System design help!

1911

Hello,

I have just joined this awesome forum after lurking for several weeks...thanks to all of those with knowledge and experience that contribute here. This site is a valuable resource.

I am starting my first solar project this week and am still in the equipment acquisition phase. I have already ordered some items that i felt were non-negotiable but would appreciate any input/help with the remainder of the parts ill need to finish.

First, here is what i ordered or have already:

-2 x Trojan AGM 31 100ah (on the way from NAWS!...thanks!)
-ProMariner battery charger model # 43020 12v 20amp 2 bank
- Honda EU2000i
-Spectra Watermaker Aquifer 150 with a 30ah battery and a guest 2620a battery charger mounted in the case

What i think i need:

-Solar Charge Controler...Midnite the kid?
-solar panels...how many?...what size?
-inverter....what size? Exeltech? ( just because it might be handy, not necessarily to support the watermaker)


The entire purpose of this is to run the Spectra Watermaker 150 in the event of an emergency. It is a 12v system that uses about 110-120 watts an hour.

From the Spectra website

POWER REQUIREMENTS
Pump Horsepower 1/8
Amp/Hr per Gallon (12 VDC) 1.4
Watt/Hr per Gallon 17
Current Draw (12 VDC) 9 Amps
Gallons per hour 6.3

Ideally, I would like to have the ability to run this unit 6-8 hours a day. Also, i want to build the system into Pelican cases so it is portable and protected. I have a pelican 1620 and a 1650 and might pick up another if necessary. I would preferrably not want to rely on the generator.

Any input would be appreciated.

PS- i live in San Diego so the sun is fairly reliable.


Here are some pics of the unit i want to power.

1911

Re: System design help!

According to some of the "solar calculators" I've used online...

So if it uses 120 watts per hour x 8 hours a day it will use 960 watt hours a day.

A 12 volt system x 960 watts = approx 80 amps

If I don't require any back-up days of power then a 200ah battery bank should be fine...

If i can rely on 6 hours of sun a day...

I'll need 4 100w solar panels ( im looking at the Renogy panels on Ebay but am open to suggestions)

I was also kicking around the idea of getting a dozen small 30 watt panels and using a Pelican case to store them...not sure what the trade offs are of several small panels vs fewer larger panels.

Cariboocoot

Re: System design help!

Welcome to the forum.

Okay let's look at what really goes on.
Your Spectra unit draws up to 9 Amps. It is 12 Volts.
Now, how long do you need it to run for? 8 hours maximum: 9 Amps * 8 hours = approximately 72 Amps hours consumed.

I say approximately because of variations in current @ Voltage as the battery declines and the possibility that some of the power may be provided 'directly' by the panels.

So you would be looking at 144 Amp hour 12 Volt battery minimum. You've got two 100 Amp hour 12 Volt batteries on the way. So far, so good.

Now you want to be able to recharge them from solar, probably while the unit is running. For that you're looking for around 20 Amps of current from PV. That would be about 350 Watts of 'standard' 12 Volt panels on a PWM controller or 312 Watts if you use an MPPT controller such as the Kid. Probably not worth investing in a $300 charge controller unless you're planning expansion.

What you could use:
Three 130 Watt panels http://www.solar-electric.com/solartech-spm130p-s-n-130-watt-multicrystalline-solar-module.html/ & a 30 Amp PWM controller http://www.solar-electric.com/inverters-controllers-accessories/chco/mochco/stpwmchco/ps-30.html about $1,000.

Two 190 Watt panels http://www.solar-electric.com/topoint-jtm-190-72m-solar-module.html & a 30 Amp MPPT controller http://www.solar-electric.com/inverters-controllers-accessories/chco/misoclchco/midnite-solar-kid-mppt-charge-controller/midnite-solar-kid-mppt-solar-charge-controller.html about $725

What you could probably get away with:
Two 140 Watt panels http://www.solar-electric.com/kyocera-kd140gx-lfbs-140-watt-polycrystalline-solar-panel.html/ & a 20 Amp PWM controller http://www.solar-electric.com/inverters-controllers-accessories/chco/mochco/stpwmchco/ss-20l.html about $634

Look around. Lots of folks here have found good deals on Renergy and DMSolar panels too, but you have to shop for them.

1911

Re: System design help!

Cariboocoot,
Thank you for the suggestions, i like that first package.
Thanks,
Tim/1911

mike95490

Re: System design help!

What is the source of your raw water ? Pond, ocean, spring ?

And stop buying stuff till you have the system designed, or you may find you have under/over bought things.

