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Discussion Starter · #1 ·
We've been running our house "part time" on my self designed offgrid solar setup for about 2 years now and it's worked out well. We used the solar power during the day, and at night it switched back to line power (automatically). We cut our electric bill in half and at the same time had had full time power in the event of a power outage from the power company without the need of a generator.

With the cost of LifePO4 batteries (lithium iron phosphate) dropping considerably (we had been using sealed lead acid deep cycle batteries), we decided it was time to make the jump to the new LiofePO4 batteries. We also decided that the current setup of using 2 decent sized inverters (one was 6,600 watts, and the other 6,000 watts) introduced additional hurdles to overcome (by splitting out our electrical panel to use the power of each inverter to split the load), so we also got a much larger inverter (18kw with a 30ms surge rating to 54kw).

We are still waiting on 2 more LifePO4 batteries (we currently have 600 amp hours, but are adding 2 more for a total of 800 amp hours). I finished the upgrade yesterday and after the batteries get their first full solar charge today, we'll be going full time solar (flipping the transfer switch to full time solar).

I still have to design, build, and weld a steel rack to house and protect the batteries, but I just held it together with wood for now.

I did all the electrical work myself. I used to be a general contractor, so for me it's rather simple.

Here is what our setup looks like.... I was testing the loads on the new inverter last night and everything performed perfectly.

716775
 

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Very interesting. What do you think your total cash outlay will be when all said and done? My highest electric bill is like 370 is the summer. Trying to figure how long the investment would take to pay off.
 

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Discussion Starter · #3 ·
Very interesting. What do you think your total cash outlay will be when all said and done? My highest electric bill is like 370 is the summer. Trying to figure how long the investment would take to pay off.
Our normal electric bill (without solar) was $160, but I also had my house custom built with efficiency upgrades which included icynene spray foam insulation, and double pane windows with UV block and argon filled glass.

The first investment was about 9k which included:

(28) 340 watt mono panels
(2) Midnite Solar Classic Charge Controllers
(2) Inverters
(16) SLA 12v 100ah Batteries
Assorted Electrical supplies and switches

The upgrade was (when all is said and done) right at 18k and that included:

(8) LifePO4 100ah 48v batteries
(1) 18kw inverter
(1) 200 amp Manual Transfer Switch
(1) 6" x 6" x 36" trough box
Assorted electrical updates

The batteries were the biggest hit at about 13k, but with the charge cycles it'll handle (excess of 9,000 cycles or about 24.5 years at 50% DOD), they will be the last batteries I'll ever have to buy (I'll be dead when they are exhausted).
 

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That's an awesome system. My math shows a bit under 15 yr payback not including any overage that can be sold back to the grid.
 

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Discussion Starter · #5 ·
That's an awesome system. My math shows a bit under 15 yr payback not including any overage that can be sold back to the grid.
Thanks. Nothing is sold back to the utilities.... I use it all. This is completely off grid. The shear fact that I'm no longer dependent on the grid was the selling point for me. Originally I was going to buy a whole house genset, but when you calculate overall cost, it was cheaper going solar.
 

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That's an awesome system. My math shows a bit under 15 yr payback not including any overage that can be sold back to the grid.
One thing with selling back to the grid. According to a friend who has solar but does not have batteries.
Anything extra the power company has to buy from you but at the wholesale rate. then anything he uses he buys at the retail price.
Example He generates extra through the day. the power company pays for example .02 per KW.
Then he needs power at night, He pays .10 per KW.
Even if he generates more through the day then he uses at night he is still loosing money.
 

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Very nice! I'm sure you've already done the math but what was your 2-year monetary savings vs cost of the "part time" system you designed and implemented and do you have any ballpark calculations on how many years to break even? Not having to pay a licensed electrician/contractor for the design and installation certainly saved a substantial labor cost.

I've had no less than ten solar sales folks knock at my door here in western MA trying to sell me their system. I let two of them schedule an appointment to give me their presentation. The outright cost for me to own their "part time" systems based on our current power usage was in excess of $40,000 each and that's with no battery system like you have which was an extra up-front cost to us. I would get to realize the (one time) federal income tax benefit. Any excess generation would be directed back to the grid and I would realize that benefit also. We were given a 20-year life expectancy on the solar panels but can't remember how their output deteriorated over time. In the end we decided not to have either system installed. Maybe its time to look at it again.
 

