IHS Predicts 9% Of Solar PV Installations Will Have Battery Energy Storage Systems By 2018



Attached Energy Storage To Grow In Coming Years (via IHS Technology)

Tesla's stationary energy storage

Tesla’s stationary energy storage

Good news for Tesla Motors and others in the battery energy storage market:

“IHS…announced that 9 percent of solar photovoltaic (PV) systems in North America will include attached storage in 2018. Led by commercial systems, IHS expects 700 megawatts (MW) of PV systems with energy storage will be installed by 2018, compared to just 30 MW in 2014.”

“The commercial PV energy storage market in the United States has gained huge momentum in recent months,” said Sam Wilkinson, research manager for solar and energy storage for IHS Technology.”

Tesla’s entry into this segment is mostly focused on residential, but rising usage in all segments will be a plus for the electric automaker and others who supply energy storage systems.

Press release from IHS below:

According to the IHS “Energy Storage in PV Report – 2014,” commercial buildings are subject to peak demand charges, which are based on the maximum power drawn from the grid during the billing period. These charges can make up a significant portion of a business’s electricity bill; however, using a battery and PV to reduce peaks in grid power consumption can reduce these costs significantly. “Incentives, like the Self Generation Incentive Program offered in California, are also making the economics of such systems extremely attractive; but there is no guarantee that electricity tariff structures won’t be adjusted, which could affect the economics of existing systems,” Wilkinson said.

The North American residential market for PV systems with attached storage will be limited, as the only real incentive for homeowners to install these systems is to provide back up for power blackouts. Although having a source of back-up power is desirable, particularly in areas that have experienced long blackouts, it is rarely valued enough to justify the high cost of a battery system. In a number of markets in Europe, such as Germany, Italy and the United Kingdom, the economics of a residential PV system are improved, when the system owner is able to increase the amount of power that they self consume, which has been the primary reason the PV energy storage market in those regions has developed more than it has in North America.

The market growth for energy-storage PV systems has been largely driven by suppliers like STEM and Green Charge Networks. IHS anticipates that Solarcity, a leading U.S. solar installer, will also be increasingly active in the attached storage market this year. In fact, Solarcity is already offering Tesla batteries with its PV systems, in order to offer peak demand reduction services.

“Solarcity’s third-party ownership business model has enabled it to become the largest residential and commercial solar installer in the United States,” Wilkinson said. “The company already has highly established sales channels and financing agreements in place that will make it another major driving force in the commercial PV energy storage market.”

IHS Technology’s “Energy Storage in PV Report – 2014” provides detailed analysis and forecasts for the potential of energy storage to be adopted in the quickly expanding solar industry.

IHS Technology

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75 Comments on "IHS Predicts 9% Of Solar PV Installations Will Have Battery Energy Storage Systems By 2018"

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This is hard to understand for those who enjoy net metering. Net metering, where your utility pays the same for your generated electricity as the price you purchase electricity is absolutely the way to go.

Unfortunately, net metering is not available to everyone. Peak demand charges like those mentioned in the article will be one sector. Another will be offsetting electrical co-op that pay wholesale only for generated electricity.

My co-op for instance charges me 12 cents/kWh for their electricity and pays me 5 cents/kWh for my generated electricity. Over the life of a 5kWh array, the delta could be $7,000-$9,000 depending on your usage. Combine an $8000 delta with current renewable incentives, 30% fed and 35% in my state, and I am watching keenly Tesla’s APril 30th announcement.

Hi Mark.

Thought you might be interested in what the latest proposal before the Arizona Corporation Commission is.

The utilities want a flat charge of 21$/month for new solar customers. This is a charge to just have access to the grid.

The result of this kind of rule is that it incentivizes solar customers to install as large a system as possible…..and in addition to install battery backup.

Well you either install a large PV system with no battery.

Or you install a large PV system, a battery, and then disconnect from the grid.

But the latter is not a good solution if you have an EV and want to charge it up quickly.

I’d have to look at the specifics of what AZ wants to do, but I don’t think there’s anything conceptually wrong with a grid connection charge. I think $21/month sounds high, but that might be their opening offer, to be bargained downward later?

I live in AL and have a grid tied system attached through a TVA distributor. Our local distributor requires a separate meter that costs ~ $21/mo, so I understand. However, TVA pays a reasonable rate for solar generated {or wind or micro hydro, etc} electricity so it is still a win for us.

