Any recent experience with buying a solar system for your house?

[NW-Bound]

By the way, I like the new development of the microinverter, which is installed one-on-one with each 200W+ panel. It allows for economical incremental add-on installation.

I have been tempted to install a few panels to play with, without claiming any credit.

 

[NW-Bound]

...From what I can tell, the main solar production calculators that are used to set the production rates for a system in our area seem to understate the actual production by about 10% or so. This was based on discussion with others who have installed systems and based on our limited (less than 90 days) experience, this seems to be the case for us. If our production beats the predictions, good news. I think our being able to orient the panels in the perfect direction and without any obstructions really will work to our favor...

The solar output is often less than possible because of less than ideal orientation, shading by trees and nearby structures, equipment losses, etc...

When looking into this, I was reminded that not all places with the same latitude are equal in potential solar production. Yes, one has more insolation at a lower latitude, but the cloud cover and atmospheric conditions can knock down the sunlight intensity.

In the map below, states along the Gulf coast have the same latitude as the SW, but have cloud cover that reduces the solar output. This map is made with actual measured data collected over several years. The insolation is averaged over 12 months; the daily output at the peak of the summer is shocking!

My boonies home is in the perfect spot for a solar installation. It has sunshine mostly throughout the year, even in the winter, just like at the lower desert. Yet, being at a higher altitude, the air is clear with no pollution and is also thinner (people who ski at high altitudes know they can get a heck of a sunburn). The ambient temperature is a lot lower than at the low desert, which means the solar panels will have a higher efficiency. Too bad I cannot make use of these advantages.

PS. I also have high winds. Winds of 20-30 mph are common, with occasional 50mph blowing entire days!

 

[BBQ-Nut]

We did a solar install last December, got the permission to operate before the end of 2013 to claim the Fed Tax credit on our '13 return.

$19K for a 4.71 kW system in San Diego.

Not the highest bid, not the lowest, but from a company with lots of installs in our area.

Done quick, done right.

I'm pleased.

We own it outright as we plan on staying in our home for decades to come.

It is generating more than we use by a couple hundred kWh per month.

So, slowly hacking away at the balance due from last December using net metering and the 'settle up' come Dec '14.

 

[Totoro]

A bit late to the discussion, but still.

Few items to consider in the purchase process:

• Even if a company is backed by the government, municipality etc .. don't trust their claims by default. Ask for proof.
• Specifically, check whether the projected yield (generated energy) is garantueed or certified. Salesmen have an incentive to oversell. Your local government is as well now that they committed.
• Garantuees on the system don't mean much if the company issuing the garantuee will not be around. Many companies have gone bankrupt in the fast moving industry. So check who is giving the warranty and how stable they are.
• As a purchaser you have two main weapons: time and choice. They took away one from you already (competition between companies), don't let them take the other one! (time) Walk away when pressured to commit.
• All of the above items are important to sort out, you might get some push-back. Don't give in.

Market wise consider the following:

• Solar power has been dropping fast in price. Solar power - Wikipedia, the free encyclopedia
• The above is EU data, but the trend is the same everywhere. Price drops will level off a bit (Chinese race to the bottom is almost over), but further price reductions are likely
• Incentives to install solar will reduce with time
• It might happen that in the near future solar panel owners will have to start paying a special tax for their systems. This is already happening in some countries! Reason is that revenue paying for the network infrastructure is falling fast (less power taken from the grid), while the costs are rising (solar generating power requires smarter grids).
• Realize the secondary effects of everybody installing solar power: The demand for power drops thus energy prices will drop too, also for non-panel owners! This is happening in the NL for example.
• Your fire insurance may go up. Some fire departments also refuse to come near the roof of your house due to electrocution danger. Had a case like that in Belgium.
• Solar panels on your roof will impact the value of your house, positive OR negative. This should be included in the payback number.

If you take all of the above into account your payback number of 10 years (or 10% yield) might shift dramatically.

 

[travelover]

...........Some fire departments also refuse to come near the roof of your house due to electrocution danger. ...........

Similar things were said when hybrid cars first came out. Largely a non issue.

 

[ERD50]

Similar things were said when hybrid cars first came out. Largely a non issue.

