I want to say we have 320w panels. Also- winter production sucks because we have some pretty tall pine trees on the south side of our house. Summer with high sun we make a ton but winter when it is lower our roof is more obscured by the trees. I'm considering a guerrilla mission to cut them down. Hahaha
CyberEric said:In reply to Antihero (Forum Supporter) :
Thanks for the info. I'm curious: how much power do you make per day with that system? Do you know how much you use?
Right now, in summer, which isn't hot (SF Bay Area) and we don't have AC anyway, we almost always consume less than 12 kwh per day, and usually less than 10 kwh.
My wife and I think we could be even more sparing with our energy usage, for example we still use our dryer. If we could use a $3k system to go off grid, it would definitely be worth the upfront costs. I was seeing more in the line of 9-10k, but that's for people who use more power than we do.
And Curtis, I know you were kidding, but we recycle our pee (it goes on our compost pile), and we siphon our gray water from the tub and washing machine for use in the garden.
Re net metering, yes they do it here, but it's fractions of pennies on the buy back, so it doesn't really amount to much. Around here, if you do grid-tied solar WITHOUT the battery, it's basically the same cost-wise as regular power, due to the tax breaks. We are considering going off-grid if we can make the upfront cost work. I still need to look into whether or not we can go off-grid here without penality.
I really dont know how much I use or make. I will say I consume way way way less that 10kwh a day.
If you were to run that system you literally couldn't have any electric appliances or heat. So, no refrigerator, no stove, no microwave, no furnace, no dryer etc. It would all have to be gas appliances.
I heat with wood and if I need it cooled down it's just fans at night blowing cold air around. We do have a washer and dryer but we only use it on generator once a week or so. Generator is used for heavy loads, but usually I just use it when I pump up the pressure tanks so it's not "extra" generator time
Here's a decent online calculator to see what you can get from your solar array in your location, just enter your location to get started and then DC kW size, if your roof isn't exactly south you can account for that too. You can download the data in monthly or hourly formats if you want to dig in that deep. The hourly data will give you an idea of when the sun is actually shining and how long you might have to go with your panels producing nothing running off of batteries or a generator.
https://pvwatts.nrel.gov/index.php
Some utilities up here provided you have a smart meter will let you download your daily or even hourly data of your actual usage. If that is the case that will be very valuable as you size your system and get a really good look at your actual usage.
The National Renewable Energy Labs PVWatts calculator does a good job of assessing your roof's potential and in my experience is accurate to a few percent. https://pvwatts.nrel.gov/
You will want an accurate site survey, including a site obstacle/shading survey. Things that don't look like they'll be a problem tend to become problems in winter when the sun is really low, decreasing your already low output. You can do this yourself if you don't mind climbing up on the roof, and I understand that there are cell phone apps that work pretty well. I used a Solar Pathfinder - old tech but it worked. Pay attention to small things that throw shade - poles, antennas, even wires. They have a bigger impact than you'd figure.
Finally, and once you have a good idea of what you're doing, I'd start calling some contractors for quotes. You'll get more respect and better treatment if you have a clue. The best deals around here used to be mid sized solar specialists and sometimes electrical general contractors but in your area (and some years later) it's probably different. Get at least a couple of all-in quotes from shops that can provide references and that check out as reputable. Unless you're a massive DIY geek, it's generally not worth going at it yourself especially since you're going to have to get an electrician involved to connect to the grid and pass inspections, etc..
Finally, it sounds like you figured out the one real downside of going off grid - you have to oversize the system in order to have enough capacity during the low sun times of the year. (or get a generator to top up when you need to) I think California allows you to bank your excess production and settles up at the end of the billing year. (or maybe they used to) That lets you right size the system to your overall needs and is probably your best bet.
In reply to CyberEric :
In North Carolina, If you generate more electricity than you use, the power company has to buy it by law. So I would spend a little more on the system since you are spending quite a bit anyway.
Electric expert here. Given the rules in California, a grid-connected system means that your monthly bill will be zero, or, given your low usage, a positive cashflow to you.
However, with a grid-connected system, when PG&E shuts your power off you're subject to a blackout. The easy solution is a Tesla Powerwall array. Or even just a single one, as they store 13.5kwh, more than you use every day. So you buy a system with a Powerwall and set it up so that in a blackout it is your backup. You can also arrange it so that it is a source of income (charge during day, discharge at night), or just cut your utility connection. The best $ value is using it as a source of income; the middle ground is to keep your grid connection but have the battery as a backup.
Good luck! It's a fantastic time to install solar panels.
This is interesting, thanks everyone.
BTW, about the effects of shade and a less-than-optimal panel location: I took an old panel (6W, I think) and hooked it up to an ammeter and started playing. You would not believe how fast power generation drops off when there's even a small shadow on part of the panel. Also, angle is really important. This is all well understood but it was a real eye-opener seeing it in person and just how big a difference it all made.
One other factor to consider, are you ever going to sell?