The local “coop” tried desperately to kill it before it started, but the membership voted by a huge majority to make it happen. It was a long and ugly process to work through.

If you are net metered with a TOU rate, then increasing self consumption of solar during off-peak hours so you can export more energy during peak rates can be hugely beneficial, especially since most peak TOU rates start around noon.

I don’t expect net metering to last very long. It’s a subsidy to people with panels because it gives them free use of the grid by effectively paying them a retail rate for the power they upload. This made sense when solar panels were expensive and needed help as an emerging technology, but as panel-generated electricity reaches grid parity that subsidy ought to go away. I think it’s the fair thing. On the other hand, it’d be interesting to see what the utilities pay on a wholsesale basis for power during the times when panels are generating power.

The other issue that I forsee in the Southwest and Florida would eventually be stranded assets. We’re not going to see it hit for a while — solar is only 0.45% of U.S. electricity generation — but it’ll hit in certain areas long before other areas.

Net metering in my case is a subsidy for the utility. I’m going to be giving roughly 1/2 of my yearly production back to the utility (as I’ve stated I’ve grossly oversized my system).

I expect to be paid 3 cents / kwh (wholesale) for the overage. That occurs on my aniversary date every year at which time all counters are zeroed. THe juice goes to the pole and to the next door neighbor’s meter, which the utility loses at best 1/4 cent/kwh; and then sells it for 12 cents. So they are PROFITING 8 3/4 cents/kwh from my overage.

So I should drive more or use my Sauna or Air conditioning more, or something.

My above analysis is slightly flawed when I neglected to include the 1% loss of the to and fro from my own piggy bank operations throughout the year. So its not 8 3/4 cents profit on the overage, but lets call it 8 1/4 cents gift per kilowatt-hour.

The ‘flaw’ in NY State’s accounting is that I should not be paid ‘wholesale’ for the overage. The electricity is already in my neighborhood and doesn’t have to have transmission and distribution charges because ‘ its already there ‘, and the other neighbors are charged full retail from my juice 100 feet away.

But it does encourage people not to oversize their systems.

Well Mark you probably won’t get too much sympathy from someone in California nor downstate NY especially since the electric rate is 31 cents / kwh, unless you go for time of use, then it is up to $1.20/kwh BEFORE taxes and fees every municipality adds on. I’m trying to take an objective view, and don’t own any utility stocks nor work for one anymore, so I’m basically of 2 minds about this. On the one hand, the electricity they buy back from you at 5 cents/kwh is immediately sold to your neighbor (with a maximum 5% loss) at 12 cents, so that means they are getting at least 11 cents of usefulness out of the excess electricity you generate. Obviously you’d be a candidate for a small battery, since you might as well ‘KEEP’ your own excess, and not play your utility’s game. On the other hand, you’re in NC? you get PLENTY of sun and with not too much investment you get a huge amount of output, made even better by fed and state incentives such that you only end up paying 1/3 the cost. Its about the same here in NY State, of course, in Western NY… Read more »

Nope, residential owners with solar are out of luck with APS’ recent gains against NEM.

Most residential solar is TPO (e.g. lease) and the leasing companies have admitted that their pricing model assumes NEM forever and thus, only saves the average homeowner $10-$20 a month. With an increased in static grid connection charges, that savings can disappear.

Would you care to define your acronyms for those of us who are too stupid to know them? Thanks.

Most humans do not care or know where their electricity comes from, until attitudes change solar PV and battery storage will remain insignificant.

With recent drops in solar PV and battery costs, the focus is now on something that most people do care about: reducing their electric bill.

solar + batteries would offset the most expensive electricity for TOU electricity customers: peak & off-peak. Leaving the customer to draw grid power only during super-off-peak rates ( less than 10c/kwh ) and a few cloudy days.

Give people the ability to save money without any hassle to themselves, and they’ll gladly help the environment.

You could not be more wrong. Solar has significantly impacted electrical utilities in CA by allowing customers paying the highest rate to bypass. Hence the huge but failed effort by the utilities to stop net metering.

This has started something of a death spiral. As the best customers bypass, the costs formerly born by those customers get spread among the remaining customers, pushing their rates up. This in turn provides incentives for the next best customers to bypass. Basically the same process which killed the land line phone companies.