1911

Re: System design help!

mike95490 wrote: »

What is the source of your raw water ? Pond, ocean, spring ?

And stop buying stuff till you have the system designed, or you may find you have under/over bought things.

The watermaker is a reverse osmosis seawater desalinization model....and yeah, good advice on designing before buying...that is primarily why I am here. When I first started looking at this solar stuff a few weeks ago I thought to myself "how hard can it be?" Lol

Now if I could just get somebody to itemize a list of wires, connectors and fuses I'll be in business!

(I think I'm going to buy the first combination listed by cariboocoot...3 x solartech 130w and the Morningstar prostar 30)

1911

Re: System design help!

This is the case I was planning to mount the batteries in. I am wondering if these Trojan AGM 100ah batteries need air circulation to keep them cool....i have been thinking about ways to mount them in the box....i could cut the foam real close and it would probably keep them secure from movement, but I wonder if they would get too warm mounted in close fitting foam.

The other option would be to use some angled aluminum and make a mounting bracket on the floor of the case with some nylon straps to hold them down.

Anybody have any suggestions for mounting large batteries in a mobile case that could potentially be placed on end or jostled around?

Also, how close can i mount a battery charger to a battery? Does the charger get hot? I could probably squeeze two batteries and the charger in the case if putting things right next to each other isn't a problem. If air-space is required around the individual components i'll need to figure something else out.

BB.

Re: System design help!

Is this going to travel by air? Does not look like it will be mounted somewhere permanently.

If shipped, you will have to look at the method to see what battery type will work best. AGM are usually pretty safe (spill proof)--But still heavy lead acid. LiFePO4 batteries are very light and have some interesting charging characteristics and might not ship by air (not sure)--But they are expensive (and some other issues).

-Bill

1911

Re: System design help!

Bill,

No, i do not anticipate flying anywhere with this equipment. I do envision loading/unlading these in a vehicle on an annual basis though for testing/practice...maybe even every six months.

I went with AGM batteries because i live in a small apartment with the only available storage in a small storage space off of our living room. My wife is pregnant with our first child so I figure encapsulating these batteries in an extra layer of protection like the pelican case is only a good thing.

I just looked at Trojan's website and they said the maximum operational temperature was 131* F.

I couldn't find any temperature info for the Promariner sport model battery charger.

The sunsaver CC said it was good up to 180* F.

It looks like these components can tolerate a little heat. Im thinking the foam mounting solution might be back on the table.

Would it be important to use anti-static foam?

Tim

BB.

Re: System design help!

Batteries like to be at "room temperature" (roughly 40-90F with ~75 as standard test conditions). Note that for every ~18F (10C) increase in temperature, the batteries will age 2x faster. And conversely, the cooler the batteries are, the slower they age/self discharge.

So, in hot weather, foam is a bad thing. In subzero temperatures, insulation can be a good thing.

With electronics (and especially power electronics), motors, insulation, and basically anything--That 18F/10C and a 2x/0.5 change in life rule is a common engineering design factor. If those motors/controllers generate a lot of heat, putting them in Pelican Boxes with no air flow is not a good thing... Good ventilation and protection against water/rain infiltration will be a help too.

Batteries are not static sensitive... However, electronics can be. The power connections (battery cables and such) are probably not going to be affected by a small spark from the plastic. But control lines/communications lines (RS 232/RS 422/raw digital lines) are not very happy with electrostatic discharge.

AGM batteries kept cool can reduce self discharge and allow them to sit for 3-6 months between charges... But some sort of good quality float charger can be helpful.

Batteries do age--And you may need to budget to replace the AGM batteries every 2-5 years (in general).

And remember that solar panels are single weight tempered glass (~1/8" thick). While they are much stronger than regular non-tempered glass--They still are fragile and suitable to shattering if dropped on edge or other hard knocks on the surface. When setting up the array, the panels should be mounted/staked in such away that wind/people will not knock them over.

Other questions can include what happens if you need to roll this stuff out during bad weather. Are you going to have/need a genset+fuel for backup?

Average hours of sun per day for San Diego CA with fixed panels mounted to 32 Degrees from horizontal using PV Watts:




Month
Solar Radiation
(kWh/m²/day)


1
4.83


2
5.35


3
5.91


4
6.52


5
6.05


6
5.98


7
6.26


8
6.62


9
6.02


10
5.88


11
5.16


12
4.67


Year
5.77




-Bill

mike95490

Re: System design help!

