Tuesday, May 29, 2012

more reservations (part 3 "subsidy surfing")

So I'm stalling out, right? I could afford the proposed system (lucky) and I happened to have the cash at the time (way lucky - we'll take up this "financial-ization" of the solar biz later I promise.) But my side questions were getting in the way of, "yes."

I also hate waste of all sorts. The idea of surface area that could be used being left out worried me. As does not getting the most out of a visit to the roof. Cranking up a project on the roof is dangerous and expensive (relative to doing nothing - which is an option.) Also, so much of the cost is labor and just getting folks to the site. Add to that the fixed project management costs and it seems a waste to install anything less than the maximum system. If we get the maximum system we can spread those costs across the most productive system. Seen from this perspective the roof needs the maximal coverage to get the costs down.

But this is not how the estimators see it. And they are right. Back then (and this is a moving target) the goal was not to put the maximal system in but instead to ride the cost curves accurately by not over building. The big cost factor that is not addressed in my little optimizing discussion in the preceding paragraph is "Tiered Billing." I have a fairly thrifty lifestyle relative to most Americans and live in a mild climate (lucky again) and this has particular impacts on my electricity bill. But the biggest impact comes from the tiered system of billing. The idea of the regulation is (I surmise) to keep the cost of electrification low for the modest users and charge more for customers who use more (and can afford it more easily.) So the first few thousand watts usage a month are cheaper than the subsequent thousands. In California it is based on a fairly complex system of average daily use for your zone (mostly about climate)  for a home of your size and kind.  If you like rabbit holes of regulatory complexity... take a look at how this sausage is made. Yikes.

The boil-down (you are welcome) is this: Solar panels, cheap as they were, were still, all told, unable to match the price of the first couple of tiers of electrical pricing. So the smart estimators instead plan to offer you a system geared to replace your later, more expensive tiers of electricity. Those later tiers solar can compete with... So you get a lower electricity bill and a solar system.

One more complexity is the crazy shifting incentives program. I say crazy but it does have a logic. The state of California has a per thousand watt incentive program that phases out slowly as a way to wean the market from the subsidy. Smart. It provides some urgency and motivates folks. At the same time the cost of panels and other elements have been dropping so figuring out the way prices are going is tricky work.

But back to our story. The salesperson proposed a layout based on the system suggested and had no provisions for adding more later. This is, again, reasonable from the most common perspective which boils down to return on investment (setting aside all other concerns.) But I, of course, have other concerns. Like keeping room for thermal somewhere and future expansion and denying bankers a cut. I know we pay them great sums of money as a society because the work is so hazardous and unpleasant. But we have established that I am a jerk in some contexts and here is one: I don't like bankers and the outsized role they've taken in the economy.

Looking at the plan I suggested a different orientation for the panels and some racks that would be installed and not used, yet.  The idea being to not waste space by inefficient tiling of the panels and toe not waste trips by workers to the roof by getting the maximal amount of racking installed as one project and the maximum number of panels I could afford today. Then as my electrical savings change the cash flow story and as panel prices come down (which they did) I could add more panels. This did require using different inverters (so called mini-inverters.) My theory was I could offer the installer a deal: Fill in the remaining spots in the rack a couple at a time every quarter at your leisure. Get a spare half day with a crew or need to do some training or want to push some panel order up to the next price break level... add mine and keep your savings on all of them. I'm in no rush. The longer I wait the better the panels and the lower the price.

Now there are plenty of fine reasons to say, "no" to my plan (even "don't wanna" is a fine reason.) But my salesperson thought I was trying to work the subsidy program. The assumption was that I was trying to maximize that end of things. It would not surprise me if that was the primary motivating factor in many customer's reasoning. But not mine. I was told, "If you want to fool around with the rebate calculator I can point you to it online, but I can't go back and forth on this, it takes too much of my time." (That is a paraphrase - I just reread the email to check my understanding, that was a mistake - I was offended all over again.)  I wrote back trying to clarify that mine was a "yes and" rather than a "why can't I?" exchange, but I never got a response.

So, I'm one that got away. The solar business is going gang busters so frustrating folks like me is not a problem for the industry... But these issues started me on the path I'm now on and I am trying to keep fresh the memory of my "novice mind," which should come in handy soon.... more on that later.

Next up. Lazy roofs!

Thursday, May 24, 2012

more reservations (part 2 - blackouts)

Still working through the list of questions and concerns raised by the proposal for rooftop solar.... Next Up? Why can't a guy (or a gal, or a group of guys/gals in any combination for that matter) use the electricity from the panels during a blackout?

This is not important. Really. I don't have medical equipment or other life critical loads. I just needed, way down deep in my "check to see if you are dealing with folks who really know their stuff" brain, to know why the electricity generated needs to go to the grid first and then come back rather than stop here at the house first if I need it and then join the grid if I don't need it.  This conception, I hope you gathered from context, is wrong. It makes intuitive sense - but it can't work that way with current technology.  I know that now (and will endeavor to explain it to you my kind reader in a moment.) But for now lets address the sales communication issue: the customer (me sitting with my checkbook) wants something, thinks it is possible and you cannot (nor can anyone else) deliver it. What do you do when faced with these questions? Well if you want one of those checks, you don't dodge the question, you address it.

Maybe I am a jerk (OK, I am certainly a jerk in some contexts) but, if you can't answer questions about how this stuff works (and does not work) you and your buddies don't get to put high voltage gear on my wooden house filled with my flammable family. For any price.

