Our solar production

[QueenBee]

Oversized? You mean in terms of cost I suppose. I'd have put in twice the capacity if I could have afforded it, because I just like making my own electricity and the more the better! In-state components maximize the incentive so we used them. No shade on array; it is sited on a nice bare south facing slope. Using micro inverters because of a lengthy cable run from the array to the house. All specifications including sizing were provided by the contractor. One could spend much less for this but there are a lot of reasons we were unable to DIY this job.

Oversized as in all the production over 9,300 kWh you are not getting any more of the 54 cent per kWh production incentive, just savings on the utility bill since there is the $5,000 a year cap.

I'm wondering what the ROI difference between your all made in WA system and say a same sized system with all made in WA ~10kw connected to your production meter then a second array of say Enphase and SolarWorld/SunPower not connected to your meter. That way you would have gotten the $5,000 annually but not had to buy the much more expensive WA made components.

A friend has a similarly sized system and he decided on using Enphase microinverters and instate iTek panels which allowed him to just hit the $5,000 limit but use the superior Enphase microinverters.

Actually did they provide a quote for an all Enphase and SunPower/SolarWorld system? For the same amount of initial investment you could have gotten an even larger system and I'm wondering what the ROI would be.

Interesting that they wanted to do microinverters vs just mounting the central inverters to the ground mount as that seems very common.

Anyway, just thinking out loud as you are the first person I've talked to who has used in state components well over the $5,000 cap

 

[DNAinaGoodWay]

6.72 kW ground mount viewable here: https://enlighten.enphaseenergy.com/public/systems/c56P87385" onclick="window.open(this.href);return false;

First two years of operation made 9412 & 9417 kWhs, more than expected, but less than I need now that we're driving electric.

So, going to start adjusting the tilt seasonally and see how that goes.

 

[RegGuheert]

6.72 kW ground mount viewable here: https://enlighten.enphaseenergy.com/public/systems/c56P87385" onclick="window.open(this.href);return false;

First two years of operation made 9412 & 9417 kWhs, more than expected, but less than I need now that we're driving electric.

Nice system! I can see bits of it behind the array picture. Any chance you can upload a couple of photos to the Enlighten site? (You need to log into your page and then click on the gear to upload photos.)

So, going to start adjusting the tilt seasonally and see how that goes.

That will help some! What angles can you adjust it to?

 

[DNAinaGoodWay]

Can't seem to upload photos from this iPad, will try from desktop later.

Array is mounted on DPW rack, details here: http://dpwsolar.com/images/PDFs/ApplicationInformation/MPM-G2%20%20Assembly%20Instructions%20V1%20Rev%20D.pdf" onclick="window.open(this.href);return false;

Page 14 has a chart with the available angles. Using the 40 degree hole set now, although I measure the angle at between 41&42 degrees with a level and large protractor.

My best options seem to be 30, or 35 for summer solstice, and 45, or 55 for winter solstice, I'll work it out with PV Watts later. Was going to use the shadow lines on the summer solstice to set it, until I came across a bolt that must have got stripped at install, so have to wait until they come fix that.

I figure between tilt changing and having a couple kids graduate and move out in a couple years, it should make enough for the house and car.

 

[RegGuheert]

Can't seem to upload photos from this iPad, will try from desktop later.

Array is mounted on DPW rack, details here: http://dpwsolar.com/images/PDFs/ApplicationInformation/MPM-G2%20%20Assembly%20Instructions%20V1%20Rev%20D.pdf" onclick="window.open(this.href);return false;

Page 14 has a chart with the available angles. Using the 40 degree hole set now, although I measure the angle at between 41&42 degrees with a level and large protractor.

Looks nice! I'm impressed that those plates can withstand the wind loads.

My best options seem to be 30, or 35 for summer solstice, and 45, or 55 for winter solstice, I'll work it out with PV Watts later. Was going to use the shadow lines on the summer solstice to set it, until I came across a bolt that must have got stripped at install, so have to wait until they come fix that.

