Adding solar to an old on grid homestead

[Caribou]

Boy am I late to this party.
Propane-I had a 400# tank with a 100# backup in Bethel for 25 years. Most years got to -40℉(C ) and sometimes for a couple weeks at a time. It was on the north side of the house and was not protected from the wind. I had over 30' of unprotected 1/2" copper running to my dryer and a shorter line to my range. I could run both at the same time on the coldest days without issue. I'd suggest two 500 gallon tanks and two 1000 gallon tanks would be better.

I have two generators, an 8K and an EU2000i. The EU2000 can be daisy chained with another EU2000i for 4K. I want to get a tri-fuel adaptor for each. the problem with gas generators is that the fuel will either get used up, or worse, become unusable.

A charger can maximise the fuel by running your generator at near capacity for a shorter time.

There are 3 types of power outages, short term, long term. and intermittent. Sometimes power companies turn on power to one area and then to a second, etc. When it is your turn it is your chance to charge your battery bank.

I'd start with a battery bank, a charger, a generator and an inverter. This gives you the ability to work on the grid or off.

When. I was on my sailboat I has a small solar panel, a wind generator, a towed generator, and my alternator on the engine. That ran my lights, radios, radar, and CPAP. I had a house battery bank and an engine bank. I never had to worry about electricity as I had multiple sources.

 

[viking]

It would be best for you to get an MPPT controller for your system from day one.

Here is a lightweight solar setup I had running a couple of days ago that demonstrates the benefits of an MPPT over a PWM controller:

View attachment 71154
The panel is supplying 1.8 Amps at 16.5 Volts. That is too much for safe charging of the battery, so the MPPT controller is dropping that down to 13.1 Volts. But it is also converting panel power in a way that boosts charging current to the battery to 2.3 Amps.

So the MPPT controller is charging the battery 28% faster than a PWM controller would.

I wouldn't run any other kind of controller, they really do an excellent job, our array puts out over 80 volts and the voltage never exceeds proper charge voltage for our battery banks of 24 volts, the only time change voltage is higher is for the automatic equalizing that's needed to reduce cell sulfating.

 

[Biggkidd]

Do you have a tool or way the ensure that you are at the optimal angle? I was thinking of installing a dowel or tube perpendicular to the mounting plane to act a an aligning guide... but that was just a thought>>>

I have a 6 inch piece of 1 1/4 PVC pipe screwed to the side of the panel frame with a piece of plywood screwed under it with about an inch gap between the two. I check it when the sun is straight in front of the panels if I get a round shadow the shape of the pipe with a bright full circle in the center I'm on the money if not I adjust until I do. It nothing more than a pipe sight! lol It's cheap low tech and Works like a charm !

 

[Neb]

I have a 6 inch piece of 1 1/4 PVC pipe screwed to the side of the panel frame with a piece of plywood screwed under it with about an inch gap between the two. I check it when the sun is straight in front of the panels if I get a round shadow the shape of the pipe with a bright full circle in the center I'm on the money if not I adjust until I do. It nothing more than a pipe sight! lol It's cheap low tech and Works like a charm !

Can you please share an image?

Ben

 

[Biggkidd]

I will try and remember tomorrow it's dark here now.

 

[Biggkidd]

Pics

First shows pipe & plywood. Last shows sun ring sight sun wasn't quite straight in front of the panels yet. But you get the idea. I don't bother adjusting until the sun circle is fully gone to shadow most of the time. Like I mentioned low tech works!

 

[Neb]

Pics

First shows pipe & plywood. Last shows sun ring sight sun wasn't quite straight in front of the panels yet. But you get the idea. I don't bother adjusting until the sun circle is fully gone to shadow most of the time. Like I mentioned low tech works!

