New off grid / solar setup

zipsort

I recently have purchased an off grid property that already has a solar system in place. I have never used any solar before but am pretty familiar with electronics.

Basically I am looking to start upgrading it a little bit at a time while learning. The system is totally sufficient during the day time for our use, but not at night (couple fans on and the inverter shuts down in the middle of the night..) so I assume we need to add more batteries. They said the batteries were only 6 months old but who knows

24 volt Current Setup

8 x 100watt unknown panels
Xantrex Inverter - http://www.wholesalesolar.com/products.folder/inverter-folder/Xantrex_trace_TR3624-120-60.html
Outback Controller MX-60 - http://www.wholesalesolar.com/products.folder/controller-folder/outbackmx-60.html
4 trojan L16 batteries - http://www.trojanbattery.com/products/L16RE-B6V.aspx

I get a buzzing coming from the inverter, and any TV that I plug in. So I'm thinking right now my weak link is the inverter that needs to be replaced and maybe a couple more added batteries (if possible)

I would be interested in swapping out the panels for new ones as well, but not right away. If anyone could suggest a few moves I should take I would greatly appreciate it. Maybe some basic stuff I am missing, but the batteries seem to always be around 24v when the system shuts down...

vtmaps

Re: New off grid / solar setup

zipsort wrote: »

If anyone could suggest a few moves I should take I would greatly appreciate it. Maybe some basic stuff I am missing, but the batteries seem to always be around 24v when the system shuts down...

Welcome to the forum,

My advice is to design your ideal system on paper, then look and see what you can do to get there from what you have.

Designing a system starts with determining your loads. It is sort of like buying a pickup truck... if you don't know the weight of what you want to haul or tow, you will probably buy the wrong truck.

You need to know how many kilowatthours per day you will consume, the most watts you will draw at any one time, and the time of day you draw the loads.

The second step is to choose a system voltage and battery.

The third step is to buy enough solar panels and charge controller and balance of system to keep the batteries happy.

Now, a couple of notes...

Do NOT add batteries until you figure out what batteries you need. It's possible that your batteries are already scrap... batteries can be ruined amazingly fast. You need to buy and use an hydrometer... that will tell you if your batteries are sulfated, the most common form of battery abuse. If you add battery capacity, you will also need to add charging capacity. Adding battery without charging capacity leads to chronic undercharging and sulfation of the battery. That's why, when designing a system, you choose the battery before you determine how much solar panel to use.

If you determine that you need larger battery capacity (based on your loads), you should know that it is a bad idea to add new batteries to old batteries (we can discuss that further after you check battery condition). It is also not good design to have batteries in parallel... it's often done because design and engineering is often about compromise, but you should know that parallel batteries is NOT optimal design.

Bottom line: living off grid is all about batteries. Spend as much time as you can reading about batteries.

zipsort wrote: »

but the batteries seem to always be around 24v when the system shuts down...

Most inverters have a low voltage disconnect (LVD). That means the inverter shuts off at the LVD voltage to protect the battery from discharging too deeply.

zipsort wrote: »

I get a buzzing coming from the inverter, and any TV that I plug in.

That is because your inverter is not a pure sine inverter.

--vtMaps

Photowhit

Re: New off grid / solar setup

It would appear that you have too much battery if anything... likely about 350Ah at 24 volts and your panels likely produce about 6 amps at 12 volts likely run in series for 4 strings at around 70 volts coming into the charge controller and charging voltage out at around 24 amps. Trojan recommends a charging rate for 10-13%. Things on the system you might check, what is the complete distance from panels to charge controller and to batteries? If the panels are setup as pairs to the charge controller they might not have enough voltage for the MPPT type charge controller to work properly. A Clamp meter might be in line to check the amperage coming from the panels, and coming from the charge controller, it's handy in other situations as well.

Need to check your batteries out now! another tool you'll need is a hydrometer, check the Specific Gravity (SG) of the batteries. 4 L-16 batteries can run a lot of loads, a fridge and a window air would not be out of line this time of year if you have abundant sun! So a couple of fans should not pull the system down, check that the batteries are fully charged. There is a lot of good info in the FAQ's on Batteries!

