Simple solar gal needs bigger ideas

[BB.]

Links that answer questions and/or point to good suppliers are always welcome.

-Bill

[Fiddler]

This house is in a remote area that utilizes an electric coop that is amateurish at best. I'm located south of Horseshoe down in the California swamp. I don't have an inverter and I'm confused about modified sine wave. Is this harmful to modern appliances or are pure sine wave inverters the way to go? I'm assuming I need to run 4 series of 2 modules in parallel to achieve 24 volts (correct?) With the MPPT controller and I did look at the Midnite Classic and it looks like it will do the job. Will this change the 24 volt battery configuration or should this remain the same as the panels are wired? i only plan to run the 2040 watt array just to learn what's going on. Are there other ways this could be configured to get more power? Also how much inverter will I need for a few small appliances and one 3/4 hp jet well pump? Should I be looking at inverters more than the wattage of the system say 3000 to 4000 or are smaller inverters more efficient? I'm getting about 5 hours of good sun and the rest with some shadows. I very much appreciate the opinions and thoughts and ideas of this Board. Gina

[BB.]

Here is some information on inverters:

All About Inverters
Choosing an inverter for water pumping

Basically, something like 80% of your appliances will work fine on MSW, about 10% will fail (either fail to function, or actually overheat and break), and another 10% may have shorter life over time.

What tends to "fail" are inexpensive electronic power supplies and wall plug type transformers.

What tends to work are resistance heaters, filament light bulbs, universal motors (motors with brushes like drill and cake mixers), and motors that are are "lightly loaded" such as fans and such.

Things that may or may not work--AA battery chargers, tool chargers, refrigeration compressors may run hot, CFL bulbs may or may not start/run hot, etc...

Many computers will work OK (modern desktop systems), and some that may have problems are the small "net book" type computers... It is really hard to generalize (the larger computers/electronics tend to have a function called "power factor correction" while smaller power supplies and computers may not).

If you are near stores and not too worried about a small devices failing--MSW prices are hard to beat.

If you are in the middle of no-where and/or cannot have something fail (work computer, etc.), then TSW inverters (which have the same basic wave form as utility power), are hard to beat.

And the reason we keep asking you about your loads--It is sort of the difference with a VW Bug and a small trailer vs a Mac Truck with 80 tons of freight. The both do their jobs well, but they will not do each other's jobs well.

For most people, the amount of solar panels and battery bank sizing will hinge refrigerator, A/C (or not), and well pumping for irrigation. And there can be a huge difference between a desktop computer running 24x7 vs a small laptop running 10 hours per day with "sleep" activated.

A single desktop running 24x7 can use 2x the amount of total power use of an off grid home for quite a few people here.

Grid power with some sort of backup may be quite a different solution vs trying to run a home 9+ months of the year from solar (and the help of backup genset during the winter).

For some people here, they have reduced their cabin electrical usage so much through conservation--That the local electrical co-op bills were more than using solar+genset and they were close to just going off grid.

In "cities"--The building inspectors may "red tag" a home that has no electrical power (even if they have solar).

In California, the utility does have the "right" to charge people for abandoning utility power and replacing it with solar/other power sources (basically, the utility has used the customer to borrow 40 years of revenue to pay for infrastructure in "our name"--so we have to repay the utility for leaving the grid and "stranding" their assets--Don't know if it every happened or not, but it is in the regulations and has affected many larger companies that want to do co-generation facilities).

-Bill

[Photowhit]

Wow, you got me on 'Horseshoe' I couldn't even find it via Google, Always thought California swamp, was 'Tate's Hell' on the other side of the dead lakes, and it might be, but it looks from the map that your pretty close to PC. Unless your talking about Horseshoe beach and the swamp and hunt camp areas down there, I think there were some communes down that way so perhaps thats the area your talking about... enough reminising...

We are not trying to be difficult, most of us like the idea of using solar and some like the idea of being 'off grid'. But jumping in is hard at best, looks like you are realistic and you get 2 thumbs up for that! but much of figuring out the math is having hard figures. My Guess is your 3/4 jet pump is a good place to start, I take it this is a shallow well pump. Even knowing the brand we might not be able to give you more than an idea of the current spike to start the pump. Is it currently running off a generator? if your on the grid currently, the electric company might have loaner Kill-a-watt meters (thank my mom, really! she helped put on the 'Sustanable Living' expo in Wakulla County and got some of the Electric Companies to add loaner meters to their Energy audit programs!)

I have not had any issues with MSW and wall warts, most of the 'car adapters' are MSW and pretty much made for computers/netbooks and such. ...but I agree with the rest of what Bill said. I lived on small MSW inverter @200 watt for most of 5 years, ran a couple different laptops, a 6" TV, video tape player('00-05), fans most from wall warts.

