Solar Projects the good, the bad, the cutting edge, the starter system,

I searched but could not find a thread where people talked about their systems and their choices. As I do more solar design and install and less construction I enjoy hearing people out as to why they made the choices they made. I prefer a grid interactive system if the grid is available as it cuts down on costs, I like a battery component, and I like a system that can  operate hands off if you want it to. I still like lead acid although the tipping point for lithium is getting ever closer. So To kick it off here are the basics of a system I "rescued" recently It was wired wrong, programmed wrong and was not doing what the owners needed it to do.

Installed 2013
Voltage: 48 volt system
Solar: 2x 3kw solar arrays
CHarge controllers: 2xOutback FM80
Inverter: 2x Schneider 6048SW conext Hybrid inverters paired
Batteries: Originally 32x L16 with 80KwHrs of storage
                 Currently 16xL16 with 40KwHrs of storage highly sulphated in need of replacement
Back up: 60amp grid connection, 8Kw Diesel autostart generator


I've been doing some work recently at a local Farm trying to bring their grid interactive system back to life. The system itself is about 10 years old and has 6Kw of panels on two arrays, a pair of Schneider's first generation conext inverters and originally a wopping 80KwHr of battery storage. It was sitting turned off for almost 2 years as they tried to find someone to fix it. I do like a challenge! So this is something unfortunately you come across in the industry; a system that was quite pricey but set up wrong for the clients needs. There are lots of factors that go into a successful design but the first one is always listening and observing, very permaculture in a way.  In this case the original designer chose to ignore the fact that there was a grid already present and chose to set them up as if they were totally offgrid. A backup generator would recharge the batteries when there was not enough sun and the large battery bank would store days worth of power but the solar arrays were not big enough to ever fully charge it... They never bothered hooking up the grid to the inverter or setting up the inverter properly or explaining the system to the people paying for it and running it. The consequence was a grid interactive inverter set up with one arm tied behind its back and clients left to figure things out as best they could a generator that ran all the time and a battery bank that failed from being sulphated from undercharging. After some rewiring, and mostly reprogramming of the unit, the system now uses the grid if there is not enough sun, keeps a smaller battery pack charged fully, uses as much solar power during the day as possible and in the case of an outage uses its battery reserves but then can turn on the generator to recharge. All that without any input from the end users unless they want to intervene. As it should have been from the beginning... It was a rewarding experience though a little frustrating. Frustrating because some really nice people were set up to fail due to lack of knowledge greed or close mindedness from the installer.

Hey David,

You've probably seen the details of my system in some other post but here goes:

Installed February 2020
Voltage: 48 volt system
Solar: 3.8kw solar array
Charge Controller: Magnum Energy PT-100
Inverter: Magnum Energy MS-4448 PAE 120/240V
Batteries: 8 X L16 with 20Kwhrs of storage
Backup: 2Kw gasoline generator

I ordered mine as a kit from Northern Arizona Wind and Sun. If I were doing it today I think with the experience I had from building the first system and watching loads of Will Prowse videos I would use EG4 Lithium Iron Phosphate batteries instead. I think I would also go for a slightly larger solar array. It works fine for our 600 sqft cabin but I'm in the process of building a 200 sqft guest cottage that will have low power needs (lights and converter chest freezer/fridge) but will push our system close to its limit.

Here's my system install video:


And some stills:

David Baillie wrote:I searched but could not find a thread where people talked about their systems and their choices.

Installed 2013
Voltage: 48 volt system
Solar: 2x 3kw solar arrays
CHarge controllers: 2xOutback FM80
Inverter: 2x Schneider 6048SW conext Hybrid inverters paired
Batteries: Originally 32x L16 with 80KwHrs of storage
                 Currently 16xL16 with 40KwHrs of storage highly sulphated in need of replacement

I'm surprised you haven't seen any of my previous posts?  Just about the only thing I talk about here is off-grid solar.

I couldn't agree more that the root-cause of this failure is inadequate solar.  I am ALWAYS admonishing people that the panels are so cheap these days that there is no reason whatsoever not to max input.  I like to recommend that they use 1/8th of C as their target, and always to include a fudgefactor to correct for lower then spec solar output.  I like to use 85%.  Assuming those L-16 batteries are 400Ah each, and you have four strings of 48V, the math I would have used would be.....

(400Ah X 4 strings)/8 = 200A     To get 200A out of the whole array that would be (200A X 50Vcharging)/85% = 11,765W.  Just call that 12,000W and be done.  As you can see, the previous installers only positioned 6,000W, about 1/2 of what I would have done.

Michael Qulek wrote:

David Baillie wrote:I searched but could not find a thread where people talked about their systems and their choices.

Installed 2013
Voltage: 48 volt system
Solar: 2x 3kw solar arrays
CHarge controllers: 2xOutback FM80
Inverter: 2x Schneider 6048SW conext Hybrid inverters paired
Batteries: Originally 32x L16 with 80KwHrs of storage
                 Currently 16xL16 with 40KwHrs of storage highly sulphated in need of replacement

I'm surprised you haven't seen any of my previous posts?  Just about the only thing I talk about here is off-grid solar.

