Solar Water Collectors - Large Scale Project

[BIPVguy]

Dear all,

I would kindly ask for information please.
If possible, could I be referenced with sources of good design guidelines, schematics, free-of-charge software etc to design large scale solar water systems (both for domestic hot water and hydronic heating)?

Please advise.
Thanks muchly

 

[GMcD]

And you couldn't use Google because...??

There's a lot of information out there, and the suppliers will give you all the help you need. I generally use the Viessmann catalogue, they have a number of standard hook-up schematics with controls diagrams.

Caleffi is another good source- good manual. John Siegenthaler has been publishing some good articles in PM Engineer magazine lately on different solar hot water systems.

Any material you get for free is worth exactly that. One still as to do the basic engineering, design and detailing to make the system work. There is no free lunch.

 

[BIPVguy]

Hi GMcD,

Thanks for the prompt reply.
Google can help a lot but not always as in this case. If not mistaken, many design guidelines including Viessmann's do not put much light on important issues such as stagnation or parallel vs serial tank connection or how to design large scale solar systems. Most of the internet available literature is focused on house applications. In contrsat, I am supposed to size large scale solar water system for DHW and heating.I am thinking to solve stagnation by linking collectors to a cooling tower. It is not a rocket science and I see no reason why it should not work but have not found any similar example on the web (to be precise, have not found any serious design drawings worth to be mentioned).

Regarding software, I like using REtscreen for rough space allowances, capacities , cost analysis, eq. CO2 emissions etc. Viessmann is using sophisticated custom-made software ESOP. In Europe, Viessmann's fee for consulting services is cca. 10% of the solar system cost.

Many thanks for your kind-in assistance.
Cheers

 

[GMcD]

If you use a drain-back system, even on a large scale solar panel array, you don't need to worry about stagnation. Why make things more complicated than they need to be.

 

[mikanical]

BIPVguy,

A great design guide is the publication "Planning and Installing Solar Thermal Systems" by the German Solar Energy Society.

The Viessman software is available for purchase (about $100 Cdn) and has some customized systems based on their controller schemes. Whichever supplier you end up using, they should be able to provide you with design assistance.

For tank storage configurations, you will want to maximize thermal stratification in the storage volume to ensure the lowest water temperature is being supplied to the solar array to increase the solar yield. Piping vertical tanks in series works well, with a circulator pump controlled via the temperature difference between the tanks.

For protection against stagnation there are a few options typically used:
1. a fan coil
2. a dry or fluid cooler
3. vertical boreholes

You could probably get away with a dry cooler instead of an evaporative fluid cooler since the fluid temperature only needs to be cooled below the stagnation temperature. A dry cooler will simplify the installation and save water.