Nice

Thank you

Ben

 

[viking]

Do you have a tool or way the ensure that you are at the optimal angle? I was thinking of installing a dowel or tube perpendicular to the mounting plane to act a an aligning guide... but that was just a thought>>>

When we bought our Grape Solar panels I asked one of the smart guys at the shop about using angle adjustable array mounts and he told me not to worry about that but to mount the array at the angle closest to the parallel you are on a map, we're close to 45 degrees so that's the angle I built the array frame, I also mounted the array to magnetically corrected, due south, I found that figure on a USGS site on line. One other thing I did was to watch where the sun was at its lowest point in winter so that the shade doesn't hit the bottom of the array. The peak voltage of our solar array is between 79 to 82 volts throughout the year, I'm also glad I listened to people who knew what they were talking about and got high cell count panels, ours are 72 cells a panel, their nominal output per panel is 36.4 volts, running two per series make it 72.8 volts, running that trough an MPPT controller does wonders, even on a cloudy, rainy day our system will charge the batteries and has surpassed what I had figured in designing our system, this may bode well as the years go by and the solar panels loose efficiency. One other thing that surprised me was that the array gives charge volts and amps up until the sun goes down, even though the sun angle is really steep at that time. Because of what I have experienced, I will never again buy solar panels that are close to the voltage required for our battery banks, I did that on our motorhome shelter and it was a total failure, I'm totally sold on MPPT solar controllers and high voltage output solar panels.

 

[UrbanHunter]

Today I am doing a trial run of 200 watts using my DYI frame and some older equipment... I have made a number of my own cables and am waiting to see the sun hit the panels. Watching them this morning gives me a clearer picture of the best places to place my future designs. I am also trying to see if a solar panel can charge a deeply discharged battery, I'm hoping it can bring it back to life. I have read mixed reports so it will be interesting....

 

[Biggkidd]

Today I am doing a trial run of 200 watts using my DYI frame and some older equipment... I have made a number of my own cables and am waiting to see the sun hit the panels. Watching them this morning gives me a clearer picture of the best places to place my future designs. I am also trying to see if a solar panel can charge a deeply discharged battery, I'm hoping it can bring it back to life. I have read mixed reports so it will be interesting....

Slow long charging is the best way I have found to restore life to battery that's been neglected. Often times you have to start off real high 40 to 200 amps and as soon as it starts taking a charge back it right back down to 1 or 2 amps and leave it go for days on end. YMMV

Another trick I have herd of but haven't tried yet for AGM batteries is to drain them completely flat and reverse charge them drain flat and charge back again at 1 to 2 amps for several days. Supposed to be really good for removing sulfation on the plates or some such.

 

[UrbanHunter]

Well the solar charge controller would not let the battery charge (it was below 6 volts), but I put a small float charger on it for just a second and the solar charge controller kicked in (I think it just needed to see something greater than 6 volts to start charging) and it is now charging at 14.6 Volts. One of the panels is still shaded but the panel voltage was showing at 20V before it started charging the battery, it dropped down to 18V once it started charging the battery....

FYI I did check the water in the battery before I started, but I think I need to invest in a hydrometer to maintain these lead acid batteries.....

I saw that HD has the size of Deep Cycle battery that I am using for $10 less than WM... That surprised me... Around here people use them for their trolling motors....

 

[UrbanHunter]

Well I ended up losing 1 battery from my pack, it just couldn't recover and the voltage actually dropped lower after charging and sitting over night. All my other batteries now appear okay, so I have that to be thankful for. The 200 watt frame I made worked fine, but the location does not get full direct sun till 11AM (I'm glad that I made it portable and I can actually move it if I need to). I have located a spot that will get better sun and is very well hidden. I think that there is room for about 600 watts of panels in that location. I checked today and the panels I bought on the 26th of August have gone up $10..... So I may drop another $230 before the price goes up again......

I have a large locking plastic container (big enough to hold an inverter, controller, and 3 or 4 batteries) I need to install cooling fans, a weather proof outlet, and add some more vent holes before I can start doing the component layout... I have to choose which inverter and controller I will be using because they don't have standardized bolt holes...... figures.... I think that it will be heavy enough that once it is put in place and assembled it will not be going anywhere......

