quote:

Originally posted by konata88:
In terms of scalability and utilization per dollar, it seems that solar would be more effective at a community level vs each individual residence taking into account varied usage patterns and such.

Either that, or I'm wondering if it's better to undersize my solar system (if I decide to get one). There must be a way to figure out optimal sizing for the year, rather than base on monthly average consumption. For example, size solar to ensure grid consumption stays w/in Tier 1 pricing and then maybe some percentage of tier 1 consumption.

Yes, undersizing has a benefit. If you undersize, you will use 100% of everything you generate, which gives you the best return per kwh generated. If, at the end of the year, you end up with surplus power, the utility buys it from you at a lower price than what you would pay them for it. Essentially, you buy from them at retail, they buy from you at wholesale.

Optimal return is to have your system sized to produce exactly 100% of your annual usage. That's not practical, as your usage fluctuates over time. You could under size a little bit to ensure that you use all of your power generated and never receive a refund. Or, you can over-size a little bit and relax a little bit while running the AC, or letting yourself run the landscape lights all night, or let the pool filter run a little longer each day, or future proof for an electric vehicle.

I'm oversizing my system a bit, as I rather add another year to my break even point for the luxury of running the AC continuously.

I need to review solar options, lots of tech has improved over time, things have changed significantly.

quote:

Originally posted by Aeteocles:
My solar build out is being quoted with Hanwha Q-Cells.

Korean company, German RD, manufacturing in US/Malaysia/China/Germany.

I think the primary delta's between makes include: 1) reliability / life, 2) efficiency, 3) cost.

Any idea's what the diff is between this and LG or Panasonic or Sharp? I'm not finding a lot of info in how to choose which make. Does Tesla guide you through their options and let you pick? I'm defaulting to Panasonic at the moment but not sure if I need to limit myself here. If there is a cost premium, would like to understand why I'm getting for it. But not sure how to find out....

quote:

Originally posted by Aeteocles:
Konata, I think the disconnect from the grid problem isn't a technical issue, as whole house transfer switches have existed for a while now (for generators, as you mentioned).

I think the issue is with the utility provider not allowing it.

Thanks - this was a good clarification. So sounds like I need powerwall or generator if I want a backup for outages.

Still not sure why we can't safely do net metering and also allow for solar when the the grid goes down - just some grid based interlock that prevents power feedback when no power is detected on the grid side. But accept the current state.

So, I'll treat financials and outages orthogonaly and may need different solutions for each.

quote:

Originally posted by Aeteocles:
Yes, undersizing has a benefit. If you undersize, you will use 100% of everything you generate, which gives you the best return per kwh generated. If, at the end of the year, you end up with surplus power, the utility buys it from you at a lower price than what you would pay them for it. Essentially, you buy from them at retail, they buy from you at wholesale.

Optimal return is to have your system sized to produce exactly 100% of your annual usage. That's not practical, as your usage fluctuates over time. You could under size a little bit to ensure that you use all of your power generated and never receive a refund. Or, you can over-size a little bit and relax a little bit while running the AC, or letting yourself run the landscape lights all night, or let the pool filter run a little longer each day, or future proof for an electric vehicle.

I'm oversizing my system a bit, as I rather add another year to my break even point for the luxury of running the AC continuously.

Thanks. I'll run some numbers and see what the costs and BE point would be for 100% and undersized (need to determine what to use as the basis for undersizing). I'd be actually interested in a meaningful BE point acceleration - not sure how much longer I'll stay here. Really depends on whether local current socio-political trends slow, reverse or accelerate. If I stay longer, I assume I could always add panels.

That said, it seems like I get about 15kWh / day for free. If that remains stable, then if my average daily usages is 30-40KWh / day, then perhaps I can undersize to allow for 15-25kWh / day.... ETA: ouch, quick numbers seem to suggest $12k vs $25k....

quote:

Originally posted by konata88:

quote:

Originally posted by Aeteocles:
My solar build out is being quoted with Hanwha Q-Cells.

Korean company, German RD, manufacturing in US/Malaysia/China/Germany.