Cheap battery backup simply removes the ability of utilities to take net metering away.

This is proving very helpful for electrical vehicles because electrical utilities are beginning to see that EVs are the best source of revenue growth. Hence the proposal to have the utilities spend hundreds of millions to build out EV charging networks.

Could you please provide a link to support your statement that solar has “significantly impacted electrical utilities in CA by allowing customers paying the highest rate to bypass?” I think it’s quite a bit premature to suggest a “death spiral,” but I can be convinced by factual evidence. Similsrly, as someone who had a career that involved all kinds of telecommunications, including wireline and wireless voice and data providers, I can say that your statement about the ongoing shift of residential telephony away from wireline hasn’t “killed” the landline operators.

At a matter of fact, wireline is alive and well. It’s shrinking in the residential market, but it’s alive and quite well in the business market — which was always much more profitable, by regulatory design. That said, I expect residential provision of electicity by utilities to be impacted by solar in some areas, starting in about 10 years. I don’t think it’ll be any kind of death star, though.

People care very much about the cost of their electricity. As soon as the cost of solar is cheaper than what comes from the utility, at the same reliability, people will start making the shift. Today, it’s very difficult to get reliable numbers.

Battery storage systems for solar will remain small as utilities move to ban them from being connected to the grid. Simply put, the Utilities think solar battery storage systems will promote fraud-simply charging off-peak and selling back electricity to the grid rather than actually generating it by solar.

It is not fraud. It is a utility customer contributing towards grid infrastructure peek balancing. Some smart forward thinking utilities will be promoting the concept rather fighting against it.

It is fraud when the user is selling it back as solar-generated.

Hardly. Whether or not the photons that liberated the electrons were captured now or later doesn’t change how the hydro was gathered.

“the hydro?”

“the Hydro” – this is an anachronism back from when Canadians got the majority of their power from Niagara Falls.

All electricity to a Canadian is “HYDRO”

In my state the distinction is not made. Other than for fire inspection purposes, no one officially cares how I make the juice. It could be solar, wind, or a microcogeneration, where I am buying fuel from one utility and selling it back to the electric utility at a profit. The only real scam I see going on is in Ontario, Canada where solar is 80 or right now for new installations, 51 cents/ kwh. These installations have ‘backwards’ meters on their own electric services since 100% of the juice goes back to the grid and their existing service/meter is unaffected (why would you not want to sell ALL the solar at 51 cents when you can buy any electricity for 17 cents?) At the Toronto Tesla dealership, I struck up a conversation with a young McMaster university student who was picking up his folk’s model S for service. He was MAD he had to pay 17 cents / kwh (whereas it used to be around 5 cents years ago, since he is subsidizing the solar bonanza). In fairness, I think part of the now high priced ontario electricity is due to the high cost of Nuclear Power Ontario in… Read more »

It’s even more ridiculous in Seattle, which is not only far north but the cloudiest city in the continental United States. The Kool-Aid drinkers convinced WA State to pay more than 60 cents/kWh for the output of solar panels.

Even at that subsidy, the theoretical payback is about 10 years. At the expense of the ratepayers. I considered putting panels on my garage roof, which has a southern exposure. I decided against it on ethical grounds. I really didn’t want to be part of a group of people who soak the working middle class for what, in Seattle, amounts to a really foolish eco-vanity statement.


(New Post)

If you get 60 cents from Solar Production, then quite obviously everyone doing this must have separate electric services for the installation. Obviously the solar panel owner would want 100% of the solar output generating the 60 cents/kwh, and the owner would just use electricity from his existing service as his neighbor does since he can always buy juice cheaper than 60.

If you run the life cycle of the batteries, losses due to round trip efficiency and the effective cost of energy in almost every case it does not yet make sense to load shift. (ie charge at night sell in day without generation on site)

Thank you for your posting. This is a topic I’m very interested in. I’d really appreciate it if you’d explain your statement in more detail, and maybe with a link or two. Thanks much.


energymatters has it. Battery power is MORE expensive than solar power, so trying to pass off stored electricity as solar generation is like counterfeiting 1-dollar bills. You might get the sick thrill of a score, but not a big score, and you won’t last in the game long enough to make a dent in the overall picture.