According to Solmetric your optimum year-round tilt would be 36 degrees, but that site does not tell you what to use for a partial year. I use 60 degrees for winter between the fall and spring equinoxes and 15 degrees (IIRC, maybe 25) in the summertime. Since your latitude is higher, you will likely need to use steeper tilts to optimize your array. My guess is you will want 55 degrees for wintertime and 20 to 30 degrees for summertime. As you say, the best way to make a determination is using PVWatts.

I figure between tilt changing and having a couple kids graduate and move out in a couple years, it should make enough for the house and car.

One other thing to consider: We saved more than enough electricity to fuel our LEAF by replacing our resistive electric water heater with a heat-pump water heater. (Of course if you use gas for your current water heater, this would be an additional electrical load.) One thing nice about the heat-pump water heater is that it cools and dehumidifies the basement in the summertime. (Unfortunately, it does that in the wintertime, too! We keep it in an insulated room with the door closed for wintertime. You always have the option to switch it to resistive heat in winter, as well.)

 

[DNAinaGoodWay]

Have solar hot water too. Can't pass up tax credits. Already paid for itself with the way teenage girls shower.

 

[RegGuheert]

Have solar hot water too. Can't pass up tax credits. Already paid for itself with the way teenage girls shower.

I looked at solar hot water here. I couldn't figure out a way to make it pay for itself. So I went with more PV and a HPWH.

 

[QueenBee]

Have solar hot water too. Can't pass up tax credits. Already paid for itself with the way teenage girls shower.

I looked at solar hot water here. I couldn't figure out a way to make it pay for itself. So I went with more PV and a HPWH.

Yeah, I'd be really curious what the ROI calc looks like vs just more panels. I did the same thing. The complexity of solar hot water in an area that freezes alone is enough to stay away but even ignoring that I just couldn't see how the payback would be decent, especially compared to more PV.

 

[WisJim]

We have a somewhat complex PV/wind system in western Wisconsin, about an hour east of St Paul, MN. We started in 1977 with a 1940s vintage Jacobs wind generator powering our off-grid home which was set up for 32v DC using surplus telephone company batteries. Around 1981 we bought our first 4 Arco PV panels, 35 watts each, and used them primarily to charge a 12 volt battery (more telephone company cells) to run our brand new Sunfrost 12 v super efficient refrigerator. Over the years we moved, taking the PVs and wind generator with us and reinstalling them at our current home as a 24 volt battery to inverter system, with grid tie using a Trace SW4024 inverter and a set of new 2volt 1500 amp hour cells. Currently we have, in addition to the original system components, 12 Kyocera 125 watt panels charging the batteries through an Outback MX60, a pair of 85 watt 12 panels of a discontinued brand, and 12 Evergreen 205 watt panels grid tied with Enphase M215 microinverters. Our Leaf purchase was in part justified by our surplus power production, for which we get paid avoided fuel costs or some miniscule amount annually. Using our own energy to charge the Leaf is like using 2 or 3 cent a kW-hr electricity. Our Enphase system is online at https://enlighten.enphaseenergy.com/pv/public_systems/2Mrs143640 Monitoring of the rest of the system is less accurate, primarily keeping track of output of one array with the MX60 and monitoring the battery with a TriMetric meter.

 

[sparky]

No idea if this has been covered here:
My solar production this year has taken about a 10% hit. After a sub-par May, usually my best month, I climbed up on the roof and gave the panels a good scrub. We're in a nasty drought so I had some guilt for using the water (prob only about 10 -15 gal). My production shot right back to what I had come to expect, an immediate increase of about 10-12%.
So, I wondered if the increase in production from my cleaning easily offset the water I used. In other words, if my municipal utility needs x gallons of water per kWh for it's gas-fired turbine, what's the payback time if I added 6 kWh per day by spraying 15 gallons of water on my panels?
Anyone done this calc?

BTW, I sent this question to my utility, but just crickets so far.

