Upgrade from PWM to MPPT controller

Kentill

I would like to upgrade my system to a TS-MPPT-45 charge controller. I would like to keep the 12v batteries.
Yes I know 24v system is better all away around but I don't want to buy a new 24v PSW inverter right now.
Below are the panel spec.

Pmax. 150 Watt
Vmpp 18.5 V
Impp 8.11 A
Voc 22.2 V
Isc. 8.88 V

My questions is do you think the TS-MPPT-45 can support 4 - 150 watt panels in parallel or in series?
The other question, will the above panels support a 24 V battery bank?

Thank
Kent

waynefromnscanada

Re: Upgrade from PWM to MPPT controller

Hi Kentill, welcome to the forum!
Yes, the TS-MPPT-45 would handle those 4 panels no problem. Assuming they were putting out full power, it would translate to roughly 33 amps @ roughly 12 volts, well below the 45 amps max output. However, if there is ANY chance you might later want to expand your system, for the price difference, you might consider the TS-MPPT-60.
Also, I would highly recommend you wire the panels in two parallel strings of two in series. The VMPP of 18.5 volts is too close to the battery voltage, and with two in series, it would give you a VMP of roughly 37 volts at half the amperage, thus reducing line loss between the panels and the controller, AND giving a more or less ideal input voltage for the controller when charging a 12 volt battery. Leaving the panels all in parallel, will reduce or eliminate any gain the MPPT controller could otherwise provide, rendering it of little more use than your old controller.

westbranch

Re: Upgrade from PWM to MPPT controller

What are your loads?
The panels probably should support a 24 V system, of the same size loads as you have now, assuming it works for you, but we need to balance the loads with the panels or Visa versa...
ps all your wiring should be well sized if going to a 24V setup.

Icarus rule #1 loads always grow over time.

Kentill

Re: Upgrade from PWM to MPPT controller

The system was setup originally to learn about solar and provide backup power when we don't have the grid available. We lose power 2 - 3 time a year anywhere from 3 hrs to 20 hrs. Since last Summer I have preformed many test with the batteries and the panels.
With 4 batteries and only 3 panels in September I was able to add 900 watts back into the batteries in 4 hrs. Project has been very enlightening and fun.

vtmaps

Re: Upgrade from PWM to MPPT controller

Kentill wrote: »

The system was setup originally to learn about solar

Plan ahead! If this system grows you will want to be at 24 volts. At that point you will need a new inverter.

When you go 24 volts, your MPPT controller will still be part of the system and will have double its 12 v capacity. Your four batteries can be reconfigured to work at 24 volts.

Your panels can be reconfigured to supply higher Vmp per string (you might want more panels, also).

I suggest you make a paper design of where you might want to be (24 volts) and see if it helps you make decisions now at 12 volts.

Any chance you might want to be grid-interactive in the future?

--vtMaps

Kentill

Re: Upgrade from PWM to MPPT controller

vtmaps wrote: »

Any chance you might want to be grid-interactive in the future?

--vtMaps

No chance of going grid-interactive, my house roof faces west so adding panels on the roof would be expensive. Currently the panels
Are on the roof of my back yard shed.
I have a Honda eu3000i and a eu2000i that I use when the grid power goes down for long periods. Usually a neighbor or friend gets to use the small eu2000i. The solar would be used for short term outages since it is easy to push the inverter remote button and have instant power without starting the generator. I would love to get off the grid but at my age it's just not in the cards.
Thanks for everyone replying

westbranch

Re: Upgrade from PWM to MPPT controller

Kentill wrote: »

No chance of going grid-interactive, my house roof faces west so adding panels on the roof would be expensive.

If you have an E/W array orientation you can have panels facing in 'opposite' directions for a 'virtual tracker ' effect. The mid-day peak output is just a bit lower.

Kentill

Re: Upgrade from PWM to MPPT controller

westbranch wrote: »

If you have an E/W array orientation you can have panels facing in 'opposite' directions for a 'virtual tracker ' effect. The mid-day peak output is just a bit lower.

I like the idea of virtual tracker but my neighbor would be very unhappy. How does the total output compare with South faced panels?

BB.

Re: Upgrade from PWM to MPPT controller

Try PV Watts... Just run your East/West results vs a pure south facing array 2x as large as an individual array.

In some-places, like my area in California, we have 1 year net metering with time of use... Meaning we get 3x as high ($0.30 vs $0.10 per kWH) of payments for summer weekday afternoons.

So, for my area, a West facing GT connected array is actually a "good thing".

-Bill

Kentill

Re: Upgrade from PWM to MPPT controller

BB. wrote: »

Try PV Watts...

-Bill

I like the PV calculator, I think it said I would need 4kw of DC and 3kw. AC. The other problem is that I have trees in front and in back. I'm sure the neighbors would not like to cut their trees down.
Kent

BB.

Re: Upgrade from PWM to MPPT controller

Solar is all about location/access to sun... If you have trees/buildings that shade your roof--It is usually not even worth trying.

Solar panels only generate power when illuminated by direct sunlight (roughly between 9am-3pm). Sometimes, you can do OK with a pure East or a pure West array--but it takes more calculations and understanding of your loads/power requirements.

You already have a battery based systems--How it is performing for you now. And how many more panels can you fit "in good light"?

-Bill

Kentill

Re: Upgrade from PWM to MPPT controller

BB. wrote: »

Solar is all about location/access to sun...
You already have a battery based systems--How it is performing for you now. And how many more panels can you fit "in good light"?

-Bill

My shed is only 10X12 and 4 - 150 Watt panels take most of the roof space. Am I happy with what I have, no i would like more but I have no space available. However a 24 v system looks attractive.
Thanks for all the info.
Kent

Kentill

Re: Upgrade from PWM to MPPT controller

I have been thinking about changing from a 12 v system to a 24 v system however now my PWM cc charges my 330 Ah battery bank at about c/14 which is a little low. My research says if I use a MPPT cc my new charge current would only be 20 amp at 28.8 volts Or the new amps in are c/16? And if that is correct will c/16 be enough to charge my battery bank properly?

Cariboocoot

Re: Upgrade from PWM to MPPT controller

A 600 Watt array on an MPPT charger to a 24 Volt bank should supply about 19 Amps peak. If your 330 Amp hour bank can be reconfigured to 24 Volts it would be 165 Amp hours and the charge rate would be 11% or around C/10.

Right now you should have a peak of about 34 Amps to the 12 Volt 330 Amp hour bank, and that would be 10% or C/10 also. In other words the change would be small in theoretical numbers, but the system will be slightly more efficient over-all.

If you change the battery bank in Volts and Amps the result will be different.

Kentill

Re: Upgrade from PWM to MPPT controller

Ok what you are saying is watt are watts and I can agree with that. I have come to the conclusion that I must change to 24v.
That's good news thanks.
Kent