That said, a big motor like your well pump would very much like a pure sine wave. If it's running off of a genny that's a start, if it's running off the grid, you can likely read the power label on it and 1st see if it's 110/120Volt. I've never tried to run a well pump so others will likely chime in and speak to the use and pressure settings (I take it you have a big tank that the well draws water into, and the pump maintains a pressure level in the tank?) And the possibility of swapping out the pump for something more effiecent, or less spikey(new word!)

As to the Midnite classic (and all MPPT Charge controller) they take in the power within their ability to do so and output power that you need. So long as the CC will accept it you should be fine, it might run a bit more effiecently at about 2x the output, but if you can limit the number of strings of panels to 1 or 2 you will not need a combiner box (fuses for each string) so to keep expenses down 1 or 2 strings will be cheaper and simpler.

[Fiddler]

Wow, you got me on 'Horseshoe' I couldn't even find it via Google, Always thought California swamp, was 'Tate's Hell' on the other side of the dead lakes, and it might be, but it looks from the map that your pretty close to PC. Unless your talking about Horseshoe beach and the swamp and hunt camp areas down there, I think there were some communes down that way so perhaps thats the area your talking about... enough reminising...

We are not trying to be difficult, most of us like the idea of using solar and some like the idea of being 'off grid'. But jumping in is hard at best, looks like you are realistic and you get 2 thumbs up for that! but much of figuring out the math is having hard figures. My Guess is your 3/4 jet pump is a good place to start, I take it this is a shallow well pump. Even knowing the brand we might not be able to give you more than an idea of the current spike to start the pump. Is it currently running off a generator? if your on the grid currently, the electric company might have loaner Kill-a-watt meters (thank my mom, really! she helped put on the 'Sustanable Living' expo in Wakulla County and got some of the Electric Companies to add loaner meters to their Energy audit programs!)

I have not had any issues with MSW and wall warts, most of the 'car adapters' are MSW and pretty much made for computers/netbooks and such. ...but I agree with the rest of what Bill said. I lived on small MSW inverter @200 watt for most of 5 years, ran a couple different laptops, a 6" TV, video tape player('00-05), fans most from wall warts.

That said, a big motor like your well pump would very much like a pure sine wave. If it's running off of a genny that's a start, if it's running off the grid, you can likely read the power label on it and 1st see if it's 110/120Volt. I've never tried to run a well pump so others will likely chime in and speak to the use and pressure settings (I take it you have a big tank that the well draws water into, and the pump maintains a pressure level in the tank?) And the possibility of swapping out the pump for something more effiecent, or less spikey(new word!)

As to the Midnite classic (and all MPPT Charge controller) they take in the power within their ability to do so and output power that you need. So long as the CC will accept it you should be fine, it might run a bit more effiecently at about 2x the output, but if you can limit the number of strings of panels to 1 or 2 you will not need a combiner box (fuses for each string) so to keep expenses down 1 or 2 strings will be cheaper and simpler.

Hello there, I have a laptop connected to a 42" LCD screen that runs about 120 watts total for both. I have a new energy efficient Maytag 13 Cubic ft. Fridge, and a LG washer. All the lights are LED about 9 watts each. 10 or so are usually on. The pump is a Starite 3/4 hp 110 with a 20 gallon pressure tank. A 70 foot run from the battery box to pump. Coffeemaker in use a lot. Washer twice a week. A lot of grilling done outside. Two ceiling fans, that's about all. The computer and TV are on about four hours a day. I'm pretty conservative when it comes to power usage. I catch rainwater for irrigation and live a very simple life. When I hook up panels in a series should I use Y cables 2+2+2+2? and if I wanted to relocate the panels about 70 ft away from the batteries how much voltage would I lose?

[vtmaps]

When I hook up panels in a series should I use Y cables 2+2+2+2? and if I wanted to relocate the panels about 70 ft away from the batteries how much voltage would I lose?

I think that what you are trying to say is that you want to put two panels in series (which makes a string) and have four of these strings in parallel. You will need a combiner box to put the strings in parallel, and each of those four strings will need a circuit breaker in the combiner box. The combiner box is weatherproof and very near the panels. You also need a ground rod and lightning arrester at the combiner box. Then you run a cable from the combiner box to your charge controller. You will want the 70 ft cable to be at least 6 gauge copper (4 gauge would be better), and it should be buried in conduit.