 

[Bacpacker]

Urban ill try and send you a pic of the set up we built at work using a good sized Pelican box. They have worked out well [18] units. Just don't mount the panels to it

 

[UrbanHunter]

Because the solar panels are working and the batteries are staying charged, I thought it was time to move to the Load side of the equation.

So, this morning before the sun came up, I connected my smallest (1000 watt, also cheapest) inverter just to see what it could power. Definitely couldn't handle my irrigation water pump, it tried and promptly tripped itself out, but it could handle the led lights at one of my growing stations... I know it's not a lot, but if I can off load a few hundred watts off my grid every day and still have back-up power available for the important stuff I think this will all work out....

Tomorrow, I will swap out the inverter with a slightly larger one and see if it can handle the pump.... I would prefer to use the smallest that I can get away with because it is outside and I would like to preserve my best equipment as reserves...

 

[UrbanHunter]

I've been reading how to wire a battery bank so it can be charged as a 24Volt system, but can power 12V devices, theoretically you can have 1 large 24V/48V Battery bank and Solar array feeding smaller 12V inverters.... Anyway, I am making baby steps and documenting what I find along the way.

 

[Hardcalibres]

Make sure the batteries you are banking together are balanced.

That means the same type, brand, age, state of charge, place in their service life.......

"Odd man out" batteries within a bank can get very, very hot - like hot enough to catch fire.

I know someone who had a bank of mixed batteries that burned down his garage (and two cars).

I saw the aftermath with my own eyes - so that risk is very real (as apposed to some internet data fragment).

 

[Bacpacker]

Make sure the batteries you are banking together are balanced.

That means the same type, brand, age, state of charge, place in their service life.......

"Odd man out" batteries within a bank can get very, very hot - like hot enough to catch fire.

I know someone who had a bank of mixed batteries that burned down his garage (and two cars).

I saw the aftermath with my own eyes - so that risk is very real (as apposed to some internet data fragment).

This situation will also kill good batteries. Like the entire bank.
Critically important and expensive mistake

 

[Biggkidd]

I've tried to explain balancing batteries until I was blue in the face and most people still refuse to understand. All my batteries are the same down to the batch number or lot number.

 

[viking]

I've tried to explain balancing batteries until I was blue in the face and most people still refuse to understand. All my batteries are the same down to the batch number or lot number.

All twenty of our batteries are set up by manufacturing dates, but I highly recommend using a battery hydrometer to make sure you don't have any batteries that are really out of balance.

 

[UrbanHunter]

Today I switched out to a slightly larger inverter to see if it could run my water pump for the irrigation system. Before I could do that I needed to make up some new power cables because the lugs on the inverter were 7/16" and the 00 cables I had made up had 3/8" holes.... Anyway I made the cables last night and connected it all up this morning. The results were promising the pump ran, the inverter seemed happy at about 60% of capacity and I am pleased.

Because of the increased current draw this inverter will work best with a larger battery bank..... But I am moving towards being able to get useful work. The one thing that I didn't like was the relatively high idle current draw from the new inverter, but I can deal with that as things progress....

I am beginning to think that the smaller inverter will be more useful to me over the winter as it can power all my growing station LEDs and has a much lower idle current draw.

 

[Bacpacker]

Great job testing Urban.

 

[kd4ulw]

Try to get as many things as you can to run directly off of 12V. You won’t get the loss from the inverter.

 

[UrbanHunter]

This weekend we had friends over and the (Male) discussion moved to solar generators, seems he had been looking at a number of them and the cost is all over the map ($500 to $5,400). He mentioned a few by name and so I started looking them up and learned a lot, compared prices looking at it from 2 perspectives $/watt output and $/watt-hr and then the average of the 2; the results were not surprising ranging between $1.80 and $0.80 per unit but there was no logic between battery size and cost. Only 2 of the 12 that I looked at actually had solar panels included and both of them only 80 watts of solar. So the cost for a complete system would be much higher, however most of them have a charge controller built in, but the largest was 400 watts.

