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Assuming you pay $0.12/KWh, can you ever come out ahead going full offgrid?

10 Cents a Kwh here. Would take foreeeevvvvvvver to pay back.

You would never pay it back.

You're losing money if you spend 25k on solar VS just like putting that into T bills and seeing which one nets you more at the end of the 20 years.
 
robby said:
..

That will not increase PV production but it does wonders for long distance Ham Radio communications when the cycle is at its peak.
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Interesting.. thank you for going Ham.
Solar Cycle reference is kind of a way of referring to the cycles that humans go through as they fuse all of their thoughts... or something.

Dealing with the sun seems to be a more stable endeavor than dealing with any organization of humans, for now.

Each country does things slightly different, but the sun (Sol) is quite consistent.
 
Alkaline said:
Ok So I talked with some people that haves solar near my area and most of them that have batteries are using these gigantic 2v 1100AH lead acid batteries I think they are 7s setups, looked to be about 35KW ish I think. They swear by them no issues in 12 years.
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Interestingly, I got a solar quote a few years ago for a similar sized system, and surprise, surprise, they were still installing FLA batteries.
 
Alkaline said:
I figure total cost with my setup would be about 64KW of batts and 13 KW of inverter power (dual inverters sungold power clone LV6548), and 15KW solar panels would be about $45,00.00 assuming I do most of the work.
Click to expand...

Assuming the AIO inverters and charge controllers last 10 years, and the solar panels stay above 80% for 20 years, then you're looking at $50k for 20 years of electricity.

In general, for every kW of solar panel installed, texas delivers 4.8kWH per day on average throughout the year. Obviously sunny summer days with panels pointed optimally will deliver double that, and cloudy days with panels pointing suboptimally will deliver less than 10% of that.

If you install 15kW of solar panels, and use all that energy, you would be collecting 72kWH/day. Multiply that by 365.25 days, and 20 years and you'll have collected 526MWH of energy.

Divide that by your $50k cost, and your cost per kWH is $0.095/kWH.

Given your current cost is $0.12/kwh (and I'm assuming you're factoring in all the costs of your current power source - ie, gov't charges, taxes, fees, etc) then over those 20 years you'll save $13,000, assuming the cost of electricity, inflation, etc doesn't change at all over the next 20 years.

Or, in other words, if you're going to consume 526MWH over the next 20 years, then you can pay at least $63k to the utility company, or you can pay $50k now. Get a low interest loan and you might be able to save more if inflation + electrical rate increases is above your loan interest rate.

This, of course, doesn't account for gov't rebates, or waiting for good sales and deals, or buying second hand panels and other equipment. Quite frankly, your system seems expensive for a DIY project, but I'm frugla/cheapskate, so I'll assume your pricing closely aligns with your needs for support/warranty/reliability, and won't delve into that further.

So given all that, I don't understand why you feel this won't pay for itself, unless you've described a system that will generate half a terawatt over its lifetime, but you'll actually only use maybe half that - at most - making the apparent cost of the solar system closer to $0.19/kwh or more.

The system you've specified is for a house that consumes an average of 72kWH/day.

Have you done a full energy audit? Have you already optimized your power consumption - for instance, are your air conditioners 20 SEER already? Are the windows all double or triple pane, argon filled, with appropriate solar coating to reject heat? Is your roof at least R-60, and walls R-30? Is your stove induction? Are your hot water and dryer heat pump types? Have you thrown out your oven, or at least use a smaller convection oven, and that only sparingly?

If not, then for every dollar you put into creating a more energy efficient house, you're going to save $3-$10 on your solar system needs. For instance, if you have a standard R-15 roof, paying for professional spray foam insulation to bring it to R-40 or preferably R-60, will reduce your energy consumption overall enough to reduce your solar system needs by 2-3 times what the insulation cost.

If you're consuming 72kwh/day and there's little to optimize because it's already close to passive house standards, then you must be in a 10k foot house and people are leaving windows open or something, or perhaps you're already saving $$$ by driving an electric car hundreds of miles a day. In which case, yes, that $13k savings on a $50k system means the payback will occur sometimes after 15 years, which isn't the 7-10 year payback people are trying to get. Most of us are still driving gas guzzlers, or hybrids, because spending $20k - $50k on a car isn't feasible, but spending $5k - $15k on a solar system is.

