During the past year, southern Maryland has had several power outages, most recently one at the beginning of July which lasted 4 days. A handful of the neighbors have invested in ginormous diesel backup generators which cost $30,000 and burn 30 gal of fuel per day.
So I wondered aloud if solar couldn't be an optimal solution. And thus began my journey.
The Clift notes version goes: PV Panels go for about $1 to $1.50 per watt. Tesla makes a battery backup system. Credits and rebates are a minimum of 30% credit for all materials and labor, in addition to state rebates and energy credits. In Washington DC you could almost break even in the first year.
The first thing I noticed was that NO solar installation company posts their prices on their website. It's as frustrating as it is transparent, and probably accounts for the reason why panels cost $1 per watt but final installations go for $6 per watt. That just isn't right. Two master electricians each making $100 an hour for two days would only cost $3,200. My gut tells me this markup is because 95% of the people who start out researching this kind of project (myself included) don't have the necessary electrical knowledge to effectively comparison shop, become overwhelmed, and go with the first qualified contractor who gives us an estimate. That doesn't mean you shouldn't arm yourself with knowledge. If you want to be as hands on in the decision making process as possible, demand that you be able to separate the materials bid from the labor.
Solar panels (a.k.a. pv modules) are made up of solar cells (a.k.a. wafers) arranged in an array and encapsulated in glass. Most panel manufacturers are not cell manufacturers, the latter falling into the realm of semiconductor nano technology. Most cells are at least 14% efficient, with 19% being the new bar. Some run 30% efficient and one claims to have hit the 50% mark.
Soaring efficiency has led to plummeting prices. I don't know if this is a good place to buy solar panels, but it's a great place to shop for them. Keep in mind that in 10 years, you'll probably be able to buy twice the wattage at half the price, which is why most consumers are dragging their feet on early adoption.
Enter the credits and rebates. Until 2016, a tax credit of 30% the total cost of materials and labor is available for all residential solar installations, even those not on your primary residence.
On top of that, each state has their own added incentives. Here in Maryland, it's a $1,000 rebate for systems < 20 kW and $4,000 for systems larger than that.
Down in the District of Columbia, they're practically giving the systems away, with a credit of $1.50 per watt up to 3kw and then $1 per watt for the next 7kw. I figure the average Glover Park townhome could fit 4kw on its south sloping roof. So some quick back-of-the-napkin math:
$5,500(panels) + $3000(inverter) + labor.
30% x $8,500 = $2550
4kw @ $1.50 per watt = $6,000
30% of labor
So residents of DC could get quality, made in USA PV panels with a room to grow 6kw inverter for just 70% of the labor costs.
It's a pretty sweet deal.
But wait, there's more!
It isn't the first time this has been diaried here, but there are something called SREC credits which would give a DC resident $1500 a year at today's prices.
You see, many states have mandated that utilities start obtaining their energy from renewable sources. Here in Maryland, the mandate is that by 2022, 20% of the energy produced must come from renewables, and at least 2% from solar. In DC the requirement is 2.5% solar by 2023. It is a gradual implementation, and right now it's 0.5%.
The key to understanding this is each utility is responsible for meeting that mandate, and if they don't then there is a fine. Right now the fine is hefty - $500 per Megawatt hour. As 2022 approaches, the requirement creeps upward and the fine slowly drops.
Instead of building acres of solar arrays themselves, the energy companies can buy renewable energy credits (SRECs) from the people who earn them. Anyone who owns a PV power setup is an energy producer earning renewable energy credits, even if you use all of that energy yourself.
In DC, the biggest fine a utility company can get stuck paying is $500 per SREC credit (1 mW hour), so their goal is to pay you less than that for your credits. The credits get bought and sold at auction, and currently the credits trade at $200 in Maryland and $300 in DC. The price will taper off slowly as 2023 approaches, as long as solar installations proceed at the expected rate. If the residents and businesses of a state are reluctant to adopt solar, in a few years when the utilities have to obtain credits for 1% of their production and the state hasn't doubled its installed PV capacity, there will be increased competition for the SRECs. Or, as in the case with New Jersey, SRECs could sell for $600 a pop and bring in so many gold hunters that the price crashes.
My example 4 kW solar array will produce about 5 mW hours in one year. These 5 SRECs are worth $300 each in today's auction market = $1500 and that is what they call "real money." Not to mention the $400 which didn't go to Pepco.
One key piece to my PV proposal is a battery backup. It should be able to run the HVAC system and the refrigerator for at least a couple of days. Normally this is the bulkiest and most hazardous part of a PV setup since a wet cell lead acid battery gives off noxious gasses. To the rescue comes our friends at Tesla who partnered with Solar City to make a residential lithium ion battery pack. This really sets off my gadget desire and it got my imagination racing: Since this system is being installed with emergency power as its #1 function, what would happen during an extended winter storm where I'm off the grid and there is no sun? Well, wouldn't it be neat if that Tesla battery came with the same port that electric car charging stations use, and it could be removed and brought to a charging station in an emergency? I thought so and today I emailed Solar City. Their prompt reply? "I believe this is something our team has been thinking about."
Of course, I haven't taken into account the cost of framing, conduit, fuses, fees, licenses, etc., so this is by no means meant to be comprehensive. But it's a decent starting point and hopefully it will save you from the websites that demand your home address and phone number before they'll kick down any numbers.
Tue Aug 07, 2012 at 11:23 PM PT: Oh yeah, one thing I wanted to mention was that it's all-or-nothing as far as sunlight goes. The biggest source of deterioration for a solar panel is partial shading as it creates an area of negative resistance. It also gives the output a whack.