TDSF Power Plant – TieDyeSeniorFi

April 12, 2026

TDSF Power Plant Report – Year 7

At the end of year seven the meter reading was 99532, meaning we have produced about 468 KWh more than we consumed over the past 7 years. Year 7 was our lowest producing year so far, about 8.04 MWh. Our panel’s fiscal year begins/ends on March 26.

Year	Total MWh This Year	Cumulative
1	9.67	9.67
2	9.1	18.77
3	9.33	28.1
4	9.1	37.2
5	9.02	46.22
6	8.22	54.44
7	8.04	62.48

The first five years we produced more electricity than we consumed. Years 6 and 7 we consumed more than we produced. Its possible that by next year’s reading the meter will be in positive territory. Still, we have not had to pay utility rates for almost 62.5 MegaWatt Hours of electricity since we went live.

This brings us to the question, have we ‘broken even’ yet? Meaning, have we saved enough on our electric bill to pay for the system? The short answer is not quite.

When we went live electricity rates were much lower. This was the supply price at the time:

Delivery was about 4 cents/KWh so the total was 10.7 – 11 cents per KWh. Today that total number is 20-22 cents per KWh, depending on the time of year. Both supply and delivery prices have increased, doubling the cost of electricity we have to pay for out of pocket.

Our total system cost, after federal, state, and local tax credits was $16,500. At current rates, 62.5 MWh (62,500 KWh) would cost about $12,500. We have also received about $3200 for our Solar Renewable Certificates (SRECs), and about $500 for annual surplus reconciliation. Total avoided cost plus compensation equals about $16,200. At this rate we would break even a few months into year eight.

Accounting for the lower electric rates in the earlier years, we have saved about $9,300 through year seven. Add in the $3700 for the SRECs and the surplus payments brings our total savings to about $13,000. Assuming we continue getting 8 SRECs per year at $50/SREC, we will save about $2000 per year in the years ahead, bringing our break even point to about 8.75 years. (Even as rates continue to rise, the value of SRECs are dropping, so it is hard to determine this date with precision).

Delivery cost this past January (I only get charged delivery if I have a negative month) was a little over 6 cents per KWh:

Five cents went to BGE and 1.3 cents went to EmPower MD, a program to make some homes more energy efficient.

The longer term outlook is very good. We will generate close to 200 MWh in the first 25 years of the system. Before SRECs and the annual spring surplus payout that comes to 8.25 cents per KWh. Including the SRECS at $50 each (which going forward is iffy) and counting the net spring surplus check at $60 year, or $1500 total, produces the following calculation:

$16,500 – starting price

less $10,000 (200 SRECs at $50 each)

$6500

less $1500 ($60/year surplus refund)

= $5000 system cost, which is 2.5 cents per kilowatt for pre-buying our electricity. That is less than half of what BGE charges to deliver it (currently over 6 cents per KWh).

The SREC number will probably be a bit lower and the spring surplus may be a bit higher but even if the final number ends up around 4 cents per KWh, this was a great deal!

By the way, the panels continue producing in year 26, they are just no longer under warranty.

To be fair, our inverter is warrantied for less time (I think 12 years) and the panel warranty does not include labor, so there will be additional costs. I just got a new WIFI router for my house and I am having a devil of a time connecting it to my inverter, so another expense is in my near future. All in all though, it does seem to be a good deal.

April 6, 2025

TDSF Power Plant Report – Year 6

At the end of year six the meter reading was 99065, meaning we have produced about 947 KWh more than we consumed over the past 6 years. Year 6 was our lowest producing year so far, about 8.22 MWh. Our panel’s fiscal year begins/ends on March 26.

Year	Total MWh This Year	Cumulative
1	9.67	9.67
2	9.1	18.77
3	9.33	28.1
4	9.1	37.2
5	9.02	46.22
6	8.22	54.44

I asked the company that services my panels if they could detect any issues that would explain the drop-off in electricity generation this year. They reviewed their monitoring information and determined this was just due to this past year’s weather.

My panels are only pitched at 25 degrees, so when snow accumulates on them it does not slide off as quickly as it does on my neighbor’s panels, which are inclined much more sharply. So if snow is followed by freezing weather, as occurred this year, we can go many days with no solar production. See January 2024 below.

Now look at January 2025:

It snowed and stuck both years but the 2025 snow lasted much longer. Other months produced comparatively less electricity as well. We accumulate a surplus during the summer months which tends to run out sometime during the winter, typically late January to mid-February This year it ran out in December. We had to buy grid electricity for part of December and all of January and February this year for electricity we used over and above what the panels generated.

