Newbie here... Need advice/opinions

Re: Newbie here... Need advice/opinions

Welcome to the Forum Solarnutt!

I will take a shot at what you ask below--But it may be kind of confusing... I will make some very Yes/No type statements. However, be aware, everything in solar is shades of gray and levels of complexity. So--Feel free to stop me and question my statements and/or supply further information any particular point.

solarnutt wrote: »

This system is meant as an emergency back-up system and to power up an entertainment system on a daily basis. I’m trying to keep costs down so good quality components for less is a plus.

Just from a simple point of view--Solar as an emergency system is generally very costly, both for the initial install and for ongoing maintenance (primarily battery bank replacement every ~3-8 years or so, and new hardware every 10-15 years).

For a purely emergency system, a small genset and 20 gallons of fuel (or natural gas / propane) may be a better option.

Really depends on your power needs and how long you would like to go without power (days/weeks/months?)...

For me, I made the decision to go Grid Tie Solar to reduce my power bills (I do not trust the California Public Utilities Commission). And a Honda ue2000i (1,800 watt) genset (recycle the 20 gallons of fuel through the car once per year). Have yet to fire it up after 10 years (a handful of power failures that have lasted an hour or two in that time).

I live in SoCal and will get at least 6 hours of sun per day.

Are you closer to Palmdale/desert area than the coast? The marine layer can really kill solar production (I live near SF CA).

Solar PV power is very weather (and shade) dependent... Poor weather or any shading from power lines/trees/etc. will kill much/most of a solar array output.

Lets say your somewhere near Dagget CA , using PV Watts, and 1,000 watt array (1 kW) for nice round numbers, and 0.52 for overall system efficiency (yes, 1/2 the rating of the solar panels) we get:

"Station Identification"
"City:","Dagget"
"State:","California"
"Lat (deg N):", 34.87
"Long (deg W):", 116.78
"Elev (m): ", 588
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 34.9"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:","12.5 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 5.59, 85, 10.62
2, 6.03, 80, 10.00
3, 7.10, 105, 13.12
4, 7.74, 109, 13.62
5, 7.42, 104, 13.00
6, 7.42, 98, 12.25
7, 7.33, 97, 12.12
8, 7.40, 99, 12.38
9, 7.34, 98, 12.25
10, 6.76, 97, 12.12
11, 5.78, 83, 10.38
12, 5.20, 80, 10.00
"Year", 6.76, 1135, 141.88

Pretty nice area for sun. You can expect (20 year average) around 80-109 kWHours per month or around 3 kWH per day +/- average (maximum average--For an off grid system you rarely can use 100% of your generated power every day).

Requirements
System to power the following:
• DirecTv DVR: 60W@1A (24/7) (1440 WH)

Future Addition:
• LCD TV: 130W (6 hrs. day operational – 780 WH)
63W Power Save mode
.1W Sleep mode
Calculated power requirements: 2220 WH/day+10%=2500 WH/day

So, a 1kW array would nicely supply your needed power, without needing a genset, for much of the year (weather permitting).

System setup
Array
(4) Kyocera's PV rated 51W@18.5V
(6) Arco Solar M668 rated 50W@18.5V
Total Wattage:500W

We will have to discuss what battery bank voltage you will want--You can squeak by OK with 12 volt bank. But with a 48 volt bank, you may have some issues matching your series/parallel using existing panels and matching them with the new panels (>100 watt panels these days are usually less expensive ($$$/Watt) than the smaller panels, but these large panels seldom come in the Vmp equals around 17.5 volts (or multiples there of) for 12/24/48 volt battery banks.

So, you may have to use two controllers, one for the older set of panels, and a second one with a different Vmp-array for your new panels (if you choose to purchase another 500 watts or so worth of panels).

To be Purchased?
• Batteries: (4) Trojan T105 connected Series Parallel (370AH)

We like to size batteries to your load requirements... Basically 3 days of no sun" and 50% maximum discharge (for long life)... Using your 2.5kWH daily load:

• 2,500 Watt*Hours * 1/12 volt bank * 3 days no sun * 1/0.50 max discharge * 1/0.85 typical inverter efficiency = 1,471 AH @ 12 volt battery bank

Your 4x Trojan battery bank is around 225 AH. Four in series parallel are 450 AH at 12 volts... Your daily loads would be:

• 2,500 WH * 1/12 volts * 1/450 AH = 0.46 capacity used in 24 hours...

That is nearly 50% use in one day. You can certainly do that, but deep cycling the battery bank daily will tend to wear them out pretty quickly (year or two?)--Assuming that most of your loads are after dark.

For an emergency system--deep cycling and "short" battery life is not your biggest issue.

• MPPT Charge Controller: Solar Boost 3024DiL, Morningstar TS-MPPT-45 or Rogue MPT-3024

My two cents--the Morningstar or Rogue as first choices.

• Monitor: TriMetric 2025-RV?

Good value for the money.

• Inverter/Charger: Xantrex TR512 (pricey)

Should work OK... Larger inverters do have higher standby losses. Also, for many inverters you need a power switch/breaker to kill the inverter's DC input power when not being operated... They can have 10's of watts of "standby" losses which will drain your battery bank even faster.

Questions
• Do the components I've selected have the correct power specifications for my application?

See above--If your power requirments are "fixed" at 2.5kWH per day--then I would go with 1,000 watts of solar panels.