The buzz is likely due to the type of inverter, you have a modified sine wave inverter. This type of inverter doesn't play well with some electronics and motors. Once you decide on the needs of your system(loads), you might look into a true sine wave inverter.

BB.

Re: New off grid / solar setup

Is the "buzz" irritating, or are your AC loads not working at all?

I would suggest that you review the present design (clean terminals, look for loose/corroded cables, run the genset and top off the batteries, check specific gravity, etc.). And start running your loads and see how much power you need for your lifestyle...

Once you have your daily loads (and any seasonal changes/guesses in power usage), then you can look at designing/repairing the system so that it supports your needs.

More than likely, as said above, you will need to add more solar panels to your existing system. The recommended rate of solar charging is around 5% to 13%:

370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.05 rate of charge = 697 Watt array minimum
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.10 rate of charge = 1,394 Watt array nominal
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.13 rate of charge = 1,812 Watt array "cost effective" maximum

If this is a weekend/season home/cabin, then you may get away with a 5% rate of charge. Otherwise, panels have never been cheaper -- So a 10% to 13% rate of charge is going to make for a much nicer system. Based on a 4 hour per day estimated sun for ~9 months a year for much of the "sunnier" US, a 10% rate of charge system would produce:

1,394 Watt array * 0.52 end to end system eff * 4 hours of sun = 2,900 Watt*Hours of 120 VAC energy per day

That is a good sized system for off grid cabin/small/energy efficient home... I suggest a 3.3 kWH per day system if you have LED lights, laptop computer, LED TV, small well pump, and a full sized energy star refrigerator.

In the end, energy usage is a highly personal set of choices--And the better you can measure/estimate you loads, the better chance your off grid system will support your power needs and avoid unnecessary costs for an over-sized system.

-Bill

Photowhit

Re: New off grid / solar setup

I forgot to add that, motors in a system can create 'noise' that might create a buzz in a TV as well. I know my little O2cool fans don't create a problem for the TV, but interfere with Wi-Fi and Phone signals (Radio interference) you might try turning off the fans to see if this is a cause of your TV problems.

zipsort

Re: New off grid / solar setup

Thank you all for your replies. I figured the battery bank was solid enough to power our needs at night as well, and figured something was up with the charging / inverting. The batteries are pretty new but I will order a hydrometer right now and start messing with that

BB. wrote: »

Is the "buzz" irritating, or are your AC loads not working at all?

I would suggest that you review the present design (clean terminals, look for loose/corroded cables, run the genset and top off the batteries, check specific gravity, etc.). And start running your loads and see how much power you need for your lifestyle...

Once you have your daily loads (and any seasonal changes/guesses in power usage), then you can look at designing/repairing the system so that it supports your needs.

More than likely, as said above, you will need to add more solar panels to your existing system. The recommended rate of solar charging is around 5% to 13%:

370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.05 rate of charge = 697 Watt array minimum
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.10 rate of charge = 1,394 Watt array nominal
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.13 rate of charge = 1,812 Watt array "cost effective" maximum

If this is a weekend/season home/cabin, then you may get away with a 5% rate of charge. Otherwise, panels have never been cheaper -- So a 10% to 13% rate of charge is going to make for a much nicer system. Based on a 4 hour per day estimated sun for ~9 months a year for much of the "sunnier" US, a 10% rate of charge system would produce:

1,394 Watt array * 0.52 end to end system eff * 4 hours of sun = 2,900 Watt*Hours of 120 VAC energy per day

That is a good sized system for off grid cabin/small/energy efficient home... I suggest a 3.3 kWH per day system if you have LED lights, laptop computer, LED TV, small well pump, and a full sized energy star refrigerator.

In the end, energy usage is a highly personal set of choices--And the better you can measure/estimate you loads, the better chance your off grid system will support your power needs and avoid unnecessary costs for an over-sized system.