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Discussion Starter · #8 ·
Very nice! I'm sure you've already done the math but what was your 2-year monetary savings vs cost of the "part time" system you designed and implemented and do you have any ballpark calculations on how many years to break even? Not having to pay a licensed electrician/contractor for the design and installation certainly saved a substantial labor cost.

I've had no less than ten solar sales folks knock at my door here in western MA trying to sell me their system. I let two of them schedule an appointment to give me their presentation. The outright cost for me to own their "part time" systems based on our current power usage was in excess of $40,000 each and that's with no battery system like you have which was an extra up-front cost to us. I would get to realize the (one time) federal income tax benefit. Any excess generation would be directed back to the grid and I would realize that benefit also. We were given a 20-year life expectancy on the solar panels but can't remember how their output deteriorated over time. In the end we decided not to have either system installed. Maybe its time to look at it again.
Thanks. I never did the calculations for a break even because I looked at why I wanted it for a different reason. The original idea was to buy a whole house generator for backup power. That cost (about 20k) exceeded what I would have spent had I gone with the LifePO4 batteries in the first place, but 2 years ago they were very expensive. So spending the money for solar was a no brainer by the time I would have had to pay for the generator (22kw), 1000 gallon LPG tank, installations and inspections, and finally the continuing costs of LPG (even if you could get some with an extended power outage).

I'm sure I saved 3k or 4k doing all the work myself, but in the long run I figure that into the savings as well.

Solar panels do degrade over time, but not as much as people think they do. My panels are rated for 80% output at 25 years, and when you do the calculations, you've only lost 1,904 producing watts (out of the 9,520 watts when new) at around the 25 year mark.

I didn't apply for any tax credits as it would have alerted the government that I'm producing solar in the event they start figuring out a way to tax people who have it. I live rural, and my solar panels can't be seen from the street.
 

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How do you get 240 voltage (split phases) for motor loads if it all starts with a battery? Are those inverters that trustworthy?
 

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Very nice! I'm sure you've already done the math but what was your 2-year monetary savings vs cost of the "part time" system you designed and implemented and do you have any ballpark calculations on how many years to break even? Not having to pay a licensed electrician/contractor for the design and installation certainly saved a substantial labor cost.

I've had no less than ten solar sales folks knock at my door here in western MA trying to sell me their system. I let two of them schedule an appointment to give me their presentation. The outright cost for me to own their "part time" systems based on our current power usage was in excess of $40,000 each and that's with no battery system like you have which was an extra up-front cost to us. I would get to realize the (one time) federal income tax benefit. Any excess generation would be directed back to the grid and I would realize that benefit also. We were given a 20-year life expectancy on the solar panels but can't remember how their output deteriorated over time. In the end we decided not to have either system installed. Maybe its time to look at it again.
So here is a perfect example of where you live will justify or not solar is cost effective. Now lets take into consideration you have no interest in the green initiative which we all should but I live in the south east area of Ma. First you need to shop around for the best price and guarantee. My system is designed that if the financial numbers that I was given miss the Solar company (in my case Boston Solar) will pay the difference. I opted to go with the most efficient and best warranty LG panels that are covered for the full 20 years. My 35 panels after 20 years will still produce 89% of what they did day 1 and my system was sized to take that into consideration. My system list price was $36,000 dollars of which 30 percent of that was Federal tax credit or $11,000. Now that is only credited to taxes that you pay so if you only paid $6000 your first year credit would be 6k and the next year you can deduct the other 5k if your taxes remained the same. In my case I received 12k since I was still working and paid enough taxes. Ma allowed for another $1000 credit, the financing bank credited us another $3500, Boston Solar credited us $1000. So my total cost was just under 20 grand total. My average E bill is 350 month (4200/yr) but it goes up every year, I get paid 22 cents for everything I put on the grid as a credit, I get paid in cash 14 cents for every KW that my system produces via Mass Smart Program that averages close to $2000 a year. So for the last two years I have had no electric bill, have a E bill credit today of $800 have been paid close to $4000 for Mass Smart however it is designed to cover the cost of the system and stops after 10 years. I plan on buying a E car for obvious reasons and now that I am in retirement I have extra income and no E Bill for the next 20 years Guaranteed. I paid the system off after I got the $3500 bank credit. Now these credits and income sources vary within Ma and other states and with Eversource I am eligible for better credits and income sources then David is who probably uses National Grid. In my circumstance it was a no brainer. In Kevin's situation he wanted independence from the grid and designed his system based on that. Also the Federal credits are going away unless Biden kick starts them again. In my case it was a wise financial decision.
 