Perhaps, but it would be worth asking your local FD if they are prepared for this.

-ERD50

 

[FIGuy]

4k for a 3kW system is a damn good deal. As incentives dry up, I expect this to go up actually. Generally speaking, $2 / watt is about grid parity in many locations with current financing approaches.

Figure about 1,000 kWh per year from each kW installed (varies a good bit, but ballpark). If your electricity is $.10 per kWh, then your 3kW system is worth 3 kW * 1000 kWh * $.10 = $300 / year. Systems have about a 25 year lifetime. Inverters maybe 10. So, this is maybe a 12 year payback and thus a decent investment. I'd go more off how the aesthetics of your house and thus house value will be affected if this is purely a financial deal. It's also inflation protection as the price of the electricity is basically fixed (or goes up with inflation if you like). It's like pre-purchasing all your coal at the utility or something.

 

[davemartin88]

A bit late to the discussion, but still.

• It might happen that in the near future solar panel owners will have to start paying a special tax for their systems. This is already happening in some countries! Reason is that revenue paying for the network infrastructure is falling fast (less power taken from the grid), while the costs are rising (solar generating power requires smarter grids).

I've also seen some discussion about changing the credit being given to the local owners of the system to give a reduced rate of payback, maybe a wholesale rate or something similar. Might not completely satisfy the concerns but might be a step.

Personally, I can see how receiving a lower rate of credit would make sense. Having said this, any excess power we generate while our system is producing goes back to the grid and is available for the power company to use. The utility still bears the cost of the grid for distribution so some offset seems reasonable to me but they do have the power for their use to meet other requirements?

Power companies will have to consider any benefits a reduced generating capacity might give if residential or local systems become more widespread. I think the fact that solar panel based systems provide power during daylight hours when usage peaks is another factor to consider for the utility when arguing for or against setting or changing the rates of payback to the local users.

Some interesting discussions in the thread- hope the original poster doesn't mind the diversion from getting specific feedback about our own installs!

 

[Zathras]

I've also seen discussion of giving solar producers an increased rate of credit.
And ERD, at least in my area, everyone does gain from my solar panels.
There is less drain, and upgrades on our utility's equipment as I am using less power, some of that during peak loads.
When my house is using 10kWh of power from my panels, that is 10kWh + grid inefficiencies less power my utility needs to transmit.
The utility won't need to build additional power generation as quickly as they would have, helping to keep rates from increasing as fast.

Sure, it isn't a lot, but there is some benefit. Does it balance out? I don't know, but lots of other subsidies for oil, coal, children, schools, etc don't either.

 

[Totoro]

Power companies will have to consider any benefits a reduced generating capacity might give if residential or local systems become more widespread. I think the fact that solar panel based systems provide power during daylight hours when usage peaks is another factor to consider for the utility when arguing for or against setting or changing the rates of payback to the local users.

There is also this: peak usage happens during the day, but not necessarily in the residential area where the generation happens. This means you need to transport the excess from residential to office & industrial. Managing many small fluctuating loads is also a bit tougher than one central load (like a coal plant) as well. Don't know the overall effect though. In areas with much air conditioning in homes it's probably less pronounced.

Another aspect is the difference between the distributing company and the generating one. I'm assuming it is split up (like here in Europe). The generating companies will suffer economically (less demand, and more volatile demand) but can't do much about it in the short term. Might lead to bail-outs a few years down the road. The distributing companies will complain to the government and demand more money in the short term for grid upgrades. And somebody will have to foot that bill ..

There are turbulent times ahead.

Within five to ten years I wouldn't be surprised if most developed countries will get all its power from solar on sunny summer days. And 0% on dark winter nights

After that, it is a matter whether battery tech can keep up. I think it won't at first.

Interesting times indeed!

 

[samclem]

The utility won't need to build additional power generation as quickly as they would have, helping to keep rates from increasing as fast.

I hear this a lot, but I wonder. Don't the rates charged for electricity cover the construction of needed generating capacity? And if they are increasing the generating capacity, doesn't that mean they are selling more "units"? If so, why would building a new plant necessarily increase the >rate< charged for electricity?