By all means, taser54, please buy a grid-scale system and cycle it daily. Go right ahead.

“Battery power is MORE expensive than solar power, so trying to pass off stored electricity as solar generation is like counterfeiting 1-dollar bills”

False comparison. Batteries store power. Solar panels generate it.

So, we have yet another example of that Musk fella figuring out where we’re headed and setting up his company to take advantage of it by being a first mover. Color me not at all surprised.

Musk is showing what happens when someone with his resources can analyze a situation objectively, without all the baggage of being a “car guy” or a “utility guy” for decades.

In general, we are headed for a period of considerable diversification in transportation and electricity generation. In transportation, we’re moving from a time when, in the US, nearly all cars were gasoline fueled (even if non-plug-in hybrids) and heavy duty vehicles were diesel, to much greater use of CNG and electricity, with a few hydrogen vehicles thrown in for humor value. In electricity generation, the renewables, mostly solar PV, are set to have a huge impact.

Someone mentioned upthread the “death spiral” effect of solar PV. Google it, and you can find examples of utility companies themselves calling it that. They’re in a very bad place right now, as the rules of their market are being rewritten in ways they can’t predict (perhaps they should ask Uncle Elon) or control.


Elon Musk’s entire game is all second mover. Just ask:

-TRW and Barber Nichols Inc. Along with “Big Gemini.”

-AC Propulsion, Panasonic, Mercedes, and the guys who ACTUALLY founded Tesla.

-Later, the people who will ACTUALLY build something like a hyperloop, since Musk is smart enough to let others blow their money first.

To be both fair and factual, Tesla has yet to make a nickel on the business. Thus far, the only “profits” have accrued to TSLA stock speculators and to the company’s suppliers.

Only stock investors seem to confuse “not making a profit” with “reinvesting all profits into expanding the company”… which is exactly what Tesla Motors is doing with the surprisingly high profit margin it’s making, as compared to other auto makers: 25% gross profit.

Everybody else seems to understand the concept perfectly well. Just because Tesla chooses not to pay you any dividends, Mr. Stock Investor, doesn’t mean they aren’t making a profit.

You don’t know how to read financial statements, and there isn’t enough space or time for me to teach you. Bruefly: Gross margin is not reinvestable profit. Tesla loses money on a GAAP basis, on an EBITA basis, and on a cash flow basis. The only reason they are still in business is because Wall Street likes them. That can change quickly, to put it ever so gently.

Interesting that you should mention this….. I’ve never commented on it, but there have been a few one sentence comments on it by others. So apparently, people ARE watching what is going on…

As far as this site is concerned, I’ve always been intrigued as to a financial analysis of the Supercharger Stations.

My point is, I’d think 135 kw car charging stalls are going to be ‘it’ for a long time. Some want 1000 kw and have accused me of ‘lacking vision’. I counter that with, show me the cost of the EXISTING system before you say I’m stupid to not insist on something bigger, hehe.

I’d love to know the numbers surrounding the “superchargers,” but I’d be (pardon the pun) shocked if Tesla ever released them. I probably wouldn’t do so if I were them, either.

Energy storage is critical for solar but lithium will not be the solution. Flow batteries are far better for this application, and once solar gets cheap enough, electrolysis.

I am also skeptical of lithium-ion on cost grounds. Please tell us what a “Flow battery” is, and provide a link that an intelligent non-engineer can follow. Does it have anything to do with molten metal batteries?


From a materials standpoint there is no reason for lithium iron phosphate batteries to be very expensive. NMC or similar batteries, like Tesla’s, may have a problem there.

Flow batteries store the energy in the electrolyte. The most well known flow batteries are the vanadium redox flow batteries, which suffer from the expense of vanadium. Vanadium is pretty common, though, so this might be overcome with scale.

Got any links that discuss this in more detail, including costs?

Wikipedia covers everything except cost quite well. Cost is speculative at this stage. Unlike Three Electrics, I’m not optimistic.

IHS was originally Information Handling Services. Eventually it was renamed to IHS, with no official link to any words.

I predict that they are wrong unless the utilities are successful in shutting down net-metering programs.

Get the Tesla battery, charge it at night at low TOU rates, then use it during the day.. Cut your electric bill down by 10x, done and done..

If that became common, TOU rates would be changed to include a cap on the amount of power billed at that rate.

