My Solar Panel Power Project

[Loren49]

Rob - my panels are about 5 feet higher on my homemade mount. I would have problems with snow depth with your height - mine are hinged near the top and are set at an angle except for during the winter. I'm at 43.8 north latitude.

Loren

 

[Kyle_in_Tex]

Great thread! Real systems and real data from real users. I'm on a COOP with no incentives but I'm still looking at falling prices for systems. It gets really hot here and I'm looking at replacing my shingle roof to a reflective galvalume metal roof. I wonder how much the initial heat plus reflective heat from a metal roof would effect efficiency. Say the air temp is 100 deg F. and add reflective heat from metal roof (maybe 40 more degrees?) what would the effiency drop to? Or would it be even hotter than that? Does total heat exposure lower lifetime?

 

[Rob-D]

Great thread! Real systems and real data from real users. I'm on a COOP with no incentives but I'm still looking at falling prices for systems. It gets really hot here and I'm looking at replacing my shingle roof to a reflective galvalume metal roof. I wonder how much the initial heat plus reflective heat from a metal roof would effect efficiency. Say the air temp is 100 deg F. and add reflective heat from metal roof (maybe 40 more degrees?) what would the effiency drop to? Or would it be even hotter than that? Does total heat exposure lower lifetime?

Hi Kyle,
Heat is always the enemy of electronics.
With that said you should look at a few panels in your price and wattage range and then get the specs on them from the manufacturer. (All panels have readily available specs)
Can you pick a color for your roof? Up here you can get an array of colors and if you pick a light color it will be cooler. Years ago when I did photography we did an experiment and found that sticking your head under a white cloth was 25F cooler than a black one. Also if you're handy you can make you own mounts on the ground. I like ground mounts much better than roof mounts, cooler too.

Incentives are nice but I'd do PV even if there weren't any.

Rob

 

[varmint]

Kyle- I just happened on this thread, and will have to go back and read it! I installed solar panels on our little barn's roof last fall (well, we had it done) but before hand, I cleaned and painted the old aluminum corrugated metal roof. I got an Energy Star rated white elastomeric roof coating (that means certain areas where heat is an issue have tested and approved it, like Miami-Dade) that we sprayed on. Man, what a difference it made! On hot and sunny days, the roof is now cool to the touch, and the barn's loft is a lot cooler. Hopefully, I will see increased output from the PV system this summer, since they are over a cooler surface. Spraying it was easy, once I found an airless sprayer that could handle the viscosity. Water based, and should last a long time. Uniflex is the source, if anyone is interested, and I got it thru Sherwin Williams.

 

[Kyle241]

This is a great thread. :thumbsup: Pete, I am envious and have been looking at alternatives (including MicroFit in Ontario) and am still on the fence on what to do. Hopefully one day in the near future I will make a decision to help reduce/eliminate hydro bills as they are going up, up and up!

 

[Rob-D]

I think we're seeing an interesting phenomena. Oil prices are a spiking and PV is dropping and becoming easier to install.
Rob

 

[varmint]

Having read the whole thread, I am very impressed by the explanations and care that has gone into Pete's installation. When we installed our little system last fall, we sized it to fit the barn's roof, our "budget comfort zone" and, most importantly, our annual usage- down to around 4KWH a year and not easy to take it any lower. We may achieve about 90+ % of our annual usage from PV- so far, I think we are exceding design output a bit). We had extra costs, since we opted for the mirco inverters from Enphase, (shading issues from trees) the best panels, to maximise output and service life, and we had to have our main electrical panel replaced since it was old, full, and I mean full. Pete is obviously an electrical engineer, and knows what he's doing, which makes projects like his sooo much more interesting to read about. I'm just a handyman, do it all sort of guy, who tries to stay out of trouble and do it right, but with very limited exposure and knowledge, you have a handicap going into projects. I thought about doing it myself, but with the required permits, it didn't make any sense. I did recoat the roof after reinforcing the rafters and leveling them across the roof... this is a farmer built barn, and 40+ years old to start with.
So far, after a little over 6 months, we show a net meter reading of around 100 KWH total used from the grid- and it's been a cloudy and rainy spring. Summer, with better sunshine, better panel angles, and more usage from the AC will be very interesting to watch. I know climate change, subsidies and the like are not good issues for this forum, so let me just say we did it because we felt it was a good thing to do, and if we can save money over 10 or 15 years, that's just icing on the cake.