Going off grid, without changing your energy consumption, is going to require a premium, because your energy use isn't constant, and isn't even well aligned with the solar input. In Texas and states with moderate climates it's far cheaper to go off grid because the air conditioning is well aligned with solar input, and you rarely have one or more weeks in a row of cloudy weather, placing a heavier demand on energy storage and energy collection in low light. Doing this in Michigan, where I'm located, is quite a bit more difficult as we have weeks where there's 20% or less of the sun hitting the ground during the day, and these conditions are the rule for 1/3 of the year.

So my payback only occurs because I'm not going fully off grid. I choose a time of day rate - $0.18/kwh 11am-7pm, and $0.16/kWH otherwise. I'm fully off grid during the high rate hours during the summer, and often for several hours after the rate lowers, and in the winter I'm only off grid on particularly sunny days, but my workshop is off grid almost all the time.

What this does for me is reduce my power bill during the months where it's most expensive - summer with the AC on, it offsets my bill the rest of the year, and it provides backup power for outages and storms - which are rare, and usually not long for me, but it brings a significant peace of mind given the apparent fragility of the grid, and heightened tensions in the world. The only reason my power is stable is because I'm on a 12 mile rural loop which has multiple connection points to the grid. Just two miles away from me the power goes out a few times a year for an hour or more, and every year or two it goes out for 1-4 days.

In most sunny, temperate locations, payback occurs within 20 years in a fully off grid system with no rebates/incentives, and assuming inflation and utility rate increase are both zero.
In almost every location, payback occurs in 7-10 years in a grid-tie system with rebates/incentives, assuming inflation and utility rate increases are zero.
In most locations, payback occurs in under 7 years in a grid tie system with rebates, incentives, and taking into account 3% inflation.
If you use time of day rates, and engage in arbitrage - charge your batteries on the lower nightly rate - then payback is even sooner than the above three circumstances suggest.

Your electricity is cheap - well below the national average, so no, it's not clear cut, and unless you don't move for those 20 years it's quite likely that you won't get payback, because this system won't increase the value of your home by the amount it costs.

So taking this from a pure cost perspective, going off grid is far from a sure bet, and I'd tend towards it being unlikely to be cheaper.

But if you're going from a pure cost perspective, going off grid, even if you do break even, is nowhere near as much savings as going grid tie.

Do a grid-tie under your circumstances and it'll pay for itself at least twice over before its end of life, if you don't export. Export and it may reach 3x payback before its end of life, even without net metering.
 
I noticed in the News this morning that over in England due to the Winter cold snap they are proposing to pay people to not use electricity during heavy demand time. That would sure make a difference in if your solar setup was amortizing itself.

Now if my grid company would pay me 12 cents for every kWH I decided not to consume (I figure I would consume a whole bunch) my experiments in solar power would pay for itself in no time.
 
@Alkaline

I think the answer in all Residential cases is YES
So here are the numbers I am seeing in Texas:

1600kwh/kw/year (grid tied) -battery system inefficiency (~10%) =1440kwh/kw/year
Let's do a 2000kwh per month target

-16.7kW of solar needed @ $9k
-30kwh of LFP batteries at 46% nighttime vs daytime usage @$9k
-12kw ac output inverter/ inverter stack with mppts for DC coupling @ $3k for 6.5x2 or $8300 for solark 15k
-roof racking (ground mount will add) at $.10/watt @ $1600
-Wiring at $700
-Rapid shutdown at $.05/watt @ $800

$24100 for "basic"

$29400 for SLRK//Deye

if average life of parts is 20 years then 480000 kwh in the lifespan

24100 + rebuild fee x2 ($1000 for stack) $26100 Divide by 480,000 kwh = .054/kwh - 30% = 3.8 cents per kWh
if your cost of capital is a 20 year 6% loan then $18270 after credit = $31414 total payments = 6.5 cents per kWh
If you get an installer to be fair and do the work for $15k in 2 days tops then you say $24100+ $15000 - 30% = $27,370 = 5.7 cents per kWh
if your cost of capital is a 20 year 6% loan then $27370 after credit = $47060 total payments = 9.8 cents per kWh
All of this is under the 12-cent mark and 12 cents WILL go up at a rate exceeding inflation over the next 20 years

there are other pitfalls/ mods here but the 20 year life is unfair to the panels, they are 33% + of the costs and they will go for 30 years, ground mount bifacial may have a higher ROI as well, SLRK/Deye style inverters add 20% here but that is still in the ballpark, and we know those are coming down drastically in the next 2 years (which will make installing easier and ownership trouble less) The SLRK/Deye style most likely will have an overhaul cost at 10-12 years average, Schneider may outlast them but will not see a reduction in costs
 