Electric prices have gone up a lot since we installed our panels. At the time of installation we were paying 10.7 cents/KWh. That price included both supply and delivery. Additionally the monthly customer charge was fixed at $8.22. The following chart, from the Energy Information Administration (EIA) shows 2025 and 2024 residential rates per KWh for Maryland and our neighbors:

Full chart is at https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a

Notice that Maryland is now over 18 cents/KWh! So for 8220 KWh generated this past year, we saved (avoided) about $1500. In addition, we got $400 for our Solar Renewal Energy Credits (SRECS). That’s real money sent to us. We also received about $72 for our March/April 2024 surplus last May. That’s a total value of almost $2000.

I expect that electric rates will continue to rise. Maryland was about to take a coal plant offline. Higher than expected demand has caused the local utility to keep it on-line for the next two years, as there is not enough electricity available to import from other states. In exchange for keeping this plant open, customers will soon see a new monthly fixed fee on their bills of about $4. Additionally, the normal monthly customer charge has risen to $9.97/month.

East Coast states north of us (New York – Maine) are already paying 25-30 cents per KWh. As prices rise, the economics of rooftop solar make more sense. At current prices I would encourage anyone who can install rooftop solar to do so, especially before retiring, when income becomes more fixed.

March 31, 2024

TDSF Power Plant: Year 5 report

At the end of year five the meter reading was 98767, meaning we have produced about 1240 KWh more than we consumed over the past 5 years. The first three years we were slightly in the hole, as the meter read 00387, so the gain has come in the last two years. At the end of year four it was 99602 so we came out ahead by 835 KWh this year.

What is surprising about this is that this was our lowest year of production yet, producing a rounding error less than 9 MWh, whereas the first four years we did a little better than 9 MWh. We generated our 46th MWh on March 20.

Is this because the panels are losing their production capacity? Probably a little bit. They are guaranteed not to lose more than 1/2% per year after the first year. However, weather probably plays a factor as well. This past summer we were impacted by smoke from Canadian wildfires. This past February we had two back-to-back snows with freezing temperatures, so the panels produced no power for about 10 days. Just adding what would have been 80 kilowatt hours over that period back into our totals would be enough to get back over the 9 MWh mark.

We had built up enough surplus over the summer and fall that I was sure we would cover the winter deficit. We did cover through January, but the 10 day February shortfall used up the surplus and left us with a small bill (about $22) for that month. Fortunately, we are back in surplus again in March.

As a review, the way our billing works, the March/April bills produce a large surplus (days are longer, sun is higher, no AC) but this gets zeroed out at the end of the April billing period and we get a check in May for the supplier portion of this surplus. The utility keeps the delivery portion.

(Incidentally, the delivery portion has roughly doubled recently, from 2.5 cents to about 5 cents per KWh so electricity now costs about 16 cents per KWh – it was about 10.7 cents early in our journey).

This means we resume building a surplus to carry us through the winter (October – February) starting in May.

I sometimes get asked about the ‘payoff date.’ This is the amount of time until the savings from not paying an electric bill equals the cost of the system. Honestly, I don’t know when that will be as one factor is the current cost of electricity. As that increases, now up about 50% from when we went operational, that date shrinks.

I have rather focused on what the cost of electricity will be for us over the 25 year guaranteed life of the panels. By the way, they keep producing electricity in year 26!

Assuming our panels generate at least 200 MWh over the 25 year period (which seems conservative, as they have generated 46 MWh in the first five years) and assuming the SREC market supports a price of $50/MWh (this is not guaranteed at all – it is currently about $4/SREC in Ohio and over $300 in New Jersey and DC), and that our March/April surplus averages about $60/year, the total cost of the power our panels will generate will have cost us about 2-4 cents per KWh. That is a good deal.

Of course we will have to pay market rates for anything we consume above what the panels generate, but that is to be expected. As of now though, our electricity use continues to decline, as evidenced by the meter continuing to run backward, compared to the same month of the prior year. Should we get an EV sometime in the future, or convert our heat and hot water to electricity this will of course change.

Whether solar panels are a good deal are very much dependent on site location, federal and local $$ help with the project and whether there is something like an SREC market. For this project specifically, it seems to be a great deal.

Here is the comparative overview of the past 5 years on a monthly basis:

April 10, 2023

TDSF Power Plant: Year 4 Report

Our solar panels have been active for four years. In the first two years we used more electricity than the panels produced. I know this because I follow the electric meter almost obsessively. When the meter shows a low positive number, it means we are using more than we are producing, as of that moment in time since the panels went live. If the meter runs backwards (into the 99000s), then we have cumulatively produced more electricity than we have consumed.