We’ve had an on-grid 15.7 kW PV system since December 2006. So far we have generated 136 MWh. Thanks to converting to fluorescent and LED lighting (and sending our boys off to college), we’ve had a net negative electric bill for our last three annual cycles. Southern California Edison has tiered rates from 15 to 32 cents per kWh. Each month we receive a debit or credit based on these rates and out usage, positive or negative. However, at the end of the annual cycle our net credit was recalculated based on net kWh’s at 11 cents. The rationale makes sense. We pay nothing for the grid (except a monthly bill of one or two dollars) so SCE is allowed to only pay us the same rate as they pay their wholesale suppliers. We do not use TOU metering or ask for any special rate to charge our i3. I don’t think it would be immoral to take energy from the grid off peak even if we used TOU metering. We’d just be contributing to SCE needs at peak times. Any net dollars would just be recalculated at 11 cents per net kWh when our annual cycle was over. The… Read more »


1. Please correct me if I’m wrong, but that looks like 45-1/3 kWh a day. (136,000,000/100 months/30 days = 45,333).

2. How much did your system cost, before and after and tax credits or other subsidies? Could you break this down by panels and other components?

I have a bunch of other questions, but I’ll leave it at those two for now. This isn’t a matter of my disbelief, but rather genuine curiosity. I am all about factual numbers from people who actually have the systems. Thanks.

1. I misstated the total yield. We had to replace one of the inverters and I’d lost its yield in my total. The real total from sunny portal.com, which records our system output every 15 minutes is 190 Mwh’s.

2. We were early adopters because our electric bill was running about $7500 a year. The net cost was approximately $81k after $33k in rebates. The rebates ware so high because we split the installation into two phases over two years and got a legal rebate each year! The 84, 187 watt panels were $69,300. The total for 3 inverters was $9800. Add rack system, labor and taxes to reach a total of $114K. The rebates for the two years added up to $33K.
You can see details of the layout and performance by going to sunny portal.com as a visitor and searching for sites. Just use USA and zip code 91011 to find us.

“They also discuss a problem occurring in Germany where PV is becoming a significant enough part of the energy supply that it is becoming hard to control the grid. This is happening because he grid controls were designed assuming a few large sources of energy, not thousands of little ones.”

Bob, funny that you should mention this. I just read a few days ago that Germany is having no problem controlling its grid with all that PV generated electricity. Here is the link. Its a good read. 🙂


Germany’s electricity rates are 2-1/2 times America’s, and one-sixth of Germans are classified by their government as living in “energy poverty,” unable to afford their electric bills.

I would imagine Germany’s ridiculous electric rates can only be rationalized in terms of their even more ridiculous natural gas rates.

My mistake here is that I’ve oversized my solar system. I make way more than I use and the vast majority of it goes to power my 2 EV’s. The rest of my relatively good sized home uses little, other than the central air conditioning in the summertime.

My home’s majority energy supply is natural gas, which I use even for a large hot tub.

The only think I use electric heat for is for a swedish style sauna, but relatively, that is not many kwh per month. Absolutely everything else requiring heat (except the electricity used to keep the car batteries warm) is natural gas, since recently it was only 2 cents / kwh (as opposed to 12 cents from the electric utility) – or 1/6 the price.

If I lived in Germany, most of these things would be electric since the gas price would be prohibitive. Natural Gas is essentially free these days by comparison in the States.

I am very interested in having detailed discussions with owners of PV panels. I live in Seattle now, but am toying with the idea of moving to the eastern side of the Oregon Cascades where there’s a lot more sun, and the latitude is 44 degrees.

I’d think about solar — PV, hot water or both — but only if the costs makes sense. I don’t necessarily trust dealers to tell me the facts and all the operational issues. The frustration online ids that owners of PV systems, like owners of EVs tend so strongly to be promoters and evangelists, and tend to regard unsentimental factual discussions and questions as hostile. All I am is Joe Friday on this stuff.

If you’re willing to have a candid and factual discussion about your system — costs, output, operational issues — I’d be both interested and grateful.

Unfortunately, talking to someone else about their experience with solar energy isn’t likely to be sufficient to approximate how much benefit you’d get from a solar power installation in your home. Obviously it would help if you can talk to someone in your area, so at least you’d get someone who shares the same latitude, daily insolation (assuming no significant shade at your home or his), and aveage cloud cover.

