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Matthew Nistico wrote:
Phil Swindler wrote:Last March we installed a grid tied system on our roof...
The electric bill we paid for this last December was $11.53. That was all just taxes and fees. We haven't paid for any actual electricity since August. If we didn't air condition, we wouldn't have paid for any electricity since April.
We don't have battery backup. But, if you can pull that off with your budget, I would encourage you to go for it.
Yes, if you are looking for a whole-house system - very different than what the OP is proposing - then it is often very attractive to go grid-tied. Glad that your own experience has been so good! Batteries are great for self-reliance, but unless your power needs are very, very low, buying a suitably large battery bank can be cost-prohibitive. Even in the best circumstances, batteries will certainly be the most expensive part of your system. If I were to buy lithium batteries for my own small (3.8kW), whole-house system right now, enough to ensure off-grid capacity for my needs, they would cost at least twice as much as all other system hardware combined.
However, a word of warning to any newbies who might be reading this thread: your grid-tied mileage may vary! If you're interested in grid-tied photovoltaics, then before even wasting your time researching other aspects of your system, look up what net-metering rate schedule is offered by your utility. Without good net-metering terms, you may decide to go another way. And those terms vary enormously from utility to utility, based on what your state government has forced them to offer. I say "forced," because the general rule is that your utility really doesn't want you to generate power, even while you sell them the excess for cheap; they are invested in the traditional model of selling you electricity that they distribute from a centralized generation facility.
With growing federal requirements to transition to renewable energy, you'd think they might be happy for you to add grid-tied solar - for which they get to claim the federal renewable generation credits - to their system at your own expense, right? Nope. They are building they own solar farms. So they intend to remain within the traditional model: they generate power centrally, albeit renewably, they control the distribution, you buy their power.
My own utility is switching from a very attractive net-metering schedule, to an almost-as-nice interim option, to just this month a new option going forward that is so unattractive it is practically punitive to the home generator. How is that for boldly going into a renewable energy future?! With a little luck, I should be grandfathered into the interim schedule for years to come. But if I were to end up on the newer "punitive" rate schedule, it could be so bad that I literally would save little-to-no money even while generating most of my own power! Yes, that bad.
The point is that net-metering can make or brake your plans for a grid-tied PV system. If I didn't already have a solar system, and my only choice was the newer rate schedule, I might well consider investing that money somewhere else entirely.
Full disclosure: my own economic situation relative to utility bills is somewhat unique simply because I consume so little energy. A more typical American household that consumes at least two, or maybe three, or even four times more energy than I do would likely still find at least some benefit to home generation, even under my "punitive" net-metering rate schedule example.
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Dianne Justeen wrote:
My husband is the one investigating solar. Seems like the priciest part is the batteries. He's doing further research on DIYing the battery bank. Can't be super-helpful on that one yet but it may be possible and much more cost efficient. Anyone know anything about that?
We'll need enough to power the well pump and the bare essentials for at least several days with minimum recharging if the weather is bad. Considering some wind powered charging since we have fairly steady wind but yet to tackle looking into that. We're guessing it could be tied into the solar setup but could be wrong.
Katherine
Daniel
Daniel Kaplan wrote:Hi Mike,
You've bit off a big project. I started work on a similar system but you're quite a bit more ambitious than I was. Others have run through most of the practicalities. I was going to mention line loss from the panels to your house but someone beat me to most of it. Same with how fast you can charge different batteries. I can, however, add a little to line loss on your runs from the barn to the house. In electrical circles it's called voltage drop and it's pretty much solely based on how many amps and what size wire. A 10A load running over 10A wire is going to lose as many volts for a 12v system as for a 120v system. But you'll get 10x the power through on the higher voltage system. That's why panels and batteries are commonly run in series.
For example your initial 6 330 watt panels on the barn all in series. (my 260W panels are 37V open-circuit so I'm using those numbers.)
First off, I'd guess you won't get a straight shot. Estimate it's probably 250' of wire. (Might be optimistic)
The panels will, under laboratory conditions make 222V @8.9A
Run that the 250' to the house using #10 wire and you'll lose 5.1V or around 45 watts
Using #12 wire you'll lose 8.2v, or 73W
Using #14wire you're at 13V or 116W
however, one leaf or patch of snow on one of those panels will cut your production significantly. Not sure if it's more or less than half.
So obviously having panels close to the house would be better if you had sun exposure.
I'm not sure how much useful sun you'll get in WI. I'm in CO and have trees running north-south on both sides of the house. I've been getting about 1kwh per day out of 520w of solar panels. You'll need more than you think.