I couldn't agree more that the root-cause of this failure is inadequate solar.  I am ALWAYS admonishing people that the panels are so cheap these days that there is no reason whatsoever not to max input.  I like to recommend that they use 1/8th of C as their target, and always to include a fudgefactor to correct for lower then spec solar output.  I like to use 85%.  Assuming those L-16 batteries are 400Ah each, and you have four strings of 48V, the math I would have used would be.....

(400Ah X 4 strings)/8 = 200A     To get 200A out of the whole array that would be (200A X 50Vcharging)/85% = 11,765W.  Just call that 12,000W and be done.  As you can see, the previous installers only positioned 6,000W, about 1/2 of what I would have done.

For the above listed system you have to remember it was put in 11 years ago. Design has changed since then. Their design was not great but Panels were going for 3 to 4 dollars a watt so 6 Kw total was pretty good. There is a grid present but the equipment would need to be upgraded to do net metering  so that's out. My recommendations to the owners were to replace the existing sulphated batteries with 8 L16 size batteries as funds become available(always a problem on a farm) use the grid to keep them from cycling deeply so they have a nice long life in standby but are ready in case of outage. The trick with any of the "self consumption" or "net zero" grid connected systems is actually to figure out what to do with all the extra summer solar capacity. That 6 Kw of array is putting out 9KwHrs a day in the winter time but a whopping 30KwHr a day in peak summer.  In their case we will use the electric water heater,since they have an outdoor wood boiler for hot water in the winter time, and an outdoor pond aerator to suck up all those extra KwHrs. The balance we will have to do with some lifestyle changes around laundry and appliance use.

10kW Solar Array @ $7,000
12kW Sol-Ark @ $7,000
15kWHr LiFePO4 Batter @ $7,000
4kW Backup Generator @ $2,000
Misc @ $2,000
sub-Total = $25,000

We're tiny.

1.72 kW solar
440 AH, 12v AGM battery bank
Midnite Classic controller
An inverter I don't care enough about to know who manufactured it because we only use it for the fridge.
Cheap-o generator who we run pretty hard for 3 weeks to a month in the middle of the rainy season but, hopefully, after we add a wind turbine and TEG this summer, will never be run again.

Thomas Crow wrote:We're tiny.

1.72 kW solar
440 AH, 12v AGM battery bank
Midnite Classic controller
An inverter I don't care enough about to know who manufactured it because we only use it for the fridge.
Cheap-o generator who we run pretty hard for 3 weeks to a month in the middle of the rainy season but, hopefully, after we add a wind turbine and TEG this summer, will never be run again.

thanks for posting Thomas; I love seeing what people have. If I had suitable water I would for sure do Hydro. That Midnite is probably loaded now. That's a decent array. How do you charge batteries with the Genny?

If you have 3 100watt panels connected in parallel in two strings can you connect these strings in series? I.e. parallel positive of one string to parallel negative to the other string creating a single series of two parallel arrays?

William Attenborough wrote:If you have 3 100watt panels connected in parallel in two strings can you connect these strings in series? I.e. parallel positive of one string to parallel negative to the other string creating a single series of two parallel arrays?

This appears to be a totally unrelated question?  You have a total of six 100W panels?  You want to wire together two parallel strings of 3 panels each?  That would be written as 3S2P, meaning two parallel strings of three panels in series.

This depends a lot on your electronics, and your battery voltage, and it's a yes or no answer depending on what you have.  If you have a PMW charge controller, you MUST match the panel voltage closely to the battery voltage.  Assuming your 100W panels are putting out ~18Vmp, and your battery is 12V, then you MUST wire the panels in parallel, no series connections.

If you have a MPPT controller, then yes, you may wire panels in series, but only up to the voltage limit of your controller.  So, we need to know what brand/model of controller you have?  Let's say for example you have a budget MPPT controller like the Epever Tracer4210AN.  That has a voltage limit of 100V and a 40Amp limit.

Let's assume your panels have a Vmp of 18V and a Voc of 21V, putting out 5.5A.  Vmp means the voltage when under load, making power.  Voc means the voltage when the panels are disconnected, such as when the battery is full and the controller stops current from flowing.

Remember the electrical mantra, in Series, Volts add while amps stay the same.  In parallel, amps add while volts stay the same.

So, if you wired three of your panels in series, you'd get 18V + 18V + 18V = 54V at 5.5A.  If you had two of the strings paralleled, you'd get 54V at 5.5A + 54V at 5.5A = 11A at 54V.  Does that make sense?  

You can NOT wire all six panels into one single string with that controller because your voltage would exceed 18Vmp X 6panels = 108V.  The Voc is even higher, at 21V X 6 = 126V.  So, when the battery gets full and shuts off the current, the controller suddenly gets exposed to 21V X 6 panels = 126V.  The controller then goes poof and likely starts a fire.