-Bill

This is actually my full time home. Living completely off grid, outside of hollister in the mountains 2600ft up we get a LOT of sun.

All bulbs are LED. laptop with 12 hour battery life. So really all the solar is powering is daily things like the fridge and some tools here and there, cell phone chargers. No well pump. We have not had a problem during the day time, only night so far (and we have used a lot of tools and things during the day recently)

Our only cooling right now is ceiling fans (which sucks) and we had two of them on overnight and shut off the inverter a few hours into the night.

So i've been looking at getting new panels anyway. Looks like I should get around 2kw worth of panels and a battery tester? I also want to swap my inverter for a nicer one.

zipsort

Re: New off grid / solar setup

Photowhit wrote: »

It would appear that you have too much battery if anything... likely about 350Ah at 24 volts and your panels likely produce about 6 amps at 12 volts likely run in series for 4 strings at around 70 volts coming into the charge controller and charging voltage out at around 24 amps. Trojan recommends a charging rate for 10-13%. Things on the system you might check, what is the complete distance from panels to charge controller and to batteries? If the panels are setup as pairs to the charge controller they might not have enough voltage for the MPPT type charge controller to work properly. A Clamp meter might be in line to check the amperage coming from the panels, and coming from the charge controller, it's handy in other situations as well.

Need to check your batteries out now! another tool you'll need is a hydrometer, check the Specific Gravity (SG) of the batteries. 4 L-16 batteries can run a lot of loads, a fridge and a window air would not be out of line this time of year if you have abundant sun! So a couple of fans should not pull the system down, check that the batteries are fully charged. There is a lot of good info in the FAQ's on Batteries!

The buzz is likely due to the type of inverter, you have a modified sine wave inverter. This type of inverter doesn't play well with some electronics and motors. Once you decide on the needs of your system(loads), you might look into a true sine wave inverter.

The distance is very short from panels to charger to batteries. No more than 10 ft of wiring i'd say?

BB.

Re: New off grid / solar setup

The battery is the "heart" of your system. And you can pretty much look at each load/charging system "in isolation" as a start.

So--First thing, figure out what is happening with charging. Are you getting the current/energy per day that you expect from your present array+charge controller+wiring to battery bank.

If you don't yet have one, get a DC Current Clamp DMM (like this cheap/good enough one from Sears).

For an 800 Watt solar array with a well discharged battery bank (say less than 80% state of charge or lower):

800 watts * 0.77 panel+controller derating * 1/29 volt charging = 21 amps

If you are getting close to (or better) than 21 amps from your battery bank in the middle of the day, then your array is working OK.

Next, look at the charge controller/battery bank charging voltage... Ideally, you want the battery bank to see ~29 volts for several hours per day minimum (assuming deeply cycled battery bank). If the battery never reaches this voltage--You need to figure out why. It could be the charge controller/wiring having problems, or it could be a battery bank problem (shorted cell), or it could be simply you are taking too much energy from the battery bank for it to properly/quickly fully recharge in just one day of sun.

You have 4 batteries--So you want to measure voltage on each battery (night, day, charging/loaded, etc.). You are looking for "differences". If the batteries are all equal voltage--generally "good". If you see battery with high or low voltage relative to the others, a problem that needs to be investigated.

Even monitoring your distilled water usage... If you need to add some water every ~1-2 months--probably charging voltages are fine. If you need to fill the space above the plates every month or more often, over charging. If you don't need to fill them every 6 months or longer--not enough charging voltage/energy.

Just to give you an idea--A "balanced" system will use about 25% of the battery bank's capacity overnight.

370 AH * 0.25 = 92.5 AH per night (for two nights maximum--for longer battery life)

9.25 AH * 24 volts * 0.85 AC inverter efficiency = 1,887 Watt*Hours per night

If you are going dead in a few hours (AC inverter shuts down)--That would be a lot of power draw. You need to watch the battery bank voltage/state of charge when the inverter shuts down (typical inverter would shut down at ~21.0 volts, or a "really dead" and damaged lead acid battery bank).