I record the meter reading every March 26th around 1:30 PM, the approximate time we went live in 2019. Following are the readings and cumulative production totals at the end of each year:

Year ending March 26	Meter Reading (Kilowatt Hours)	Cumulative Production (MWh)	Annual Production (MWh)
2020	00455	9.67	9.67
2021	01098	18.77	9.1
2022	00387	28.1	9.33
2023	99602	37.25	9.15

After year’s one and two I had concluded that we should have installed a few more panels to be energy neutral. However, I also knew that over time we would probably use less electricity and that has proven to be true. We are now 853 KwH ahead (398 to get back to all 00000 + 455 above that.

Should we get an electric car or convert to electric heat/hot water (currently on natural gas), we would be under producing.

Under the current Maryland net-metering system, excess generation is paid out in May, based on the surplus KWh at the end of April meter reading. Since March and April are both good surplus months (days are longer, sun is higher, but no AC yet), this means the typical customer receives a check each May for the commodity portion of this surplus. Recall that the other major portion of a bill is the delivery fee. This is kept by the utility company.

There is one issue with this current system. Because the March/April surplus is paid out (albeit at about 2/3 the actual rate), we do not quite generate enough surplus May-September to carry us completely through the winter, although this year we came pretty close. This means we have to pay the full price for the energy consumed once our surplus is used up. Our first two winters this cost us about $135 each. We got better though in year’s three and four building up our summer surplus. These winters only cost us about $26 and $11 respectively.

A new law has recently passed the Maryland General Assembly that, if signed by the governor, will create an additional option, to accumulate this surplus indefinitely until the surplus is used up (for example by buying an EV) or until the account is closed.

Is solar a good deal in Maryland?

I continue analyzing our experience in light of the question, is this a good deal, and if so, for whom. Most people think in terms of payback time, which for us is looking to be about 10 years. Since the panels have at least a 25 year life span, this seems like a good deal if one has the money to install the system and one expects to stay in the home long enough to realize the benefit.

Another way to look at the problem is Total Cost of Ownership (TCO). My after tax cost for my system was $16,500 (This is documented in previous posts). To determine 10 year TCO we have to make some assumptions:

MWh generated : 90
SREC $$ generated: $4500 ($50/MWh)
May surplus re-imbursed: $600 ($60/year)

Subtracting the SREC payments and the May surplus checks from my after tax cost brings my 10 year cost to $11,400. Dividing this by 90 yields about $127 per MWh or 0.127 per KwH. This is about what rates are now. Will they go up over the next 6 years? I expect so, but I do not know.

Over a 25 year period, these TCO numbers look even better:

MWh generated: 200 (assuming a decline in output as the system gets older)
SREC $$ generated: $10,000 ($50/MWh)
May surplus re-imbursed: $1500 ($60/year)

This brings the cost down to $5000 for 200 MWh generated, which works out to $25/MWH or 0.025 (two and one-half cents per kilowatt hour). This seems like a great deal to me.

Note that we do not know how long the SREC program will exist or how the May reimbursement program will work – if we end up switching to the infinitely cumulative surplus, we could perhaps build enough surplus to power an EV for a long time, so these calculations are all subject to change. The point though is that the lifetime cost of the panels should be significantly less than the utility rates for the same amount of electricity.

March 31, 2022

TDSF Power Plant: Year 3 Was a Great Year!

In my Year 2 Report, I mentioned that we would have needed 2 more panels to generate more electricity than we consumed. That’s because the meter reading at the end of year 2 (March 26, 2021 at 1:30 PM) was 01098 and our worst panel had produced about 257 KWh/year.

What a difference a year makes. On March 26, 2022 the meter reading was 00387. This means we consumed 712 KWh less than we produced this year (1098 – 387). The 3 year reading for our worst panel was 778.2 KWh. So one more panel that was at least as good as our poorest producing panel would have put is in the black (the meter reading would have been negative).

Does this mean we produced 712 KWh more this year than last year? No. Here are the meter readings and total production for the first 3 years:

Meter Reading	Annual Total	Cumulative Total
0455	9.67	9.67
01098	9.1	18.77
00387	9.33	28.1

First 3 years of production

We produced a little more in year 3 than in year 2 (230 KWh), but the main reason for the improvement was a reduction in consumption (482 KWh). This reduction allowed us to build up a greater surplus going into the winter months so that we only had an electric bill for two months of the year, for a total of 200 KWh. The only reason we had these two bills at all is because BGE, our utility company, zeroes out the surplus after the April reading and sends us a check for the surplus supply amount we generate each March and April. This means we do not have enough credits by the end of the winter and so we have to pay for what we do not produce those last few months.

