water heating and pumping

System

Hi, I bought 4 130watt panels, a xantrex c60 controller and a xantrex 4000 inverter last year. I have a big 110vac to 220vac transformer, I still have to get my batteries. I want to put in a additional pre water heater to adsorb the surplus power from the panels. I want to use the c60 to divert the power to heat the water after the battery bank is full. I have a 3/4 hp deep well pump and I want to pump my water with the full charge batteries going through the inverter. My questions are:
1. Can I hook the inverter to the batteries direct or do I need a 2nd c60 controller to go between the battery band and inverter ?
2. How many batteries and what type would be the best.

I will probably only use the water pumping when grid power is not available. But pre- heating the water all the time. And the grid Im on goes down all the time. I live in Michigan
Any suggestions will be appreciated.

mike95490

Re: water heating and pumping

We need to know what size pump you have, 3.5A 240V ? 8A @120V? 24V 30A? Does the pump run 24/7, or only 3 hours daylight, 7 hours night ? Once we know what sort of load / power the pump draws, it becomes easier to guess at the inverter it needs, the size of battery bank, and what it will take to recharge. Is the pump above ground, or down the well shaft - how long are the pump wires 12 feet or 230 feet?

You generally, only want to drain your battery bank to no deeper discharge than 50%. That means if you want to consume 80AmpHours of power, you need at least a 160AH battery pack. Going with a higher voltage pack (48V) has less wire losses, than the same batteries wired in parallel for 12V What's the voltage of the panels ? (brand, model)

Your 500W of panels will not net you too much in the way of pre-heating water:
1) 500W is not much - you will seldom see more than 400W out of it.
2) 400W will likely be consumed with recharging battery bank.
3) Consider a rapid grid powered charger - so if grid comes back for 5 min or so, you can dump a fast charge into the batteries (you know more than I, how well this may work, if the grid never flickers back on it's pointless)
4) Any consideration for a small backup generator ? How long is the grid down for 4 hours, or 4 days? How much do you need to store in the batteries (500W of panels wont drive too big of a bank)

System2

Re: water heating and pumping

Thank you for your help, the pump probably does not run more than a hour a day at present. It is a deep well and its 125 ft down and about 70 of wire to the panel box, its a 3/4 hp 220AC type. I don't want to use soloar to pump water only in case of grid down.
That is why I want to dump any electric into a hot water heater until needed for water pumping. I just want batteries to be full and ready when I need them for pumping. So the water heater will be good place to put electric when grid is up.
I don't have any batteries yet, don't know what type to get,, I plan on adding more panels after I get the battery back set up. down the road! thanks again

Mangas

Re: water heating and pumping

My well contractor told me there is a pump on the market that runs on AC 220/110 and DC with control box.  Senses voltage inputs.

System2

Re: water heating and pumping


WOW ! If such a pump exists, I would expect it to be VERY expensive. But who knows with modern electronics, the price may drop to where they could become "the standard" pump.
Would be interesting, with only light wires required for 220 Volt AC, but huge wires for 12 Volt DC.
Sounds (a bit, or a lot) fishy though, and it was posted on April Fools Day. LOL
Wayne

Mangas

Re: water heating and pumping

Try this website. Do a search on Solar and select SQFlex Awards. I believe it runs on 30-300 VDC and 90-240 VAC.

http://www.grundfos.com/web/homeus.nsf

System2

Re: water heating and pumping

Back to the original post/question.

Hi, I bought 4 130watt panels, a xantrex c60 controller and a xantrex 4000 inverter last year. I have a big 110vac to 220vac transformer, I still have to get my batteries. I want to put in a additional pre water heater to adsorb the surplus power from the panels. I want to use the c60 to divert the power to heat the water after the battery bank is full. I have a 3/4 hp deep well pump and I want to pump my water with the full charge batteries going through the inverter. My questions are:
1. Can I hook the inverter to the batteries direct or do I need a 2nd c60 controller to go between the battery bank and inverter ?
2. How many batteries and what type would be the best.

Thank you for your help, the pump probably does not run more than a hour a day at present. It is a deep well and its 125 ft down and about 70 of wire to the panel box, its a 3/4 hp 220AC type. I don't want to use soloar to pump water only in case of grid down.
That is why I want to dump any electric into a hot water heater until needed for water pumping. I just want batteries to be full and ready when I need them for pumping. So the water heater will be good place to put electric when grid is up.
I don't have any batteries yet, don't know what type to get,, I plan on adding more panels after I get the battery back set up. down the road! thanks again

I will probably only use the water pumping when grid power is not available. But pre- heating the water all the time. And the grid Im on goes down all the time. I live in Michigan
Any suggestions will be appreciated.

crewzer

Re: water heating and pumping

1. Can I hook the inverter to the batteries direct or do I need a 2nd c60 controller to go between the battery bank and inverter ?
2. How many batteries and what type would be the best.