But your roof geometry is also an important consideration, unless you’re willing to install elevated frames for the PV panels so they don’t just lie flat on your roof.

You should definitely look into the possibility of direct solar heating of water; that can be a significant energy saver. But if the temperature in your area often dips below freezing, then you’ll need a more expensive two-stage system.

As a first step, I’d recommend Googling “solar energy calculator”, and using the calculator at a few different websites to get at least a ballpark estimate of a cost/benefit analysis for solar power at your house.

@Bill Howland, notwithstanding Lesnman’s posting, I’m interested in having a conversation online if you’re willing.

Sure, and I hear exactly what you are saying. There are PV calculators that tell you your amount of sunshine in your area. I’m supposed to make 9300 kwh per year but in 10 1/2 months I’ve only made 6500. So I don’t know whether the ‘calculation’ is with Solar dimming that I talked about included, or so it seems, it was not taken into consideration. I’d think at first blush Oregon would have more sunshine, all things considered. I have cheap chinese 240 watt rated panels, which almost never put out that. Since the voltage output goes down with the heat, the highest output is on a bright, sunny, extremely COLD day. Their rated efficiency is 14% overall. If you spend more you can get 300 watt or larger American Made Panels that are much higher efficiency. Of course, Solar Water Heating is much, much more efficient, that is if your family uses alot of hot water… At Least 60% efficiency. Some systems may be even higher, but much much better than anything photovoltaic. I might go that route, but since as mentioned natural gas currently is so inexpensive that its not a lot of bucks anyway, and a… Read more »

Thanks very much for your willingness to share data. I really and truly appreciate it, more than you know. It’s 1 a.m. right now and my brain is running half empty. Tomorrow (today, I guess) will be busy. I absolutely WILL be back to ask you more.

I am quite capable of looking up specs, but in my experience nothing beats talking to people who actually own something. Thanks again, big time, for your willingness to engage, and I’ll be back when I can better organize my thoughts.

Since you’re a numbers guy, here’s some I forgot: I have an old-fashioned system, since I wanted the cheapest thing I could get, so I made a deal with the solar company to have me do the AC part of the job. In NY State, we no longer need an outside disconnect for residential solar, so that saves some bucks. Our green state agency NYSERDA, gives me a $ a watt. So I went with a 9120 watt, 38 panel system (fortunately they use the higher theoretical figure, not what I actually get out of buffalo’s weak sun). So $9120 goes straight to the contractor. My cost otherwise (plus a few $hundred for the work I had to do) – backboards, cabling, loadcenters, revenue meter and socket, etcettera) was $19,080. There is a 30% fed and 25% state income tax credit off this figure. I have 2 – 4kw German inverters, with the absolute maximum output of 8100 watts, which I’ve almost, but actually never seen. ON these particular models, the input is 2 loops per inverter, so there are 4 ‘independent’ loops, even though I only have them in 2 places, so I really need only 2 independent loops.
Bill, thanks for your posting. You couldn’t possibly have hit the nail squarer on the head when you wrote, “You’re a numbers guy.” True, true, true, true on steroids. 1. My understanding from what you wrote is that the before-subsidies cost was $9,120 for the panels plus $19,080 for the trimmings, for a total pre-subsidy of $28,200. Is this correct? You wrote that you did some work. Is it possible for you to guess what those costs would’ve been if you’d had someone else do it? 2. Were the tax credits a total of 55%, or were there any overlaps between the state and federal numbers that held it down? Were you eligible for the entire amount of the credits? Can you tell me how much in tax credits you were able to capture? 3. Could you discuss the production from your panels? You wrote that your cheap panels are rated at 9,300 watts a year (775 watts a month), but that you have gotten 6,500 watts in 10.5 months (619 watts a month) — or 80% of rated production. Is this because of the latitude, or something else? And are the numbers I just used correct? 4. I have… Read more »
(NEW POST – time to start a new paragraph) Don’t use watts, use watt-hours. Simple concept: Does your engine while running use 1 gallon, or 1 gallon per hour. If you have a gasoline well (HAHA) in your backyard does it yeild 1 gallon, or 1 gallon/day? Gallon/Day is power: which is the rate of doing work: in this case 125,000 btu/day. 1000 watts for 1 hour is 3413 british thermal units, which is the amount of heat needed to heat 1 pound of 37 degree fahrenheit water 1 degree fahrenheit. Other handy conversions: Natural gas companies in the states sell gas by Centum Cubic Feet (CCF) or ‘therms’. Since a cubic foot of natural gas has a heat content when oxidized (the so called exothermic reaction) of 1020 btu, 1 ccf is 102,000 btu. My gas energy supplier charges my gas company 31 cents for this (I pay more). A therm is somewhat less (what some utilities bill by), or 100,000 btu. To convert your gas bill to your electric bill, since there are 29.3 3413’s in 100,000, simply assume 1 therm or 1 ccf is 29.3 kwh of heat. Watts is power: 746 watts is one typical London… Read more »