Now, the amperage.  Assuming two strings are putting out 11A at 54V, when the controller transforms the current down to battery charging voltage of ~13V, that becomes  600W/13V = 46.1A.  That's about 15% higher than what the controller can handle.  But, a usual rule of thumb is panels almost never produce their rated output.  Assuming that you don't get more than 85% of nameplate (which I've measured) then expect to see a maximum of 46.1A X 85% = 39.2A.  So, six panels, wired 3S2P and connected to a Tracer 4210AN controller will work to charge a 12V battery.

Now, you need to supply us with the accurate numbers for your own panels, controller, and battery, so we can give you more accurate answers.

William Attenborough wrote:If you have 3 100watt panels connected in parallel in two strings can you connect these strings in series? I.e. parallel positive of one string to parallel negative to the other string creating a single series of two parallel arrays?

hi William, if I understand correctly you have 3 panels total, two of them hooked up together in parallel and a single in a separate string... Is that correct? The 100 watt panels are probably feeding into a pwm charge controller at 12 volts? If those conditions are correct You could do it that way but I would usually do 3 strings of one panel each for balance.

Hi David, thanks for getting back to me. I should clarify my original statement. If you have 6 100w panels (19.23v 6.26amp each panel). You wire string #1 with 3 panels in parallel and string #2 with 3 panels in parallel, can you then connect these two strings into a Series by connecting the positive of string #1 to the negative of string #2? So it would be 2P1S, Is this safe? Would this wiring configuration provide 38v± @ 19± amps? All of this feeds an Epever 1050watt 100v 40amp MPPT in 24v configuration. This feeds (12) 220amp 6v Flooded GC2's wired in 24v series-parallel.

Grid-tied system. 4.4 kWp in 12 360W panels, half on a north-facing roof plane at 15 degree pitch, and the other half facing west at 45 degrees. This gives an elongated peak to the production curve, from noon to about 4 pm, and in the longest days of summer we're still generating at 8 pm. Enphase micro inverters with Envoy grid tie controller. We do net metering and the retailer pays us about 6.5c / kWh and charges 4-5 times that for what we use, so the other piece of the system is an interactive controller to sense whenever the panels are generating more than our aggregate load, and divert that excess to the hot water cylinder to create a thermal battery.

Here is what today looked like:



Good sun most of the time, with some cloudy periods shown by the dips. The blue is generation and the orange is consumption. The grey is import from/export to the grid of the excess in either direction and you can see how in the early afternoon the hot water reached its max (70 degrees) and at that point we started selling to the utility (boo). If the EV hadn't already been fully charged we would have plugged it in around 1 pm and taken advantage of all that juice.

Oh, and the system all up, including installation, was $14K NZ (~ $10K US) in October 2020. We financed it with our savings pool, so no interest.

Phil Stevens wrote:Grid-tied system. 4.4 kWp in 12 360W panels, half on a north-facing roof plane at 15 degree pitch, and the other half facing west at 45 degrees. This gives an elongated peak to the production curve, from noon to about 4 pm, and in the longest days of summer we're still generating at 8 pm. Enphase micro inverters with Envoy grid tie controller. We do net metering and the retailer pays us about 6.5c / kWh and charges 4-5 times that for what we use, so the other piece of the system is an interactive controller to sense whenever the panels are generating more than our aggregate load, and divert that excess to the hot water cylinder to create a thermal battery.

Here is what today looked like:



Good sun most of the time, with some cloudy periods shown by the dips. The blue is generation and the orange is consumption. The grey is import from/export to the grid of the excess in either direction and you can see how in the early afternoon the hot water reached its max (70 degrees) and at that point we started selling to the utility (boo). If the EV hadn't already been fully charged we would have plugged it in around 1 pm and taken advantage of all that juice.

Oh, and the system all up, including installation, was $14K NZ (~ $10K US) in October 2020. We financed it with our savings pool, so no interest.

That is a m
Wonderful looking system. Any thoughts or plans of adding in a battery component. I know emphase has been marketing it's battery solution pretty hard. Price wise that is very reasonable.  I would be very interested in the name of that interactive controller as switching a hotwater tank would be very useful for me without all the modifications it usually requires.
Cheers, David Baillie

William Attenborough wrote:Hi David, thanks for getting back to me. I should clarify my original statement. If you have 6 100w panels (19.23v 6.26amp each panel). You wire string #1 with 3 panels in parallel and string #2 with 3 panels in parallel, can you then connect these two strings into a Series by connecting the positive of string #1 to the negative of string #2? So it would be 2P1S, Is this safe? Would this wiring configuration provide 38v± @ 19± amps? All of this feeds an Epever 1050watt 100v 40amp MPPT in 24v configuration. This feeds (12) 220amp 6v Flooded GC2's wired in 24v series-parallel.