As you may recall from previous posts, the electric bill is divided into supply and delivery (and smaller amount for the meter charge and taxes). The delivery amount is about 3.5 cents per KWh.

Date	KWh	Rate (Supply)	Check Amount
5/20/2019	446	0.0879	39.20
5/22/2020	535	0.082809	44.30
5/24/2021	913	0.071446	65.23
Total	1894		148.73

Payment for March/April Surplus

I will not get a check for this year’s surplus until late May, but using .08 per KWh as an estimate for the supply rate and 300 KWh for the March surplus (300 * .08 = $24), we can guess that the total March/April surplus by the end of year 3 is about $173.

The $24 amount is interesting for the March surplus, as the cost for the 200 KWh that we got charged for in January and February (due to the zeroing out the previous March) was approximately $24 as well. If BGE did not zero out the surplus each year we would have essentially had no electric bill this year, except for the (approximately) $100 per year they charge for the meter (labeled as a customer charge).

Looking at this over the 3 year period, we used 129 KWh more per year (averaged out) than we consumed. This is calculated by dividing the meter reading (00387) at the end of year 3 by 3. Rounding a bit, using 0.12 per KWh or $120 per MWh, in theory we should have paid on average $15.48 per year, or $46.44 total over three years. In fact, because we are not compensated for the delivery portion of the March/April surplus, we paid more. Following is the approximate reconciliation:

	Amount	Comments
Amount paid	$595	What we sent BGE over 3 years
Meter charge	$300	Approximate (varied from $8.22 – 8.75/month)
Net paid for electricity	$295	$595 – 295
Surplus BGE paid us for	$173	includes guess for March 2022
Actual bill for electricity	$122	$295 – 173
Delivery not reimbursed	$77	Approximate using .035 per KWh
Net should have paid	$45

Reconciliation of what we should have paid vs actual based on meter reading

So the amount we should have paid reconciles with the amount we actually paid. Effectively, the March/April surplus zero-out cost us an additional $2.14 per month.

How did we reduce consumption by almost 1/2 MWh? I’m not sure. Some of it was intentional. We found a few more bulbs to convert to LED. We set our thermostats a little differently, focusing on comfort at the end of the house we were in and reducing/increasing the setting at the other end. We took a couple of short trips, 3-5 days each and set the thermostat higher while we were gone. Finally, my wife required more sleep this year due to her health, and so she was generating less electricity while sleeping. I expected we would use less over time as we got older and as appliances got more efficient, but we have not replaced anything yet.

I have noted previously that the amount of solar energy we convert to electricity is highly dependent on how cloudy/rainy it is. Panels theoretically degrade slightly as the year goes on. However, we can see from this snapshot that more recent quarters sometimes produced more electricity than older quarters.

One last picture, to show that we had surpluses (or accumulated surpluses to zero out our bill in every month this past year but two:

One last note. As our annual production was over 9 MWh each year, we produced our 28th SREC on March 22, 4 days before the end of year 3.

Please respond with any comments or questions. I enjoy helping people decide if solar panels are a good opportunity.

April 1, 2021

TDSF Power Plant – Year Two Report

(This post is now the latest in this on-going series. Here is Part 1).

The sales information on solar panels state that year two may see a loss of power produced of about 2%. Unfortunately, there is no way to tell if that occurred for our panels. In order to measure this, the weather would have to be identical each year, including the timing and density of clouds and rain. These two items play a much larger factor in how much this site produces.

This year snow was a small factor. Usually we have a warmer, sunny day after a snowfall. This year it snowed just ahead of the polar vortex that caused so much trouble in Texas and other places, so instead of melting off almost immediately, the snow stayed on the panels for several days, reducing output for those days.

Did I mention that my dog ate my homework? OK, enough excuses, here are the numbers:

Annual Electric Usage for March 27, 2020 – March 30 2021

Again we had 8 months of 0 billing and partial billing for 4 months. The sun does not provide much energy in the winter months.

Following are the meter readings at the beginning and at the annual anniversaries:

Date	Meter Reading	Accumulated Production	Annual Production
03/26/2019	00012	0	0
03/26/2020	00455	9.67 MWh	9.67 MWh
03/26/2021	01098	18.77 MWh	9.10 MWh

Data needed for calculating $ benefit of our solar panels. Readings taken at 1:30 PM on these days

The meter reading indicates that we are falling further behind (continuing to use more power than we produce.