Also check the voltage at the battery bus and on the inverter's DC terminals. There should be almost no voltage drop (not more than ~1.0 volt drop under heavy AC loads).

Batteries need to be properly managed. It is easy to kill them with over discharging, under charging. But it is also easy to kill them with over charging/boiling the electrolyte level below the top of the plates (exposed plates quickly fail due to exposure to air).

The above are "step one".... Get your battery bank under control and check the wiring/charging system.

-Bill

vtmaps

Re: New off grid / solar setup

zipsort wrote: »

So i've been looking at getting new panels anyway. Looks like I should get around 2kw worth of panels and a battery tester?

Battery tester? Do you mean an hydrometer, or something else?

You mentioned that the batteries are only 6 months old. Perhaps they are replacing a different brand or model of battery and their needs are different than the old batteries. What are the charging parameters set to on the MX-60? Another possible issue relates to panel voltage and configuration... if your panels are 12 volt panels and are in four strings (with two panels, in series, per string), the voltage may not be high enough for your new batteries.

Your 800 watts of panels are capable of charging your new batteries if you have modest needs, enough sun hours per day, and have the panels properly configured and your charging parameters set correctly.

That said, it wouldn't hurt to increase your array. No need to replace your current array... you could add another 800 watts of panels and a 30 amp MPPT controller to your current system.

As I mentioned in my earlier post, what you really need to know is your loads. Then you will know whether your present battery bank is adequate for your needs, and whether you need more panels, and how many.

--vtMaps

stmar

Re: New off grid / solar setup

Would it not be a good idea to get a generator? I did not see any mention of that and it would be good to have a backup for stormy weather and until you get more solar you could keep the batteries charged. As you can see a lot of the forum guys have the Hondas, cost more but quiet and reliable, but I am sure there are other options out there and it is good to have one with these systems.

Photowhit

Re: New off grid / solar setup

I personally don't want a generator, if you have long periods of clouds, they may just be a fact of life...

Your MX60 in a 24 volt configuration, I think can handle 16-1800 watts of panels if you can find panels that are compatible, This may not be easy, since you likely have 12volt nominal panels (VMP of around 17.5 volts) If you hunt you may find some 35 volt VMP panels that will work as well.

You don't need to order a hydrometer, though there are nicer ones available, most auto parts store should stock a hydrometer. O'Rileys has a glass hydrometer($5-6) that I use mostly unless I have issues. It matches my more expensive one closely.

You appear to have problems somewhere. You might also want to add a Kil-A-Watt meter to your tools. This measures the amount of electric used by AC appliances. Your fridge would prefer a true sine wave inverter, a compressor is motor. Your ceiling fans will also prefer a true sine wave inverter. Motors run more efficiently on a true sine wave inverter as well! Older ceiling fans can be energy hogs, and may well use more electric on an hourly basis than your fridge! Particularly if you have a newer fridge and old ceiling fans...

mike95490

Re: New off grid / solar setup

stmar wrote: »

Would it not be a good idea to get a generator? I did not see any mention of that and it would be good to have a backup for stormy weather and until you get more solar you could keep the batteries charged. As you can see a lot of the forum guys have the Hondas, cost more but quiet and reliable, but I am sure there are other options out there and it is good to have one with these systems.

You can chose to have a back-up generator, fuss over loads and unplug stuff, or buy new batteries often. I have 3 generators, because I get 7-10 days of clouds/rain in winter.

You want to examine your inverter - does it have an integral charger that can use the generator to rapidly charge batteries (common plug-in chargers are usually limited to 1800watts)

Also, inverters can have Generator Support. The Schneider Electric/Xantrex XW and maybe their other series, has working generator support, so I could hook up a 2kw generator, and start the pump, toaster and blowdryer, and the inverter will assist the loads, till there is relief, and it will go back to charging.

