I need help picking system components for my size panels

Red · July 2017

Hi all, I'm new to the solar power generation and would like some help. I came across

5 panels, KD140SX-UFBS

4 batteries, Gel type not sure of brand off hand (made for solar)

Charge controller, ProStar 30 version PS-30M

Misc. breakers and wires that came with the original charging system

I've been looking at other peoples systems and was set on having a grid tied with battery backup but its starting to look like it will be much harder to do since my panels are lower voltage than the higher wattage panels. it also looks like having an odd number of panels will also hurt me.

I've looked into the micro inverters such as the enphase m250 and a couple others but it looks like they need higher voltage to stay running. Which I could do by running my panels in series but I also read that the micro inverters can't be hooked to two panels.

My main plan was to get an MPPT charger, a grid tie inverter, and then I was going to hook a 120V coil contactor and time delay relay in line with just a single circuit in my house (my living room) so if I lost power the battery power would be isolated from the grid and I would still have a room with lights, TV, and internet (I know... not really the basics, but the girlfriend would like it).

That is my main plan if anyone can help with components I should use or why my plan wouldn't work let me know. I've watched a lot of videos on other peoples systems and there is always a reason why I think mine just wouldn't work if I did it the same way. So I'm looking for some insight before I just buy something and then find out it wont work.

Thanks in advance,

Steve

Red · July 2017

This is the spec sheet for the panels I have. (KD140)

mike95490 · July 2017

Not sure if you are considering buying this, or if you did buy it.
Gelled electrolyte batteries are NOT suitable for solar, they can only be trickle charged. AGM (absorant Glass Mat) batteries ARE good for solar use, they can accept fast recharge from 5 hours of solar. And 5 panels is tough to use, 4 or 6 is much easier.

bsolar · July 2017

you can find inverters on ebay that function like a ups and can charge your batteries to, i wouldnt even worry about it if its from china personally i wouldnt mess with grid tie, the idea sounds good, but unless your offsetting large loads in the daytime its not worth the aggravation .. thats probably what i would do for a small system like your describing ..... as far as voltage if you need another panel to make it work out then get it ..

Estragon · July 2017

As bsolar mentioned, what you've described is more of a UPS application. It's only grid tied in the sense that battery charging will be primarily from grid, with solar charging during grid outages. An off-grid inverter/charger should include an internal tranfer switch to handle th transition.

Your next step should be to figure out the maximum instant load and running wattage your tv etc will draw.

It would simplify wiring if all the backed-up loads are on the same branch circuit.

Estragon · July 2017

Also, with the right controller, the 5 panels can be wired in series so shouldn't be a big problem.

Red · August 2017

Alright I have a new question.

What would you guys do with these panels? It doesn't have to be a big power maker or really good with batteries. I got all of this for free and this is basically an experiment to see if I want to actually get a bigger and better system.

I can have 90Vdc and 140W in series or 18Vdc and 700W in parallel
my 4 batteries are 8G30H DEKA solar gel batteries. (Spec sheet attached)

Please include parts/chargers that you would use. I'm just starting in this and don't have a good feel on how everything combines. After I make one system (with your help), I'll be able to get a better grasp and make a better system with better components in the future.

Model Number

Type

Voltage

5 hr Rate

20 hr Rate

100 hr Rate

Watts Per Cell

Weight (lb.)

Length (in.)

Width (in.)

Height* (in.)

8G30H-DEKA

Gel

12

80.5

97.6

108

N/A

68.5

12.93

6.74

9.75

Estragon · August 2017

As an experimental system, you probably want to keep your costs reasonable. A Morningstar Tristar 45 PWM charge controller, $167 from our host, would work okay.

For charging with no sun, an Iota dls45 charger, $133.

You haven't quantified loads, but something like as Samlex 600w pure sine wave inverter, $209, may work for a tv, router, and a few lights.

This would be a simple low cost system with no automatic transfer from grid to battery. To power loads, you'd unplug them and plug them into the inverter. With breakers, wire, and a box, roughly $600.

To do it with an MPPT controller, and inverter/charger with transfer switch, closer to $2,000.

Raj174 · August 2017

Hi Red,
Wiring all the panels in parallel will not produce 700 watts. It would be closer to 470 watts. PWM controllers do not down convert the voltage above 12 volts to usable power. If you want 700 watts then you need an MPPT charge controller and wire all the panels in series. If you configure the batteries to 24 volts, 2 parallel strings of 2 batteries, then an MPPT controller like the Midnite Kid would be able to down convert the 90 or so volts to charging voltage for the 24 volt battery. The full 700 watts minus about 20% due to heat losses, would be available to charge the battery. The charge current in full sun should be about 23 amps, or about a 12% charge rate.
This is the way I would do it, but it's just one of several ways to build a system with the components that have been discussed.

Rick

I need help picking system components for my size panels

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