14 December 2010

Solar system estimated output using RETScreen.net

RETScreen.net was used to estimate the amount of radiation received on the solar panels to estimate the yield we could expect for our systems. Here are the main input parameters:

  • 4.9 kW of panels [20 panels that are 245 Solarworld panels
  • 135 deg azimuth
  • 40 deg slope on panels
  • Guelph
  •  5.0 kW inverter
The revenue would be the total annual 6.140 MWhrs at $802. Using 3.5% interest rate and a 10 year loan the system has a calculated simple payback of 6.9 years. Net revenue after 10 years is $9,000 and after 20 years is $55,000.
Month
Daily solar radiation - horizontal
Daily solar radiation - tilted
Electricity export rate
Electricity exported to grid

kWh/m²/d
kWh/m²/d
$/MWh
MWh
January
1.67
2.74
802.0
0.375
February
2.84
4.13
802.0
0.505
March
3.70
4.40
802.0
0.584
April
4.53
4.64
802.0
0.580
May
5.63
5.30
802.0
0.667
June
6.31
5.74
802.0
0.682
July
6.13
5.66
802.0
0.687
August
5.28
5.24
802.0
0.637
September
3.88
4.24
802.0
0.509
October
2.59
3.24
802.0
0.415
November
1.36
1.81
802.0
0.234
December
1.25
1.94
802.0
0.264
Annual
3.77
4.09
802.00
6.140

I shall be comparing this with PVWatts in the coming days.

10 December 2010

Production summary - daily from 25 Sept 2010 to 10 Dec 2010

There is considerable variability of daily power production. The following chart shows the daily revenue [at $0.802/kWhr]. The chart points are the daily values, the solid horizontal line is the daily revenue required to break even on the 10 year loan payment. Generally the system has been earning more than it has cost, though the time frame has been too short to give a proper assessment. Note the last couple of days in November are clustered around $1. This was caused by several days of continuous full or partial snow cover. This chart will be updated approximately monthly.

Production summary - monthly from 25 Sept 2010 to 10 Dec 2010

This is a summary of the generation from our system from 25 Sept to 09 Dec. I shall be comparing these stats with RETScreen.net and posting that info in the coming days. October was our best month, the last few days in November were very dark, cloudy, and several days with snow cover on the panels. The first 9 days saw several days with partial snow cover on the panels. At this rate the panels would yield approximately $150 in Dec. [we need $332 to break even].
Monthly Stats    kWhr    Rev
2010-08    141    $113.08
2010-09    450    $360.90
2010-10    457    $366.51
2010-11    355    $285.01
2010-12-09    62    $49.45

01 December 2010

Enphase micro-inverter projects

Micro-inverters are an alternative to string inverters. Inverters convert the DC power from the panels to AC. A micro-inverter is wired to one panel, so you have as many inverters as panels. A string inverter has all the panels wired to it - only one inverter is converting the DC to AC power. Everyone has an opinion on which is better, especially sales people. I won't enter that debate now.
The purpose of this entry is to provide a link to a solar company website with solar PV sysetems with Enphase micro-inverters installed here in Ontario. Sentinel Solar has six projects listed on their website. [Oddly enough, when looking at each system some seem to be installed by different solar companies, not necessarily by Sentinel. Nothing like advertising for your competitors]. You will notice some things about these systems:
  • the Enphase micro-inverters provide panel-specific monitoring - interesting to see the variability between the panels
  • the web monitoring is nice if you are curious about instantaneous and historical power production
  • you can see the difference between the various systems all in one spot
  • you can't compare one system against another as some are roof mounted, others are trackers, and the panels are likely different at each location
  • individual panel monitoring can help you understand the power production, however if you see the inherent differences between the panels it is quite likely you won't be doing much about it. It might just drive you crazy wondering why
Keep in mind, we don't see the costs of the different systems. Monitoring and power generation is interesting, but installation and maintenance costs are also part of the equation!