Ah... Well that would be a non standard way of doing it... You could do it but Your voltage would be lower and your amperage higher; somethings we try to avoid. You also would not get the full benefit of your mppt charge controller. In your case I would create 2 strings of 3 panels each. each string would be wired positive to negative for roughly 57-58volts each string at 6.26 amps. you then combine those two parallel strings to form one feed of 57-58 volts at 12.52 amps. You are still well within the voltage levels of the epever and are putting in less amps more volts so you get less voltage loss and a thinner wire...
Cheers,  David

Thanks David. Thank you for your patience and help.

William Attenborough wrote:Thanks David. Thank you for your patience and help.

no problem at all. I'm actually waiting on hold with customer support so it helps the time go by.
David

Battery storage is very much on the horizon as soon as we have the bulk of the cost paid back, David. I tend to lean toward the long-lived and abuse-tolerant forms of storage that don't require scarce elements to manufacture, so Ni-Fe has always held an attraction. So have flow batteries. We'll see.

The diverter is made by Paladin: http://www.paladin.nz/
  and can be used with any intensive load, including EV charging.

Phil Stevens wrote:Battery storage is very much on the horizon as soon as we have the bulk of the cost paid back, David. I tend to lean toward the long-lived and abuse-tolerant forms of storage that don't require scarce elements to manufacture, so Ni-Fe has always held an attraction. So have flow batteries. We'll see.

The diverter is made by Paladin: http://www.paladin.nz/ and can be used with any intensive load, including EV charging.

Very interesting controller. Solar is not nearly as advanced in Ontario. It's nice that you still get power bought back. Here all they are doing is kw hr swaps so you bank credits for future use. All surplus reverts to the utility after a year and you have a base meter charge you can't credit... Kind of killed the grid tied market. Grid zero is where it's at here and now. When the time comes look hard at the numbers. Emphase is really just rebadging well proven cells and they have the size to back up their product going forwards and it would play nice with the equipment you already have without having to insert another inverter...
Cheers, David

It's been ongoing for a couple of years now starting with 2*100W panels and a few 6V golf cart batteries as an experiment.
Now it's 24 used 250watt panels on my south facing roof, which fortunately is at the perfect summer/winter compromise angle, giving me a theoretical 6Kw, but in reality I've never seen more than 4kw.
Feeds into two MPP all in one 48V units linked in series, then into my 6 DIY LiFePo4 banks, 4 with 16*200A cells and 2 with 16*280A cells, so about 55Kwh capacity, all with the associated fuses, breakers and BMS units.
Been powering the house, including 2 mini split A/C heat pumps, and so far very few problems.
It's been overcast and cold today and even with both heatpumps running flat out the batteries are all around 90% - 95% full at 2PM.
I knew it was uneconomic when I began so it's more of a hobby than anything else, but so far, it works and it's been fun, especially when you hit an 11 on the smug scale when mine is the only house with power during one of the regular outages around here.

Neil Bendy wrote:It's been ongoing for a couple of years now starting with 2*100W panels and a few 6V golf cart batteries as an experiment.
Now it's 24 used 250watt panels on my south facing roof, which fortunately is at the perfect summer/winter compromise angle, giving me a theoretical 6Kw, but in reality I've never seen more than 4kw.
Feeds into two MPP all in one 48V units linked in series, then into my 6 DIY LiFePo4 banks, 4 with 16*200A cells and 2 with 16*280A cells, so about 55Kwh capacity, all with the associated fuses, breakers and BMS units.
Been powering the house, including 2 mini split A/C heat pumps, and so far very few problems.
It's been overcast and cold today and even with both heatpumps running flat out the batteries are all around 90% - 95% full at 2PM.
I knew it was uneconomic when I began so it's more of a hobby than anything else, but so far, it works and it's been fun, especially when you hit an 11 on the smug scale when mine is the only house with power during one of the regular outages around here.

HI Neil, thanks for sharing. Never underestimate the smug factor. I've wondered if solar would be where it is without it! Roof mounts suffer from excess heat so don't beat yourself up on production. Do you do better on sunny days in the spring and fall? Based on your roof angle description I would assume so. That is a serious amount of storage. Where did you procur the lithium cells from?
CHeers,  David

I don't notice much difference between the seasons to be honest. May be something to do with solar panels being more efficient when cold and me being possibly the worlds worst for keeping records.
The first set of cells I bought from Craigslist and they are still holding up fine. Some I ordered direct from China (Aliexpress) which gave me a mix of fairly good ones to absolute junk depending on the supplier.
The 280A cells I bought from a US supplier who is the authorized distributor for EVE calls, and these are brand new, and actually much the same price as the Chinese suppliers. They do sell grade B cells as well and advertise them as such.
Not sure of the policy regarding links to suppliers, but if admin give the go ahead I'll post it, especially as they are having a sale at the moment.