This question about why a photovoltaic array was not able to stand as backup power in emergencies was also a, "let me see if I (and you) understand (each other)" sort of question. I like that sort of question because I often uncover non-obvious misunderstandings this way. One just restates the thing.  Does it still works in different words? Or does that restating flush-out some unstated exception, or remind the interviewee of some detail.  Somewhere along the line I developed the habit and it has left me in very good stead.

Are you still wondering why we cannot use the electricity from the panels in a blackout? A couple of things make it too complicated and expensive and dangerous to do it. First off, the electricity needs to be converted to alternating current (AC) from the direct current that is created by the photovoltaic materials if it is to be used by your appliances or put on the grid. If you had some batteries (direct current) and/or some appliances that run on DC you'd be good to go in the blackout. But most of us don't get blackouts often enough to justify having all that expensive gear just for the once every few year blip in the power supply. So in the place of a battery (which can be thought of as a TIVO for energy - the energy comes when it does and comes out when you need it) you use the electrical grid. The grid functions as a super cheap battery if it is already available. One of the tricky bits in this "putting it onto the grid" business is timing the too and fro of the alternating pulse (at 60 hertz* in the US and other rates elsewhere) so that rather than cancelling out the energy you add to it. Grid-tie inverters do just this: the convert (invert) the DC to AC and pay out the AC at a rate that matches the frequency of the grid.

Imagine kids jumping a long shared rope. The rope has a pace and to get in and join the jump you'll need to watch and get a sense of it before you jump in or you'll mess it up for everybody. With the grid, you need the energy you add to the grid to alternate at the same rate and in the same phase as the larger system. In this way you can add to the energy stream. If you don't, you'll be a load for the system rather than a source. For this to work the inverter is built to be a follower of the dominant signal from the grid so it can hop in and join rather than go it alone. The danger in trying to lead rather than follow is when the grid is down... you end up "back feeding" the grid. When line-workers are out restoring power, the last thing they need is energy coming "back" from "down stream." Ouch.

The electrical grid and the wiring of your house are also based on a super abundance model. There are breakers and fuses to protect against too much power. But the case of too little power is weird. Unlike you body, which will reroute blood to vital organs at the cost of peripheral body parts in a shortage, the electrical system of your house will give every appliance as much as it asks for. Even if there is a shortage of electricity, as long as it is beneath the maximum limit of the circuit breaker each item that is turned on can take what it likes. This can lead to all kinds of squirrely (is so a word) behavior.

In theory, we could have house wiring systems that divvy up power for higher uses (like your kegerator or iron lung) first. And we do have some protections in place for hospitals - for instance the grid managers try to hold them out of rolling brownouts. OH and hospitals have generators too. But, in general, when the demand outstrips supply, there is a need to shut down parts of the grid to get demand below supply. The same is true for your house. But constantly watching the supply and shutting down circuits is expensive and complicated stuff for spaceships and submarines and such. Instead we just try to keep ahead of demand by predicting how much will be needed and in what increments it might spontaneously grow and where and then run the supply in anticipation of those needs.

In the commercial energy world (like running your big box retail store) there is something called demand priceing that measures the sorts of jumps in power demand you might put on to the grid all at once. They charge you to have that amount standing in reserve. It is expensive and has lead to some smart demand management systems that pay for themselves in short order as they save on these demand fees. Things like spinning up air-conditioning units one at a time or in small groups rather than all at once.  Same with factory floor equipment.

Anyhow, standing alone as an energy producer is one task, participating in the grid is another, and jumping from one to the other on the fly is tricky (read expensive.) But not as expensive as having a customer stall out because you have not established trust.

So on to subsidy surfing...

*(named after Heinrich Rudolf Hertz - still more proof that all the good units of measure are taken!)

Thursday, May 10, 2012

more reservations (part 1, no thermal?)

Other things about the proposal were not on the page but still gave me pause...  No place for thermal collection. Huge fractions of the energy used by a home are thermal. That's why moves like wrapping your hot water heater are such winners. When the numbers are big small percentage gains are still worthwhile.... Anyhow. The proposal was just for photovoltaic panels - so only for electricity... I guess hoping for a thermal component in the proposal is a bit much. Kind of like expecting a plastic surgeon to suggest getting some sleep. You might need some sleep - it could even help with the bags under the eyes but if you have a box of sharp knives everything looks like a knife problem.

Where was I.... THERMAL. Yeah.  Along with a different skill set (electricians vs plumbers) there is the new problem of very very cheap natural gas around here. Used to be your payback period (I'll rant on that bankrupt idea some other time) was something like 5 years. Now the gear is still about the same but the cost it is competing with (natural gas) is going down. But still, if you want to knock down your carbon footprint solar hot water is a great way to go and it is a fine use for part of the roof with less good exposure. ¿Less good? (Oy, does a blog instantly make you a language slob?)

So solar now seems to mean PV first and nothing else second. And not seeing hot water on the proposal slowed me down.  But for me, once you start climbing on the roof and poking holes you should do all the work at once, no?  Next up: Blackouts.

and so it began

Back in the summer of 2008 I got an estimate or solar panels for the house. Seemed reasonable. Our house is older so the roof could use some more beef before it could take the load but nothing crazy. I read through the estimate and saw this:

De-rating... is... a... bummer... 

But it is not BS.  Those factors really do run down the performance of a solar module and a system overall. The two that really leaped out at me were the temperature and the conversion losses.  Let's call them the "ugly 80's." Now I was not  interested in batteries so it was just an academic interest that drew me to the .86 de-rate factor over there, but the temperature de-rate really hurts (these are cumulative.)  I joked with the estimator that we should install them on the garage to take advantage of the shade there. She was not amused. 

Three more things about the estimate bugged me... thermal, blackouts, and subsidy surfing. More on that next time.