When Kroger builds a new store across town, I don't worry that the prices in my neighborhood Kroger will be going up to pay for the construction. When Honda builds a new plant, I don't conclude that CR-Vs will need to go up in price to cover it.

Obviously, the regulated nature of the market, the restricted number of suppliers, etc, makes the situations a bit different, but I'm not sure the case is automatic that more power plants equals higher rates. If it does, then they could close some plants and reduce rates--which doesn't make much sense. If the problem with the new plants is much higher build costs than existing plants, then it's easier to make a case for centralized solar installations (on a $$ per watt basis) than these tiny rooftop installations (per ERD's earlier post).

 

[MooreBonds]

And ERD, at least in my area, everyone does gain from my solar panels.
There is less drain, and upgrades on our utility's equipment as I am using less power, some of that during peak loads.
When my house is using 10kWh of power from my panels, that is 10kWh + grid inefficiencies less power my utility needs to transmit.
The utility won't need to build additional power generation as quickly as they would have, helping to keep rates from increasing as fast.

Sure, it isn't a lot, but there is some benefit. Does it balance out? I don't know, but lots of other subsidies for oil, coal, children, schools, etc don't either.

There are other factors at play. For example, most HVAC codes require increased fresh, outside air intake versus what used to be required 20-30 years ago. As new buildings are built, and existing ones are remodeled, they have to upgrade HVAC units with more fresh outside air. Which means more outside air has to be conditioned in the summer. Which means more electricity usage during peak times.

The problem with peaks is that you have to design for full capacity for it, to avoid rolling blackouts. And even though your 10kW solar panel is producing netbacks to the grid, the big thing is the starting/stopping of your AC unit. When a large motor kicks on for an AC compressor and fan, there's a HUGE relative surge in electricity for a second or two, far beyond what your solar panel is producing. So even though they may have 10 homes on a grid producing excess electricity, there's still that huge initial jump when the AC units go on that the utility has to design and build for.

Same for the commercial markets.

I hear this a lot, but I wonder. Don't the rates charged for electricity cover the construction of needed generating capacity? And if they are increasing the generating capacity, doesn't that mean they are selling more "units"? If so, why would building a new plant necessarily increase the >rate< charged for electricity?

When Kroger builds a new store across town, I don't worry that the prices in my neighborhood Kroger will be going up to pay for the construction. When Honda builds a new plant, I don't conclude that CR-Vs will need to go up in price to cover it.

There are 2 big factors at play:

1) NIMBY - they can't stick a power plant anywhere, so there is a fair amount of infrastructure that has to be built/upgraded, typically a good distance from the existing grid, in order to bring the new plant into the grid. It's far easier for Kroger to put a new store in a relatively efficient place (and have far fewer protests) than it is for a utility to plop a new power plant in a "grid efficient" location.

2) New regulations - looking at proposed coal regulation, the switch to far more expensive sources of power will be a significant increase in the cost to utilities. And remember that unless you want rolling blackouts like California, there always has to be excess power being produced by the utility to meet peak demand. You can't just flip a switch and shut down a coal burner at 7pm because a lot of demand has dropped off -it's far more efficient to keep a coal plant burning 24/7, than shutting it down at 10pm, letting it cool down, and fire it back up again at 4am (many commercial HVAC systems start their summer morning cool-down programs at 4am-5am)

And you could switch to natural gas burners that could shut down when there's some reduced demand - but that's not cheap to replace or build new, compared to an existing or new coal burner.

As there is a slowing growth in electricity demand, the utility companies must still design their grids to meet maximum peak demand, despite an average electricity load that may not be as high as before. So that means a lot more 'wasted' electricity is being produced in order to meet that high peak demand, to avoid the rolling blackouts due to peak demand not being satisfied.

If you have solar panels or windmills that are variable in their electricity output, it's even more of a challenge to the utilities. Imagine if 10% of your electricity output were based on the unpredictability of the wind or how much cloud cover you have? In order to avoid blackouts, that means you essentially have to have as much as 10% excess electricity output from your coal/natural gas plants to make up for the shortfall in the event the solar panels/wind turbines are only producing a few percent.