Nov 2010 results, how much energy are the panels producing

It is very difficult to determine what size panels and inverter to get. One option is to slightly oversize your panel wattage output compared to your inverter capacity. For example, installing 20 panels of 235 kW gives you a theoretical maximum of 4.7kW output from the panels. Installing a 4 kW inverter means your panels are over-sized for the inverter by 18%. I have heard that solar installers often will "oversize" the panel array for the inverter by 10%-20%. The logic is that you can save a little money by buying a smaller inverter because the likelihood of the system frequently producing maximum power is low. Also, inverters are often most efficient when operating towards their top end of output. Therefore, installing an over powered inverter means it may be operating at less than its maximum efficiency - and that is an power conversion loss to you.
Another reason why panels will be over-sized is for people installing a 10 kW array. The microFIT program limits you to 10 kW of either panels or inverter, whichever is the lowest rated output. Therefore, the system would install 10% or more watts of panels of the inverter capacity - to maximize the amount of energy generation in the mornings, afternoons, and cloudy days. You pay a little more for the panels, but in the long run you make more power under suboptimal radiation periods. And the project would still qualify as a =<10 kW project for the microFIT rules.
My situation was a little different. At first I was going to have 20 235 W panels, however, I eventually had 20 245 W panels installed, and I had a 4 kW inverter. Instead of my panel array being over-sized by 18% it was now 23%. I had no reliable way to assess if I would have a significant power generation loss over the year with an inverter that could now be notably undersized. Additionally, when I ran the Fronius configuration tool [online version] my panel voltages were now going to exceed the inverter optimal ranges under certain temperature regimes. My solar installing company graciously switched my inverter to a 5 kW Fronius IG 5100. My inverter is now a little over-sized for my 4.9 kW system, but I am pleased that I'll not be losing power generation during peak radiation periods.
So... during a relatively cloudy, cool November, how much energy do my panels produce? I downloaded the entire month, except today's data [a very dark rainy day] and calculated the per panel 15 minute average power generation in watts.
Some stats:
  • there were 1103 15-minute measurement intervals from 1-29 Nov [will be higher in the summer when the sun is up longer]
  • the cloudy mornings, afternoons, and other very dark periods meant that quite often the average panel output was less than 21.5 W [that's less than 10% of the panel capacity]
  • maximum output was 215.5 W, there were only 7 15 minute periods where power was greater than 194 watts
  • maximum total output was 4311 W, this is somewhat low as higher values have been recorded in August and September
 I'll publish similar results for the forthcoming months.

30 November 2010

MicroFIT projects in Guelph - info from Guelph Hydro

According to Guelph Hydro yesterday, there are currently 16 microFIT projects in Guelph, all solar. There is one system operating under the Renewable Energy Standard Offer Program [RESOP, which is the predecessor to the Ontario Power Authority's current Feed-In Tariff Program]. Apparently, though, there are about 100 microFIT applications being processed by the OPA according to Guelph Hydro.

Energy Generation Report From Datalogger - Nov 2010

This chart shows you the Watt*hours generated from our 4.9 kW solar system during the month of November [except for 30 Nov which is tomorrow]. Note this is Watt*hours, not kW*hours. I wanted to show this chart as it shows some interesting information:
  • There are 7 days where we generated over 20 kWhr. That is over 4 kWhr/kW of installed capacity. Or over 4 hours of accumulated solar radiation converted to electricity
  • There are 7 days of very low generation, with the lowest day, 22-Nov a very dark rainy day. It snowed on the 27-Nov and about 1cm of snow accumlated on the panels. The sky was overcast and the temperature about -2C. There was not enough heat to melt the snow off the panels.
  • The 28-Nov was a fairly cloudy day, however several of the panels still had partial snow cover. This seems to have decreased the overall daily output for that day. 
  • There was a very small amount of remnant snow on 2 panels on the morning of 29-Nov, but it appears to have melted off early in the morning.
  • There is considerable variability from day to day.
  • Month-to-date generation was 354 kWhr, that is $284, plus whatever I generate tomorrow. The system must generate approximately $300/month to cover the cost of the loan. This is one of the lowest solar radiation months of the year. We'll find out how low Dec and Jan are soon!
We'll see if tomorrow yields $16 so we break even.
I started recording the daily output from the system since August by reading the utility meter. I will publish those in the coming days.