Generator choices, electric start, fuel, automatic remote start, conventional alternator or Inverter? Most of the inverter style have little surge capacity beyond their nameplate, where rotating alternators have the mass of the flywheel and engine to help "grunt" through a motor starting surge.

zipsort

Re: New off grid / solar setup

BB. wrote: »

Is the "buzz" irritating, or are your AC loads not working at all?

I would suggest that you review the present design (clean terminals, look for loose/corroded cables, run the genset and top off the batteries, check specific gravity, etc.). And start running your loads and see how much power you need for your lifestyle...

Once you have your daily loads (and any seasonal changes/guesses in power usage), then you can look at designing/repairing the system so that it supports your needs.

More than likely, as said above, you will need to add more solar panels to your existing system. The recommended rate of solar charging is around 5% to 13%:

370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.05 rate of charge = 697 Watt array minimum
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.10 rate of charge = 1,394 Watt array nominal
370 AH * 29.0 volts charging * 1/0.77 panel+controller losses 0.13 rate of charge = 1,812 Watt array "cost effective" maximum

If this is a weekend/season home/cabin, then you may get away with a 5% rate of charge. Otherwise, panels have never been cheaper -- So a 10% to 13% rate of charge is going to make for a much nicer system. Based on a 4 hour per day estimated sun for ~9 months a year for much of the "sunnier" US, a 10% rate of charge system would produce:

1,394 Watt array * 0.52 end to end system eff * 4 hours of sun = 2,900 Watt*Hours of 120 VAC energy per day

That is a good sized system for off grid cabin/small/energy efficient home... I suggest a 3.3 kWH per day system if you have LED lights, laptop computer, LED TV, small well pump, and a full sized energy star refrigerator.

In the end, energy usage is a highly personal set of choices--And the better you can measure/estimate you loads, the better chance your off grid system will support your power needs and avoid unnecessary costs for an over-sized system.

-Bill

Photowhit wrote: »

It would appear that you have too much battery if anything... likely about 350Ah at 24 volts and your panels likely produce about 6 amps at 12 volts likely run in series for 4 strings at around 70 volts coming into the charge controller and charging voltage out at around 24 amps. Trojan recommends a charging rate for 10-13%. Things on the system you might check, what is the complete distance from panels to charge controller and to batteries? If the panels are setup as pairs to the charge controller they might not have enough voltage for the MPPT type charge controller to work properly. A Clamp meter might be in line to check the amperage coming from the panels, and coming from the charge controller, it's handy in other situations as well.

Need to check your batteries out now! another tool you'll need is a hydrometer, check the Specific Gravity (SG) of the batteries. 4 L-16 batteries can run a lot of loads, a fridge and a window air would not be out of line this time of year if you have abundant sun! So a couple of fans should not pull the system down, check that the batteries are fully charged. There is a lot of good info in the FAQ's on Batteries!

The buzz is likely due to the type of inverter, you have a modified sine wave inverter. This type of inverter doesn't play well with some electronics and motors. Once you decide on the needs of your system(loads), you might look into a true sine wave inverter.

Totally understand where you're coming from. Its tough currently to determine our energy use as we just moved in and have been doing tons of construction work and been using more than normal. We should find out in a few weeks what our normal usage will be.

As for an update, I've checked all the batteries with a DMM and they are all sitting at 6.1v steady, and been topped off with distilled water always. I will order/buy a hydrometer asap to check that but i have a feeling the batteries are fine. Also checked the wiring @ the terminals and at the panels and no voltage drop.

I'm leaning towards the inverter. It buzzes, gets almost too hot to touch, and found out some people messed up by using power tools on our system (circular saw, sawzall, cement mixer) and Im thinking that could have damaged it. I have a hard time seeing the outback controller going out on me.

Is it possible that a bad inverter is the cause of our problems? Even though it still works decently during the day? The only reason I don't think its 100% is because the batteries are only resting around 25.3 volts max, I don't see 29 or so.

Going to try hooking up a generator to it and see how that goes here today when we get gas.

Thank you all again for your time! I will keep checking for replies and will update.