Anyway, switching back to something relevant, I have been looking at the wife's medical equipment and recording the wattage draw, one is a piece of cake 50 watts for 8 hours, requiring 400 watt-hours @ 12 Volts that is a battery capacity of 40 AH... no problem. The other device runs more and at steady state draws about 375 watts, it can be shut off for a few hours each day but it usually runs about 18 hours a day and definitely needs to be covered for 10 hours, using 12 volt batteries I would need at least 321 AH of storage (3 deep cycle marine batteries). The good news is I could run both off a single 1000 watt inverter and I have tested them and they will work with a modified sine inverter (I just happen to have a couple ) But they are not in the same room, I don't know if a 25' extension cord would increase the small device draw but it's something to keep in mind.

So tonight I started making my new power box: It is going in a plastic storage box so the first thing was to install vent holes at the top along the end where the batteries would sit, then install a thermostatically controlled 12V cooling fan, then a set of 12 gadgets, a 12 cigarette lighter socket, 1 volt meter, 2 USB ports, and a switch to turn them on an off. I mounted a 1000 watt inverter to the side and cut a hole in the end to provide access to the switch and 115V AC outlets. Everything has been tested and it is sized to fit 2 100AH deep cycle marine batteries, I could fit 3 if I dumped the 12V accessories and mounted the inverter to the end. I still need to setup some SAE connectors to allow quick connect between either a solar charge controller output or a 12 volt battery charger. On the power cable side I have a couple of ANL 50/100 amp fixtures and fuses, I had to order a ratcheting crimping tool to put ends on the custom fit cables. The plan is to eventually make 2 boxes.

But based on the data that I am seeing, I would need a much larger system to cover the wife's medical devices and the food storage freezers....

 

[Hardcalibres]

This weekend we had friends over and the (Male) discussion moved to solar generators, seems he had been looking at a number of them and the cost is all over the map ($500 to $5,400). He mentioned a few by name and so I started looking them up and learned a lot, compared prices looking at it from 2 perspectives $/watt output and $/watt-hr and then the average of the 2; the results were not surprising ranging between $1.80 and $0.80 per unit but there was no logic between battery size and cost. Only 2 of the 12 that I looked at actually had solar panels included and both of them only 80 watts of solar. So the cost for a complete system would be much higher, however most of them have a charge controller built in, but the largest was 400 watts.

Anyway, switching back to something relevant, I have been looking at the wife's medical equipment and recording the wattage draw, one is a piece of cake 50 watts for 8 hours, requiring 400 watt-hours @ 12 Volts that is a battery capacity of 40 AH... no problem. The other device runs more and at steady state draws about 375 watts, it can be shut off for a few hours each day but it usually runs about 18 hours a day and definitely needs to be covered for 10 hours, using 12 volt batteries I would need at least 321 AH of storage (3 deep cycle marine batteries). The good news is I could run both off a single 1000 watt inverter and I have tested them and they will work with a modified sine inverter (I just happen to have a couple ) But they are not in the same room, I don't know if a 25' extension cord would increase the small device draw but it's something to keep in mind.

So tonight I started making my new power box: It is going in a plastic storage box so the first thing was to install vent holes at the top along the end where the batteries would sit, then install a thermostatically controlled 12V cooling fan, then a set of 12 gadgets, a 12 cigarette lighter socket, 1 volt meter, 2 USB ports, and a switch to turn them on an off. I mounted a 1000 watt inverter to the side and cut a hole in the end to provide access to the switch and 115V AC outlets. Everything has been tested and it is sized to fit 2 100AH deep cycle marine batteries, I could fit 3 if I dumped the 12V accessories and mounted the inverter to the end. I still need to setup some SAE connectors to allow quick connect between either a solar charge controller output or a 12 volt battery charger. On the power cable side I have a couple of ANL 50/100 amp fixtures and fuses, I had to order a ratcheting crimping tool to put ends on the custom fit cables. The plan is to eventually make 2 boxes.

But based on the data that I am seeing, I would need a much larger system to cover the wife's medical devices and the food storage freezers....