 

[ERD50]

...
And ERD, at least in my area, everyone does gain from my solar panels.
There is less drain, and upgrades on our utility's equipment as I am using less power, some of that during peak loads.
When my house is using 10kWh of power from my panels, that is 10kWh + grid inefficiencies less power my utility needs to transmit.
The utility won't need to build additional power generation as quickly as they would have, helping to keep rates from increasing as fast.

Sure, it isn't a lot, but there is some benefit. Does it balance out? I don't know, but lots of other subsidies for oil, coal, children, schools, etc don't either.

There are benefits for others, but I think they are tiny, tiny compared to the way the subsidies are charged to others to benefit the few. The utility still needs to have peak power capacity if a cloud passes, I really don't think there is any meaningful reduction there.

Drop the other subsidies, I won't go along with the 'two wrongs make a right' argument. And at least any 'subsidies' for coal & oil (and it's arguable what is a 'subsidy' versus what is a regular business expense deduction that every business gets) seem to be spread out over all the customers. My neighbor doesn't get a different NG rate than I do. Exploration lowers the cost of NG to everyone evenly.

... Within five to ten years I wouldn't be surprised if most developed countries will get all its power from solar on sunny summer days.
...

And we will all have flying cars! Try doing the math to see how much solar would need to be installed each year to handle a summer day in ten years (roughly 10% of current peak capacity a year), I don't think you would find that to be a reasonable number at all.

Storage is expensive, and potentially very, very dangerous. Small scale solar is only 'cost-effective' (on a micro-economic scale with many paying for a few) due to subsidies. If you go large scale, those subsidies don't have the same leverage, you have many paying for many - it all levels out.

And w/o storage, utilizing a significant % of solar when it gets above 10% or so is far trickier than it might appear. I've read some interesting blogs on seeking-alpha on this subject. It's a real balancing act - utilities don't want to cut their cheap baseline coal (very slow to respond to changes) if clouds are passing through - they know that means they need to kick in the more expensive Natural Gas peaker plants. So more of the solar goes to waste than you might think. And more variability from solar means more peaker plants, which also add to the expense of solar.

-ERD50

 

[ERD50]

There are other factors at play. For example, most HVAC codes require increased fresh, outside air intake versus what used to be required 20-30 years ago. As new buildings are built, and existing ones are remodeled, they have to upgrade HVAC units with more fresh outside air. Which means more outside air has to be conditioned in the summer. Which means more electricity usage during peak times. ...

Interesting, I wasn't aware of that.

But I wonder how big of an effect this is? I would assume that if you are required to draw more outside air than normal leakage, you are going to use one of those heat exchangers, which recovers some (most?) of the lost heat/cooling. And A/C is far more efficient now than 20-30 years ago.

I see now that my previous post cross-posted with similar comments from others.

-ERD50

 

[NW-Bound]

... Managing many small fluctuating loads is also a bit tougher than one central load (like a coal plant) as well...

This was foreseen and talked about in engineering publications in the early 1980s. And that was way before photovoltaic panels were economically viable even with subsidies. The people working in the field knew a lot more about this than laymen.

Here, this problem is starting to surface and electric utility companies are bringing this up to the state commission. I do not follow this closely, but catch a bit of it here and there from the media.

I was thinking in terms of an even more fundamental EE problem. A grid-tie inverter acts like a negative resistor, in that its current is proportional to the grid voltage, but its current flows into the grid, instead of out as drawn by a load. Therefore, these inverters rely on the frequency stability and the "rigidity" or low impedance of the local grid for this to work. The grid-tie inverters are just following the grid. If we ever get to a point where, say 80% of the homes in a neighborhood is on solar, we will get into trouble with instabilities.

The situation is similar to stock index investing that relies on the traders to set the market price. If everybody buys stocks by indexing, the price of stock A is fixed with respect to price of stock B, and they rise and fall together no matter how the companies are performing relative to one another. Mispricing would not surface until it's too late and the market will eventually collapse. Index investing works if it does not control the majority of the market.

 

[ERD50]

... Therefore, these inverters rely on the frequency stability and the "rigidity" or low impedance of the local grid for this to work. The grid-tie inverters are just following the grid. If we ever get to a point where, say 80% of the homes in a neighborhood is on solar, we will get into trouble with instabilities. ...