If so you have an expensive and time consuming hurdle to cross. There can be liens against your property or taxes and getting them removed or subordinated to the Buyers new financing crashes most home sales I've see, and I own a mortgage company.
It's not that solar is bad, although it's not quite ready for prime time yet, it's the way it's sold.
Of the ones I have seen closed they've never closed on time even if your moving van is in the driveway.
I'm on several industry specific forums and solar and home values was just a hot topic. In most parts of the country solar ads NOTHING, as in $0 to your value, and in many areas causes a drop in value. And of course that's not what those siding salesmen, wait I mean solar salesmen tell you.
In reply to carguy123 :
One other factor to consider, are you ever going to sell?
If so you have an expensive and time consuming hurdle to cross. There can be liens against your property or taxes and getting them removed or subordinated to the Buyers new financing crashes most home sales I've see, and I own a mortgage company.It's not that solar is bad, although it's not quite ready for prime time yet, it's the way it's sold.
Of the ones I have seen closed they've never closed on time even if your moving van is in the driveway.
I'm on several industry specific forums and solar and home values was just a hot topic. In most parts of the country solar ads NOTHING, as in $0 to your value, and in many areas causes a drop in value. And of course that's not what those siding salesmen, wait I mean solar salesmen tell you.
You are describing solar leases and power purchasing agreements, which have little in common with buying a solar system for your home. CyberEric is also in the CA Bay Area, one of the most expensive energy areas in the country and also one of the hottest housing markets. He will most definitely increase his home value. That said, definitely be careful with a solar lease, read all of the terms. There is a wide variety. Buying is much better, as there is an ROI. But for those that don’t have the cash, a well shopped lease can still be better than paying PG&E.
Lots of good advise on here, but I’ll point out one thing that seems to always get left out in this discussion. Shop around, but cheaper isn’t always better. Component quality varies greatly. Most of us don’t buy appliances and electronics by whatever is cheapest, we buy for value. Same for solar. It’s gonna be on your roof for 30 years, don’t buy crap. Especially the mounting points. Many installers save a buck by installing cheap mounts. The quality of the labor is very important. There are good installers and horrible installers, and you can’t always tell by the price of their bid.
On battery backup, it’s still expensive, and hurts the ROI. It is a viable alternative to generator, but more expensive if back up power is your main goal. That said, PG&E will be getting more aggressive with it’s time of use charges. You may find yourself sending cheaper power back to the grid during the day, and getting charged for more expensive power in the evening. A battery can save your day generated power to use at the peak time.
In reply to Boost_Crazy :
Regarding the cheaper vs more expensive argument, interestingly, the best bids for my house were using more expensive, higher efficiency panels but fewer of them. The biggest installer in my area only had less efficient panels.
Keith Tanner said:This is interesting, thanks everyone.
BTW, about the effects of shade and a less-than-optimal panel location: I took an old panel (6W, I think) and hooked it up to an ammeter and started playing. You would not believe how fast power generation drops off when there's even a small shadow on part of the panel. Also, angle is really important. This is all well understood but it was a real eye-opener seeing it in person and just how big a difference it all made.
Yup. And one panel underperforming affects the whole serial string. Hence the suggestion for a really good site survey. If it's unavoidable, using microinverters helps reduce the problem but at a higher cost and a little less efficiency, although that may have gotten better since I last looked at it.
You can model the effects of panel angle and direction with PVWatts.
Finally, I stopped by to drop off this article. It looks like Tesla might be a good option for somebody that has a good idea of what they want to do. https://www.tesla.com/blog/lowest-price-home-solar
I personally wouldn't consider doing a place with string inverters? Micro is good for anywhere up to 10% more array efficiency depending on the size and ratings of your panels. Yes, technically if everything is absolutely perfect and there's no clouds or shadows then string can be a slight edge to an array of extracting exactly the same output panels, but in the real world I've never seen an example of they being the case.
For example, if you look at my array over it's lifetime:
You can see that due to the trees and angle of the sun, the upper left gets slightly less output throughout the year than the rest.
If I had a string inverter, all of these would be limited to the 1.82 MWh of the upper left corner panel, which would mean my lifetime production so far would be 80.08 MWh instead of 93.35.
carguy123 said:
I'm on several industry specific forums and solar and home values was just a hot topic. In most parts of the country solar ads NOTHING, as in $0 to your value, and in many areas causes a drop in value. And of course that's not what those siding salesmen, wait I mean solar salesmen tell you.
Like any home improvement, it likely only adds "saleability" appeal and no real monetary value.
Aren't all home values, for purpose of negotiation of purchase price, based on an appraisal anyway? I thought appraisals don't take into account interior updates but they do factor in exterior updates like roof, etc., do they take solar into account now or will they be?
Zillow did a study on this and similar houses with PV sold for 4.1% more than homes without. It was a little higher in SF, not sure what the difference would be in the east bay area. Appraisers do factor in solar since it does affect the value.
chada75 said:In reply to CyberEric :
In North Carolina, If you generate more electricity than you use, the power company has to buy it by law. So I would spend a little more on the system since you are spending quite a bit anyway.