I have a grid-tied system of 5.2kw, no battery backup.  I've had it since 2017 and it is awesome!  People in the area have been bitching about how electricity has shot up in price, but mine has remained steady.    I also have a separate system of solar hot water, since my hot water was oil heated when I bought the house.  That I've had since 2011.  I love that it has an 80 gallon tank so that when the sun is heating the water, it heats the whole tank, but in the winter when the panels are covered with snow, there is electric backup that heats only the top 30 gallons.

I have a question for you guys and gals.
Can you use car or boat batteries for energy storage?

Dee Jacobs wrote:I have a question for you guys and gals.
Can you use car or boat batteries for energy storage?

yes and no. Car ones especially won't last long. Car batteries have many very thin lead plates in them so they can give off the maximum amounts of amperage for a very short time for starting and usually don't ever get discharged since the alternator immediately boosts them back up. Deep cycle batteries are designed with thicker plates to take the stress of heavy charging and discharging. The "marine deep cycle" can be a good starter solar battery as it's a compromise between the two.
Cheers, David

I'm living in a small cottage with a 50 yo in the wall electric furnace (not used much until the last 2 years) and I'd like to add solar electric. I've preliminarily spoken to two different companies, not sure what I think of either one, but both think putting panels on the roof is cheaper than putting panels on the ground in the open area. The cottage roof panels would require new roofing which has about 5 - 7 years of expected life and cutting down the trees which have grown up close to the building. While both things would need to be done eventually, the open area installation seems more immediately cost and effort effective. In addition, the ground-based system in the open area could be used to power the workshop, the garden shed and the eventual small barn planned for the open area (the workshop and garden shed are existing). Any words of wisdom?

325w panel 24v with 4 75 amp hour batteries run In parallel...but all it runs is a dorm fridge and charges our phones...we heat and do everything with wood.

Mary Haasch wrote:I'm living in a small cottage with a 50 yo in the wall electric furnace (not used much until the last 2 years) and I'd like to add solar electric. I've preliminarily spoken to two different companies, not sure what I think of either one, but both think putting panels on the roof is cheaper than putting panels on the ground in the open area. The cottage roof panels would require new roofing which has about 5 - 7 years of expected life and cutting down the trees which have grown up close to the building. While both things would need to be done eventually, the open area installation seems more immediately cost and effort effective. In addition, the ground-based system in the open area could be used to power the workshop, the garden shed and the eventual small barn planned for the open area (the workshop and garden shed are existing). Any words of wisdom?

Hi Mary, Stay on the ground. Between added costs of rapid shutdown, engineering and city permits the costs of roof mount add up. Now maybe your area does not have any of that if so then maybe but clearing and new roofing is a cost as well. Ground mounts can be perfectly aimed at the sun and if you choose the right racks can be adjusted with the seasons for best gain and if snow is an issue easily cleared. I have to say heating and solar electric don't usually work well together unless you do a net metered connection to the grid. Is that the plan? Usually when you need heat the days are shorter and there is less solar potential so without the grid to balance out the seasons it's challenging.  A good choice might be switching out that electric resistance wall furnace for a mini split heat pump which will use one third the electricity for the same amount of heat
Cheers, David Baillie

I do not have solar panels but I have a question how does one clean the grime off the panels?  When one looks at them the should appear from the side to be coated in brown dirt coating not shiny and dark.  I have even seem this build up on huge panels on businesses.  We have not had heavy rains lately just one which creates a damp surface them the wind shifts and dust and pollen are added on the previous stuff.  So much power is being lost due to grime.   I would think Dawn dishwashing the one used in a sink blue formula would be best since it claims to be safe for the environment.  I wonder is the power hose cleaner would be good as well.      I do wonder about how they the panels are redesigned to be in the weather.  

Sandra Gill wrote:I do not have solar panels but I have a question how does one clean the grime off the panels?  When one looks at them the should appear from the side to be coated in brown dirt coating not shiny and dark.  I have even seem this build up on huge panels on businesses.  We have not had heavy rains lately just one which creates a damp surface them the wind shifts and dust and pollen are added on the previous stuff.  So much power is being lost due to grime.   I would think Dawn dishwashing the one used in a sink blue formula would be best since it claims to be safe for the environment.  I wonder is the power hose cleaner would be good as well.      I do wonder about how they the panels are redesigned to be in the weather.  

Power washing works wellThe solar farms usually have a maintenance schedule in place, panels on private businesses probably not. I prefer ground mount because tasks like that are made easier. I rarely clean mine as I get adequate rains and wind to do the job. I do have to brush off snow.

We installed our 9.6 kW system just a few months ago.  It's grid-tied and totally self-running.  

We monitor it quite closely with its truly outstanding Solar Edge interface.

We also upgraded our roof to metal, making everything easier and cleaner (esp. rainwater harvest).

• 26 Silfab 370-watt PV modules
• SolarEdge 7.6kW Energy Hub inverter
• LG RESU16H Prime 16 kWh Li-ion battery

When grid power goes down, the system kicks in near-seamlessly.  The momentary glitch whacks the microwave clock, so when we wake up and it is flashing, we know the power went out.  Otherwise, we wouldn't even know!