It’s my understanding that the C60 can be configured for PV charge control, diversion control or load control, but only for one mode at a time. Accordingly, I believe that you’ll need one C60 for a PV controller, and a second one for the diversion controller.

For the PV application, the basic block diagram would be 24 V PV array -> C60 controller #1 (configured for PV charge control mode) -> 24 V battery bank -> 4024 inverter -> AC loads. For the diversion application, the additional connections would be 24 V battery bank -> C60 controller #2 (configured for diversion control mode) -> diversion load (i.e., water heater element).

The Morningstar TriStar controller might also be worth considering for your application.

For your 520 W STC PV array configured for a 24 V system, a 24 V x ~260 Ah battery bank should be appropriate. One configuration would be four 6V T-105 (“golf cart”) batteries wired in series for 24 V x ~225 Ah. Another solution would be a pair of size 8D 12V batteries wired in series for 24 V x ~250 Ah. Both battery types are available in either flooded-cell {cheaper but require equalization, maintenance, ventilation and are ~80% efficient (Wh out / Wh in)}, or VRLA (AGM or gel) models (more expensive, but don’t require equalization, typically don’t require much maintenance or ventilation, but are ~90% efficient).

For your Michigan location, you’ll probably need remote battery temperature sensors for the controllers.

HTH,
Jim / crewzer

System2

Re: water heating and pumping

:-D Thanks Jim, I was wondering on the 2nd charge controller. I have the c60 controllers. I have the outback x-240 for the water pumping. Ill bend up a sheet steel cover for it as its just the bare transformer.
On the 2nd in the book that came with the 4024plus it just shows the block diagram of the set up and off to the side of the solar panel it says (or diversion load) and no details for it. Also in the c 60 book it shows examples of diversion loads. Such as hot water heater elements ran at different dc voltages. Could I just run it at 120 or 240 from the 4024 and with the inverter set up to stop at low battery level and not heat again till the batteries were fully charged? Instead of using a dc element in the water heater. Any comments on which would be better? Thanks again for the information. Wont be too long and I hope to be getting the system put together. Placement of the panels probably will be on the south end of my house Im still in contruction in the basement so Im going to build a closet for it all on south end of the basement. Ill then run 240ac to the other end of house where the well hook up and water heater will be. about 75 feet I would think. Any suggestions on wire size?
I checked on these batteries SunExtender PVX-2240T 224 Amp Hour, 6 Volt. 4 of these for around 900 shipped to Michigan,Would I need 4 of these?

crewzer

Re: water heating and pumping

Could I just run it at 120 or 240 from the 4024 and with the inverter set up to stop at low battery level and not heat again till the batteries were fully charged? Instead of using a dc element in the water heater. Any comments on which would be better?

This will work technically. You’d just to make sure the water heater element is 4,000 W or less.

Whether this is a practical solution for solar energy is another matter. For example, roof-mounted solar water heaters can be as much as 80% efficient. However, considering that PV modules are but ~12% efficient and that the effective system efficiency is but ~67% efficient, that makes PV-based water heating ~8% efficient.

Another issue is that heating water is energy intense. Assuming ~96% efficiency, a 40 gallon electric water heater requires ~3,414 BTU’s (1 kWh) to raise the water temperature by ~10 F. Assuming 2,000 W heating element and 90% inverter efficiency, the batteries will be supplying ~93 A at 24 V. This load will discharge your batteries (~180 Ah at 2 hours rate) by ~50% in one hour.

I suspect that I’d use a second controller and a DC diversion water heater if I were faced with this situation.

Thanks again for the information. Wont be too long and I hope to be getting the system put together. Placement of the panels probably will be on the south end of my house Im still in contruction in the basement so Im going to build a closet for it all on south end of the basement. Ill then run 240ac to the other end of house where the well hook up and water heater will be. about 75 feet I would think. Any suggestions on wire size?

The SW4024’s manual recommends #6 AWG wire for AC cable in conduit between the inverter and the AC subpanel. See page 132. Wire sizes from the subpanel to the loads will depend on the breakers and loads… I’d recommend consulting the NEC.

I checked on these batteries SunExtender PVX-2240T 224 Amp Hour, 6 Volt. 4 of these for around 900 shipped to Michigan,Would I need 4 of these?

These are AGM versions of typical “GC-2” golf cart batteries. They are apparently very good batteries. Four of ‘em in series will work fine as a 24 V x 224 Ah battery bank. AGM batteries are sensitive to overcharging, so I recommend you carefully follow Concorde’s charging and maintenance instructions when configuring your charge controller. If possible, measure the charging voltages at the battery terminals to confirm the controller’s settings. Don’t forget the remote battery temp sensor for the controller. An alternative battery consider is the PVX-2580L… you’d need two in series.

Note that I had a battery-to-battery voltage imbalance problem with my 12V AGM batteries wired in series/parallel. I solved the problem by installing a pair of PowerCheq battery “equalizers”. More info about the problem and the solution is available here.



HTH,
Jim / crewzer