Grid-tied solar

[newbury]

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However, if I was buying a house with a PV system already installed, I would be very reluctant to pay extra for it unless 1) I really understood how it worked, 2) I calculated how much money it could save me, and 3) I had it checked out thoroughly by an informed electrician.
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And a knowledgeable trusted residential structural engineer.

For those who weren't around in 1984 - There was a BIG government tax incentive for "energy efficiency". Contractors, good and bad, flocked to it. Around Northern Virginia there was a big push for solar hot water heaters on the roof.
Now I'm not a big fan of putting holes in my roof and running water thru it, but a lot of people bit the bait.

A contractor would bid a $10,000 system for $1,000 worth of parts, $2,000 worth of labor (if it was done right) and $7,000 worth of smoke to blow up a part of your body that rhymes with a former planet. After tax rebate etc. IF IT WORKED AS PROMISED you had a $3,000 system for $5,000 out of pocket but you had to pay $10,000 up front. They sprung up all over my neighborhood.

They lasted about 5 years before they were started being torn down. I'm pretty sure they are all gone today.

I can envision a lot of poorly installed PV systems being the same. Contractors gone and the roof caves in.

 

[dave1949]

And a knowledgeable trusted residential structural engineer.

For those who weren't around in 1984 - There was a BIG government tax incentive for "energy efficiency". Contractors, good and bad, flocked to it. Around Northern Virginia there was a big push for solar hot water heaters on the roof.
Now I'm not a big fan of putting holes in my roof and running water thru it, but a lot of people bit the bait.

A contractor would bid a $10,000 system for $1,000 worth of parts, $2,000 worth of labor (if it was done right) and $7,000 worth of smoke to blow up a part of your body that rhymes with a former planet. After tax rebate etc. IF IT WORKED AS PROMISED you had a $3,000 system for $5,000 out of pocket but you had to pay $10,000 up front. They sprung up all over my neighborhood.

They lasted about 5 years before they were started being torn down. I'm pretty sure they are all gone today.

I can envision a lot of poorly installed PV systems being the same. Contractors gone and the roof caves in.

An average solar PV panel puts less than 3 pounds per sq. ft. load on a roof. Not nearly enough to cause roof collapse.

I noticed that solar hot water systems suddenly became more expensive when the rebates became available. I think your point about some contractors is a valid one, and some of the increased expense is also due to more expensive materials and techniques, such as evacuated-tube style collectors.

Since my goal was to eliminate or greatly reduce my use of propane for domestic hot water, I originally went looking for a solar hot water system. I envisioned a small shed behind the house with the roof slanted to the optimal angle, run the lines to the house inside sched 40 PVC, all well insulated, circulation pump in the house, etc.

When I explained my goal to the project sales person, he pointed out that solar electric costs have gone low enough to make them a more attractive choice to power an electric water heater versus the cost and inevitable higher maintenance of hot water collectors. They sell both types of systems, so it isn't like he was pushing me into one or the other. His point was that long-term, the solar electric is going to be the least troublesome of the two and the costs are comparable.

Cost-wise, there is no equivalent of net-metering for solar hot water. I don't need the excess hot water when it is available, and I would be burning propane when the system output falls below my DHW needs.

Everyone's situation and needs are a bit different, but for the two of us in our location, I think I made the best choice. It's early days, but so far the Rheem/Marathon elec. water heater appears to be a very low energy load for our use.

 

[sdkubota]

I installed a solar panel (air) on my 26' x 40' garage a few years ago using some salvaged parts I had laying around. It blows 100+ degree air into the garage when the sun is shining. Until you build them you don't realize how infrequent that may be.

 

[madmax12]

I installed a solar panel (air) on my 26' x 40' garage a few years ago using some salvaged parts I had laying around. It blows 100+ degree air into the garage when the sun is shining. Until you build them you don't realize how infrequent that may be.

Do u mean u r getting less from your solar system than u expected? R u dissatisfied with your choice?

 

[madmax12]

One of the technologies that I don't hear people using yet, even though they've been out for years, is solar shingles. Instead of panels on top of the shingles, the shingles are small panels...

Had u you guys looked into those at all? If u did, why did u choose not to use them?

 

[sdkubota]

Do u mean u r getting less from your solar system than u expected? R u dissatisfied with your choice?

I consider every btu gained as a plus since I had very few dollars invested. I use 2 4800W electric heaters to keep my garage between 36-40 degrees during the winter. The solar panel when running prevents the electric heaters from coming on plus will usually gain 5 to 10 degrees temp that will slowly bleed off during the night. I track my electric usage but it is very hard to tell what $ benefit I am getting because every day has different weather. Without a doubt they are making a difference and considering I have maybe $200 invested...payback will be a short time. Below is a picture of the electric fan opening into the garage that is controlled by a 70 degree snap switch.

 

[madmax12]

I consider every btu gained as a plus since I had very few dollars invested. I use 2 4800W electric heaters to keep my garage between 36-40 degrees during the winter. The solar panel when running prevents the electric heaters from coming on plus will usually gain 5 to 10 degrees temp that will slowly bleed off during the night. I track my electric usage but it is very hard to tell what $ benefit I am getting because every day has different weather. Without a doubt they are making a difference and considering I have maybe $200 invested...payback will be a short time. Below is a picture of the electric fan opening into the garage that is controlled by a 70 degree snap switch.

Oh yeah... $200 is well worth investing in any potential gain. Thankyou for clarifying.

 

[sdkubota]

Hate to hijack this thread but if I built another auximllary building I would probably mount some solar panels on the side although they wouldn't be commercial due to the cost. Glass is fairly inexpensive and steel sheeting is also.

 

[madmax12]

Hate to hijack this thread but if I built another auximllary building I would probably mount some solar panels on the side although they wouldn't be commercial due to the cost. Glass is fairly inexpensive and steel sheeting is also.

As long as OPs don't mind, hijacked threads provide some of the best learning, IMO.

 

[BillG_in_TX]

Those are all good points. While it may seem futile, u could start a spreadsheet tracking past bills without solar and then tracking the difference from solar panels on... If u keep all your bills in a "for when I sell the house" file, it may not take very much convincing.

Yes, I have an affliction which causes me to spreadsheet everything. One spreadsheet which tracks production vs. usage can be found here.

This chart shows very clearly that the availability of "net metering" is essential for a grid-tied system to make sense financially. Even though my system was sized to supply 35-40% of my total requirements, we are only using about 61% of the production. If I had to give away that 39% we're not using, my system would only supply about 22% of our requirements.

By the way, the company that installed our 4.6 kW system projected annual production of 6227 kWh, and we have averaged 6320 kWh for the first three years, with the first year being the lowest. Our cost savings have not been as high as projected, due to the drop in electricity costs over the same time. Here in Texas, the cost of electricity is tied directly to the cost of natural gas, and we have a glut of that now. That's OK with me because I would rather save on the electricity I still have to buy, rather than have my payback projections be on target .