The stove and hot water heater are about the only things not on the solar back-up panel.  We heat exclusively with wood.

You can see from the last photo, we're in a prime situation to add a sun-room on the south side of our home.  We're making zero use of passive solar as-is.  We just bought the home 1.5 years ago and it's 35 years old, so lotsa updates/upgrades to do.  That new (timber-framed!) sunroom roof will get lined with another 10+ panels, a relatively easy investment/upgrade given all the other infrastructure is already in place.

Now it's all done though, truth be told, I don't like it (this solar PV system).  Too expensive, too complex, too limiting, too vulnerable.  Too many-other-things.  I personally think there are a large number of other better ways to manage electricity/energy production and consumption, all of which are well covered here on Permies.  First and foremost, use less!

Dee Jacobs wrote:I have a question for you guys and gals.
Can you use car or boat batteries for energy storage?

Neither.  Starter batteries definately not.  They are not designed at all for deep cycling.  They MUST be immediately recharged by a car's alternator after the electrical draw to start the engine.  They suffer damage and degrade if not immediately recharged.

With "boat batteries" I'm assuming you mean "marine batteries".  They are a somewhat better choice than starter batteries, but they are by design a compromise battery, that can both start the engine and be drained a bit deeper than a starter battery.  But, they are still not the best battery for deep cycling.

The best batteries are those designed for deep cycling, without immediate recharging.  A golf-cart battery is at the smaller end of what is considered deep-cycle off-grid batteries.  Trojan's L-16 RE-B is a good example of a large off-grid deep-cycle battery.

Mary Haasch wrote:... the open area installation seems more immediately cost and effort effective. In addition, the ground-based system in the open area could be used to power the workshop, the garden shed and the eventual small barn planned for the open area (the workshop and garden shed are existing). Any words of wisdom?

I chose long-distance ground mounting.  When you use an MPPT charge controller, it acts as a transformer, taking raw high solar voltage, and transforming it down to battery charging voltage.  I wire four large residential grid-tie panels in series to get 120VDC, which I then run ~130 feet from the array to the controller next to the batteries.  I see no measurable voltage drop with the 10 gauge solar wire I am using.  At the controller, the 120VDC solar voltage gets transformed down to the 26-28VDC battery charging voltage, with the extra volts being converted into extra charging amps.

Depending on the brand, and model, you can get MPPT controllers with voltage limits of 150-250VDC, and even a few pricy models in the 300-600VDC range.  Price of course goes up as the capacity goes up.

When working with high-voltage solar though, you must remember to include cold-weather voltage compensation.  As the temperature goes down, the voltage does up.  For freezing, use a conversion factor of 1.12X.  For -40F, use 1.25X.  Let's say you are out in Montana, where it might go down to -40F in the winter.  An array that puts out 120VDC in the summer, might put our 150VDC at -40F.  So, the controller needs to be able to handle at least 150V in the winter.

David Baillie wrote:

Mary Haasch wrote:I'm living in a small cottage with a 50 yo in the wall electric furnace (not used much until the last 2 years) and I'd like to add solar electric. I've preliminarily spoken to two different companies, not sure what I think of either one, but both think putting panels on the roof is cheaper than putting panels on the ground in the open area. The cottage roof panels would require new roofing which has about 5 - 7 years of expected life and cutting down the trees which have grown up close to the building. While both things would need to be done eventually, the open area installation seems more immediately cost and effort effective. In addition, the ground-based system in the open area could be used to power the workshop, the garden shed and the eventual small barn planned for the open area (the workshop and garden shed are existing). Any words of wisdom?

Hi Mary, Stay on the ground. Between added costs of rapid shutdown, engineering and city permits the costs of roof mount add up. Now maybe your area does not have any of that if so then maybe but clearing and new roofing is a cost as well. Ground mounts can be perfectly aimed at the sun and if you choose the right racks can be adjusted with the seasons for best gain and if snow is an issue easily cleared. I have to say heating and solar electric don't usually work well together unless you do a net metered connection to the grid. Is that the plan? Usually when you need heat the days are shorter and there is less solar potential so without the grid to balance out the seasons it's challenging.  A good choice might be switching out that electric resistance wall furnace for a mini split heat pump which will use one third the electricity for the same amount of heat
Cheers, David Baillie

Thank you so much for those words of wisdom. Now I know what I should insist on and I hadn't thought about aiming for the seasons although I did think about clearing the snow and there's plenty of it. I'm not trying to go off grid completely, at least not yet, since I work from home so this would be a supplemental power source and perhaps a backup when the grid lets me down. I know that the electric furnace isn't going to last forever so I very much appreciate the suggestion for a mini split heat pump. Lots to consider. Has anyone heard if there are incentive programs for the companies that only happen with a roof installation?

