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Old 01-25-2022, 09:47 AM
Location: Lost in Montana *recalculating*...
19,779 posts, read 22,673,762 times
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We currently have a 6.10 kW system. Roof mounted over metal installed in 2019. We have an all electric home with the exception of a propane fireplace and cooking range. We took advantage of the Federal Tax Credit and a state program through DEQ. We have a net metering agreement which allows us to carry forward any energy surplus in the form of a 1:1 credit for a rolling 12 month period. We do not generate enough to take advantage of that-yet.

The math fleshed out to a savings of almost $900 p/yr. Thus far it has been more than that. The system should pay for itself in 9 years, leaving 11-16 years of generation based on the useful life of the panels.

We're considering adding additional solar to our shop roof, self installed. I've got a lot of real estate on the shop roof..

We like it. Even here in Montana the math works out in our favor.
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Old 01-27-2022, 12:12 PM
Location: Not far from Fairbanks, AK
20,293 posts, read 37,189,297 times
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Originally Posted by guidoLaMoto View Post

No ROI on grid power, but you forget the lost investment potential of tying up so much capital on the solar installation & the expense of interest if you don't pay cash up front for the installation...and the maintrnance/repair costs & inconveninence of your own installation.

Most areas of the country don't have enough sun to make the switch to solar worth it. You're in ID on the lee side of the mountains-- plenty of sun. Here in WI, for instance we average only 4 hrs of useable sun per day over the course of a year.. ..Snow & ice accummulation in winter is an inconvenience and possibley a hazard...Then there's the added cost of routine roof repair/replacement AND-- you gotta replace your entirie installation every 20-25 yrs-- more capital expemse.

Unreliables will always remain a niche application for most people in this country.
You are correct, and so Retire from PA, but not the poster above you
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Old 01-27-2022, 12:35 PM
Location: Not far from Fairbanks, AK
20,293 posts, read 37,189,297 times
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Originally Posted by RetireinPA View Post
I have been working on this for over a decade now, but I started small. I have been trying to make it work for my RV as we boon dock a lot (no campground services - use what ya brung) and while I can get systems REASONABLE to charge the coach batterIES (note the plural) 12v system, there is no viable alternative for the 120v system.

IF they came up with absorption cooling systems that are (once again) REASONABLE for the AC, this would be more doable.

some of the examples:

1) to park in full sunlight means *a lot* more daily heating, making the AC demand higher
2) to park in the shade to lower heating of the coach, means the solar effectiveness drops by an even larger percentage.

*extrapolate both of those data points for a home - shade trees or full baking sunlight?*

3) solar does not work sunup to sundown cuz we dont aim the panels - and realistically wont for any application
4) battery storage must be adequate. In a rv application where an inverter is needed for nighttime AC use - anyone who owns one can testify how miserable they can be at night using just windows - a small AC would need around 6-8 large size golf cart batteries and when you do that the battery wiring is UBER complicated (just ask if curious). This many batteries can put an rv quickly over tongue or axle weight and if enclosed...that is a lot of hydrogen off-gassing. Given the current state of LiPO3, I dont wanna sleep over top fire bombs that have shown adept ability to just go up in smoke with no warning - while OFF

*for a house tongue and axle weights are not a consideration but you will need a detached, vented structure with flood fire suppression in the case of lithium storage.

5) for an rv with a majority 12v system, standard panels from anyone work and the el-fake-o luggage rack on top is a great place to mount them. You can use 12v panels at all times and the total size will be generally under 5-600W which means an inverter for 120V for tvs - not appliances - will suffice.
6) for a house, the inverter has to be robust and with the panels required to duplicate what you have now, you need 44000 watts base load, but in the modern age, save any dryer and any resistive heating we can drop this - the bottom line will be the starting and running watts of AC and fridges, dehumidifiers, washers. Figure 10000W to cover the AC (since once again, absorption cooling is not REASONABLE) In this case the inverters have to be beefy and perhaps in the 36-48v DC input voltage. This is not rocket science, higher voltage controllers and multi voltage selectable panels are available everywhere.

so we are back to how much juice and how do you get it.