I'll still ask the source of your water. If you are not doing sea water, there are other routes you can go. Filters eventually plug and need replacement, UV tubes fade and need annual replacement.

1911

Re: System design help!

Bill- thanks, a lot of good information in your post. As far as bad weather, i did purchase a Honda EU2000i. My grandmother who lives nearby has the same Honda to power her CPAP in an emergency. I plan to get a kit that will allow me to link the two generators for a total of 4000w. I was also looking at music instrument cases to mount the solar panels in. Unfortunately, Pelican doesn't make anything big enough but several music inst. case makers do...plus ebay had some good deals on used ones. I also got 5 nice gas cans for a total of 25 gallons...my biggest problem is that im running out of room to store this stuff.

Mike- i live near the bay/coast in San Diego....Mexico to the south....LA to the north...desert to the east....ocean to the west...one big freakin fault line that binds them all together, Lol. As far as source water....it would be the bay or coast. I have 20 micron prefilters, and 4 seawater RO membranes, and all the chemicals to clean/preserve them. I never thought about UV...im not sure if i need it with the RO...ill look in to it...thanks.

Cariboocoot

Re: System design help!

Nota Bene: A Honda EU2000i is 1600 Watts, not 2000 (that is its 'peak' or 'surge' rating). Link two and you get 3200 Watts.

BB.

Re: System design help!

Is there some specific need for the water (dialysis?) or is this just general earthquake preparedness? If for medical needs, you may need to look at the RO and Chemical treatment of the water to ensure that they are compatible with each other. And a TDS meter (to ensure your water has low salt content--No broken RO membranes, etc.).

I commend you looking at water... That is more critical than food and more difficult to store/transport large quantities.

By itself, if you use 1 gallon of gasoline every day for ~8-10 hours of power per day--That is >3 weeks of shelter in place. In major cities, probably plan on 3-5 days of taking care of your own needs before supply lines get stabilized into the metro area (worst case).

However, if the city infrastructure is severely damaged, such as the sewage pumping system/pipes/storm drains (if raining), etc., may make your immediate area uninhabitable anyway. We have one person here that put a septic field shutoff valve in his main sewer line to the house--Problems with pumping station failures in the past have shown that it backs up into his place.

At that point will will be leaving to a more secure area anyway. So--Don't get too wrapped up in the personal support needs without looking at plans to evacuate (use some of that stored gasoline to leave the area, etc.).

-Bill

1911

Re: System design help!

Bill- we don't have any specific medical problems per se, but we do have several older family members and several new babies in our local family. If there was an earthquake we would't be able to leave very easily just due to the age and health of our older family members and circle of friends. Also, my wife and I both work in healthcare...it would be difficult to drive away knowing that our patients were vulnerable. We would probably have to stay put no matter what....which leads to the water problem. From what I understand, the Southern California water system is old and fragile....this is not even to mention all of the recent conversation of 'grid down' scenarios.

When i began to understand the scope of the potential problem i appointed myself the 'water czar' of the family and started buying extra cases of water...it kind of grew from there. I initially bought the watermaker without much research....i thought to myself "hey, 150 gallons a day of drinking water from the ocean at the flip of a switch...pretty cool." Come to find out, its not that simple.. Lol...i didnt give the power requirements enough consideration. But, i Think this new solar project will fix my problems.

After being on here a couple of days I am starting to consider doubling the size of my set-up...one more Pelican 1620...2 more Trojan 100ah batteries for a total of 400ah....A yet undetermined number of panels/watts and an electric water pump to replace my Honda gas powered water pump ( the pump to get water form the bay to the actual RO unit…the case has a little one built in but i don't want to tax it too much).

westbranch

Re: System design help!

Not knowing how close to a major fault line you are may make this suggestion sound kinda dumb... here goes:
Are you in a semi rural area or large lots?

If so why do you not put in storage tanks that would last 5 - 10 days, at each home filled from the existing water supply, and have it so these tanks are cycled from daily so that if/when the BIG ONE hits there will be a weeks supply for human consumption and not flushing... If it goes 'off' before used then use the purification system on it.

How far from the ocean are you , why not set up a pump to fill 55/45 gallon drums for 'flushing water' from the sea? Most people can lift a 2 gal bucket...

All this rather than trying to do the ocean supply for human consumption.

BB.

Re: System design help!