Mary Haasch wrote:

David Baillie wrote:

Mary Haasch wrote:I'm living in a small cottage with a 50 yo in the wall electric furnace (not used much until the last 2 years) and I'd like to add solar electric. I've preliminarily spoken to two different companies, not sure what I think of either one, but both think putting panels on the roof is cheaper than putting panels on the ground in the open area. The cottage roof panels would require new roofing which has about 5 - 7 years of expected life and cutting down the trees which have grown up close to the building. While both things would need to be done eventually, the open area installation seems more immediately cost and effort effective. In addition, the ground-based system in the open area could be used to power the workshop, the garden shed and the eventual small barn planned for the open area (the workshop and garden shed are existing). Any words of wisdom?

Hi Mary, Stay on the ground. Between added costs of rapid shutdown, engineering and city permits the costs of roof mount add up. Now maybe your area does not have any of that if so then maybe but clearing and new roofing is a cost as well. Ground mounts can be perfectly aimed at the sun and if you choose the right racks can be adjusted with the seasons for best gain and if snow is an issue easily cleared. I have to say heating and solar electric don't usually work well together unless you do a net metered connection to the grid. Is that the plan? Usually when you need heat the days are shorter and there is less solar potential so without the grid to balance out the seasons it's challenging.  A good choice might be switching out that electric resistance wall furnace for a mini split heat pump which will use one third the electricity for the same amount of heat
Cheers, David Baillie

Thank you so much for those words of wisdom. Now I know what I should insist on and I hadn't thought about aiming for the seasons although I did think about clearing the snow and there's plenty of it. I'm not trying to go off grid completely, at least not yet, since I work from home so this would be a supplemental power source and perhaps a backup when the grid lets me down. I know that the electric furnace isn't going to last forever so I very much appreciate the suggestion for a mini split heat pump. Lots to consider. Has anyone heard if there are incentive programs for the companies that only happen with a roof installation?

First off where are you Mary?

Unlike the many electrically knowledgable permies, even though I've been off-grid since 1994 I know nothing about my solar power system and I don't want to know!  I can and have walked into a stall with a raging stallion, I've roped angry llamas, I've captured and released rattlesnakes, and I've armed myself and faced down an intruder in the night (with the sheriff's dispatcher on the phone listening while units were sent to my place).  But I'm terrified of electricity.  

Unlike many permies who want to make their own power, I never could afford to just go out and buy what was needed, new -- but not going solar wasn't an option.  Our place is a mile from the last electrical pole and the power company wanted nearly $25,000 to bring power to our building site.  The cost would have been added on to our mortgage, to be paid off monthly.  The only thing was, we didn't have a mortgage and we didn't want one.  The whole point back then was to not have monthly bills.  I'm ever so grateful we made that choice and stuck to it.

So in 1994, with the help of a friend, we cobbled together a small system out of used components.  When the system would fail for whatever reason, I simply replaced whichever component was the problem with another used component, hooking the replacement up exactly the way the old one was wired.  I didn't learn a thing from doing it that way.

Thus nearly 30 years later, when I was finally able to buy a whole, brand-new system (small! I didn't win the lottery!) I bought a plug-and-play kit put together by a local solar company.  Since the company is local they can't escape me when I've got questions.  I did research them first, and I interviewed them before buying.  They've been wonderfully tolerant about my idiot questions.

My point is that I'm one of those people who want to live a homesteading lifestyle but I don't want to have to be rich or to become an expert mechanic, plumber, electrician, etc. to do so.  When something breaks I patch what I can, replace with used if possible, or do without.  I find this lifestyle suits me just fine.  I'm not necessarily recommending how I've gone about doing things, but I am saying that you don't need to buy the newest and the bestest to be off-grid.

There are all kinds of ways of doing solar just like anything. We were fortunate  to have bought a straw bale off grid home in mid Missouri. It has a 1kw array about 20 years old ($6 a watt then!) to which I’ve replaced batteries ( most expensive part)twice: first with Trojan L16s now with big Trojan Ind6 industrial batteries. We’re run an old trace c-40 controller with a newer magnum pae 4024.
Since then we added a second system using 12 newer us solar 235 watt panels on our barn roof ( note to self: don’t do that again- too hard to get snow off them). 4 sets of three panels. Wire runs 120’ underground to midnight solar 150 classic sl thence to the old trace 24 v inverter and 4 rolls surrette 300 pounders.
I did all the work on second system myself using best deals I could find to keep costs down.
You can do it for less yourself if you’re conscious of $ and safety. Good luck.
Try solarbiz. They did me right on the batteries!

