solar thermal system monitoring

[Eddie70]

Hello: I am getting a solar system installed and want to monitor the system results as cost efficiently as possible. The cheapest product on the market appears to be the Web Energy Logger (WEL) for temperature monitoring. Where I'm still unclear is whether I need to purchase a flow meter to be installed on the solar circuit as well or if that's an unnecessary expense. Your advice is appreciated. Thanks.

[Mike90250]

Each vendor (brand) has their own data structure.
Xantrex has some nice freeware you can find on the web
Morningstar MPPT 45 & 60 A charge controllers have web servers in the, just hook to Ethernet.
enphase you must pay for monitoring after year 1.
My PV page 2 has some examples of different data collections for different vendors.

http://livesolar.net/sumpage.htm

http://72.64.236.87:80

http://welserver.com/WEL0043/ - thermal

http://data.digitalgnomon.com/users/tallgirl/

[mountain]

Measuring your results is ultra motivating. Do it!

It is easy to calculate the instantaneous power of a solar-thermal system. You need to know :
- delta-T : temperature rise across the collector (2 temperature sensors)
- F : flow rate (can be derived) in cfm, gpm, or cu-m/s

P = K x F x delta-T
where K is the thermal co-efficient of thermal capacity for the transfer medium (water?)

For an example (using direct-air solar harvester), look at page-3 on this document : http://www.mountainelectric.ca/hotbox/hotbox_1.pdf

The air-flow of a fan is printed on the nameplate, and is usually very accurate, providing there is no back-pressure. Timing garbage-bag fill-rate is easy confirmation.

To derive water flow, cheapest method is to measure the pressure past the pump, and look at the pump-curve data for your specific pump. You'll have to convert pressure to head, and then cross over to the correct curve for the pipe you are using.
An accurate pressure gauge is very inexpensive, and you should only have to do this calculation once for a constant-speed pump.

http://www.engineeringtoolbox.com/pump-system-curves-d_635.html

The least expensive flow sensor type is an insertion paddle-wheel. They actually tell you the flow velocity. You will still have to correlate the velocity to flow, for the pipe diameter you are using. These cost much more than a pressure guage, and require a long-run of straight pipe (10 Pipe diams ahead, 5 after)

If you're not afraid of a bit of high-school math, and are cheap like me, pick the pressure-measure method. Got more money than brains (or can't find the pump-curve data)... buy a flow-sensor.

Timing a bucket-fill method is misleading, since when you open your pump-loop, your pressure will drop drastically, so the results are completely invalid.

To measure accumulated energy, integrate the instantaneous power over time. (Measure at 1/1000 hr = 3.6 sec intervals) if you measure P = 1 kWatt, then each 3.6 seconds you accumulate 1 WH.

For this stuff, I used a little microcontroller with a display, as shown in the above pdf file. This stuff is way more fun than watching TV!

M

[russ]

Hi Mountain - Missed seeing your posts for sometime! İ used to be a moderator at eco huddle until they hooked up with green options - a group that İ have zero respect for.

How about an update on your solar thermal air heater please? İ guess you have completed the first full winter with it.

[BuzzBuds]

Morningstar MPPT 45 & 60 A charge controllers have web servers in the, just hook to Ethernet.[/url]

This sounds interesting for several reasons to me
but I will save those for another topic later on
But for now if it is internet connectable I am asuming you could have your website installed to some therefore you should be able to not even pay after that year is up by using your own webspace domain right

[mountain]

Hi Mountain - Missed seeing your posts for sometime! İ used to be a moderator at eco huddle until they hooked up with green options - a group that İ have zero respect for.
How about an update on your solar thermal air heater please? İ guess you have completed the first full winter with it.

Well, the solar-thermal air heater worked very well overall, especially through last spring when the weather was generally sunny & the hours long. Attached (I think) is a histogram of the effect on household energy consumption. I should add that some of the benefit came from a air-recirculating system that drew warm air from the roof-peak (inside) & blew it into the basement.
Oct262010.JPG

I built a second direct-air panel on my backyard tool-shed & it is superior. here is a photo-linkhttp://www.mountainelectric.ca/hotbox/shed_HB3.JPG
Vertical orientation works great for northern latitudes where snow is typically on the ground in front during winter. This cost less than $100/sq-m and produces 975W/sq-m.

This past fall I have been very busy building a domestic HW boost system that draws energy from our wood-stove & puts it into the HWT. It works like a damn. I'll do an article on it soon.

M

[russ]

Hi Mountain - Glad to hear from you! Your projects are interesting!

I suppose you are getting into your busy season these days?

The results from your air heater look great and looking forward to haring about your HW boost system!

Russ

[greenHouse]

This sounds interesting for several reasons to me
but I will save those for another topic later on
But for now if it is internet connectable I am asuming you could have your website installed to some therefore you should be able to not even pay after that year is up by using your own webspace domain right

My company makes a product that is compatible with the TrakStar charge controllers and allows you to integrate other vendors' gear -- such as OutBack inverters with MS charge controllers. Or vice versa.

It also allows you to monitor environmental sensors and control equipment based on those sensors.

And it is very internet enabled and requires no monitoring service (though we offer one if you need one).

[mountain]

My company makes a product that is compatible with the TrakStar charge controllers and allows you to integrate other vendors' gear -- such as OutBack inverters with MS charge controllers. Or vice versa.

It also allows you to monitor environmental sensors and control equipment based on those sensors.

And it is very internet enabled and requires no monitoring service (though we offer one if you need one).

If possible, please post the URL of an example system on-line with an external IP address viewable from the WWW. I am looking for a smart embedded server that can dynamically & in real-time produce trend graphs & histograms, viewable as image files.
I would really like it to have two isolated network ports, one with an internal network IP address (for control, critical & non-critical monitoring), and another with an external WWW accessible IP address (non-critical monitoring only)

There are lots of flexible IP/serial servers out there. For commercial and industrial applications, we use the simple & rugged units sold by B&B electronics. These are suitable for network connecting legacy serial monitoring & control equipment.
http://www.bb-elec.com/product_family.asp?familyid=2 We use both rs232 and rs485 versions, with 100% success.
Not the cheapest, but you get what you pay for.

[greenHouse]

The link in my signature to "phone" is a development version of the web interface. You'll have "guest" access when you connect. There are images for many of the sensors and devices. You can also download CSV files for device history.

The product is currently available for OutBack and a fair amount of Morningstar gear for the solar PV side, and supports a number of other environmental data gathering devices. MSRP is $359 for pure OutBack and $399 for Modbus support. Additional options are available at additional cost. Volume discounts apply. More solar thermal support is scheduled for 2Q11, but that may become 1Q11, depending on how the 2.01 release goes -- which is very well at the moment.

The software is very configurable and includes the ability to change the "skin" as well as have an installer / system integrator provided logo and website link.

Please don't hammer on it. Also, please remember that it is the current =development= release and is subject to breakage, going down, etc.