Be aware that Lead Acid (LA) batteries won't do well if you regularly discharge them below 50% charge. So if you need 321Ah then you will need at least SIX 100Ah Deep cycle Marie batteries to do that regularly. Also, that will rely upon you getting all those six batteries fully recharged EVERY day (which will be a lot more difficult on cloudy/rainy days).

In my experience, when you are charging LA batteries, C number of amps for D number of hours will not achieve C x D amp hours of charge - there is some inefficiency factor.

Also, as the batteries get up around 70-80% charge, the controller will taper off the current (even where the solar can supply more). The controller will be doing this as the charge voltage climbs. So, the process of calculating typical charge times is difficult (and is always more than the minimum that the system should be able to achieve).

In my experience, LiFePO4 batteries are much quicker to charge and come closer to those simple calculations about charge hours.

Many manufacturers of 100Ah LiFePO4 batteries are happy for them to be charged at 50 Amps

You can't do that with any LA battery I have ever seen.

 

[UrbanHunter]

This morning I checked the data on the Killo-watt device that was attached to the smallest freezer, I was pleased to see that it typically is only drawing about 60 watts, but was not happy to see that there were spikes up to 900 watts. If all the freezers are like that it could require some staggered utilization to avoid them all providing a massive surge at one time...

Then I moved back to my power box... my temperature controls for the cooling fan came without instructions, I found an image of the wiring diagram and was able to wire it up and test it. Figuring out how to set the temperature set points was a PIA but once I figured it out I was ready to test, I set the temp target to 70F, placed the sensor bulb in my hand and hop skippidy jump the temperature climbed to 90F, the fan came on. I then set the temperature target to 100F. After all that I decided to see if the device had a memory or if it would reset every time the battery was disconnected, I was soo happy to see my settings remained in tact. Now all I need to do is make my final cables, install a breaker and fuse, and install the charge connections.... Without the batteries it weights about 10 pounds, add that batteries and I'm not moving it...

 

[UrbanHunter]

Be aware that Lead Acid (LA) batteries won't do well if you regularly discharge them below 50% charge. So if you need 321Ah then you will need at least SIX 100Ah Deep cycle Marie batteries to do that regularly. Also, that will rely upon you getting all those six batteries fully recharged EVERY day (which will be a lot more difficult on cloudy/rainy days).

In my experience, when you are charging LA batteries, C number of amps for D number of hours will not achieve C x D amp hours of charge - there is some inefficiency factor.

Also, as the batteries get up around 70-80% charge, the controller will taper off the current (even where the solar can supply more). The controller will be doing this as the charge voltage climbs. So, the process of calculating typical charge times is difficult (and is always more than the minimum that the system should be able to achieve).

In my experience, LiFePO4 batteries are much quicker to charge and come closer to those simple calculations about charge hours.

Many manufacturers of 100Ah LiFePO4 batteries are happy for them to be charged at 50 Amps

You can't do that with any LA battery I have ever seen.

I agree the LI-x batteries do have significantly higher capacities, charge and discharge rates and would be a good choice for me if they didn't cost so dang much... at over 3X the cost I just can't swing it right now. This current set-up is just to figure out the details and for a quick emergency backup, I have less than $400 in this one including 2 100 AH batteries, I can't buy the lithium batteries for that...

 

[Hardcalibres]

This morning I checked the data on the Killo-watt device that was attached to the smallest freezer, I was pleased to see that it typically is only drawing about 60 watts, but was not happy to see that there were spikes up to 900 watts. If all the freezers are like that it could require some staggered utilization to avoid them all providing a massive surge at one time...

...

When I use my solar to provide backup power for my domestic fridge/freezers, I set them up on separate systems (and independent of the house wiring). Each one has a dedicated battery, controller, inverter and solar panels. This also avoids the need to bank batteries together.

It is more expensive to have that many controllers and inverters - but it does make for a system with redundancy and avoids that issue of compressor current spike stacking.