 

[QueenBee]

No idea if this has been covered here:
My solar production this year has taken about a 10% hit. After a sub-par May, usually my best month, I climbed up on the roof and gave the panels a good scrub. We're in a nasty drought so I had some guilt for using the water (prob only about 10 -15 gal). My production shot right back to what I had come to expect, an immediate increase of about 10-12%.
So, I wondered if the increase in production from my cleaning easily offset the water I used. In other words, if my municipal utility needs x gallons of water per kWh for it's gas-fired turbine, what's the payback time if I added 6 kWh per day by spraying 15 gallons of water on my panels?
Anyone done this calc?

BTW, I sent this question to my utility, but just crickets so far.

I think I'd look at it from a cost point of view to get an idea. What's 15 gallons of water cost?

The national average for a gallon of water is 2/10ths of a cent per gallon. Many municipalities also charge sewer rates based on water usage, so to compensate for that, we’ll calculate it at a rate of 3/10ths of a cent per gallon.

So 15 gallons costs a few cents and 6kwh cost 60 cents so from a green (energy, money, and environmental) point of view I'd say you definitely made an improvement.

 

[sparky]

OK. I dug around a little and found something closer to what I was looking for:

http://www.nrel.gov/docs/fy04osti/33905.pdf

In thermoelectric plants, 0.47 gal (1.8 L) of fresh water is evaporated per kWh of electricity consumed at the point of end use. Hydroelectric plants evaporate an average of 18 gal (68 L) of fresh water per kWh used by the consumer. The national weighted average for thermoelectric and hydroelectric water use is 2.0 gal (7.6 L) of evaporated water per kWh of electricity consumed at the point of end use. From this information, different types of building cooling systems can be compared for relative water consumption.

So at most, 2kWh per gallon. I take this to mean, when I spray 15 gallons of water on my panels to clean them and perhaps increase the production by 6 kWh/day, it takes at most, 5 days to recover that water loss due to my decreased need for thermo-electric juice from GWP. This might be useful data the next time my neighbor, Connie 'tsk tsks' me about using the hose on my roof. Although my preference is to pretend I don't see/hear her (why is she always in her backyard when I get on the roof).
Furthermore, to all of us drought-stricken Cali rooftop solar people... we're saving water just sitting on the couch! I saved 17+ gallons just today!.

 

[dgpcolorado]

Can't seem to upload photos from this iPad, will try from desktop later.

Array is mounted on DPW rack, details here: http://dpwsolar.com/images/PDFs/ApplicationInformation/MPM-G2%20%20Assembly%20Instructions%20V1%20Rev%20D.pdf" onclick="window.open(this.href);return false;

Page 14 has a chart with the available angles. Using the 40 degree hole set now, although I measure the angle at between 41&42 degrees with a level and large protractor.

My best options seem to be 30, or 35 for summer solstice, and 45, or 55 for winter solstice, I'll work it out with PV Watts later. Was going to use the shadow lines on the summer solstice to set it, until I came across a bolt that must have got stripped at install, so have to wait until they come fix that.

I figure between tilt changing and having a couple kids graduate and move out in a couple years, it should make enough for the house and car.

For fixed panels one generally chooses an angle equal to one's latitude or a bit flatter to the sky to emphasize summer production or steeper to emphasize winter production. With adjustable tilt, one can have fun with it. I've been adjusting my panel angles for six years now.

My bracket angle choices are 15º, 25º, 35º, 45º, 55º, and 65º. So, what to use and when? I wrote a spreadsheet that calculated and plotted the angle of the sun at solar maximum for any north latitude and then plugged-in my latitude:

Using that as a base, I then tried for an angle that would optimize the production about an hour before or after solar max. After tweaking my angle change dates over the years I've eliminated the 65º around winter solstice (although it makes pulling snow off the panels very easy) and just go with 55º for several months. And I've increased the time at 15º around the summer solstice because the sun rises in the NE and sets in the NW so having the panels nearly flat to the sky is best. The shoulder seasons, around the equinoxes, now move much more quickly through those middle angles. And fall/winter angles are a bit higher than I originally used because I found that boosting production during the shoulder hours of the day was of greatest importance, as opposed to the hour or two around solar max.