Interesting, I never thought about that problem!

In simple terms, all these inverters play 'follow the leader', but as you say, if they become the majority, there is no leader - who follows who (whom? I hate grammar!).

Maybe as we approach that point, all newer systems would need to have a separate control signal to lead them? Maybe a higher frequency signal riding the AC line? Maybe an RF control channel, or maybe tap into GPS or any local radio broadcaster for a reference signal?

But then, there are propagation delays in the two separate systems that could be a nightmare!

-ERD50

 

[NW-Bound]

Yes, the problem can be solved with more sophistication that is currently lacking. After all, the current power grid is a distributed system, and the hundreds of power plants manage to synchronize with one another. I am not a power engineer, so do not know the exact mechanism they use.

PS. I believe that "whom" is the right word to use above.

PPS. All grid-tie inverters have the "smart" to turn themselves off if their connection to the grid is broken. And this has to be done extremely fast to prevent power surges that would destroy the electronic appliances inside the home, when the grid is suddenly not there to act as a load.

Stand-alone inverters for off-grid use and little inverters that we plug into cigarette plugs generate their own 60Hz reference which is not synchronized to anything, hence do not have this problem. These act like a voltage source, and not a current source like the grid-tie inverters.

 

[Chuckanut]

I tried buying a solar system but the Martians weren't selling.


Sent from somewhere in the world with whatever device I can get my hands on.

 

[ls99]

Power companies use a very expensive gizmo, called the synchroscope to sync generators to the grid. Mesuring phase and voltage differences until both are matching the grid before connecting. Happy homeowners can parrallel small generators by using light bulbs. Honda inverter generators use the inverters to sync, not the engine speed.

Once generators are parralled they will be synchronised and locked to the grid frequency. If there are diiferences in the grid frequency and the local genset frequency and are connected anyway, the grid will sync the oncoming generator, with usually destructive results. Ie. bent drive shafts, or catastrophic failure.

There is a concept of power wheeling where a local generator will be powered more than the need to maintain sync,the resulting leading phase angle will feed more current from that particular generator to the grid. This is the simplified description.

 

[Totoro]

And we will all have flying cars! Try doing the math to see how much solar would need to be installed each year to handle a summer day in ten years (roughly 10% of current peak capacity a year), I don't think you would find that to be a reasonable number at all.-ERD50

Try reading up on the current numbers, you'll be surprised. All this from wikipedia:

Germany has 50% of its peak right now, and doubled on average every 1.5 years for the past 20 years.

The US is growing at 70%+ per year. They were installing something like 10% of Germany's capacity in 2012. At least one report forecasts by 2025 that indeed 10% of US electricity will come from PV. That report was from 2008, before the boom really got going.

Spain had 2.7% of electricity production covered by solar in 2010.

Italy was at 3.2% of electricity production covered by solar 2011.

Growth is insane, the breakthrough has happened.

0.38% of the world's electricity is now generated by solar, and the growth rate is something like 40% per year.

One telling chart: Growth of photovoltaics - Wikipedia, the free encyclopedia

Now flying cars .. that's another story ..

 

[clifp]

Thanks for the input so far!

travelover: both good points. on the rush to judgement, I actually only have to sign on as "interested" by the end of the month, then a contract would need to be signed by end of July, after assessment of my roof's suitability (by the non-profit), and specific estimate for my house by the installer.

MRG: we don't get much hail, and the panels are supposed to withstand 1" hail at terminal velocity, but I had not thought about insurance implications. suppose I would need to talk to my home insurer.

scrinch: nice to hear you have had a good experience!

I installed a 4.5KW solar system a last June. Rather than buying the system outright I spent $12K to buy 20 years worth of electricity. At the end of 20 years the unit belongs to the leasing company Sunrun. At the end of 20 years it will cost more for them to remove than it is worth so I am sure they'll let me buy it for a nominal amount. It is saving me between $200-210/month in electricity bills. Honolulu electricity is .$35 KWH 3-5x more than the rest of the country.