Year 1: 9.67 + 0.433 means we used about 10100 KWh

Year 2 the meter went up 643 KWh over Year 1 (01098 – 00455). So year 2 usage is 9.10 + .643 = 9743 KWh. So we cut our usage by about 357 KWh for the year, but due to some combination of weather and normal 2nd year reduction, production dropped 570 KWh. Clouds got in the way.

Here is the full spreadsheet:

Two years of BGE electric bills after installing our solar panels.

Our cumulative spend for this period is $469.07. Subtract out about $200 for the meter costs (typically $8.32 a month) for an adjusted cost of $270.

BGE zeroes out any accumulated surplus based on the end of April reading. They pay us for the supply price of the surplus we generate in March and April. We will not have this number until late May. The cumulative total of the previous 2 checks was $83.50.

Assuming for the sake of discussion we get about $40 this coming May, these checks total about $123.00.

The price of electricity all in (supply, delivery, taxes) has actually gone DOWN since we installed our system. It was a little over 0.12 per KWh in year one and a little less than 0.11 per KWh in year 2. For a quick calculation, let’s use .1125 to see how much we have saved:

18770 KWh * .1125/KWh = $2112 – estimated value of energy produced.

Our last data point is the dollar value of the SRECs produced. To date we have received $895. In May we will receive $55 for the SREC produced in March, bringing this total to $950.

Approximate dollar value realized to date – $3185:

$2112 + $950 + $123 = $3185 – This is how much we did not pay ($2112) + real checks we got from BGE. Our installation cost after incentives was $16500. To date we have recovered about 19.3% of these costs (3185/16500). Because electricity costs have gone down (and perhaps because of those persnickity clouds) we are on track to recover our costs in a little over 10 years now.

The following chart shows that weather may play the most important role in power production:

Monthly Generation – Predicted vs Actual
	Predicted	2019 Actual	2020 Actual	2021 Actual
January	487.8		326.78	302.78
February	607.3		516.92	376.02
March	944.8		848.07	1020
April	1095.4	949	1010
May	1231.5	1110	1150
June	1295.4	1260	1260
July	1284	1310	1320
August	1121.7	1130	1040
September	950.2	831	733
October	765.4	463	428.86
November	473.3	349	305.71
December	392.9	254	231.54
adjustment*	354
	10649.7	8010	9170.88
*Note: April, May 2019 had some reading errors so totals are really higher
About 355 KWh readings not recorded properly

Predicted generation vs actual, by month

As noted above, April and May of 2019 had some monitoring errors (corrected by the company that collects the data) so these numbers are not necessarily comparable against 2020. It is clear that this past fall we had much poorer conditions than the previous fall. But then look at March 2021 – Much better readings than March of 2020 and much higher than the predicted number.

Last year I concluded that if we had installed two more panels that produced at least as well as our poorest producing panels we would break even. That still seems to be about true:

Two years of solar production per panel.

The worst panel shows a two year cumulative production of 513.62 KWh. The best panel produced 621.13 KWh during this period. So, 2 panels producing somewhere in-between would have broken even more or less.

As the surplus generated in March and April is paid off in May instead of crediting against the following fall/winter shortage, it would take another panel or 2 to avoid having a bill at all, except for the meter cost.

April 4, 2020April 7, 2020

TDSF Power Plant – One Year In

(This is the latest in an on-going series. Here is Part 1).

In my 9 month update I predicted the following:

As the days get longer and the sun gets higher, here are my predictions for the next 3 months:

January we will still be in the red, using more than we produce, but less than December. I am hoping we cut the December overage (475 KWh) in half.
February we will do even better, and I hope we cut the overage in half again.
That would mean we get billed for about 240 KWh in January and 120 KWh in February, or 360 KWh total.
In March I expect we will generate a surplus.

So, how did the year turn out, and how good were my predictions?

Not as good as I had hoped. I got January very wrong (240 predicted, 416 actual), was closer for February (120 predicted, 169 actual), but we did have a surplus in March. It was a very cloudy winter and as the song says, ‘clouds got in the way.’

The full year looks like this:

Annual Electric Usage for first year with Solar Panels

Total cost for the year was $233. About $100 of this was for the meter, which we would have had anyway, so the net cost was about $133. After factoring the $39 that BGE paid us in May (this is an annual payment that zeroes out the surplus each year), our cost was $94.

I logged our accumulated production on 3/26 at 9.67 MWh. Adding this to our meter reading, it appears we used 10,120 KWh and produced about 9670 KWh this past year.

