Thinking about putting solar panels on the roof

[summand]

Hi!

I am thinking of putting solar panels on my roof. Please note that the state aids quite a bit, so economical reasonableness is improved greatly.

Statistics show that the area has about 45 days with less than 20% clouds and 110 days with more than 80% clouds and an average of 33676 J/cm² per month (10.000 in December, 56.000 in July). The house is oriented Southwest - Northeast with a pitched roof. There is a second building which is oriented Northwest - Southeast. So, I pretty much can choose on which of them I would put the panels.

What do you think? What do I need to take into account?

 

[GlennB]

Double-check which hemisphere you live in

(sorry, couldn't resist)

 

[Beady]

You don't say where you live. I live in northern Vermont, near Lake Champlain. If I knew then what I know now, I would have installed a windmill as soon as possible. You get the same tax breaks, but you generally get more wind than sun (especially at night!). I priced it out, once, and a windmill would pay for itself in eight years or so, and then start turning a profit. Don't know about solar panels, but there's no saying you couldn't install both.

 

[Andy_Ross]

Install both and put in a Ground Source Heat Pump. In the UK at least you can get a subsidy for them all. When they built a new Catholic Church close by they put in a Ground Source Heat Pump system it works quite well, it cools the aircon in summer and provides heat in the winter.

 

[lionking]

Solar panels are heavily subsided in Australia, and when I had an energy consultant out to our house (government funded) he said that we could get $15,000 worth of solar panels for $6,000. I assume that it's the same in the US and the UK, where you can get a credit for any excess energy you put back to the grid. At the moment the credit is a much higher rate than the cost of electricity you use (many times higher) so if you use little electricity during the day, you can get a "positive" electricity bill. We are looking very closely at it. We have a lot of sunlight where I live.

 

[leonAzul]

Think about how soon you'll need to re-tar and shingle your roof. Or let the next owner worry about that.

Just sayin'…

 

[Rolfe]

I'm also wondering about this. Here's my pad. That's a south-facing roof, and there's quite a lot of it. On the other hand, it's not always as sunny as the day Google's camera van came up our street. It's quite windy too, but on the other hand windmills look a lot weirder than solar panels.

I heard someone suggest that ground heat pumps may not be a renewable resource - basically that it takes a long time for that ground heat to build up, and if you keep extracting it you'll eventually use it up faster than it's being replenished. Anyone know it that's true?

Rolfe.

 

[rjh01]

I'm also wondering about this. Here's my pad. That's a south-facing roof, and there's quite a lot of it. On the other hand, it's not always as sunny as the day Google's camera van came up our street. It's quite windy too, but on the other hand windmills look a lot weirder than solar panels.

I heard someone suggest that ground heat pumps may not be a renewable resource - basically that it takes a long time for that ground heat to build up, and if you keep extracting it you'll eventually use it up faster than it's being replenished. Anyone know it that's true?

Rolfe.

You are very far from the equator. I would have thought that solar panels would not be very good for that reason. Am I wrong? For example can you have solar powered hot water systems that will provide 6 months hot water without using electricity?

 

[Rolfe]

I don't know much detail. One of my neighbours has a couple of solar panels though.

Riolfe.

 

[Cuddles]

I am thinking of putting solar panels on my roof.

What do you mean by "solar panels"? Are you looking at photovoltaic panels for power generation, or solar thermal panels for heating? There's a big difference between the two. Heating panels are much cheaper to install and maintain, and still work reasonably well even in cloudy weather. For example, my parents have one installed in their house and still get their hot water tank to ~60^oC in the winter. In Wales. In the same conditions, photovoltaic cells would be close to useless. On the other hand, if you live somewhere nearer the equator and a bit sunnier, you can get a pretty decent output from photovoltaics.

The best advice is really to ask the people who actually work with them. Whatever you're going for, get a few different companies around to give quotes on what the actual output will be for your specific situation.

It's quite windy too, but on the other hand windmills look a lot weirder than solar panels.

Wind turbines aren't a bad idea from a power point of view, but it can be a lot more difficult to actually get permission for them. Even small ones are still really quite big, and planning permission can be quite an issue even in fairly out of the way places. I guess that will depend quite a bit on the country you're in though.

I heard someone suggest that ground heat pumps may not be a renewable resource - basically that it takes a long time for that ground heat to build up, and if you keep extracting it you'll eventually use it up faster than it's being replenished. Anyone know it that's true?

No, it's not. Heat pumps are renewable in exactly the same way wind, solar, and most other renewables are - it's all just energy straight from the Sun. If you use a bit up then there will be less wherever you took it from, but that's really not a concern on the scale we're currently capable of doing anything. You're not about to cool down the Earth by putting a small heat pump in your garden.