I think the primary delta's between makes include: 1) reliability / life, 2) efficiency, 3) cost.

Any idea's what the diff is between this and LG or Panasonic or Sharp? I'm not finding a lot of info in how to choose which make. Does Tesla guide you through their options and let you pick? I'm defaulting to Panasonic at the moment but not sure if I need to limit myself here. If there is a cost premium, would like to understand why I'm getting for it. But not sure how to find out....

I haven't done a site walk through with the installer, but as far as I can tell, nobody has given me an option to look at more expensive panels.

I have to thank y'all for this discussion... my wife is in the process of discussing installing solar on our home with a guy from our church who is a consulting engineer.... he does not do the installing but designs the system and then finds the best company to do the install. Now I have a number of questions to ask him.

quote:

Still not sure why we can't safely do net metering and also allow for solar when the the grid goes down - just some grid based interlock that prevents power feedback when no power is detected on the grid side.

This person seems to explain it:Link.

Basically, a grid tied system is the cheapest solar power generation system there is. It relies on the grid to generate the proper frequency and waveform for alternating current. It also relies on the grid for storage (night, clouds, etc.) and peak power needs (starting an electric motor draws 2-3x as much power takes to keep it running).

While Aeteocles' system maybe oversized compared to his monthly electric bill, it is severely undersized to provide off grid power to his home. In effect, he's getting a lot of free benefits from the grid. To truly power his home with solar, at the very least, he'd need a giant inverter and a lot of batteries which would easily double the upfront cost of his system, not to mention the increased maintenance and battery replacement costs in the future.

quote:

Originally posted by trapper189:

quote:

Still not sure why we can't safely do net metering and also allow for solar when the the grid goes down - just some grid based interlock that prevents power feedback when no power is detected on the grid side.

This person seems to explain it:Link.

Basically, a grid tied system is the cheapest solar power generation system there is. It relies on the grid to generate the proper frequency and waveform for alternating current. It also relies on the grid for storage (night, clouds, etc.) and peak power needs (starting an electric motor draws 2-3x as much power takes to keep it running).

While Aeteocles' system maybe oversized compared to his monthly electric bill, it is severely undersized to provide off grid power to his home. In effect, he's getting a lot of free benefits from the grid. To truly power his home with solar, at the very least, he'd need a giant inverter and a lot of batteries which would easily double the upfront cost of his system, not to mention the increased maintenance and battery replacement costs in the future.

Thanks. Seems like a wealth of info.

I tried reading the link; will have to go back and read again. Really long and semi-technical so not really understanding some of it. But the gist seems to be no solar w/o the grid.

So, financials - solar. Outages - generator, battery may be an option but seems complicated and costly.

In any case, I guess if I decide to do solar, I'll focus on financials for now. Figure out how to address outages later assuming all options would not be built out.

quote:

Originally posted by Blume9mm:
I have to thank y'all for this discussion... my wife is in the process of discussing installing solar on our home with a guy from our church who is a consulting engineer.... he does not do the installing but designs the system and then finds the best company to do the install. Now I have a number of questions to ask him.

Just a reminder, if you are so inclined, that if you want to spec out a comparison with Tesla (if available for your area), I have a referral link that gives you a little spiff. I all honesty, I benefit more from the referral than you do, but such is the incentive for me to hustle on Tesla's behalf.

The three consultations I had used satellite images of my house, and computer generated modeling of my roof angles and identification of any shade/obstructions. Without visiting the home, all 3 came up with similar install plans.

As far as I can tell, its just determining the number of panels required to produce the the desired number of average daily watts given your specific roof orientation and lattitude/geographic location.

quote:

Originally posted by trapper189:

quote:

Still not sure why we can't safely do net metering and also allow for solar when the the grid goes down - just some grid based interlock that prevents power feedback when no power is detected on the grid side.

This person seems to explain it:Link.

Basically, a grid tied system is the cheapest solar power generation system there is. It relies on the grid to generate the proper frequency and waveform for alternating current. It also relies on the grid for storage (night, clouds, etc.) and peak power needs (starting an electric motor draws 2-3x as much power takes to keep it running).

