Re: query about photovoltaics (solar panels)
From: Sharon Villines (
Date: Tue, 13 Oct 2020 07:46:54 -0700 (PDT)
> On Oct 12, 2020, at 10:34 PM, Lisa Wolf <tigerlisa [at]> wrote:
> I'm Lisa Wolf, a member of Bay State Commons Cohousing, which is in the
> process of constructing our new home in Malden, MA. The Eco Committee is
> currently discussing how to make photovoltaics (hereinafter referred to as
> solar panels) happen. We decided to ask other cohousing communities that
> have installed solar panels for electricity about their experiences and
> results.

We installed a solar system to produce electricity for the CH and lighting on 
the grounds in 2015. We didn’t have enough roof space to cover units as well. 
Something to think about as you design your structure. Ours is 3-4 floors so 
roof space is reduced.

The panels have produced at least if not more than they promised and I’m sure 
everyone here would say it was a good investment. We had been looking at solar 
since we built in 2000. Several times we had consultants advise us. The verdict 
was always "solar isn’t ready yet." Mostly because it was not worth the high 
prices. At one point, their cost was inflated because Germany was buying 
everything the US could produce.

We had members who worked for the Department of Energy and others who were 
pretty much experts on solar. They were able to interview installers, evaluate 
possibilities, and do a financing plan. We had no problems with the 
installation or since. There was some work over a few months to calibrate the 
equipment in the basement. (Converters?)

It took several people at least a year to put together the proposal, get bids, 
hire consultants, and work out all the kinks including financing. The cost of 
the system was ~$190,000.

We were 15 years old so we had available funds. We borrowed from Reserves, used 
recent donations from resales that the donor had requested be spend it on 
solar, projected savings from electrical bills, and income from excess energy. 
There were also tax credits and reimbursements for installing solar.

Figures from 2016—you can skip these if numbers and random letters make your 
eyes swim:

> We just received our first payment of $19,875.68 for our SRECs (Solar 
> Renewable Energy Credits).  It covers the 44 SRECs we generated from January 
> through June of this year (One SREC per megawatt-hour).  Our payment for the 
> second six months of the year should be similar.  When we installed the 
> system last year, SREC prices were scheduled to start decreasing next year, 
> but the DC City Council just passed an amendment to the Renewable Portfolio 
> Standard that extends the current payments through 2023, so we should 
> continue to receive roughly $40,000/year for the next seven years, 
> $32,000/year for 2024-2028, $24,000/year for 2029-2032, and $4,000/year from 
> 2033 on.  Between the SREC payments and the roughly $10,000+/year we're 
> saving on electricity bills, we should pay for the system in four years, or 
> six if the cost of the roof replacement is included.  Subtract a year from 
> those if you include the tax credit.
> We've gotten nine monthly electricity bills from Pepco since the system was 
> installed.  In the 273 days since 2015/11/06, we've used 40120 kWh 
> (147.0/day) at a cost of $-1599.44 ($-5.86/day), and generated 59480 kWh 
> (217.9/day), generating 148.3% of what we've used.  For comparison, in the 
> 281 days starting 2014/10/30, we used 63280 kWh (225.2/day) at a cost of 
> $10120.31 ($36.02/day).  Our average daily consumption has decreased by 
> 34.7%.  Our average monthly bill has dropped from $1095.61 to $-178.25.

(You can see we had experts who could do this analysis.)

Our roof was scheduled for replacement in 3-5 years so we decided to replace it 
before putting up the panels. The replacement had a 40 year life while the 
initial one had a barely  20 year life and was already requiring repairs. 
Replacing it early was a win-win and we had been saving in the reserves for the 
replacement. By replacing it before the panels were installed, we wouldn’t have 
to remove the panels to replace the roof later, and the new roof was in perfect 
condition for the installation.

We are actually using ~34% less energy than we had previously been using. I 
assume this is from increased efficiency of producing electricity on site, new 
metering, etc. There were no other changes.

The various credits and paybacks were considerable. We expected the system to 
pay for itself in 4 years or including the costs of replacing the roof, 7 
years. The last time I looked at numbers we were ahead of that schedule. There 
were no monthly reductions in condo fees because we were still paying ourselves 

(Good reserves are worth every penny you put into them.)

Sharon Villines
Takoma Village Cohousing, Washington DC

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