 

[Rob-D]

Having read the whole thread, I am very impressed by the explanations and care that has gone into Pete's installation. When we installed our little system last fall, we sized it to fit the barn's roof, our "budget comfort zone" and, most importantly, our annual usage- down to around 4KWH a year and not easy to take it any lower. We may achieve about 90+ % of our annual usage from PV- so far, I think we are exceding design output a bit). We had extra costs, since we opted for the mirco inverters from Enphase, (shading issues from trees) the best panels, to maximise output and service life, and we had to have our main electrical panel replaced since it was old, full, and I mean full. Pete is obviously an electrical engineer, and knows what he's doing, which makes projects like his sooo much more interesting to read about. I'm just a handyman, do it all sort of guy, who tries to stay out of trouble and do it right, but with very limited exposure and knowledge, you have a handicap going into projects. I thought about doing it myself, but with the required permits, it didn't make any sense. I did recoat the roof after reinforcing the rafters and leveling them across the roof... this is a farmer built barn, and 40+ years old to start with.
So far, after a little over 6 months, we show a net meter reading of around 100 KWH total used from the grid- and it's been a cloudy and rainy spring. Summer, with better sunshine, better panel angles, and more usage from the AC will be very interesting to watch. I know climate change, subsidies and the like are not good issues for this forum, so let me just say we did it because we felt it was a good thing to do, and if we can save money over 10 or 15 years, that's just icing on the cake.

Varmint,
How do you like the Enphase? I'm going with them on my intertie. They just came out with a new inverter that will be avalable the beginning of June.
My roof is east/west so it is actually cheaper to run the Enphase as opposed to say two Sunny Boys.

I'm not crazy about the fact that they keep dropping their MTBF though.

Rob

 

[eepete]

Looking back on the article, it looks like I never posted the logging of the panel's performance. So here it is. You can see a bit of a day where it was variable cloudy. The next full day was no clouds at all. The other day I saw a peak power out of 9200 watts! The brown trace on the graph labled "Light" is just a relative indication of the amount of sunlight there is. There are no units associated with this graph. You can see that at "3 days ago" we had very cloudy skies.

I've had a half a year to reflect on all this. It's looking like the panels will provide about 50% of the power I use, and my bill is about 1/3 what it was. It's averaging out to about 2 cents per square foot per month. Can't wait to have a years worth of data....

As for the cost of solar going down, the mounting stands for the panels need a lot of work. Probably due to low volume, they are extruded and drilled pieces. A little design work here and the install time would go down quite a bit. It also doesn't help that each manufacturer is different. Generic panel sizes and mounting would be nice for the consumer, not so nice for the manufacture. Think "Flat Screen Mounting" where there is a sort-of standard that lets there be one bracket that works with all TVs. Need the same thing with panels.

The inverter cost is way to high. Volume and competition will help that. I can see the micro-inverters driving that too. It's easier to make a box that outputs 250W of AC than a box that outputs 10KW. Between that, eliminating shading penalties and eliminating single point failures that take down the entire system I see a lot of promise there if the "big" inverter prices don't come down.

During the next year, I'll be bringing more automation and logging on line, and should be able to do a better job of explaining where all that energy goes...

Pete

 

[Rob-D]

Looking back on the article, it looks like I never posted the logging of the panel's performance. So here it is. You can see a bit of a day where it was variable cloudy. The next full day was no clouds at all. The other day I saw a peak power out of 9200 watts! The brown trace on the graph labled "Light" is just a relative indication of the amount of sunlight there is. There are no units associated with this graph. You can see that at "3 days ago" we had very cloudy skies.

I've had a half a year to reflect on all this. It's looking like the panels will provide about 50% of the power I use, and my bill is about 1/3 what it was. It's averaging out to about 2 cents per square foot per month. Can't wait to have a years worth of data....

As for the cost of solar going down, the mounting stands for the panels need a lot of work. Probably due to low volume, they are extruded and drilled pieces. A little design work here and the install time would go down quite a bit. It also doesn't help that each manufacturer is different. Generic panel sizes and mounting would be nice for the consumer, not so nice for the manufacture. Think "Flat Screen Mounting" where there is a sort-of standard that lets there be one bracket that works with all TVs. Need the same thing with panels.

The inverter cost is way to high. Volume and competition will help that. I can see the micro-inverters driving that too. It's easier to make a box that outputs 250W of AC than a box that outputs 10KW. Between that, eliminating shading penalties and eliminating single point failures that take down the entire system I see a lot of promise there if the "big" inverter prices don't come down.

During the next year, I'll be bringing more automation and logging on line, and should be able to do a better job of explaining where all that energy goes...

Pete

Pete,
Great software!

I have the same issues with mounting systems. The Unirac (?) is 69 cents a watt. Now that you can get watts for 2 bucks that stinks! It will add about $5k to my intertie so I'm looking into the "Quick Mount PV" system where you just buy the plates and materials to attach to your roof and then you can use any system you want. It also saves the cost of shipping long rails.
I'm going to my steel mill and getting aluminum angle. I'll MIG weld it into channels if I cant's get extruded aluminum in the shape I want.
Anyway you look at it saving several grand on the mounting is a big deal. I understand installers can't take the time to do this but they just transfer the cost to the buyer so it's nothing to them, for us it's a big saving.

Rob