All my systems are designed to be fully portable. The only banked batteries I have are the two 250Ah LiFePO4 batteries in the Camper Trailer. They run a 3000W Inverter that can run the RC air conditioner, microwave, electric stove element, air fryer, induction cooktop, rice cooker, hot water heater, pressure pump, clothes washer, etc, etc

I agree the LI-x batteries do have significantly higher capacities, charge and discharge rates and would be a good choice for me if they didn't cost so dang much... at over 3X the cost I just can't swing it right now. This current set-up is just to figure out the details and for a quick emergency backup, I have less than $400 in this one including 2 100 AH batteries, I can't buy the lithium batteries for that...

Yep - Lithium are expensive - but I am also watching them come down in price quite quickly.

I still have a lot of SLA batteries, but the Lithium has become the backbone of my capability.

Weight, performance and service life were the key factors that headed me in that direction.

 

[viking]

In the past we have used RV/Marine type batteries, trouble is that they are an in between type battery designed for starting engines as well as longer term draw down, but are not always good for high amperage draw down, I've seen many of those fail and that's why we use GC-2 batteries with a minimum rating of 205 amp hours, our inverter can be set for low voltage cut out to avoid below 50% draw downs. A good MPPT controller will keep the batteries in best charge conditions possible. I know that LA batteries have their short comings but GC-2's are very common and considering prices, affordable, they also put up with a wide swing in temperatures, ours are in an unheated shed and have never failed to do their job. They do need to be checked regularly for electrolyte levels but I don't mind. I always try to remind people that are considering generators or solar for emergency back up, that they have to figure in the start up amperage of any motors to be used, it's called Locked Rotor Amps, it's all about the initial amperage needed to get a motor turning, especially if the motor has to start with a load already on it such as well pumps and refrigerator/freezer compressors, if they are rated at a run amperage, say 6 amps, it frequently takes double that amount, 12 amps over a few seconds to get it running at full RPM. If this is not figured in, generators and inverters will fail.

 

[Rebecca]

When I use my solar to provide backup power for my domestic fridge/freezers, I set them up on separate systems (and independent of the house wiring). Each one has a dedicated battery, controller, inverter and solar panels. This also avoids the need to bank batteries together.

It is more expensive to have that many controllers and inverters - but it does make for a system with redundancy and avoids that issue of compressor current spike stacking.

This is basically what we have done as well. Ours isn't a backup though, but in daily use. But we do have multiple set up's and all that goes with it: controllers, inverters, solar panels etc. Each system has its own independent wiring to run certain appliances. Looking to add another one in the next few months. It also allows us to buy the LiFePO4 batteries when we can afford them, rather than a large number of them at once, but still avoids putting batteries of different ages or makes in the same battery bank.

Another major benefit is redundancy, that way if one system is damaged or fails for whatever reason, we don't loose all our electricity. All the set up's can be mobile, some easier and faster than others.

 

[Hardcalibres]

This is basically what we have done as well. Ours isn't a backup though, but in daily use. But we do have multiple set up's and all that goes with it: controllers, inverters, solar panels etc. Each system has its own independent wiring to run certain appliances. Looking to add another one in the next few months. It also allows us to buy the LiFePO4 batteries when we can afford them, rather than a large number of them at once, but still avoids putting batteries of different ages or makes in the same battery bank.

Another major benefit is redundancy, that way if one system is damaged or fails for whatever reason, we don't loose all our electricity. All the set up's can be mobile, some easier and faster than others.

Agreed.

Another thing I have found is this - while the common method of wiring several solar panels is to put them in some sort of series/parallel combination, I now do something different.

For my portable panels, I found that whenever I directly wired multiple panels in series or parallel, any shade on one panel or difference in output dragged down the output of that whole combination. When I set up each panel (typically 200W) with it's own dedicated controller and then wired the output of those in parallel to the same battery, the output/overall charge current increased (especially when any of the panels had some reason for decreased output like shade or whatever).

For a domestic system with fixed roof mounted panels, the above may or may not be important - but for portable ground mount systems and where partial shade on individual panels will happen, the controller for each panel approach seems to work much better.