Using 0.13 per KWh for an average cost of electricity delivered to our home this year, without solar panels our annual electric cost would have been 10120 * .13 = $1315.

This means our savings this year was $1315 – $94 = $1221.

Understand that each year’s savings may differ due to the amount of solar output, our consumption, the cost of electricity delivered, and the value of SRECS.

We will receive $455 for our SRECs (the check for the Jan-March quarter comes later).

This makes our first year’s net gain work out to $1221 + $455 = $1676. That is just over 10% of our net cost (after tax credits from the federal, state, and local governments).

All things being equal we are looking at a payback of around 9-10 years.

Since trends never continue perfectly any change in the above factors will change this date. But the panels are supposed to produce well for at least 25 years.

It appears the net cost of electricity delivered is trending down towards 0.12 per KWh, so the payback might turn out to be a bit longer.

Still, it is nice to have no electric bill 8 months of the year, a small bill for 2 months and a reduced bill the remaining 2 months.

The picture above shows the lifetime production of each of my 34 panels. I remembered to take it a day or two after I hit the one year mark. There was also a software error in the application that captures this information, so in both ways this picture shows approximately what each panel produced.

The best panel produced over 318 KWh. The lowest producer was about 264 KWh. In general the best producing panels were at the top and on the right (east) side of the array.

It appears to me that if we had installed two more panels that were in this range, we would have broken even for the year (meaning we would have produced as much as we had consumed).

Please let me know if you have any questions about solar panels or any related topic you want me to cover.

January 1, 2020January 7, 2020

TDSF Power Plant Part 10: 9 Month Update

(This is the latest in an on-going series. Here is Part 1).

As 2019 wraps up, I have some good news and some not-so-good news to report.

First, the good news: in November we got paid $213.32 for the 4 SRECs we generated in the 3rd quarter (July – Sep). These were SRECs 4 – 7. (1 SREC = 1 Megawatt Hour of electricity generated. )

Now, the not-so-good news: in the 4th quarter (Oct – Dec), production dropped off drastically. It took us until Dec 21, 84 days, to generate our 8th SREC.

Megawatt (SREC) History
Date	MWh	Days	Cumulative
3/26/2019	0
4/21/2019	1	27	27
5/21/2019	2	30	57
6/14/2019	3	24	81
7/6/2019	4	22	103
7/30/2019	5	24	127
8/26/2019	6	27	154
9/28/2019	7	33	187
12/21/2019	8	84	271

From the table above, you can see that the time to generate each of the first 7 SRECs ranged from 22 to 33 days. Comparatively speaking, that 8th SREC took forever.

So, what happened? As mentioned in Part 9, the sun got much lower in the sky and the days got shorter. The oak trees on the south side of my house (some of which are in my neighbor’s yard) did not drop their leaves until early December. Finally, we had a lot of cloudy days. These factors all combined to lower power production greatly. Shown below in picture form:

Through the end of September’s billing period, we had built up a surplus of almost 600 KWh. By the end of November’s billing period we had used it all up, and then some. We owed our electric company about $5 above the $8.22 charge for the meter. So in December, we were billed for all of the electricity we used, less the 255 KWh that we generated. See the chart:

Date Due	Billing Period	Current Reading	Previous Reading	Metered Usage	Carryover Applied	Accrued Carryover	Amount Owed
5/20/2019	3/26 – 4/24	99566	12	-446	0	-446	8.26
6/20/2019	4/24 – 5/23	99265	99566	-300	0	-300	8.26
7/24/2019	5/23 – 6/26	98971	99265	-295	0	-595	8.22
22-Aug	6/26 – 7/26	98982	98971	11	11	-584	8.22
9/23/2019	7/26 – 8/26	99009	98982	27	27	-557	8.22
10/21/2019	8/26 – 9/25	98967	99009	-42	0	-599	8.22
11/22/2019	9/25 – 10/28	99262	98967	295	295	-304	8.22
12/19/2019	10/28 – 11/25	99608	99262	346	304	0	13.21
1/22/2020	11/25 – 12/27	83	99608	475	0	0	65.86

In picture form, here is our electricity usage (from our utility) – solar panels went live 3/26. Our billing cycle begins about the 26th of each month (varies slightly).

Agreeing with the Judy Collins’ song, I really don’t like clouds, at all. Here is what cloudy/rainy days in December look like compared to more normal days:

The really short lines around the 1st and the 15th of the month (and a few others) are examples of very low production on cloudy/rainy days. On good days in December, production tops 10 KWh. Compare that to the summer months, where a good day produces over 50 KWh. Big difference!

