New system design with solar

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tracyj
Posts: 2
Joined: Thu Oct 15, 2015 1:29 pm

New system design with solar

Post by tracyj » Thu Oct 15, 2015 3:36 pm

I just installed a solar PV system, and it has made me much more energy conscious since I have been monitoring it everyday and trying to figure out where all my power consumption is going. That being said, I ran across the Brultech GEM, and it looks like exactly what I want. It seems like I will have to do a lot of hacking to get it to work correctly. It appears that the one cloud service that everyone was using is starting to charge a high fee, and it doesn't make much sense for me to buy this in order to cut back on electricity usage just to pay an outrageous fee to someone for storage. My intent is to use a Raspberry PI to collect the data, and set up a web server on the PI in order to access it.

My house electrical service consists of a 200 amp main service panel on the exterior of the house. The main service panel has two 100 amp breakers that feed two sub panels in the basement utility room. My solar PV system feeds into a 40 amp back fed breaker in one of the sub panels. I have two A/C units that are on 40 amp breakers, A 40 amp range breaker, and a 40 amp dryer breaker. The remaining breakers are mostly 15 amps with some 20 amp breakers. Each panel holds 12 full size breakers, but I have so many circuits that every 20 and 15 amp breaker is a twin breaker. I had to switch to quad breakers on my 220 circuits in order to free up space for my solar pv system. That means that I potentially have 48 separate circuits that could be monitored in two sub panels. Here are my questions.

1. Since I have twin breakers everywhere, and the GEM has 32 channels, Can I double up on some of the wires through a CT as long as they are on the same phase, and more that one wire will fit through the hole in the CT?

2. I would like to be able to monitor both legs of power coming into both sub panels, the solar PV 40 amp breaker in, and as many of the loads from each breaker as possible. I know that I can put a CT on each of those, but will the GEM determine the direction that the power is going so that I can see if I am pushing the power out of drawing power into the sub panel that the solar PV system is connected to?

3. When I look at the package deal for the GEM, it has all of these package options A through K or something like that, I notice that they mostly only have the micro 80 CTs. Why is it that I can't get a package deal with the micro 40 CTs? It makes sense to me that I would want micro 40 CTs instead of micro 80 CTs since all of my circuits including the 220V circuits are 40 amps or less with the exception of the incoming lines feeding the sub panel. Are the micro 80 CTs better or something? I see specs on the micro 80 CTs at 3% which isn't great, but nothing for the micro 40 CTs.

4. I plan to use a Raspberry PI to connect to this. Will btmon.py support the serial connection with an RS232 to USB adapter? Does that mean that I don't have to purchase what I consider to be an expensive ethernet adapter for the GEM? I can then use the Raspberry PI to relay the information over ethernet through a web server without having to pay for the expensive ethernet. I see that they have the dash box as well, but it seems rather high priced, and if I use a Raspberry PI, I can write the software any way I like. I would also like to incorporate ERT data from the smart meter outside and create power usage reports with respect to the solar PV system and calculate things such as how much of the solar power was consumed in the house during the day compared to how much got pushed onto the grid.

I think that is all of the questions that I have for now. Thanks in advance for any help or suggestions.
bgrubb1
Posts: 176
Joined: Fri Jun 28, 2013 1:17 am

Re: New system design with solar

Post by bgrubb1 » Thu Oct 15, 2015 6:37 pm

Tracyj welcome aboard :D
I will let Ben respond, but a couple of my inputs
If you think about it for a while, there are circuits that are easy to combine that make sense.
For example, I have 3 AC units that are 220V that have 3 115V air handlers associated with them.
that's 9 circuits - per the panel, that I have on 3 inputs to the GEM (2 for compressor plus one for air handler, tied to one input) that actually shows you the true usage of an AC unit on one channel.
I have a 325 amp service being covered by the 32 GEM channels doing this.
On most 220V circuits, you can just use one CT and use the doubling feature of the GEM (Water heater works, Dryer wont since motor runs on 115)
On the data recording, PI is a great idea, but look at the DB (Dashbox) that Brultech sells as well.
The DB gives you supported, free graphical history, and cost less than one year of SEG. With what you have invested in solar, its pretty cheap.
my 2 bits
..Barry
ben
Site Admin
Posts: 4254
Joined: Fri Jun 04, 2010 9:39 am

Re: New system design with solar

Post by ben » Fri Oct 16, 2015 9:38 am

tracyj wrote:1. Since I have twin breakers everywhere, and the GEM has 32 channels, Can I double up on some of the wires through a CT as long as they are on the same phase, and more that one wire will fit through the hole in the CT?
You can, but you'd have to measure out the wires and get a properly rated CT. We have the inner diameter of each CT posted. You'd likely be better off sticking a CT on every wire, however.