Anyway, I hope you have as much fun with it as I have!

 

[HighDesertDriver]

Our BP Solar PV array was installed in Mar 2006 and has given reliable level annual output. We had three 175W BP4175B panels fail a couple years ago and BP elected to replace 14 panels beyond the 3 failures. The stated issue was manufacturing and their representative told us to watch for similar issues with the remaining original stock. Late last month, another two failed and I temporarily replaced them with slightly newer spares purchased from an array being upgraded in size.

I contacted the BP warranty department again and sent in the panel data and photos they requested. They called back after a week and detailed their review of the previous data and conversation with the installer who did the first repair. I was quite surprised when they gave us two options, (1) pay us a fixed amouunt per watt for all new panels and installation of our choosing -- their vendor will remove and take the current panels -- or (2) their vendor will remove and replace our entire array with equivalent total wattage. Either way, BP removes us as a warranty headache. Interestingly, whatever they do will include the 17 new panels installed during the first repair and three used panels I expanded the array with after the repair workers departed.

If replaced by BP's crew, the warranty will extend to the 25 years of current array. If they just pay us the flat rate and take the current array panels, our new panels will have a new 25-year warranty. I can easily do the replacement work, keeping the installation funds in the bank, or upgrading to microinverters and replacing the 3-string DC wiring. We'll likely sell the house in a year, so we're leaning toward the simpler" R&R only the panels" approach.

Thoughts?

 

[lkkms2]

OK. I dug around a little and found something closer to what I was looking for:

http://www.nrel.gov/docs/fy04osti/33905.pdf

In thermoelectric plants, 0.47 gal (1.8 L) of fresh water is evaporated per kWh of electricity consumed at the point of end use. Hydroelectric plants evaporate an average of 18 gal (68 L) of fresh water per kWh used by the consumer. The national weighted average for thermoelectric and hydroelectric water use is 2.0 gal (7.6 L) of evaporated water per kWh of electricity consumed at the point of end use. From this information, different types of building cooling systems can be compared for relative water consumption.

So at most, 2kWh per gallon. I take this to mean, when I spray 15 gallons of water on my panels to clean them and perhaps increase the production by 6 kWh/day, it takes at most, 5 days to recover that water loss due to my decreased need for thermo-electric juice from GWP. This might be useful data the next time my neighbor, Connie 'tsk tsks' me about using the hose on my roof. Although my preference is to pretend I don't see/hear her (why is she always in her backyard when I get on the roof).
Furthermore, to all of us drought-stricken Cali rooftop solar people... we're saving water just sitting on the couch! I saved 17+ gallons just today!.

On http://www.energyfactcheck.org they had a graphic with this information:

Coal: 100-1,100 gallons/MWh

Nuclear: 600 - 800 gallons/MWh

Natural Gas: 20-300 gallons/MWh,

But they also said Solar uses 0 water.

A separate question is how much water is used to produce a gallon of gasoline. (For your neighbor that drives a gasoline car).

 

[RegGuheert]

If replaced by BP's crew, the warranty will extend to the 25 years of current array. If they just pay us the flat rate and take the current array panels, our new panels will have a new 25-year warranty. I can easily do the replacement work, keeping the installation funds in the bank, or upgrading to microinverters and replacing the 3-string DC wiring. We'll likely sell the house in a year, so we're leaning toward the simpler" R&R only the panels" approach.

Thoughts?

If you are moving in a year, why not give up the old array for the money and then use it to install a new array after you move?

 

[DNAinaGoodWay]

Can't seem to upload photos from this iPad, will try from desktop later.

Array is mounted on DPW rack, details here: http://dpwsolar.com/images/PDFs/ApplicationInformation/MPM-G2%20%20Assembly%20Instructions%20V1%20Rev%20D.pdf" onclick="window.open(this.href);return false;

Page 14 has a chart with the available angles. Using the 40 degree hole set now, although I measure the angle at between 41&42 degrees with a level and large protractor.