Look at the Midnite solar combiner boxes and lightning arresters. Midnite has a good website and you can buy them at a good price from NAWS.

btw, for your inverter and charge controller you should consider one of Midnite's prewired E-panels. It comes prewired with an inverter of your choice, charge controller, circuit breakers, bypass switch, ground fault device, lightning arresters, etc. Just screw it to the wall, connect it to your battery, generator, 70 ft controller cable, and AC distribution panel.

--vtMaps

[Photowhit]

When I hook up panels in a series should I use Y cables 2+2+2+2?

NO, if you want to do strings of 2, hook one to the other and then into a combiner box with 4 fuses or breakers (info on fuses per string is on the back of the panel. If you can and want to do strings of 4 panels, first check the sizing tool, most of the info will be on the back of the panel, other info will be the high and low temps in your area and how your going to hook them up. (Classic sizing tool). If you can do strings of 4 you can hook 4 up in a string (possitive to negative) then use a 'Y' to connect the 2 strings. If the batteries will be 70 feet away this will also help with voltage loss as you will be running higher voltage, higher voltage will mean less current(amperage) wire size is based on amperage and voltage drop across a distance 140 feet round trip might be OK on 10 gauge wire at 120 volts. You can check a voltage drop calculator Sorry no link right now One of the great mods will come along and post a link shortly(I hope!)

10 lights 'usually on' would not be considered conservative in this crowd, that's 90 amps an hour x 24 hours or over 2Kwh a day. If you've done most of your conserving, what is your monthly Kwh usage? My guess is your fridge will be 2 Kwh per day (energy effiecent use 1-1.4 in a controller room but if you don't use air conditioning it will use more! Is your solar water heater a siphon pump or are there water pumps involved there as well?

A couple loads a week laundry isn't much, if you have a front load that's a plus! The TV/Laptop 4x 120 watts or 500Watt hour isn't too bad, I think my LED/LCD uses close to 70 watts and it's 32 inch. Coffee maker might be a pretty heavy draw, might want to put a kill-a-watt meter on it, be sure to turn the warming element off after you make your coffee, use a thermos to keep the coffee warm if needed, warmers use a good bit of electric.

Ceiling fans can be hit and miss, might check the current with a clamp meter, dodging the blades will be tricky (likely be able to check at the switch...lol)

[Photowhit]

If you choose to go 'off grid' you will find that you know what your current uses are, right now I'm running;

Wall warts charging cell phone, N900(minicomputer playing an audio book) and mini speakers for same, total less than
<10 watts
2 - 13Watt CF lights
26 watts
wall warts for media player and TV (I just turned them on from power strip, it takes a while to load the media center from 1tb HD, it's pizza night without pizza I went to town this afternoon.)
@10 watts
1 - 4watt LED bulb outside light
4 watts
fridge on thermostat
@1.5KWH a day.
1 honking big central air ("No sin greater...")
...more than I want to think about, it will be retired after this summer, when I take this place off grid.
water heater is off and the water is hot enough for my showers in the morning and Friday morning, unless I do a lot of cooking then I'll flip it back on for an hour.

I'm using about 20 KWH a day currently, we've had a heat wave and drought and I work security and needed to come home to a cool house. I ran last month on a more conservative mode and was down to 11KWH a day, turning off the central air when I left. I actually would be close to maintaining 20 KWH's a day with a 6.5 Kw array I will setup. After summer my use becomes very low.

If off grid I would likely air condition a single room through out the day and use a mini split on low to keep the large room/kitchen area from roasting. I also have a small cabin designed to be off grid and air conditioned and could stay there through out the summer if needed(it currently only has an fridge running...lol). I'm impressed you can manage Florida with out air conditioning. I managed here (central Missouri) for 5+ years but we normally cool down over night.

Time to turn off the audio book and watch a movie, while I pretend to pick up around the living room...lol

[BB.]

Hi Gina,

Taking a guess:

Hello there, I have a

• 0.56 kWH per day = 0.1120 kwatts * 5 hours per day laptop connected to a 42" LCD screen that runs about 120 watts total for both.
• 1.0 kWH per day Maytag 13 Cubic ft. Fridge,
• 0.250 kWH per day LG washer (per load estimate, washing only, no water heating/steam heating).
• 0.90 kWH per day = 0.009 kW * 10 lights * 10 hours lights are LED about 9 watts each. 10 or so are usually on.
• 0.33 kWH = 1.0 kW * 1/3 hour per day The pump is a Starite 3/4 hp 110 with a 20 gallon pressure tank.

======================
3.04 kWH per day (if I did my math right) [oops--missed the x10 LED lights--fixed]

I am going to round up to 3.3 kWH per day (100 kWH per month). That will allow for some days with more usage, and support additional loads (which tend to grow over time).

