If a Forum Member who lives in the Netherlands wants to build a solar power system, how can we help him calculate the number of panels needed for a given ROI?

We can also look at the payback period (years needed to pay for the initial installation) and maybe power grids, if he teams up with his neighbors. More barn roofs, more angles to South, the more the merrier!)

Here is some basic information on solar power calculations:

Calculate Your Solar Power Payback Period - Energy Sage (US-centric, so must account for local currency and local cost of materials)

Are The Netherlands offering subsidies or tax breaks for home owners? Yes!
See Government of the Netherlands - Stimulating the growth of solar energy
Looks like tax cuts, a grant scheme, grants, and  credits.

Excerpt: (the easier financial stuff)

• Gross cost of solar panel system: The gross cost of installing solar on your home is dependent on the size of the system you select and the equipment that makes up that system.
• Value of up-front financial incentives: Tax breaks and rebates can dramatically reduce the cost of going solar. 
• Average monthly electricity use: The amount of electricity that you consume monthly is an indicator of both the size of system you need and the amount of electricity that you can offset each month with solar. The higher your electricity bills are, the shorter your estimated payback period will be, as you can reduce or eliminate this bill as soon as your panels are operational.
• Estimated electricity generation: While solar installers will try to provide you with a system that matches your electricity consumption, practical constraints like the size of your roof and seasonal weather variation may impact the amount of electricity that you can produce on-site.
• Additional financial incentives: Depends on country, but can be significant.

For materials estimates, see:

Mass. Solar panels - guide to solar incentives, costs, and savings (Again, US-centric, but gives you some ball park figures for materials, even if obtained in the EU).

Considerations:

Surface area available
Pitch of roof (in degrees)
Orientation of roof - N, S, E, W
Weather conditions there historically and also adjust for any recent noticeable changes (climate change making it sunnier, cloudier?)

Sample cash flow chart for an X kW system (note you can purchase various types of kW systems - not all systems are created equal)



Not fully complete as a brainteaser, but it's a start!

Original thread by Cuchulainn: Solar panels - how many do I need? - W OT

3. Don't you have more than one "wing"? I don't know how you cope.

Is a conservatory like an orangery?

BTW how do you plant an orange tree? Are the oranges edible?

How many orangeries are there in New England?

Here is one firm (in Connecticut) that specializes in orangeries and conservatories, as well as general renovations.

Nice portfolios of each:  Parish Conservatories - Orangeries and Parish Conservatories - Conservatories

As for growing - two good sites: first my favorite house and garden maven Martha Stewart on Growing Citrus Indoors

and also explained by the Modern Farmer: How to Grow Citrus Indoors - Modern Farmer

For your inspiration - here is one view of the orangery at Versailles.
 

Imagine the heavy metal parties you could have there!

Question: We know plants like classical music - what about metal?

Those conservatories are vulgar ... Howard Roark would turn in his grave.

Well, I did provide two portfolios for you to look at. No question that some of the conservatories had a nouveau riche air about them, but others were more classical and reserved.
Vulgarity is in the eyes of the beholder?
Here is one of my favorite conservatories - it is at The Elms in Newport Do you think dear Howard would approve?

The one change I would make in this context would be to the statues of gods and satyrs that are on the grounds and in the house.

I would sew kilts for them: Black Watch plaid, probably, and each one custom tailored for the god or satyr in question.

As elegant as these places are, there is a little unexpected vulgarity here and there - with a kilt on, it then lies just beneath the surface - like a hidden condition. 

Kilt on, Risk off. I like that approach very much. : )

If Daveangel were around he might have some questions about the chandeliers.

Haha - that was a very funny day - posts from Wilmott's dark past.  

But you know daveangel was more interested in crossword puzzles and preventing Shirley from burning all those tires.

What's a heat pump?

Serious question?

I'll pretend it is.

A heat pump, rather than generating heat, extracts heat from some environment -- outside air; the ground; a body of water -- and generally uses it to heat an indoor space. Relies on some coolant and the condensation/evaporation process; basically an air conditioner in reverse. And at this point most heat pumps are essentially reversible and function as air conditioners as well.

And these days they are generally the preferred method of HVAC because, transferring rather than generating heat, they use much less energy to achieve the same result.

Getting back to going solar, in America what is typically done when someone looks into going solar is that a calculation is done to see how much electricity they use, and then the appropriate number of panels is planned to come close to matching this amount. This is because, depending upon jurisdiction, any electricity generated in excess of what is used is either taken for free by whatever electric utility is on backup, or sold to that utility at a much-below-market rate.

So the notion is that, you're basically losing money on any excess electricity you generate.

This is intellectually offensive to me. Once you have decided to have a crew on your roof and a converter installed, THAT'S your major expense. Tossing a few extra panels up there is a marginal expense.

So, globally, what you should obviously do once you've decided to go solar is to use every square inch of surface available to generate electricity. But, individually, those few extra panels you might toss onto your roof -- even as just a marginal expense -- are money losers.

Obviously Wilmotters will do the right thing and pay for the extra panels -- in order to save the planet 'n stuff -- but it really should be financially rationalized.