Uh, I need to read my posts before hitting the enter button. 746 watts correlates to the avg power of a LDHorse.
0.746kwh is the word done by one horse in 1 hour. The ENERGY EXPENDED by the horse, or the amount of WORK DONE in one hour is 746 watt – hours.

Correct: $28,200 paid to the contractor. I’d add about $700 for the stuff I did. Amplification to the previous post since as written its ambiguous: 1 BTU is 1 pound of water raised 1 degree. 3413 of them is the same amount of heat as 10-100 watt lightbulbs running for an hour. 1 watt- second is the same amount of energy as 1 joule. Therefore 1 kwh is 3,600,000 joules or, what I buy from my utility for 12 cents. A joule is a very small amount of energy. Now onto the panels themselves. My system has 2 sets of 19 panels each, running to 2 indentical 4050 watt inverters. That is a bottleneck in theory but not in practice since my 9120 watt rated panels never make 8100 watts. I have zero output Jan and Feb since they are snow-covered. 25 % credit may be rolled over for 5 years in NY State. 30% fed credit supposedly may be indefinitely rolled over, not like the $7500 ev credit which must be used in the same tax year. I’m poor this year so I’ve rolled over both credits, as my turn up date was 6/14. Now, federally, you can take… Read more »
(NEW POST) As to solar output in general, we are entering a period of ‘solar minima’ or ‘lazy sun’. This is exacerbated by the ‘crop dusting’ going on in the US, and elsewhere. They are spraying me everyday with Barium, Strontium (all isotopes radioactive), and Aluminum – just great for causing piles and alzheimer’s. This ‘Global Dimming’ (spraying of reflective particles in the sky which come down when it rains or snows), causes up to 25% reduction in sunshine. Condensation trails that USED to appear out of jets for a few seconds have their analog in tail pipes of cars that for a split second in VERY COLD weather you can see, for about as long as a tick of a watch. These chemical trails (formal name GEO-Engineering) stay in the sky for hours, and if you pay attention you can see them sometimes drawing tic-tac-toe boards in the sky. Monsanto has patents for ‘aluminum resistant seeds’…. Now, why would anyone need their seeds, except of course, if the only seeds that survived all of this was Monsanto. Now for all the magpies who are going to chime in on this, I was directly asked what was causing the piss-poor… Read more »
I got lost in the watts to watt hours explanation. Let me ask a different way. 1. I’ll presume that your panels produce electricity measured in watt hours, i.e., they have a maximum output in watts, and then you add the amount of time they’re producing to get “watt hours” of production. 2. If I’m correct about that, what’s your production in watt hours? Do you have precise records, i.e. monthly production numbers? 3. I’m a little unclear on how long you’ve owned this system. 4. How long do your expect it to last, and what’s the expected degradation of output per year? I’ve heard 1% to 2% per year. 5. Do you have any sense of the degree of how your production is affected by dirt, dust, or snow on the panels? I’ve been told that solar panels have to be fairly relentlessly kept clean, or the production will fall off. 6. Are solar panels like “series” Christmas lights, i.e. the production of all panels is no better than the production of the worst panel, or does each panel produce independently of the others? 7. Aside from what I just mentioned, are there any other “gotchas?” THANKS SO MUCH… Read more »

Yes, very interesting. Thanks.

In Seattle, at today’s rates 136 megawatts over a 100-month period would cost $13,705.60, or 10 cents/kWh. The rates are $0.557/kWh for the first 390 kWh per month (average between summer and winter rates), and $0.1189/kWh for the rest. Back that off by 15% to account for past rate increases and you get $11,649.76 in avoided electricity charges since you bought your panels — at Seattle rates, which are lower than Southern California’s.