I ended up using a local company, a good friends is the VP of Sales and gave me a deal. But honestly I was super impressed with Solar City. There price was lower before the discount, everything was computerized and done via skype and email. FYI Solar City is Elon Musk 3rd company, but he is only Chairmen of the board not CEO.

So if SolarCity does business in your state I would definitely have them give you a bid.

 

[ERD50]

Try reading up on the current numbers, you'll be surprised. All this from wikipedia:

Germany has 50% of its peak right now, and doubled on average every 1.5 years for the past 20 years.

The US is growing at 70%+ per year. They were installing something like 10% of Germany's capacity in 2012. At least one report forecasts by 2025 that indeed 10% of US electricity will come from PV. That report was from 2008, before the boom really got going.

Spain had 2.7% of electricity production covered by solar in 2010.

Italy was at 3.2% of electricity production covered by solar 2011.

Growth is insane, the breakthrough has happened.

0.38% of the world's electricity is now generated by solar, and the growth rate is something like 40% per year.

One telling chart: Growth of photovoltaics - Wikipedia, the free encyclopedia

Now flying cars .. that's another story ..

Impressive numbers, but there's a big difference between Germany and the US, and a big difference between 50% and 100%. From what I've just read, even at current levels of ~ 50% peak, Germany needs to export electricity to other countries and has plans in place to shut down some solar if the grid can't absorb the power.

Who would we export to? Germany is about the size of some our states, with several nearby countries to sell to. The economics get worse and worse as you produce excess that can't be used. That's not a problem at low %, it becomes increasingly a problem as you approach 100% of peaks. On sunny days that aren't all that hot, A/C loads won't be so high - that will be a lot of wasted power. I just don't think any utility will go that far.

If we have a safe, cheap storage technology, then solar can expand. But that's not going to be in place within 10 years. Sorry, I'll stick with my original skepticism.

-ERD50

 

[NW-Bound]

Power companies use a very expensive gizmo, called the synchroscope to sync generators to the grid. Mesuring phase and voltage differences until both are matching the grid before connecting. Happy homeowners can parrallel small generators by using light bulbs. Honda inverter generators use the inverters to sync, not the engine speed.

Once generators are parralled they will be synchronised and locked to the grid frequency. If there are diiferences in the grid frequency and the local genset frequency and are connected anyway, the grid will sync the oncoming generator, with usually destructive results. Ie. bent drive shafts, or catastrophic failure.

Yes, I have read about the way a generator is sync'ed up to the grid to match in frequency, phase, and voltage before the switch is thrown. What I do not quite understand is that there appears to be no absolute reference, and would that not cause the entire grid to slow down or speed up in frequency eventually?

Take the analogy of the stock market. Suppose you want to trade Google. How do you know how much a share costs? You look at the last trade of course, and try to sync with the market price by asking or bidding only a few pennies around it. However, there's no absolute value, and with time the stock price will drift up or down. For stocks that are thinly traded, there are "market makers" who take the lead to set ask/bid prices to get the ball rolling. These are the stocks that are most easy to manipulate. But I digress.

With the electric grid, perhaps the big "wheels" like the generating stations at Hoover Dam or Niagara Falls set the pace because they are so big, and other smaller generators have to follow suits.

There is a concept of power wheeling where a local generator will be powered more than the need to maintain sync,the resulting leading phase angle will feed more current from that particular generator to the grid. This is the simplified description.

Yes, a synchronous generator will feed more power to the grid if you try to increase its speed, because it is now leading in phase. That increase in power delivery will keep you from accelerating the shaft speed because it demands more input mechanical power for conversion to electrical power. Conversely, if you remove the mechanical power source, the synchronous generator still loafs along with the grid, acting as a motor and an electrical drag.

Anyway, a quick search found this article on the problem of synchronization in a decentralized grid.

Synchronization in a Decentralized Power Grid | SciTech Daily

 

[M Paquette]

Perhaps, but it would be worth asking your local FD if they are prepared for this.

-ERD50

They'll catch on by and by. Ours has gotten pretty good about the fancy homes here that have gas pipes and electric wires in the wall.

 

[travelover]

They'll catch on by and by. Ours has gotten pretty good about the fancy homes here that have gas pipes and electric wires in the wall.