While Aeteocles' system maybe oversized compared to his monthly electric bill, it is severely undersized to provide off grid power to his home. In effect, he's getting a lot of free benefits from the grid. To truly power his home with solar, at the very least, he'd need a giant inverter and a lot of batteries which would easily double the upfront cost of his system, not to mention the increased maintenance and battery replacement costs in the future.

And in addition, the batteries have a short life compared to the system. 5-7 years, generally.

For clarity, I am still paying a connection charge to the grid, $10-20 a month, just to maintain connectivity and qualify for net metering.

And yes, if the intent is to go "stand alone" solar without grid support, you would have to spend a considerable amount of money. As is, 8.18kwh provides enough, *on average over the course of the year* to cover 120% of my current energy usage. However, it definitely does not cover my actual peak usage at any given moment, and the system doesn't produce at full capacity during the winter.

Again, the primary benefit is a lower utility bill--not freedom from the grid or emergency redundancy.

Is solar, as an industry wide alternative to conventional or nuclear power, cheaper/cleaner/viable in the long term? I don't know. I don't run a power utility. I'm just here to save *me* money; if the government is making it happen with my tax dollars, then I will certainly take advantage of it. Similarly, I use the carpool/HOV lane when it's made available to me, without further consideration if it's truly the best use of my tax dollars. Whether or not I asked for it, tax inventives and carpool lanes are there, and I'm using both when available.

Honestly, if the utility would sell me an 8kwh micro nuke reactor that I could bury for $12k and otherwise provides me with free power, I'd consider that too.

quote:

Originally posted by Aeteocles:
For clarity, I am still paying a connection charge to the grid, $10-20 a month, just to maintain connectivity and qualify for net metering.

And yes, if the intent is to go "stand alone" solar without grid support, you would have to spend a considerable amount of money. As is, 8.18kwh provides enough, *on average over the course of the year* to cover 120% of my current energy usage. However, it definitely does not cover my actual peak usage at any given moment, and the system doesn't produce at full capacity during the winter.

Again, the primary benefit is a lower utility bill--not freedom from the grid or emergency redundancy.

Is solar, as an industry wide alternative to conventional or nuclear power, cheaper/cleaner/viable in the long term? I don't know. I don't run a power utility. I'm just here to save *me* money; if the government is making it happen with my tax dollars, then I will certainly take advantage of it. Similarly, I use the carpool/HOV lane when it's made available to me, without further consideration if it's truly the best use of my tax dollars. Whether or not I asked for it, tax inventives and carpool lanes are there, and I'm using both when available.

Honestly, if the utility would sell me an 8kwh micro nuke reactor that I could bury for $12k and otherwise provides me with free power, I'd consider that too.

Those are the types of compromises and attitude required to live in the state you live in. It's what you do to survive there. It's understandable that some would be upset over the history of the state, and the history of the solar companies over the years that led up to Tesla today. Possibly every person in the forum paid $0.01 towards your solar system? Probably less...but the point is made.

In so much of the country, solar still makes no sense without massive subsidies.

I live somewhere where the solar potential is limited when you need it most, yet even on the grid, and without local utility company cooperation, and without tax benefits...it isn't difficult to install a system that saves money very quickly. The local power monopoly (who is also tax free, like the NFL) bones people in the butt here. Mostly, because they can.

I don't heat with electricity, every appliance in my home and office is a modern high-efficiency model, and every light appliance is LED. A quick look at my books reveals that in the previous 12 months I've paid $3,191. That's $266 a month on average for my refrigerator, small freezer, LED TV when I watch it, a laptop, one desktop (which does run nearly 24/7), 2 tablets charged nightly, 2 cellphones charged every other day, and about 2 dozen various LED lights which almost never get used for 5 months out of the year.

Freedom from the grid is my goal...and Tesla doesn't bring that. Quite honestly...there have been years where buying pump gas and running a generator is cheaper than our grid power.

quote:

Originally posted by jimmy123x:

And in addition, the batteries have a short life compared to the system. 5-7 years, generally.

