is roughly $7540 (Delta Inverter and 12 Hanwha 315 panels).

@infofiles
You're right. As much as I really want a powerwal I couldn't make the math work in my favor for my 1500sqft home. I do like the idea of battery storage and if prices comes down or another smaller kWh solution surfaces we'd consider it. In the meantime there's plenty we plan to do the old fashioned way ... make an effort to cut back where possible on our frivelious energy use, leaving TV's on, coffee pot sitting on, computers on, iPads charging and on standby all day, and the list goes on.

cslaurie | 23 janvier 2020

I used cash flow and ignored amortization. I made a FHA solar loan at one hundred percent of cost for 15k, payment $118 monthly for 15 years. My average monthly bill $175, eight years ago. So from day one, I was in profit $57 a month and it has only done better over the years with rate increases. I like OPM.

Patrick | 23 janvier 2020

Amen @cslaurie - we’ve use this same strategy twice with great results. Not to mention the side benefits of increased home value and building equity vs incurring expense over time.

Passion2Fly | 23 janvier 2020

Isn’t the FHA load a secondary lien on your title? Does it need to be paid off if you sell the house?