$217.33 for a small home using 390 kwh per month?

I made a typo, dropped zero. For the first 390 kWh/month, the rate is $0.0557/kWh. Anything more is $0.1189/kWh.

In NY State, all ‘net metering’ customers to my knowledge must have a ‘power production meter’ to totalize energy production, which NYSERDA has subsidized. I bought the meter and socket for around $50. I’m up to, after 10 1/2 months of operation, (my turn up date was 6/13/14), is 7250 kwh. This system’s annual production was ‘calculated’ at 9315 kwh, but I’m assuming they are including the output from snow free panels which doesn’t exist here. The snow at least cleans the panels. But I had zero solar generation in January and February, but still $15.63 electric bills since I merely tapped my huge credit piggy bank. All this gets zeroed out in June and i”ll get around 3 cents per kwh for my credit excess. Which as I’ve explained earlier is a 8 1/4 cent per kwh (or around $250 gift ) to my utility. To be perfectly fair, they should give me at least 11 cents/kwh for the juice I made, which still will more than compensate any ‘net metering’ expenses. An intangible for the utility is I’m creating generation precisely when they need it and its most expensive for them to obtain. They don’t need to buy… Read more »

Yes the solar panels are in 4 series strings of 13, 6 on the garage, and then 13, 6 on the house.

The split up this way is kinda dumb but it doesn’t matter – both lengths of strings are within the range that the inverter can work with in all outside temperatures, which is voltages neither too low nor too high.

The fact that the garage and house are putting out similiar amounts of energy tells me all 38 panels are working properly.

On my house, each string gets an even burst of sun, I have no shading issues.

The more modern way is to have a ‘microinverter’ at each panel and then combine all the little ac outputs.

My system is old fashioned in that everything is dc until it hits the 2 inverters. I have no shading issues nor irregular roofs, so in my case series strings are not a problem. I went with absolutely lowest $/watt.

I annualized your production, applied a 1% annual degradation factor, assumed a 25-year life for the panels, and arrived at a cost/kWh of $0.157 Here are the steps:

1. 10.5/12 = 0.875
2. 7,250/.875 = 8,285 kWh year 1
3. Multiply each year by .99
4. Add 25 years = 184,075 kWh total
5. $28,900/184,075 = $0.157/kWh

This is pre-subsidy. I couldn’t figure out what your post-subsidy cost was from what you wrote above. Maybe 70% of $19,080, plus $700 for your own labor?

If 70% of $19,080 + $700 is the correct out-of-pocket cost including your labor, then the cost would be $0.076/kWh. One thing I wonder about, though, is degradation. If you don’t produce at maximum rated power levels, does degradation occur, or does degradation only happen when your the maximum production reaches a level that bumps into your actual production?

I’m including degradation for the same reason that insist on making an allowance for EV battery degradation. That’s a known fact of life, the battery degradation. I’m less familiar with solar panel degradation, but have heard about it and used a 1% annual rate, which is the low end of the numbers out there.

CP, I assume that the above analysis was to show the ‘present value’ of my installation cost me, in effect, around 15 cents/kwh, (uneconomic at 12 cents / kwh utility retail), but is economic at my subsidized price of 7.6 cents per kwh, which I assume is my real cost, assuming I could have fully utilized my tax credits in the first year. Yeah those seem about ballpark correct.

As far as solar degradation goes, I assume this is just silicon crystal aging that depends on the amount of current generated, and that, by extension, since I live in a weak solar area my panels should last longer? Maybe. They are certainly not overstressed, and are optically cleaned somewhat by the rain and snow, and I suppose it wouldn’t kill me every few years to go up on the roofs and Windex them.

NYSERDA pays a $ a watt. SO on a 9120 watt system, its $9120 off the top of , lets say $29000. So then the tax credits (I took the tax free nyserda payment and didn’t include it so that way both fed and state work at 55% of 20000 so my ultimate cost was 45% of 20000 or $9000.

So, I paid essentially 32% of the cost of the system myself. In that case you’d think that if your analysis assumed not subsidies at 15 cents/kwh, then with subsidies, it should be around 5 cents/kwh no?