Definitely invest in a good clamp ammeter like a fluke 275 so you can measure the startup currents on stuff. Kill-a-watt meters are good two but for two things: Neither of mine will tell me startup current and they only measure Watt-hours and not Volt-Amp-Hours. Watts don't actually tell you how much is being drawn from your panels or batteries. Watts is only how much energy is going to useful work but not how much is going toward inefficiencies. And these can be significant for anything with a motor, which is most of what you listed. Your kill-a-watt will give you power factor. Basically a power factor is the percentage of total energy that's producing work. So if your freezer has a PF of 70, which is completely within the realm of possibility, the watts you're measuring toward watt-hours is only 70% of the total power you're using. Most computer and cell phone chargers are abysmally low, as well. I think my computer one has a PF of 52.
Personally my system is completely isolated from any or my house wiring. I have to unplug an appliance from the wall and plug it into my off-grid system. I've thought of running dedicated wires from the inverter to a different-colored outlet next to strategic appliances I might want to power. If you're wanting to integrate your off-grid system into house wiring you need to invest in transfer switches and a lot of knowledge in how to set them up safely.
When I was first starting to tinker with this I was trying to come up with a system that I could expand. Unfortunately you want your batteries to be matched (no pairing old ones with new) or you run the risk of your batteries discharging each other. I'm not sure how big of a problem this really is. I wanted to go with Lifepo4 batteries since they claim a much longer lifespan and greater depth of discharge. Unfortunately in the end I decided that they were too expensive for the amount I'll use them plus they're a relatively new technology. Lead-acid is a much more mature technology. I figure when I get ready to upgrade to Lifepo4 they'll have gotten cheaper the tech will have matured. Sure they claim 8-10k cycles now but will they? Sort of like how 10yr LED bulbs burn out in a few months or a couple years now.
In the mean time I decided to go with a pair of Trojan T-105's (6V, 220Ah). They'll run my chest freezer for about a day and a half without sun. The freezer draws 68W when running but when first turned on it draws in excess of a kW. My 1200W inverter can't handle that without using its soft-start setting. Or, maybe more likely, my batteries don't like putting out 100A to power it. Putting another set of batteries in parallel to these might make it work better. I don't know.
Whenever the time comes to upgrade I'll probably just start another system based on everything I've learned here. For instance I'd want a 24 or 48V system for anything running an inverter but I have lots of stuff that runs off 12V. If I don't have to run an inverter that's a lot of power savings.
For instance you could have one system in your barn for barn loads and one system for your house.
Charging you're wife's Prius has its own issues. I assume it has an AC charger but the batteries need DC. Going DC -> AC -> DC will have a lot of loss. If you can find a DC charge controller for it you'll be ahead of the game. The author of http://aprs.org/my-EVs.html has experimented some with charging Prius's off solar and may have some insights on how to best do that conversion.
You might be able to use the Prius as a generator for recharging your batteries when the sun isn't shining.
Personally I think I'd recommend making a smaller system to power one load and trying it out for a year or two before throwing a whole lot of money at it. Otherwise, keep doing a lot of research so you get it right (don't get it too wrong?) the first time.
Oh, one more thing. Working with high voltage DC is a bit more dangerous than working with AC. If you accidentally grab onto an AC wire there are 120 times a second when it has 0 volts on it and thus give you a chance to let go. DC gives you no such reprieve.
Argue for your limitations and they are yours forever.
Michael Qulek wrote:[
Scroll back to post #8 of this thread. The 48V system outlined is what you would need to run a 240VAC well pumpl
I think anyone that thinks they can make or rejuvenate batteries is delusional. Tried to rejuvenate a dead battery once with the EDTA method. All I accomplished was the destruction of a good pair of pants. Good batteries are not cheap, and cheap batteries are not good. You get what you pay for!
Most people I've seen online have been disappointed with wind generation. Unless you are on the beach, or a mountain top winds are not high enough to generate meaningful power. Keep in mind that most wind generators make zero power below 10MPH, and the curve for making more power is very sigmoidal.
Sean Wood wrote:That said, if I were doing everything over again and didn't have access to micro hydro I would probably do a biogas system which uses a fraction of the footprint, provides gas for heating and cooking and water and fuel for generator and potentially vehicle as well and is just capturing existing methane production from biomass breakdown.
