Learning our system before Update/Upgrade (relays clicking!)

[koselig]

Hi all,

We took ownership of our homestead in March, in the highlands near Minnesota's North Shore of Lake Superior. It has an existing solar installation that I want to fully understand before making any alterations or updates.

The relays are cycling and making a clicking sound every few seconds or so, which I am guessing suggests some sort of error condition. When it cycles, the LED on the breadboard toggles on or off as well. I am an electrical engineer by trade, so I understand the essentials of solar but I am just learning about the various components and their role. The click is especially urgent because my wife and I sleep nearby

Any ideas what this is and how to resolve it? The big orange cable runs to the batteries and the big black cable comes from the panels.

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Cheers!
Patrick

[ButchDeal]

How old is the system. Looks like a homemade charge controller
Something like this one http://www.motherearthnews.com/diy/s...z84mazale.aspx

How many batteries and size are behind it? What is the size of the array?

[koselig]

How old is the system. Looks like a homemade charge controller
Something like this one http://www.motherearthnews.com/diy/s...z84mazale.aspx

How many batteries and size are behind it? What is the size of the array?

Thank you for your reply!

System is around 15 years old, and yes the charge controller does appear to be homemade.

The array consists of 3 free-standing panels and another 8 on a shed. At one time it powered the entire cabin although grid power was added 4 years ago. So I'd like to update whatever makes sense to switch out, including a grid-tied inverter.

There are 20 Interstate U2200 batteries. Would you recommend I switch these out or are there some criteria to determine if they can be reconditioned?

[ButchDeal]

Ok so that one odd module is concerning ? How did they wire it in? You can look at the back of the modules and there should be a sticker with specs on each.
What is the inverter?
Do you live in a state with net metering? I think you do.
Do you have a lot of power outages?

[koselig]

Ok so that one odd module is concerning ? How did they wire it in? You can look at the back of the modules and there should be a sticker with specs on each.
What is the inverter?
Do you live in a state with net metering? I think you do.
Do you have a lot of power outages?

Here is the inverter.

Yes, there is net metering in MN.

I don't believe power outages are frequent here. The service is buried in the road, which is part of the cool factor for this place, it feels very primitive. Although I need to figure out how to tie in a generator for cases where both solar & grid fail. There are 2 breaker panels - one with 100A service from the grid and the other original panel from the solar setup.

I will check the odd panel to see how it is wired.

Any ideas why those relays are clicking with the LED on the homemade charge controller toggling each time?

[koselig]

So, this seems interesting. Initially it was doing the clicking and we just put up with it (we have 4 kids and I am trying to operate a business, and we are currently only here part time). The other night I figured out it would stop if I disabled the charge controller by removing the fuses. So then I would replace the fuses in the morning once we were up, so it would charge the batteries during the day. Last night, I tried turning on the inverter and we had lights. Today, I tried turning on the inverter after having the charge controller running all day and it lights the "overload" and "low battery" LED's instantly and won't power anything.

I don't have a multimeter up here so I can't test the battery voltage directly. Any ideas as to why it is constantly clicking, and why we are now unable to use the inverter?

Thanks!

[ButchDeal]

Well I suspect that home made charge controller always clicked like that. The batteries are likely marginal.
It looks like it is a modified sine inverter at 60V DC.
are those batteries inside the home?

[Logan005]

If you now have reliable grid power nix the batteries all together.

[bcroe]

If you now have reliable grid power nix the batteries all together.

Amen. Was there a generator associated with the batteries? If you need backup, get a generator and ditch the batteries. Even with batteries
you still need a generator. Could be those panels are too little to bother with, and aren't qualified, for grid tie. Bruce Roe

[Mike90250]

Cut the blue wire. No I mean the yellow wire. Just kidding.

Seriously, if the batteries are more than a couple years old, and the system is misbehaving, it's a good bet the batteries are toast.
As an electrical engineer, I'm sure you can understand the difficulty of diagnosing a system, remotely, without even a voltmeter.

[koselig]

Well I suspect that home made charge controller always clicked like that. The batteries are likely marginal.

The batteries are definitely done for. I just don't know what to replace them with. I would prefer something nontoxic.

It looks like it is a modified sine inverter at 60V DC.
are those batteries inside the home?

Yep, they are. There is a passive vent, and that's definitely not going to work long-term if we end up with a new set of flooded batteries.

The problem with nixing the batteries is we'd spend thousands and lose the off-grid capability that brought us here. And yes, the panels (8 x Kyocera 62W, 2 x Photowatt 105W, 1 x Isofoton 150W) are out of date and would need to be sorted in order to do grid-tied.
But I really dislike the toxic nature of typical batteries. I don't know what to do in the short term as these are overdue for replacement and causing a lot of problems. We are living here now so whatever I do needs to be essentially "zero downtime".

As for generator - yes, we need one.

I talked to a company in town and they quoted $17k+ for a grid tied with battery backup setup with AGM's. With all the other expenses associated with getting the homestead going for full-time living I can't justify that expense right now, and at that I'd like to find a nontoxic battery alternative if there is an acceptable one. I know that is a controversial subject...

I am 100% prepared to invest in this system, but in the short-term we need to bias toward thrift. But with a remote homestead I'd really like to retain the option of powering the place. Maybe I need to recalibrate my thinking.

[Mike90250]

batteries, by nature, are reactive, and therefor toxic. Some less than others. NiFe come to mind, dilute the electrolyte when you are done with them and you have plant fertilizer. "Salt Water Batteries" had their "moment" and the mfg has now downgraded the specs again, and in general, they are poor. LFP are expensive, and when expired/worn out, full of expensive gunk.
for cheap, avoid AGM, toxic lead & acid that costs 2x flooded price, and lasts half as long.
If you are looking at grid tie, skip battery backup (expensive and ages starting from mfg. date) and plan on generator backup for just the essentials.

[sdold]

Your controller looks like a simple comparator circuit that uses a big relay to connect/disconnect panels based on battery voltage. If there isn't hysteresis designed in, it might cycle a lot when the battery is near full charge. We have several radio sites with controllers like that and relays that do that.

Edit: If it does it at night, the setting(s) might not match the battery voltage.

[karrak]

If you are already connected to the grid it probably does not make economic sense to use batteries.

If you do want to go ahead with batteries I would look further at Lithium Iron Phosphate (LFP) batteries. From a cost point of view per kWh of storage they are more expensive than Lead based batteries but you need far less capacity to do the same job. I have worked out the cost of power from LFP batteries to be around 30-50 cents/kWh cycled through the battery.

One plus about LFP batteries is that you can start off with a small battery and add to it later, something that does not work very well with Lead based batteries.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

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[Mdm99]

I would scrap it all and spend 1/3 of your proposed costs and get a nice whole house standby geneset