Note, for the math below--I am carrying out digits to reduce round off error, and to make it easier for you to check my math (I ain't perfect ). Choosing hardware within ~10% of the below--is virtually the same for solar calculations.

Nominally, we recommend a 1-3 days "no sun" battery and 50% maximum discharge. Use 2 days here for this example (is a happy medium):

• 3,300 WH per day * 1/48 volt battery bank * 1/0.85 inverter eff * 2 days "no sun" * 1/0.50 max discharge = 324 AH @ 48 volts

Next, charging the battery bank. We recommend from 5% to 13% rate of charge... With 10% being a good minimum for a fast recharge/good battery life:

• 323 AH * 59 volt batt charge * 1/0.77 panel+controller deratings * 0.05 rate of charge = 1,241 watt array minimum
• 323 AH * 59 volt batt charge * 1/0.77 panel+controller deratings * 0.10 rate of charge = 2,483 watt array nominal
• 323 AH * 59 volt batt charge * 1/0.77 panel+controller deratings * 0.13 rate of charge = 3,227 watt array "cost effective maximum"

Next, we need to estimate the power based on how many hours of "noon time equivalent sun" per day.

I am not sure where you are at--but using PV Watts for Tallahassee Florida with fixed array pointing south at latitude, we see:

Month    Solar Radiation
(kWh/m 2/day)
1      4.10     
2      4.86     
3      5.07     
4      6.05     
5      6.15     
6      5.73     
7      5.28     
8      5.52     
9      5.38     
10      5.32     
11      4.51     
12      3.92     
Year      5.16

Tossing the bottom three months (assume you would make up balance with generator), that would be February with ~4.86 hours of sun per day (20 year average):

• 3,300 Watt*Hours per day * 1/0.52 system end to end efficiency * 1/4.86 hours of sun per day = 1,306 Watt solar array

So, the "ideal array" for your place would be from ~1,306 Watt to 3,227 Watt solar array.

If this was "backup power system"--You may tend towards a 1,306 watt array (minimum amount of solar panel to meet your needs for ~9 months of the year).

If this was a full time off grid home--You may tend towards the 2,483 watt array (better for battery life, you could support more loads, if needed).

A 70 foot run from the battery box to pump.

A longer distance favors higher voltages--Probably 120 VAC minimum. A 120/240 VAC split phase inverter would be nice to run at 240 VAC.

There are other, much more efficient pumps--But if your well use is light, then it is probably not worth the money for a new in-well pump like a Grundfos (these are great pumps, AC or DC power, even run off solar panels only). And much more efficient. If you were to use a small "slow pump" (even solar panel only for daylight pumping)--It would fill a cistern and then use a small DC pump to pressurize the home.

Coffeemaker in use a lot.

Oops... Not on list. Using a propane powered "Mr. Coffee" is a possibility--And use a thermos to keep warm during the day.

Washer twice a week.

Check

A lot of grilling done outside.

Keep home cool. Check

Two ceiling fans, that's about all.

Those can use a fair amount of power, or not (watts*Hours per day)... There are some DC versions that are supposed to be very energy efficient.

The computer and TV are on about four hours a day.

I rounded up to five hours per day.

I'm pretty conservative when it comes to power usage. I catch rainwater for irrigation and live a very simple life.

3.3 kWH per day is a "good size" system for an off grid home with a "reasonably" modern lifestyle.

When I hook up panels in a series should I use Y cables 2+2+2+2? and if I wanted to relocate the panels about 70 ft away from the batteries how much voltage would I lose?

In general, don't use "Y" cables. Instead, you will probably need a "combiner box" (with internal fuses or breakers) plus a negative bus bar (more than two parallel strings require the fuses/breakers for safety).

Assuming you use a MPPT charge controller and/or 48 volt battery bank, array to charge controller/battery box should not be too much of an issue.

Note the above assumes a 48 volt battery bank... With the sizing above, you could possibly go with 24 volt too (if you need 24 VDC pumps, for example)... Need to look at things a bit closer.

But, before we go down the road of details--Want to make sure my assumptions about your power needs are correct.

Also, the shading still bothers me--If you have shading between ~9am and 3pm, you can lose a lot of power--Solar panels just do not work very well with any shading. And from 9-3 is the prime generating time (winter may be worse with lower sun angle).

-Bill

[Fiddler]

Wow, You guys are thorough! I'm getting the picture here but still moving ahead with this. Question: I saw an all in one controller board from Missouri Wind and Solar. Is this any good? It looks good but doesn't go into much detail about any MPPT. How I came across this I was thinking of adding a wind turbine to do night duty and they had a turbine I was looking at and saw this all in one control board. ($698) Cabin located between Horseshoe and Suwannee.