Tom Moran wrote:There are all kinds of ways of doing solar just like anything. We were fortunate  to have bought a straw bale off grid home in mid Missouri. It has a 1kw array about 20 years old ($6 a watt then!) to which I’ve replaced batteries ( most expensive part)twice: first with Trojan L16s now with big Trojan Ind6 industrial batteries. We’re run an old trace c-40 controller with a newer magnum pae 4024.
Since then we added a second system using 12 newer us solar 235 watt panels on our barn roof ( note to self: don’t do that again- too hard to get snow off them). 4 sets of three panels. Wire runs 120’ underground to midnight solar 150 classic sl thence to the old trace 24 v inverter and 4 rolls surrette 300 pounders.
I did all the work on second system myself using best deals I could find to keep costs down.
You can do it for less yourself if you’re conscious of $ and safety. Good luck.
Try solarbiz. They did me right on the batteries!

sounds like a lot of fun Tom! Have you thought of retiring the C40 rewiring the panels for a higher voltage and put in a new mppt... You would probably gain 20 percent extra production from that array especially in the winter and grey days.The Magnum is a great reliable inverter.
Cheers, thanks for sharing your system.
David

Roy Therrien wrote:We installed our 9.6 kW system just a few months ago.  It's grid-tied and totally self-running.  

We monitor it quite closely with its truly outstanding Solar Edge interface.

We also upgraded our roof to metal, making everything easier and cleaner (esp. rainwater harvest).

• 26 Silfab 370-watt PV modules
• SolarEdge 7.6kW Energy Hub inverter
• LG RESU16H Prime 16 kWh Li-ion battery

When grid power goes down, the system kicks in near-seamlessly.  The momentary glitch whacks the microwave clock, so when we wake up and it is flashing, we know the power went out.  Otherwise, we wouldn't even know!

The stove and hot water heater are about the only things not on the solar back-up panel.  We heat exclusively with wood.

You can see from the last photo, we're in a prime situation to add a sun-room on the south side of our home.  We're making zero use of passive solar as-is.  We just bought the home 1.5 years ago and it's 35 years old, so lotsa updates/upgrades to do.  That new (timber-framed!) sunroom roof will get lined with another 10+ panels, a relatively easy investment/upgrade given all the other infrastructure is already in place.

Now it's all done though, truth be told, I don't like it (this solar PV system).  Too expensive, too complex, too limiting, too vulnerable.  Too many-other-things.  I personally think there are a large number of other better ways to manage electricity/energy production and consumption, all of which are well covered here on Permies.  First and foremost, use less!

HI Roy,
that is Solar Edge's new top of the line system. Lots of bells and whistles in there.  It is a good inverter and a reputable company so its got that going for it. Lots of the grid tie central inverter companies are coming out with battery options these days. Lots of flavours. The complexity is definitely an issue with them. That app is pretty cool though.  Sounds like you have a list of upgrades on the home that you will be working on going forward to increase your resiliency in a more passive way. Thanks for posting details. The good and the bad
Cheers,  David Baillie

First off where are you Mary?

NE Wisconsin not too far from the Upper Peninsula of Michigan.

Hi David! I'm enjoying this discussion that you started, though I don't understand the technical bits.

I live in one of the most solar-friendly places on the planet, high desert at 10,500 feet in the rainshadow of the Himalayas.

I got my house built 5 years ago. I decided to use the abundant sun for passive heating of the house, and for water heating, and not (yet) for electricity. Grid connection was basically free for me, though it took a year or so to get them to put the poles up. Until then, we had an insulated wire lying on the ground, from a stolen connection from the nearest pole. (Rules are um... loser here in India)

If one of your big energy uses is heating the house or water, it's much better to use the sun's energy directly for heat rather than involving electric. Solar heating is much more efficient than converting the sun's energy to electricity, converting that to chemical energy for storage in a battery, converting it back to electricity to travel to the heating device, and then converting it to heat. Each of those transitions is not very efficient. You'd need at least ten times the area of solar collection to get the same amount of heat from solar electric than from any solar thermal method. (David or anyone, please correct me -- I'm guessing it might be 50 times the area, but panels and batteries are getting more efficient so maybe not)

The solar water heaters sold here in India are amazingly effective. They are glass vacuum tubes. You know those Chinese thermoses with a double-walled glass inside, that keep water boiling hot overnight so you can steep tea in the morning? Yeah, same stuff but 6-foot tubes. I sprung for the bigger model, 200 liter tank with electric backup. It's on my flat (desert) roof.  So far, wonderful, but the day one of those tubes breaks or leaks, my entire 1000 liter cold water storage tank will drain out onto the earthen roof and it's gonna be a huge problem.

Now that I'm settled in and living in the house for 5 years, I'm thinking I should add solar electric as well. Until now, I just have 2 big batteries (150 amp hours?  not sure) and an inverter tied to the grid, because the grid goes down for an hour or so a few times a week, and for whole days at least once or twice a year. I had two separate circuits installed to all the rooms: one circuit for lights and chargers on the inverter, and one circuit that is mains only, for the heavier devices and water pump. Especially in winter, the voltage is rarely high enough to run the pump, so I have to keep an eye on the voltage ,and quick run the pump when the voltage is 200V or above (Voltage is nominally 220-240V here. Ha!) I have 1000 liters of storage tank in the top of the house so can go a few days without a refill, if we're careful.  

I'm not at home and sorry, I don't have a photo of the whole water heater, only a snapshot we took of our half-assed pipe insulation job.