Hello everyone, I'm from Ukraine, sorry for the English, I'm writing through a translator

My rate 0,042$
My 1.2 kW power plant costs $1500 at my tariff and the presence of the sun, the payback is 47 years :)
Now we have a war, and there is electricity for 4 hours, then there is no 4 hours, and it has been like this for several months

the price doesn’t always matter, it’s just the availability, the ability to charge the phone, walkie-talkie and watch the news

my wife used to laugh at my hobby, now she is happy, we have lighting, the neighbors are dark

this is my little experience

peace and sun
 
ROI??
Funny how people get their panties in a knot ? when it comes to solar payback.
What’s the payback on that $70,000 SUV, that mink coat ?, that granite countertop etc??
Never assume the price of electricity is going to stay the same or decrease! A utility is in the business to make money ?. Plus the grid seems to be getting less and less reliable as time goes on and weather disasters get worse.
Being in California and having an electric car makes my payoff less than 6 years but I didn’t do it for that reason alone.
But sure as sh•t we just got a huge utility bill increase!
 
@mib. This ^^. So much this.

One big factor for me is to be independent of the grid companies and their often crappy grid.
In Spain (around me atleast) we have a very up and down grid with a lot of badly designed and maintained setups.
Instead of enduring all the small seconds drops to hours before getting reconnected I elected to get solar and batteries in an off-grid setup but still with the grid input on days with clouds, wintertime with less sun-hours etc.

The local kw price has also seen up to over .50 Euros per kw over the last 2 years and are now at around 0.28 Euros per kw. The pricing also plays a huge role for me in decision to get solar ^^. Edited for comma-error...

My bills went from over 1.000,- Euros per month and down to 62,- per month with solar.
 
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@LydMekk My bill per year is 450-600 :)

I have electric heating and it gets cold -20

we have very low electricity bills so far

but it's true and my house is only 1090 feet, 100 square meters
 
My utility bill was $3,600 / year. (Electric and Natural Gas)
I can spend up to $36,000 on solar for a 10 year ROI.
I'm not spending that much, so it will be less than 10 years.
 
Our electric prices used to be 11 cents per kwh and now they are around 17 cents due to rising costs.
Really depends on how you build solar and how you use it for a ROI.
Example: Solar panels degrade over time so if you think you need 1 unit of solar then you add 2 or 3 units of solar. This means that at half life you still have full unit of power. (20 years from now your power production is more than your usage.)
Lithium batteries have good cycle lifes and have even better cycle life when you discharge them the least amount. Yet by today rates one should be able to get lithium for a fraction of the price as they pay today in say 10 years.
Finding a way to live with out batteries is one goal. Heating and cooling units that can run during the day off pure solar is one option. EG4 makes the direct solar mini split. 24k btu for just under 2k and Will said you need about 2k solar ($1 watt installed) so 4k for 1 ton of heating and cooling. Which is close to the cost of replacing a small furnace and ac unit. Though the cost savings over 10 years could be there. For example I would need about 6 tons for my new triplex I am designing.That is 12k just for the heating and cooling. The life of the units are 20 (guess) years. 50 dollars per month equipment cost and zero running costs. I have opted to have extra insulation and a really nice and tight house which should be able to heat and cool the house with out the need for the grid connection. Set it coldest in the summer, set it to warmest in winter. If you are cold or hot go outside or put clothes on. Now this is factored in to the 20 year life cost if the unit last 30 years then it get cheaper. If a in a few years a unit goes on sale for half price one might pick up a replacement. Used solar panels can be cheap and they are likely to get even cheaper.
If you have solar and have excess energy you might opt to do thing a whole other way. For example you might opt to buy a few more fridges and freezers which will use more energy. If you have a well you might opt to water your lawn, grow a massive garden or flower bed. You might even put in a pond or pool. You can buy those water pump all in one inverters that are grid and solar direct powered which means you can set them to solar only and run your well pump all day for no out of pocket costs.
The thing is out of pocket cost. So if you are on a budget then you are not spending money monthly. The other factor to consider is that a service charge on your bill is something that add up over time too. For example my electric and gas service charge is 35 per month. I expect to live for another 50 years and that with out inflation is 21k that I have to give away just to have electric. Why not use that money today and get solar. As long as you build your solar big enough you panels should last 50 years with out loss of normal electric consumption.
 
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