We've been offgrid (solar/wind) for over 15yrs with our original batteries. Batteries are Unigy II AGM.

That's what I've discerned, you really are buying solar panels to feed the electric utility power and they are paying you per kwh the net amount it costs them to produce the same power.

That makes sense, no reason ever a utility should be paying anyone market end user rates for power, that would just increase power costs overall.

Basically homes are the power solar farm.

Have a company running a quote for me today, we'll see what comes of it. One of the issues in FL is that we don't allow participation in the solar credit market, where you can sell off excess credits to others in that market, this allows you to take the banked surplus credits you have with your utility and profit from them, using the funds to pay down your system faster.

When you read about someone in MA buying a $40K system and paying it off in 5 years, it's because there are huge state subsidies, on top of the federal subsidies and participation in the solar credits sale market.

All these things have to be considered when calculating payback on a system. You'll be presented with your ecologically sound faggetti arguments, and I"ve told them the only "green" I care about is in my bank account LOL.

As to the out of power situation, without battery walls, you are SOL... and those things are not inexpensive. Tesla recommended 4 power walls for $19,610 extra that provides two days of back up. So basically $5K per battery wall pack.

Just tongue in cheek - if tesla did this right, we could plug in their cars during the day, and then the cars could power the house at night.

But this thread was enlightening on how solar works. Like HRK said, we pay our money to provide electricity to the utility.

To the extent of the amount we supply and consume, we get electricity for 'free' (pre-paid for the BE period, basically free after that).

However, we are also supplying electricity for free to the utility for which they are making upwards of $0.20-$0.40 per kWh. The more we oversize, it seems, the more profitable it is to the utility.....

Something seems wrong here......

quote:

Originally posted by konata88:
Just tongue in cheek - if tesla did this right, we could plug in their cars during the day, and then the cars could power the house at night.

They are literally working on it. Tesla Model 3 is already equipped with the hardware to allow bi-directional charging.

https://thedriven.io/2020/05/2...-clean-energy-shift/

Ha! Interesting. I think I'd still rather have a delorean powered by Mr. Fusion.

MIght be cheaper to build a Tesla powered Delorean LOL

Figured I'd check with one of the local companies just to see what was out there.

First downloaded the last 18 months of power use, KWh, cost etc by month from Duke Energy.
We use on average 2400 KW per month, max use is around 3400, July-Sept are the peak months.

If we were to install I'd wait until December, get the tax credit for this year, and the KWh use is down around 1800 per month, which would allow me to build credits for the next summer over 6 months.


Here is the response.

According to your utility bill, your annual consumption is 28,682 kwh/year.

The system that we are proposing is going to produce at least 28,906 kwh/year, which is 100.78% offset.

We are using PV watts to calculate expected production - https://pvwatts.nrel.gov/


67 panel solar system:
Total size - 20,770 watts (each panel is 310 watts)
Total price - $56,079

This year there is 26% Tax Credit (in your case it will be $14,581 ), which means your total cost after tax credit is $41,498

So you'd have to drop almost $60K to pay up front and wait on $14K in refunded tax money.

Hence the December install idea, least amount of time money out of pocket while waiting on refund.

Or

2.99% finance money 20 years, roughly $320 a month, so no real significant monthly savings really since we average $367 a month on grid.
pmt is $411 for 10 years a bit more than the E-grid bill.

As I said you're simply swapping one source for another for a period of time.

One of the big concerns is, what happens if power companies decide they don't want to buy back power from solar, or they reduce what they pay per KWh, and states allow them to do this in 10 years, now you'll need to invest $$$ into a powerwall...

BTW the system proposed has zero batteries, I"m afraid to ask LOL

WOW! You use a lot of electrons per day! More than double what I use (on the average).

Seems like the battery is on the order of $8K each; you may need half a dozen...

You have a reasonable bill for the amount of electricity. I'm paying the same amount monthly using less than half (so 25-30KWh / day).