Just to make up some numbers here... 17 WH/gallon, 150 Gallons per day on a 12 volt system:

• 17 WH/G * 150 G per day = 2,550 WH per day
• 2,550 WH * 1/12 volt battery system = 212.5 AH per day
• 212 AH * 2 days of storage * 1/0.50 maximum discharge = 850 AH @ 12 volt battery bank

Need to calculate two different size of solar array. One based on Battery AH capacity and 5-13% rate of charge, and the second based on hours of sun per day. First based on size of battery bank:

• 850 AH * 14.5 volts charging * 1/0.77 panel+charge controller derating * 0.05 rate of charge = 800 Watt array minimum (backup use, weekend use, etc.)
• 850 AH * 14.5 volts charging * 1/0.77 panel+charge controller derating * 0.10 rate of charge = 1,601 Watt array nominal (daily use 9+ months a year)
• 850 AH * 14.5 volts charging * 1/0.77 panel+charge controller derating * 0.13 rate of charge = 2,081 Watt array "cost effective maximum

And the second based on daily loads and amount of sun. For you place, your winter sun is not bad at 4.67 hours of sun average for deep winter (earthquakes can happen anytime):

• 2,550 WH per day * 1/0.61 DC system eff * 1/4.67 hours of sun per day = 895 Watt array minimum

So, a daily use system with a 850 AH @ 12 volt battery bank, 2 days of "no sun", and 50% maximum discharge could pretty close meet 150 gallons per day for full time use.

Of course, this is an emergency system... You could cut the battery bank to ~425 AH @ 12 volts which would give your 825 array having a nice rate of charge and 1 day of "no sun".

Your choice as to how large a battery bank, how much water, how much solar array... I probably would go with the ~425 AH @ 12 volt battery bank. 800+ AH battery bank is just to large (moving around, 80+ amps of "ideal" charging current", cost to replace).

150 Gallons of RO water--That is quite a bit in an emergency--Closer to 1-5 gallons per day per person for emergencies... 150 GPD is quite a bit (need storage tank(s), distribution pumps, 5 gallon jugs, etc.

Not saying the above is right (or wrong)--Just an example of the how the loads drives the rest of the system design through the math.

-Bill

1911

Re: System design help!

I am in downtown San Diego...about 1/3 mile from the water. We have a small apartment with no storage. My family is also in a very typical central urban setting. I would love to have some storage. Every member of my family has a little food and water put back for "just-in-case" but when you do the math on water...it adds up quick. And then there are other problems associated with having a non-portable emergency supply....plus i just like the idea of being able to make an inexhaustible supply of drinking water from the ocean Lol

1911

Re: System design help!

Bill- once again, great info...thanks. I think ill take your advice and go with the 425ah battery bank. I have two Trojan AGM 100ah on the way and will order two more, the unit has a 30ah battery built in...a Westmarine brand gel battery i believe...i think ill change it out for a Trojan as well since I've let it sit uncharged for about a year...Dohh!

Can you recommend any good books for entry level solar/electrical stuff?

Also, any recommendations on a type 31 double battery tray? Preferably steel or aluminum? Something that could be mounted in the bottom of a case.

BB.

Re: System design help!

Living in an apartment... That is usually a very difficult thing to prep for. You may not be able to access a Water Heater for ~30-50 gallons of emergency water, cannot store fuel/run a genset, elevator's out, no water pumps for higher floors in an apartment complex, no good place for solar panels, etc.

We have had people ask how to do this before (large apartment complex, higher floors, north facing, etc.).

I suggest doing this like a camping trip (tent, sleeping bag, small stove, stored food, water treatment--if fresh water is available, some stored fuel, LED Flashlight+small radio+common batteries, backup supply of medications, etc.).

I don't have any magic answers for you. But looking for storage that is accessable in an emergency (i.e., a rent-a-space with electric gate/care taker may not be the place to store supplies you want to get at 24x7 in an emergency).

-Bill

1911

Re: System design help!

New question...I'm going to go with a 425ah battery bank...i want this entire package to be portable and modular...i have a pelican case for the two batteries I've already ordered...i also ordered a Promariner gen3 20a 2 bank charger to keep them charged when in the closet...

...now i want to order two more batteries and another pelican case...i need to replace the battery in the RO because it's near dead...the case has a Guest 20a two bank charger built in...im not sure what the other bank goes to, i assume only one goes to the battery...

If i build a second dedicated battery case and have two, each with two Trojan 31 100ah batteries...

Do i get another Promariner 20a two bank charger just to keep it symmetrical and both battery cases match?

What Solar charger should i get if im going with approx 800w of solar panels? Would it be reasonable/practical to get two solar charge controllers so the charging system could be split in two for whatever reason?