In NC, there is no way to make it make sense financially. Its purely a philospohical statement.
In reply to adam525i (Forum Supporter) :
Solar and back up can be a wind generator or diesel generator or all three.
A friend uses solar panels for day use with a back up wind generator and used cooking oil generator. He also uses reconditioned forklift batteries as his energy sink. At times the solar and wind produce enough electricity that he risks burning out his water heaters, overfilling his water tank, and other high energy users. At that point he uses charging scrap forklift batteries. While some are approaching 20 years old they still can retain 80% of their rated capacity.
The cooking oil diesel generator is used for high demand stuff like his irrigation pumps and welding. Or the rare days with no wind and heavy cloud cover. His heat is radiant hot water driven by electric water heaters and we get to 40 below in the winter.
engiekev said:carguy123 said:
I'm on several industry specific forums and solar and home values was just a hot topic. In most parts of the country solar ads NOTHING, as in $0 to your value, and in many areas causes a drop in value. And of course that's not what those siding salesmen, wait I mean solar salesmen tell you.
Like any home improvement, it likely only adds "saleability" appeal and no real monetary value.
Aren't all home values, for purpose of negotiation of purchase price, based on an appraisal anyway? I thought appraisals don't take into account interior updates but they do factor in exterior updates like roof, etc., do they take solar into account now or will they be?
appraisals definitely factor in inside. Hardwood floors and marble bathrooms increase values. Rugs and linoleum decrease valve. Plus factors like contemporary styles over dated styles. High end appliances like Sub Zero refrigerators and Wolf cooktops. Increase While contractor grade appliances decrease values. Infloor radiant heat has a higher value than forced air, etc etc etc.
In reply to jwagner (Forum Supporter) :
Zillow did a study on this and similar houses with PV sold for 4.1% more than homes without. It was a little higher in SF, not sure what the difference would be in the east bay area. Appraisers do factor in solar since it does affect the value.
4.1% is a LOT in SF, where the average home has to be over a million. Especially since there is less demand for solar there, since they don’t have much in the way of HVAC loads. Not a lot of pools either.
The thought of when/if we sell is impacting this decision in the sense that, if we move in 5 years, we will not have made an ROI. Will that be recouped in the sale of the house? Who knows! The market will probably dictate that more than anything else. Whether or not tech companies continue to do well probably has a bigger impact than solar panels on my roof.
I just don't know how long we will be here. We don't PLAN to move anytime soon, but things change. Especially now!
JWagner and Adam535i, thanks for the link. I have to admit, I don't totally understand the information it provides. I'm also not sure I input the information correctly.
I called an independent solar contractor in my area, in hopes of getting some more specific information. We'll see if he calls me back.
The truth is, there is so much to learn and understand, and I have so many other things going on in my life, I'm feeling overwhelmed.
So far, it seems like the best I could do in terms of upfront cost is around $10k after incentives before installation. But again, I need to know more to be sure that system would produce enough.
And for those who keep mentioning energy buy back, it's so miniscule from PG&E it's criminal and is not enough to really matter.
Thought I'd take a look at your situation with some back-of-the-napkin type calculations.
Do you mean 347kWh/month? Even that puts you well under half of what the average house uses. Assuming that's a monthly number, PVWatts thinks a 4kW array in Hayward would put out about 6,500kWh/year which is 542kWh/month - a lot more than you use. I used 4kW since that's the smallest array size Tesla sells and the price on that is handy: $8200 cash, $6k after incentives. If my numbers are correct, a 4kw array would more than zero out your net usage and you would be selling power to the grid on a yearly basis. A 3KW array would actually be enough to cover your yearly use.
Without running a full cost model, I would bet if you sold the house in five years you would have a positive ROI, calculating what you save plus the added value of the array to the value of the house. Remember to figure in interest, or the lack of it if you pay cash. Let me know if I can help with more free advice. (which is usually worth what you pay for it...)
Thank you Jwagner! That price is without battery correct? Seems like a good option.
Yes, our average monthly consumption last year was 347 kWh.
It’s higher in the winter, can’t remember how much, maybe 550, I’d have to double check my spreadsheet.
My concern is we wouldn’t make enough power during the winter.
In reply to Boost_Crazy :
No I was talking about purchases also, maybe purchases moreso. That is unless you pay 100% cash
CyberEric said:My concern is we wouldn’t make enough power during the winter.
You likely wouldn't, but I don't think it matters.
I'm not an expert on how PG&E works in CA, but as I understand it, they credit you for the months you make more power than you need, and you run a debit for the months you don't. They do a true up at the end of the billing year, and if you used more overall than you generate you pay the difference. As you mentioned, you don't get a lot for the excess you generate. All this info is online, it just takes some time to read through it.
According to an online calculator I use roughly 80 kwh a month.
This seems pretty accurate as we were using about 110 a month living in the city with an a/c half the year and furnace fan the rest of the time.
A question about the mounting of solar panels. Why put it on the roof of the house if you have land?
All of the mounting points could be potential leak points.
You'll need to log in to post.