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Discussion Starter · #11 ·
How do you get 240 voltage (split phases) for motor loads if it all starts with a battery? Are those inverters that trustworthy?
The inverter is split phase and produces 240v (2 hot legs and a neutral). All inverters (at least 98% of them) are built in China. I've had no issues with mine at all.
 

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I was replacing a mast on a 150 amp service a few years ago. I shut the main off at the panel but still had most of the house on.. I'm like WTF??? I pulled the meter still most of the house was on... So I very gingerly pulled the cover off the weather head and sure enough, the old guy that lived here and died had drilled a hole in the service mast right were it goes through the roof into the attic crawl space and back out down to the meter socket. He had a panel and all up in the attic crawl space. He had everything in ridged conduit to contain shorts if they should happen. He had most of the house feeing from this panel and was only paying for the lighting!!! The pipe and service was from the early sixties, Zinsco panel and breakers pipe from one of the mills here...The old timer who built the house and lived in it for 30+ years must of saved around $40 grand!!!
 

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The inverter is split phase and produces 240v (2 hot legs and a neutral). All inverters (at least 98% of them) are built in China. I've had no issues with mine at all.
My system has one inverter for each panel (35) and each provide 240 volts which feed a central control panel. 10 year replacement guarantee and if one fails my grid looses just one panel until it is repaired. I believe Kevin has two large inverters for redundancy. Correct me if I am wrong Kevin. Solar systems are not one size fits all
 

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I was replacing a mast on a 150 amp service a few years ago. I shut the main off at the panel but still had most of the house on.. I'm like WTF??? I pulled the meter still most of the house was on... So I very gingerly pulled the cover off the weather head and sure enough, the old guy that lived here and died had drilled a hole in the service mast right were it goes through the roof into the attic crawl space and back out down to the meter socket. He had a panel and all up in the attic crawl space. He had everything in ridged conduit to contain shorts if they should happen. He had most of the house feeing from this panel and was only paying for the lighting!!! The pipe and service was from the early sixties, Zinsco panel and breakers pipe from one of the mills here...The old timer who built the house and lived in it for 30+ years must of saved around $40 grand!!!
Wow just imagine the legal charges the old guy would have got if Edison caught up with him before he died. How did you leave it or did you buy the house:)
 

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One thing with selling back to the grid. According to a friend who has solar but does not have batteries.
Anything extra the power company has to buy from you but at the wholesale rate. then anything he uses he buys at the retail price.
Example He generates extra through the day. the power company pays for example .02 per KW.
Then he needs power at night, He pays .10 per KW.
Even if he generates more through the day then he uses at night he is still loosing money.
In my case anything that goes on the grid is paid to me at 22 cents a KW. Anything I import is charged the normal charge of 24 cents a KW. This was an off and on rainy day. In July I usually produce around 70KWh per day. Yesterday was a so so day and was paid $1.32 credit with no E bill plus an other $6.79 for my Mass Smart payment
716792
 

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Discussion Starter · #17 ·
My system has one inverter for each panel (35) and each provide 240 volts which feed a central control panel. 10 year replacement guarantee and if one fails my grid looses just one panel until it is repaired. I believe Kevin has two large inverters for redundancy. Correct me if I am wrong Kevin. Solar systems are not one size fits all
It's actually 1 physical box with 2 inverters inside producing 2 hot legs.
 
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