Is it ok to have 4 x 100ah batteries and one 30ah battery run together?

1911

Re: System design help!

Yeah, my place is not ideal...i figure if i keep everything portable i can set up shop at one of my family members house...living packed in like sardines makes one good at staying flexible and dynamic! Lol my water system and my future solar system will be my crown jewels...everything else is small/ portable i fifure if ya got water ( and power) you are way ahead of the game.

westbranch

Re: System design help!

This is NOT a recommendation, as I know little other than what I have read, but the standby situation of this application makes me think that LiFePo4 or like chemistry might be better for you than FLA or AGM batteries. From what I've read the LIFE batteries can sit in a partially discharged state and NOT suffer any negative effects, unlike FLA. Do a search on this forum for Lithium of LiFePo4 and you will get about 8 pages of threads...

hth

1911

Re: System design help!

westbranch wrote: »

This is NOT a recommendation, as I know little other than what I have read, but the standby situation of this application makes me think that LiFePo4 or like chemistry might be better for you than FLA or AGM batteries. From what I've read the LIFE batteries can sit in a partially discharged state and NOT suffer any negative effects, unlike FLA. Do a search on this forum for Lithium of LiFePo4 and you will get about 8 pages of threads...

hth

Westbranch- thank you for the info. I may have jumped the gun on Friday when i ordered the AGM batteries...i probably should have done more research first. While i was aware of the LIFE batteries i was under the impression they were prohibitively expensive. I was also the impression that AGM was the safest battery to keep in close proximity to people.

Is there some sort of "battery exercise" i could do for the AGM to prevent deconditioning from stand-by status?

westbranch

Re: System design help!

Best I can offer is USE THEM occasionally, like humans they need exercise... the longer they sit the staler they get/

hth

BB.

Re: System design help!

You have to decide if you are going to run the pump 24x7? Originally, you would looking at some other (AC?) loads?

We have a thread with a lot of information and links to other sources:

http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ

Much of this solar stuff is pretty similar to DC wiring of boats. I don't know your skill level, but starting here could be helpful:

Electricity for Boaters - BoatSafe.com

This post has lots of suggestions:

http://forum.solar-electric.com/showthread.php?5556-Working-Thread-for-Solar-Beginner-Post-FAQ&p=54329#post54329

Specifically about batteries:

http://www.windsun.com/Batteries/Battery_FAQ.htm
http://www.batteryfaq.org/
http://batteryuniversity.com/

And this is about AGM/Sealed batteries:

www.powerstream.com/SLA.htm

Our first suggestion--Don't spend any money/order anything more until you have a paper system worked out. These can be pretty complex systems--And while we may make some suggestions on one piece, other portions may not work out (try for "balanced" system designs).

We don't have to go very deep into the first pass of the paper designs. Basically, we design a system on your needs, work backwards to ensure that it meets your needs, and some simple cost estimates. Once you have all of that checked, understood, and "approved", then we can pick the actual hardware and make specific hardware selections.

-Bill

mike95490

Re: System design help!

1911 wrote: »

New question...I'm going to go with a 425ah battery bank...i want this entire package to be portable and modular...i have a pelican case for the two batteries I've already ordered...i also ordered a Promariner gen3 20a 2 bank charger to keep them charged when in the closet...

425ah battery bank is not going to be very "portable". You might load it onto a heavy duty nursery/garden cart and haul the batteries around on that, but if you had 4 gorillas with you, and each picked up a corner of the case, the 4 batteries will fall through the bottom of it.

Is it ok to have 4 x 100ah batteries and one 30ah battery run together?

No Parallel batteries all need to be same brand/batch

Cariboocoot

Re: System design help!

LiFePo batteries are much more expensive and also more complex, but the advantages in an application like this bear consideration: they have greater energy density (lighter & smaller for the same amount of stored Watt hours) and can be left at partial SOC without harm.

But you must research thoroughly to understand what you are getting in to.

1911

Re: System design help!

Just an update! Thanks guys for all the help.

Just received the inverter and charge controller…got the battery mount last week…still need to get one more charge controller, batteries, and solar panel. I talked to Dan at NAWS and got a parts list for all the small stuff…it's almost time to start putting stuff together:)

Also, I had to step up to a Pelican 1650…the 1620 was too small.

westbranch

Re: System design help!

What goes into that metal bracket? batteries?

1911

Re: System design help!

Yes, it is sized for group 31 batteries. I will be putting 2 x Trojan 100ah batteries in it.

westbranch wrote: »

What goes into that metal bracket? batteries?