My best options seem to be 30, or 35 for summer solstice, and 45, or 55 for winter solstice, I'll work it out with PV Watts later. Was going to use the shadow lines on the summer solstice to set it, until I came across a bolt that must have got stripped at install, so have to wait until they come fix that.

I figure between tilt changing and having a couple kids graduate and move out in a couple years, it should make enough for the house and car.

For fixed panels one generally chooses an angle equal to one's latitude or a bit flatter to the sky to emphasize summer production or steeper to emphasize winter production. With adjustable tilt, one can have fun with it. I've been adjusting my panel angles for six years now.

My bracket angle choices are 15º, 25º, 35º, 45º, 55º, and 65º. So, what to use and when? I wrote a spreadsheet that calculated and plotted the angle of the sun at solar maximum for any north latitude and then plugged-in my latitude:

Using that as a base, I then tried for an angle that would optimize the production about an hour before or after solar max. After tweaking my angle change dates over the years I've eliminated the 65º around winter solstice (although it makes pulling snow off the panels very easy) and just go with 55º for several months. And I've increased the time at 15º around the summer solstice because the sun rises in the NE and sets in the NW so having the panels nearly flat to the sky is best. The shoulder seasons, around the equinoxes, now move much more quickly through those middle angles. And fall/winter angles are a bit higher than I originally used because I found that boosting production during the shoulder hours of the day was of greatest importance, as opposed to the hour or two around solar max.

Anyway, I hope you have as much fun with it as I have!

Thanks, I'm sure it will be fun. Waiting for a new rail bracket to come in, and then we'll start. May have to re-route some wiring to simplify the process if I'm changing angles four times a year.

I'm at 42.21 N, so it's good where it is now year round. Still haven't gone up on PV Watts yet, but noticed they're up to version 4 now.

You may be interested in this Analemma photo series from Kumgaya, Japan, at 36 N it's closer to your lat:

http://spaceweathergallery.com/indiv_upload.php?upload_id=91721" onclick="window.open(this.href);return false;

 

[dgpcolorado]

...You may be interested in this Analemma photo series from Kumgaya, Japan, at 36 N it's closer to your lat:

http://spaceweathergallery.com/indiv_upload.php?upload_id=91721" onclick="window.open(this.href);return false;

That's a lot of work to be able to make that photo compilation. So the analemma you see on a globe really does look like that!

 

[HighDesertDriver]

If replaced by BP's crew, the warranty will extend to the 25 years of current array. If they just pay us the flat rate and take the current array panels, our new panels will have a new 25-year warranty. I can easily do the replacement work, keeping the installation funds in the bank, or upgrading to microinverters and replacing the 3-string DC wiring. We'll likely sell the house in a year, so we're leaning toward the simpler" R&R only the panels" approach.

Thoughts?

If you are moving in a year, why not give up the old array for the money and then use it to install a new array after you move?

Now that is an option we had not considered. Thanks for the good idea. In this case, however, I think it will be better to have an operational system rather than unoccupied racking and a dormant inverter. Power is far from cheap in this area and desert homes can use a lot of it in the summer. As a specific example, I put in a 7000W array earlier this year for a friend. He told me today that he is happy that their monthly bill was down to $400. Last year, it was over $750. Solar PV is everywhere in this area and buyers truely appreciate it's value and expect to see the capability reflected in the price of new and existing homes.

 

[dgpcolorado]

... Last year, it was over $750...

:shock: I can't even conceive of a $750 monthly electric bill. Before solar panels (and LEAF) I think mine maxed out at about $35/month, which would be about $45 today (now it is just the $17 monthly service charge, thanks to net metering). And I like to tease my carpool partner because his is usually over $100/month.

I figured a high electric bill might be something like $200/month in a climate that requires AC in the summer. No wonder people are installing gigantic solar arrays on desert houses! My 2170 watts of panels covers all my household usage and my LEAF driving (a bit over 7000 miles/year). But that's with no AC and heating with natural gas and passive solar, not electricity.