So what is the take away from this post? When we went live on March 26 our meter read 00012. When they read the meter for our Dec 27 billing, it read 00083. So in 9 months, we have used a net 71 KWh from our utility. In other words we have produced all of the electricity we need to run our house from our solar panels over this 9 month period, less about 3 days. Not too shabby.

As the days get longer and the sun gets higher, here are my predictions for the next 3 months:

January we will still be in the red, using more than we produce, but less than December. I am hoping we cut the December overage (475 KWh) in half.
February we will do even better, and I hope we cut the overage in half again.
That would mean we get billed for about 240 KWh in January and 120 KWh in February, or 360 KWh total.
In March I expect we will generate a surplus.

I will let you know how it turned out in future posts.

If you enjoy reading these updates, please drop me a note. I will be happy to respond to questions as well.

September 29, 2019October 1, 2019

TDSF Power Plant Part 9: 6 Month Update

Making the electric meter spin backwards!

We went live on March 26, 2019. Just got our latest electric bill for the period ending September 25th:

Six months in: no bill and a surplus of 599 KWh to date (months 2-6) – see next image below.

Over the summer, for the two months prior, our air conditioning usage caused us to use more than we produced, but barely. With this most current bill we made up for it and are back to generating all of our own electricity and supplying a little bit to our neighbors – not that they can tell of course.

Actual surplus is 599 + 446 – already paid for the 446.

We received a check for the 446 surplus generated our first month already, so that zeroed out the account. Adding the 599 for months 2-6 to month 1’s 446 means we have generated a surplus of 1045 KWh (just over 1 MegaWatt Hour) since we went live.

A few more numbers for readers who are so inclined. On Aug 29 we got our first check for our generation of 3 SRECs. SRECs, you may recall from earlier postings are Solar Renewable Energy Credits – one SREC = 1 MWh of electricity generated. This check was for the second quarter (April-June). It was $131.85.

On Sep 28 we just hit 7 MWh generated to date. For the 3rd quarter (July-September). This means we will get a deposit around the end of November for whatever price 4 SRECs are going for. The site srectrade tracks the daily prices, currently around $62 per SREC. Note that the broker gets $5 per SREC for their troubles and the price will undoubtedly change between today and when the transaction occurs, so it is hard to predict how much we will receive.

Our 6th month savings to date then is something like this:

BGE Payment for Month 1: $ 39.20
SREC Payment for Q2: $131.85
6 months of avoided billing: $800.00*

Total earned and saved: $971.05

*Avoided billing is an estimate based on amount of electricity generated (a little under 7 MWh) minus the surplus we generated (a little over 1 MWh). This means we used a little less than 6 MWh during this time, at a cost of about $135 per MWh (13.5 cents per kilowatt hour). We hit the 7 MWh mark Sep. 28th, 2 days after the 6th month billing period.

6*$135 = $810, so I rounded to $800.

The SREC payments will always be 1 quarter behind, so I will include the Q3 payment in another posting.

As we enter the darker days of fall and winter, our power generation will decrease, but so will our usage, so hopefully we will continue generating extra power. I am hoping that for the second half of our first year (Sep 26, 2019 – March 25, 2020) we are able to generate another 5 MWh, but it is not exactly under my control!

A shout-out to my salesman Daren Weatherby: we walked my site together and he pointed out the trees that would be an issue. The one he focused on was south and east of my roof and a decent distance away, but tall and with a wide spread of branches at the top.

I am an observer of how the sun moves over my house throughout the day and found it hard to believe this tree would matter much. How could this guy who was just seeing this for the first time, but with some years of experience selling solar systems know more than I, a 25 year owner of this property? Well, to some degree we were both right.

In the summer it does not have a great affect, as the sun rises quicker and more directly over my house. Now that we are in the fall though, the angle of the sun is lower in the sky and yes, that tree is filtering a significant amount of sunlight out for a longer period of the morning.

Hopefully over the next month or so these leaves will fall and the branches, being thinner up at the top of the tree, will have less impact. Still, props to Daren, as he knew what he was talking about!

June 15, 2019June 16, 2019

TDSF Power Plant Part 6: 81 days in, a status report

This is an ongoing set of posts about our experience going solar. For those of you reading this series for the first time, if you would like to start at the beginning, here is the link to Part 1. BTW, I have not figured out how many posts there will be. I keep figuring out more things I want to say about this.

The story so far: we signed a contract on 2/8/2019 and went operational on 3/26/2029. On June 14, 81 days in we achieved two interesting milestones.

But we will get to these milestones in a minute. First great words of thanks for the support of energysage.com for playing the part of educator and honest broker. (This link contains an affiliate code that pays me, at no cost to you, should you choose to use it).