20 November 2010

St. Pauls Catholic School PV System Connected

After school on 18th November the PV system at St. Paul's Catholic School in Guelph was connected to the grid. I'll report on this system later when i get some more details. The equipment was on-site in late August.

17 November 2010

Energy Ideas for Guelph

Guelph and Guelphites can do many initiatives to reduce energy expenses, promote renewable energy, stimulate economic development, and reduce our greenhouse gas emissions. I list several initiatives below. Some I heard this week while I attended the Ontario Sustainable Energy Association (OSEA) Community Power Conference 2010 15-16 November in Toronto. Some initiative ideas are from my own experience, and this is just the beginning of a long list that Guelph could consider.
  • Solar PV and solar heating on new public and private construction. Build it into new structures such as our new Go Train station and the new car park on Wilson Street. PV panels can be used as a shade for cars on the top level of a car park. Panels can be awnings on the south wall, or simply installed on the south wall on a bracket. Solar heating can be passive air solar walls as well as sunlight through windows. 
  • Energy sales can be included in the financial model of new construction.
  • Solar PV on brown fields now create "Bright fields". They can also be installed on city owned lands, around water sedimentation ponds, or around the various industrial parks. 
  • Solar-friendly homes can be designed and built in co-operation with the Guelph Home Builders Association. Many homes in my new subdivision are poorly suited for solar panels due to the complex, architectural roof designs.
  • Building officials should be trained about renewable energy opportunities, requirements, and initiatives. 
  • Guelph could require energy efficiencies more strict than the Ontario Building Code. 
  • A 1 year tax property tax deduction for the first year of a new home if energy and water efficiency was built into the project
  • Geothermal opportunities should be explored wherever possible, including new construction, retrofits, industrial, and institutional.
  • Biomass from agriculture could be an option for the University of Guelph.
  • Traffic research should be conducted. University of Guelph students could provide a GPS to employees and residents in various sectors and locations in the city for 1 week. All driving would be recorded on the GPS to study transit patterns. 
  • A renewable energy and energy efficiency inventory can be created so people learn about various projects.
  • The city website could be enhanced to provide more information about energy and water initiatives.

08 November 2010

Our 4.9 kW PV solar system

I have installed a 4.9kW solar system on our house in the south end of Guelph. I am pleased to share the project details:
- May 2010: applied to the Ontario Power Authority's microFIT program, approved in 3 weeks
- June 2010: solicited tenders from local/regional companies
- July 2010: selected a company, system configuration chosen, equipment ordered
- August 2010: system installed over 1 week period [roof vents moved, panels installed, electrical work, inverter installed, ESA inspection]
- August 23: requested Guelph Hydro to install meter
- August 25: meter installed and system activated at 4:30pm. 1 kWhr of electricity was produced that day [worth $0.802]

The system has worked perfectly fine ever since. I have had no maintenance to perform - I don't expect there to be any other than an annual visual inspection.

Equipment details:
20 SolarWorld 245 kW panels [4.9 kW]
1 Fronius IG 5100 grid-tied 5kW inverter
Racking system Unirac aluminum rail system and Quickmount PV flashed attachments
1 Fronius Datalogger Pro

I installed the data logger when it arrived in November.
You are able to see the system online at
url: http://solarweb.fronius.com
username: 243farley
password: 243farley
[any missing data is because it was not uploaded, not because the system was not functioning]

07 November 2010

Guelph Solar Blog

I wish to share my experience deciding to install a solar photovoltaic system on our house in Guelph, Ontario. We are contracted to sell our power through the Ontario Power Authority's microFIT program. We are now receiving $0.802/kWhr.
I will post why I decided to do this project, how I proceeded, and how it is working out. I will try to post information here that I think will be useful for others who wish to do solar PV, for people who want to learn more about it, and to hopefully encourage further development of solar PV in Guelph [and beyond].
Full disclosure: I am not a vendor of solar equipment or services. I will not be taking any money from anyone related to solar, etc. I am fully independent. I do work for the provincial government working in renewable energy, but not solar. I am approaching this as non-work related. I will avoid any opinion, just the facts [positive and negative]. I will disclose any conflicts of interest.
Despite a similar name, this blog is not associated in any way with SolarG nor Solar Guelph.