 

[ngc6205]

Hi!

I am thinking of putting solar panels on my roof. Please note that the state aids quite a bit, so economical reasonableness is improved greatly.

Statistics show that the area has about 45 days with less than 20% clouds and 110 days with more than 80% clouds and an average of 33676 J/cm² per month (10.000 in December, 56.000 in July). The house is oriented Southwest - Northeast with a pitched roof. There is a second building which is oriented Northwest - Southeast. So, I pretty much can choose on which of them I would put the panels.

What do you think? What do I need to take into account?

Renewable energy installations are usually a good idea if they are planned well and installed correctly. The easiest and usually least expensive way to use renewable energy is by installing a solar water heater. If you live practically anywhere within the continental U.S. or similar climates, a solar water heater should work well.

I do not know your level of knowledge about solar panels, the various installation options, and possible local regulations. Therefore, I suggest that you read as much as you can on the topic. The Alternative Energy Store has, IMO, a good online library on renewable energy.
Alternative Energy Library

*I do not work for or have any financial stake in Alternative Energy Store.

 

[Lothian]

I'm also wondering about this. Here's my pad. That's a south-facing roof, and there's quite a lot of it. On the other hand, it's not always as sunny as the day Google's camera van came up our street. It's quite windy too, but on the other hand windmills look a lot weirder than solar panels.

I heard someone suggest that ground heat pumps may not be a renewable resource - basically that it takes a long time for that ground heat to build up, and if you keep extracting it you'll eventually use it up faster than it's being replenished. Anyone know it that's true?

Rolfe.

Rolfe, You live in Scotland. Forget solar panels install a wind turbine and rain catcher.

Seriously I looked into this recently.

It costs around £12k for installation. You get free electricity when the sun is shining (or it is light) but the systems don't store power locally so any excess is pumped into the grid for which you get paid. Most people use power at night rather than during the day so the savings in electricity are quite modest. You can schedule washing machines, dishwashers etc to run in the day but I think you only knock around 20-30% off your bill.

The real saving comes in the grant payments you get for producing your own electrically (the generation tariff) which electric cos must pay until 2035.

Typically, you save/earn around £1k a year.
£700 Generation tariff
£200 feed in tariff (selling electric back)
£100 reduced bill.

On average they estimate you will break even in a little over 10 years.

There are companies who will install the equipment for free but they keep the generation and possibly the feed in tariffs so you only benefit from lower bills and you keep the equipment after 25 years. However you are committing to a 25 year contract so anyone buying your house has to take over the contract.

 

[Slayhamlet]

I heard someone suggest that ground heat pumps may not be a renewable resource - basically that it takes a long time for that ground heat to build up, and if you keep extracting it you'll eventually use it up faster than it's being replenished. Anyone know it that's true?

For domestic water heating and space heating/cooling, you mean? No.

(Technically, though, it's still a renewable energy source regardless of whether it's sufficient.)

 

[summand]

Well, to tell the long story:
The house belongs to my parents in Austria. The have a wood burning stove and my father still does the woodwork himself, I help him when I am visiting them. He is in his early 60s and the topic came up when we discussed how to replace the stove. He does not want to use oil as a replacement and wood, well, what happens if he can't do it himself anymore? He would have to buy it.

So, we started to brainstorm, how to limit the amount of daily work and one thing that came up was solar panels. Not as a replacement(!) for a new stove, more as an addon. Photovoltaic or solar thermal panels for heating, both are an option. Basically, if it makes sense, we might even do both.

My mother called a contractor today and he told her, that he was swamped with orders. Fukushima and lot's of media coverage in the last weeks...


Btw.: Thanks, I would never have thought about geothermal heat pumps. Not sure if a wind turbine is an option, but I will take a look at it. Who knows...

 

[kleinjahr]

You could experiment a bit. Take a half sheet of plywood and coil a length of black water hose on it. Hook it into your water supply for your water heater and supply the heater through it. Place it in the sun and keep a record of temps, fuel use etc. You might find these guys useful, http://www.builditsolar.com/.
A caution though, before installing anything heavy on your roof be sure it can handle the extra load.
As for windmills, fine if you've got a steady wind, the space to erect one and the local board/council/neighbours don't object. You'll also have to figure out where you're going to house your batteries, applies to pv as well.
With geothermal as long as the inground is below frost level works fine. Can be expensive in the excavation, especially if you hit bedrock.
You might like to look up woodgasification if your father is already using wood for heat.
http://pages.inethome.ca/a31ford/cgcmb/
http://www.gengas.nu/byggbes/index.shtml
http://www.fao.org/docrep/t0512e/T0512e00.htm#Contents