Second, many thanks to the great folks at Solar Energy World, who sold us our system and have done a stellar job supporting it.

You may wonder what the big deal is regarding post go-live support?

They did all the paperwork they had committed to and they did it right. I should also thank BGE, our local utility and Anne Arundel county, as everyone cooperated to get this project operational in less than seven weeks.

I am also receiving communication from Sol Systems, the folks who are tracking and will be brokering our SRECs (Solar Renewable Energy Credits – see previous posts). The timing was helpful as the period we went live was sunny and very solar productive.
There is a web site and a phone app I use to monitor the production. They set me up with this even before the panels were live. The app depends on communication from the inverter. In effect a cell phone is installed in the system, though just for transmitting data (and receiving software upgrades).

One of those upgrades happened about a week after installation and caused an issue. The system would stop reporting information for hours at a time, sometimes more than a day. The folks at Solar Energy World maintained contact with me the whole time. They came to the house a number of times, even on the weekend to reset the system and get it functional again.

To be clear, there was never a malfunction with the panels. They never stopped producing energy and sending it to my house and sending the excess back through to BGE. They just stopped reporting what they were producing. Really they just stopped reporting the hourly/daily/monthly statistics. The actual production meter, located inside the unit, never stopped working. The problem for me was tracking what was produced.

I was not the only person experiencing the problem, other customers were as well. Solar Energy World had a meeting with the inverter manufacturer and it turned out to be a software bug. After a few tries, they finally came out with a stable version. The maintenance support guy came and installed it on my system and we have been getting data steadily ever since.

This post-installation support, resetting my system several times, and keeping in touch with me and getting a stable version installed was why I chose a full service local company. I feel like they did a great job.

Now, about those milestones

Check out the Lifetime energy box in the upper right corner of the picture above – sometime June 14th we passed 3 MWh of production! This was day 81 of operations. This was an important milestone in that this was the 3rd MWh this quarter and we should get paid for this a few months from now.

I wish this would scale. If we produced one MWh every 27 days (3*27 = 81), we would produce over 13 MWh per year. It is reasonable to assume that we will not produce as much during the winter months, when there is much less daylight.

The following picture shows our second milestone:

99005 – this means we have sent over 1 MWh back to our utility!

When we went live on March 26th, the meter read 00012. Since then we have produced more electricity than we have consumed. In fact, we have produced about 1 MWh more! (Read this like an odometer going backwards – from 00000, as we produced the next KWh, the meter went to 99999 – since then it continued backwards to 99005).

So some very simple, rounded math:

Total electricty generated by our panels in 81 days: 3 MWh
Total electricity sent to our Utility in 81 days: – 1 MHh
Total electricity used by us in 81 days: = 2 MWh (or 2000 KWh)
Our KWh daily usage 2000/81 = 24.69 KWh/day

If we were to keep at this usage rate all year long we would only use about 9 MWh per year (24.69 * 365 = 9012). Of course the big air conditioning season is just ahead of us and we both like it cooler than most people, so our usage this summer will increase a bit.

On a humorous note, we just replaced the two light bulbs in our refrigerator (old ones were 40 watt each) with LEDs that are 1 watt each, but seriously, how often is the refrigerator door open?

Still, our rolling 12 months prior to panel installation showed us using 10.5 MWh per year, so maybe we will end up driving that down. This is one of those ‘time will tell’ items.

One last surprise

Our utility, BGE, pays any surplus production once a year in May. Since we went live March 26, our first billing period was through April 25th and we had a surplus of 446 KWh at that time. They sent us a check last month for this surplus:

In Part 2, Show me the Money, I predicted they would pay us less than retail for this electricity, as we were a vendor and they make money by buying low and selling high. I predicted this amount would be about .05/KWh or $50.0 per MWh.

As you can see from the check above, they paid us full supply retail, about .087 perKWh. This is motivating. The more we conserve, the faster the payback.

And finally, and proudly, here is our most recent bill, showing two months of no usage:

Electric bill first two months post-installation.

So 81 days in, I am a solid fan of our decision to go solar!

I have several thoughts on the next topic I want to write about:

The social utility of going solar (how it helps the neighbors and the utility company)
Some samples of daily graphs to show how much power we generate under different weather conditions
Some whimsical thoughts in the form of rewritten song lyrics about my changing attitude towards the weather. (this one may be the hardest)

If you have any ideas for future posts or other feedback, please leave some comments, or drop a note to tiedyeseniorfi@tiedyeseniorfi.com. Thanks!