1) half the day you get none
2) some of the day you only get some. hazy sunlight is better than clouds - you may need to opt for an array whose base 'cell' voltage is in the 20-24 range. unlike batteries, the base solar cells that make up a 'cell' or grid can be destroyed if the input voltage is too high. when you place a ton of .5-.6v cells in series, at some point the potential of the previous cell to the next cell is over the destruction voltage. so by using 20v panels - we have a 15v target in order to be called 12 (meaning a 36v 'panel' - 3 12v sub sections in series - is really 45vs for the controller and 60v at max. This voltage spread enables the panel array to stay above the quiescent voltage of the inverter as a cloud passes over or its not so sunny.
3) there really is no way to cheat #2 - I have tried.
4) not only does the panel array have to provide base load for the day, it has to provide charging for at night, you cannot have both from the same watt, so this has a near doubling effect on the panels - in order to get *some* charging on a rainy day.
5) snow. I live in pittsburgh. my experiences are going to be representative of *at lease* every location at the same latitude and all of canada. Elsewhere we conducted a little experiment. our 'snowmaggedon' on MLK weekend (the MSMSs words, not mine) shut off my theoretical panel array on my garage on sunday at 4pm MLK weekend. 9 days later its STILL off. Unless this old man (me) climbs up a number of times with a really long handled push broom. The snow is STILL on the roof. We call it winter. In pittsbugh, roughly 44% of the days are overcast all day - we have more cloudy days than seattle (yet they take to ledges and bridges at a much higher rate to off themselves - go figure. Musta been the coffee.) And even in the summer my declination is much greater than say Phoenix. Actual life giving sunlight is much less, when amorphic crystalline technology is in use.

so, if you live similar to me, solar - at current technology - is an assist at best. and expensive to boot. prone to failure, a maintenance *****, and we have not even talked roof rot yet.

Is short, Id LIKE to be off grid, but it aint happening at present. The boys in R&D need to keep working.
Outstanding explanation about what it takes to power a home on sunlight We have some very expensive homes that cost several million $ that are super insulated all around (floors, walls, and roof), and completely air-tight (no air leaks). Heat pumps are buried deep since the ground is warmer. Solar panels supplement the commercial electricity needed to power the entire home because of the long and dark winters in Alaska. Much easier to power the home during the summer, since there is plenty of sunlight.

Solar panels in the interior of Alaska have to be elevated a few feet above ground, or from the roof. Also, if installed on a roof, one has to figure a way so that the panels can be moved out of the way to allow to shovel the snow that accumulates on the roof. At the moment I have about three feet of snow on the roof.

To summarize: one should not forget that there is a thing as night (darkness) and day (sunlight), and also that lots of time there is not much daylight during the day. If the solar panel array can be designed to turn automatically following the direction of the sunlight, then they would be more useful.
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Old 01-29-2022, 10:09 AM
305 posts, read 294,968 times
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Originally Posted by Threerun View Post
We like it. Even here in Montana the math works out in our favor.
Glad photos for sharing.
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Old 02-04-2022, 11:34 AM
1,097 posts, read 647,541 times
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In Florida it's all about cooling. I happen to have shade trees and no room for panels other than the roof. I'm not about to direct more sunlight to my house by trimming or removing the trees. I want shade.
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Old 02-06-2022, 03:49 AM
Location: HONOLULU
1,014 posts, read 480,079 times
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I was reading up on that too. iPhone news. It came though in the form of Solar flares from the sun. And hot it got. If you got to places like Phoenix, Arizona, this would definitely be good for generating a air conditioner. From solar heat panels. In California solar heat panels are also popular. They can generate enough electricity to power the air conditioner to run the air conditioner in a closed room. And to make hot water from the Solar panels. This would be a nice thing to have. The problem though, with the weather too hot at certain times of the year, solar panels would not be as useful. There's no need of hot water during the summer time in Phoenix, Arizona. Just cold water is needed. But cold water would be difficult to make if the solar panels all turned the water in your housing to hot water. There would be no cold water to use. Hawai'i is an average mid 70s to mid 80s fehrenheit temperature. Getting a solar heater is a definite plus thing to have.
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Old 07-14-2022, 05:42 AM
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My house is perfect for solar. The main/long side faces South and there is another shorter side that faces West. I would love to have a solar system. But not the way my brother does. He had a solar panel setup built just for solar. He is paying for this for 30 years. Yes his electric bill is lower, but maybe not once he adds the cost of the panels. He does get a tax break of some type.

I have looked at the ads, but they all look like scams to me. I would want something that will work if the power goes out where I don't have to run a generator also.
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