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2024 SKIP event at Wheaton Labs
Mary Cook wrote:
Another thought. There is a lot of talk about the various options and whether they are cost effective, including whether to do this at all. I say, the time is coming when the grid becomes unreliable and perhaps goes down altogether, and it will no longer be possible to get solar panels--they are not a backyard project--they're high-tech and require high amounts of power to build. So it's up to households and communities to set themselves up with minimal power systems. Here I draw on my own experience: the first five years I lived in WV, in the late '70s and early '80s, I had no electric--and really didn't mind. But I was a childless single hippie, living on nothing. For light in those days I used a kerosene lamp. Those smell, the wicks always need trimming, and they're a fire hazard. Kerosene is also a fossil fuel. Now we use LED lights that don't smell or leak and that shed plenty of light while drawing a tiny amount of power. Here's the punchline: if you decide it's cheaper to stick with grid power, and things come crashing down, you'll be using candles. On these long winter evenings... So yes, you do need to configure your system so you can add to it later, but put a small system up NOW.
Mike Haasl wrote:
Sean Wood wrote:That said, if I were doing everything over again and didn't have access to micro hydro I would probably do a biogas system which uses a fraction of the footprint, provides gas for heating and cooking and water and fuel for generator and potentially vehicle as well and is just capturing existing methane production from biomass breakdown.
I don't want to take this thread off topic since it's full of awesome information. But I am interested in this as an alternative. Might you be able to start a new thread to describe what you'd have in mind and then we can talk about it over there? Thanks!!
Michael Qulek wrote:
I think anyone that thinks they can make or rejuvenate batteries is delusional. Tried to rejuvenate a dead battery once with the EDTA method. All I accomplished was the destruction of a good pair of pants. Good batteries are not cheap, and cheap batteries are not good. You get what you pay for!
Dianne Justeen wrote:
Mike Haasl wrote:
Sean Wood wrote:That said, if I were doing everything over again and didn't have access to micro hydro I would probably do a biogas system which uses a fraction of the footprint, provides gas for heating and cooking and water and fuel for generator and potentially vehicle as well and is just capturing existing methane production from biomass breakdown.
I don't want to take this thread off topic since it's full of awesome information. But I am interested in this as an alternative. Might you be able to start a new thread to describe what you'd have in mind and then we can talk about it over there? Thanks!!
If you do start a thread on that I'd be interested in following that as well. So please post a link to it here.
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EBo --
Master Gardener (Prince George's County, MD, USA)
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
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Mike Haasl wrote:I've been watching the shadows on the barn this week (when the sun is out) and I'm not feeling optimistic. Below is a picture from the barn with my camera at the bottom edge of where a panel would be (just above the doors) at 10am. So I think I'd have to cut down many dozens of trees to get sun on the barn. Despite how high and sunny it seemed, it's not as sunny as I thought :(
Blazing trails in disabled homesteading
EBo --
Master Gardener (Prince George's County, MD, USA)
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2024 SKIP event at Wheaton Labs
Mike Haasl wrote:The sunniest spot on the property is where the greenhouse is. So if I used a cart or ground mount it would have to be in front (south) of the greenhouse. I'll check how the sun hours are down low at that spot.
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2024 SKIP event at Wheaton Labs
EBo --
Master Gardener (Prince George's County, MD, USA)
Daniel
SKIP books, get 'em while they're hot!!! Skills to Inherit Property
Come join me at the 2024 SKIP event at Wheaton Labs
Daniel Kaplan wrote:My dad has an app on his phone that you can point at the sky and will tell you the path of the sun at different times of year. I wonder if that would let you analyze different spots around the yard quickly. Probably direct observations is better, though. Direct observation with a small system is probably better yet.
David Baillie wrote:
Daniel Kaplan wrote:My dad has an app on his phone that you can point at the sky and will tell you the path of the sun at different times of year. I wonder if that would let you analyze different spots around the yard quickly. Probably direct observations is better, though. Direct observation with a small system is probably better yet.
Hi Daniel, what app is your dad using? I'm always curious about these things.
Cheers,. David Baillie
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Ebo David wrote:I wonder if there is some sort of image processing/model that would compare the area in shadow on your roof throughout the day -- and use that to estimate the degradation in PV efficiency. I do not have time to research that now, but of you have time to dig on the net and find some potential programs I'll break away a little time to check them out. It will of course require a series of photos all from the same place if not also orientation (but I can probably adjust for that). Let me know if that is of interest.
South Facing, Jen
EBo --
Master Gardener (Prince George's County, MD, USA)
Ebo David wrote:Hope it all goes smoothly for you Jen. I would be curious what they said was not possible. There are things that are not possible (or possible but not practical), and maybe someone here has an idea if something you asked was not possible. When someone tells me something like that I ask Why -- I have learned some useful information this way, and I have sorted out some of the BS that made me decide not to use that company.
BTW, when I got into this I found out that I could take the Enphase's certified installer classes. I got to the point where I need to submit a design, do a hands-on workshop, and then build out a system to become a certified installer. IronRidge (for their rackign systems) has a similar deal.
South Facing, Jen
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