You can put multiple CTs onto one channel, 2 CTs without any jamming issues, you can combine more by splicing the wires externally.
tracyj wrote:2. I would like to be able to monitor both legs of power coming into both sub panels, the solar PV 40 amp breaker in, and as many of the loads from each breaker as possible. I know that I can put a CT on each of those, but will the GEM determine the direction that the power is going so that I can see if I am pushing the power out of drawing power into the sub panel that the solar PV system is connected to?
Each GEM channel has the ability to track outgoing and incoming power.
tracyj wrote:3. When I look at the package deal for the GEM, it has all of these package options A through K or something like that, I notice that they mostly only have the micro 80 CTs. Why is it that I can't get a package deal with the micro 40 CTs? It makes sense to me that I would want micro 40 CTs instead of micro 80 CTs since all of my circuits including the 220V circuits are 40 amps or less with the exception of the incoming lines feeding the sub panel. Are the micro 80 CTs better or something? I see specs on the micro 80 CTs at 3% which isn't great, but nothing for the micro 40 CTs.
Micro-40s have been temporarily replaced with Micro-80s as we're currently low on Micro-40s. Our Micro-CTs are typically around 1%, 3% is the extreme (check out the average plot on the graph here: http://www.brultech.com/home/store/prod ... product=46).
tracyj wrote:4. I plan to use a Raspberry PI to connect to this. Will btmon.py support the serial connection with an RS232 to USB adapter? Does that mean that I don't have to purchase what I consider to be an expensive ethernet adapter for the GEM? I can then use the Raspberry PI to relay the information over ethernet through a web server without having to pay for the expensive ethernet. I see that they have the dash box as well, but it seems rather high priced, and if I use a Raspberry PI, I can write the software any way I like. I would also like to incorporate ERT data from the smart meter outside and create power usage reports with respect to the solar PV system and calculate things such as how much of the solar power was consumed in the house during the day compared to how much got pushed onto the grid.
You can read up on btmon at http://lancet.mit.edu/mwall/projects/power. It can read from the GEM via serial. You don't need to purchase the WiFi/Ethernet combination module. I suggest also looking at http://www.emoncms.org/ for graphing purposes if you're going that route, it's open source also so you can add onto it.

If you purchase a 3rd party RS232-to-USB adapter, make sure you get a reliable chipset, avoid Prolific cables as there's plenty of counterfeit chips out there. We personally source SiLabs chip based cables. FTDI also work well.

A DashBox can be added at any time if in the future you want to go that route.
Ben
Brultech Research Inc.
E: ben(at)brultech.com
tracyj
Posts: 2
Joined: Thu Oct 15, 2015 1:29 pm

Re: New system design with solar

Post by tracyj » Fri Oct 16, 2015 1:18 pm

Thanks guys. I think I will definitely be ordering one of these. The answers to my questions were exactly what I wanted to hear. I need to figure out how many CTs I want. I didn't know that I could double up on the channels. Any ETA on more of the micro 40s? Is there any disadvantage other than cost, maybe with accuracy, by going with the micro 80s as opposed to micro 40s? All of my circuits except for the 220 circuits are only 15 or 20 amp circuits. Seems like kind of a waste to go with the micro 80s. My 220 circuits are all 40 amp.
ben
Site Admin
Posts: 4254
Joined: Fri Jun 04, 2010 9:39 am

Re: New system design with solar

Post by ben » Fri Oct 16, 2015 3:08 pm

tracyj wrote:Thanks guys. I think I will definitely be ordering one of these. The answers to my questions were exactly what I wanted to hear. I need to figure out how many CTs I want. I didn't know that I could double up on the channels. Any ETA on more of the micro 40s? Is there any disadvantage other than cost, maybe with accuracy, by going with the micro 80s as opposed to micro 40s? All of my circuits except for the 220 circuits are only 15 or 20 amp circuits. Seems like kind of a waste to go with the micro 80s. My 220 circuits are all 40 amp.
We don't have an ETA on Micro-40s, it could be awhile. The only disadvantage I could see is size if you're installing into a tight panel.

If you're worried about accuracy, we do have Micro-50s which are 1% CTs in general.

You can contact sales(at)brultech.com when you have your order together for a quote if you don't feel like fiddling with packages in the store.
Ben
Brultech Research Inc.
E: ben(at)brultech.com
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