And depending on what you get, you may end up better off with a set of matched 1,000 watts of new solar panels instead of trying to put old+new together...

However, you could, if you stuck with 12 or 24 volt battery, you could put the 500 watts on one charge controller (perhaps a less expensive PWM type), and put the "new" 500 watts on a MPPT charge controller (to match the non-standard Vmp with your battery bank voltage).

• Are the Trojan T105 batteries a good solution? What are other recommendations?

They are a good start--Really depends on your eventual battery bank size requirements--I personally like to reduce the number of parallel batteries to 1 string (and three parallel strings maximum)... Fewer cells to take care of, less problems with current sharing (bad connection/cell stops current from flowing in one of XX parallel strings), can be less expensive because each parallel string should have its own series protection fuse/breaker to reduce the risk of fire, etc... (again, this is my personal bias, many people do run more than 3x strings in parallel and they are very happy).

So, if you decide on a higher capacity battery bank, there are 4 volt and even 2 volt batteries (2 and 1 cell batteries) that have large AH ratings but are still "easy" for one or two people to move around (instead of a huge 12 volt battery that needs a forklift or crane to place in your home).

Also, there are AGM batteries... These sealed batteries can reduce corrosion and out gassing... However they are probably 2x the cost of flooded cells.

• Can I use the 2025-RV monitor? For the same price as a regular 2025, I get an enclosure

I don't see why not--but I know very little about these guys--The retailer or somebody else here can tell you more.

• Do I need a pure -sine wave inverter/charger for a DVR and TV? I also want to use me Honda EU3000 to charge the batteries.

Personally, I would get a TSW (true or pure sine wave inverter)... About 80% of the appliances will work OK with MSW--And ~10% will have their life shorted (or other problems) with MSW. It is sometimes difficult to tell which appliances will fall into which category.

If you stay below ~300 watts on a 12 volt battery bank--You might look at a MorningStar SureSine TSW inverter... It also has "search mode"--Saves quite a bit of power--Only turns on when it sees 6 watts or more of 120 VAC load.

And get a nice AC battery charger for charging with utility power / genset (during power failures).

-Bill

Re: Newbie here... Need advice/opinions

solarnutt wrote: »

I obtained the existing panels for FREE! They're already mounted on adjustable rails. I may add on later, but for right now I want to maximize a system for these. I'm trying to keep total costs under $1500

Free works for me.

I already have an EU3000 with 5 gal storage at any one time. However, gas is not a good solution for >1 week, hence the minimal solar solution.

In general, I really like to look at the genset loads--If you are powering a fridge/freezer/few lights/radio/small TV/etc. for an emergency, a small genset may use less fuel (generators tend to get "less efficient" if they are run at less than 1/2 power--the less power you use, the fuel flow remains the same). The eu3000 watt genset is really nice--but if you want longer runtimes for emergencies--Look at the minimum load(s) you will need to operate (say a single fridge+a few lights) and what genset will give you the best fuel economy.

Batteries: The T-105's sound like they would work, but the comment that I would run them down to almost 50% sounds right. Any other recommendation?

For an emergency system--50% cycling is not an "issue"...

When people want to run their emergency system daily to power a few loads around the house for free--50%+ deep cycling does wear the battery bank down within a year or two--Leaving you with either poor battery performance in an emergency (who can predict when an earthquake will hit) and/or having to replace your batteries every couple of years for the "free power".

Controller: So what I'm interpreting, a MPPT controller is really only cost efficient with mixed voltages? So there's no advantage with my system?

MPPT do two things that PWM controllers cannot do well...

First, if you have a long distance from the array to the controller--You can run the array at a higher voltage (Vmp=35-100 volts or so) and run the wiring for a longer distance with a smaller gauge wire than a PWM system with Vmp=17.5 volts (heavy wire, fairly short runs for voltage drop issues).

The other is that large (>100 watt) solar panels tend to be less expensive ($$$/Watt) than smaller wattage solar panels. And these large panels tend to be designed for Grid Tied systems, so their Vmp is usually not compatible with the ~17.5 volts that a 12 volt PWM controller can use.

Battery charger: The Iota looks good. So if/when batteries are low, I just plug in the DC output on the generator to the charger, right? I read somewhere that Honda's will not charge and output at the same time. Comments?

The 12 volt battery charger output of the Honda, in some manuals, says it cannot be used when running the 120 VAC output (May overheat the 12 volt section of the alternator?).

In any case, the 12 VDC output is not really a good battery charger... It is low current and unregulated... Really only good for "emergency charging" of a smaller battery (not sure on the eu3000i, but for the smaller Honda's, the ECO throttle has to be turned off--So 12 VDC battery charging uses a lot of fuel too).

If it's OK, I'm going to have some more questions on purchasing electrical (Wire AWG, combiner boxes etc..) components. start. I plan to have an electrician to help do the installation so I don't mess things up.

That is what we are here for.

-Bill

Re: Newbie here... Need advice/opinions

Well--Never say never.

I think the Honeywell Inverter/Generators are actually MSW (came out i... There are probably other MSW inverter/generators out there now too. You can probably tell because nowhere in the manual/sales literature do they tell you if is a MSW or TSW inverter. :roll:

mike90045 wrote: »

edit:
PS Honeywell Inverter gensets are MOD-sine output - no good for transformers

50% power = 3.3KWh per gallon

The Honda euX000i family are all TSW types (I am pretty sure).

-Bill