1st post from a solar newby re solar generator

[Eot]

I'm a retired senior new to Solar anything. This summer I purchased a new to me older SOLGEN generator. Not sure how old it is but seems to perform as expected. It came with 2 Renogy RNG-100D Solar Panels, LMS2430 PWM Controller, 1500 watt 3000 peak pure sine wave inverter and 2 UB121000 agm sealed lead acid batteries.

I have a 5500 watt gas generator for backup of fridge/freezer when power goes out but really like the quietness of solar generators and would like to explore the direction of taking this setup a bit further towards replacing the gas generator if it's financially feasible. Considered for a moment a compact generator with lithium battery but the price is more than I want to do on a fixed income.

My research has told me my solar unit is probably 5-7 years old and the controller probably needs traded out for an mppt controller and I shouldn't mix new storage batteries with old as well as I can really only use about 50% of there capacity. Appears I can add panels for $100 each.

I realize today's technology is much better than what I have and not interested in throwing a lot of money into this unless it is beneficial in moving closer to being able to part with the gas noise maker.

Sorry for the length of this and thanks in advance for any advice you can offer.

 

[snoobler]

Welcome to the forum.

Step 1 is to determine how much energy your fridge and freezer use. A kill-a-watt meter is very useful for this purpose.
Step 2 is to determine how much solar you have available (link #5 in my signature).
Step 3 is to use the above two to size your battery and panels.

At a guess, if you have a full size fridge and a chest freezer, I'm going to guess you need 3-4kWh/day.

That means you'll need 3-4kWh/day of usable battery capacity. For lead-acid batteries, that's a lot. Assuming you get 4 solar hours per day (equivalent hours of high-noon charging you get from charging all day), you'd need 750-1000W of solar.

 

[Hedges]

If a single fridge/freezer combo, maybe 1500 Wh/day.
Looking up the consumer information energy label should give a good idea.
The inverter should be sufficient to run it.
Best to turn off icemaker when running off PV. Also turn off defroster.
No need to power it at night (especially if top-freezer, which spills air to refrigerator.) That way battery is just for starting surge and flattening out power during the day.
Inverter probably has significant no-load power draw, approaching what some efficient refrigerators consume on average. So turning off the inverter rather than just putting a timer on AC side would be better.

1500Wh/4hours = 375W (actual production, not PV label STC rating)

If you pick up two or more used panels, 250W to 400W, that might do it. We pay $0.12 to $0.50/watt from some out of state vendors, but that costs shipping. You can probably find some nearby.
Two panels oriented differently will level production during the day.

A DMM able to measure 10A as well as voltage would let you check short circuit current and open circuit voltage, make sure they are performing reasonably in direct light.

 

[Eot]

Thanks snoobler & Hedges for your quick replys and helpful quidance. Any suggestions on my analysis that I need to replace the controller and if so, anything specific?

 

[2009Bounder2020]

get the panels figure out first then size the charge controller accordingly

 

[Hedges]

I think MPPT is better for most situations. PWM can be OK and economical for some.

They vary in output current, battery voltage, and maximum PV voltage (absolute limit, use PV Voc adjusted for cold day.)
You need to decide how many watt hours you need and tentatively pick PV panel model and quantity. Then you can select equipment.

SanTan solar has deals on PV panels and several models SCC available.
As I suggested, local sources for small number of PV panels would save on shipping, but check out SanTan's SCC.
Given 12V (my assumption) and up to 1000W of PV, you might want at least 80A SCC.

Epever 8420AN 80A MPPT Solar Charge Controller - SanTan Solar Store

Buy our Epever 8420AN 80A MPPT Solar Charge Controller for only $380. Click the link to start shopping today!

store.santansolar.com

But that gets up there in price.

If you had 800W of PV, half the panels oriented at 9:00 AM sun and half at 3:00 PM, I'd estimate peak 560W, about 45A into 12V.
A 40A SCC is considerably less expensive

Epever 4210 40A MPPT Solar Charge Controller - SanTan Solar Store

The Epever 4210 40A MPPT Solar Charge Controller has high quality and low failure rate components to ensure service life. Only $140!

store.santansolar.com

This is where designing the whole system upfront lets you right-size things and be more efficient with money.

Considering that PV panels can be had sometimes as cheap as $0.12/W ($120 for 1000W), Bounder's suggestion to just buy them first isn't bad. But better to get extras than not enough, since you may not find any more later. When I buy a lot of panels I get a couple extras in case I break one.

 

[2009Bounder2020]

depending on panel voltage and amps, you might be better with 2/3 smaller mppt chargers
i run 8 panels on the roof of our rv, 2 panels on each 15 amp mppt controller. i do it because of shading , helps maximize for the environment the rv is used in.

 

[Eot]

get the panels figure out first then size the charge controller accordingly

Thanks 2009Bounder2020 for your reply. I agree with your suggestion. PANELS aren't too expensive so I think I'll start with a couple of additional panels and go from there. Now I need to determine what my LMS2430 can handle before replacing it. I have a smaller spare Fridge to start experimenting with. Also, I think I'll look into purchasing a watt meter and start gathering some usage numbers..

 

[Eot]

I think MPPT is better for most situations. PWM can be OK and economical for some.

They vary in output current, battery voltage, and maximum PV voltage (absolute limit, use PV Voc adjusted for cold day.)
You need to decide how many watt hours you need and tentatively pick PV panel model and quantity. Then you can select equipment.

SanTan solar has deals on PV panels and several models SCC available.
As I suggested, local sources for small number of PV panels would save on shipping, but check out SanTan's SCC.
Given 12V (my assumption) and up to 1000W of PV, you might want at least 80A SCC.

Epever 8420AN 80A MPPT Solar Charge Controller - SanTan Solar Store

Buy our Epever 8420AN 80A MPPT Solar Charge Controller for only $380. Click the link to start shopping today!

store.santansolar.com

But that gets up there in price.

If you had 800W of PV, half the panels oriented at 9:00 AM sun and half at 3:00 PM, I'd estimate peak 560W, about 45A into 12V.
A 40A SCC is considerably less expensive

Epever 4210 40A MPPT Solar Charge Controller - SanTan Solar Store

The Epever 4210 40A MPPT Solar Charge Controller has high quality and low failure rate components to ensure service life. Only $140!

store.santansolar.com

This is where designing the whole system upfront lets you right-size things and be more efficient with money.

Considering that PV panels can be had sometimes as cheap as $0.12/W ($120 for 1000W), Bounder's suggestion to just buy them first isn't bad. But better to get extras than not enough, since you may not find any more later. When I buy a lot of panels I get a couple extras in case I break one.

I really like the idea of orienting the panels in at different angles. I certainly hadn't thought of that. Simple to do with my method of mounting my panels on poles with satellite dish mounts as this allows me to adjust my degree of angle accurately.

Now to decide the wattage of panels I can safely add to my controller without overloading it.

 

[Eot]

Anyone have suggestions on a specific watt meter that won't break the bank?

I revise, thanks snoobler. I see where you made a suggestion for the meter $25 at HF. Not bad!

 

[Hedges]

Anyone have suggestions on a specific watt meter that won't break the bank?

Everyone here says Kill-a-Watt (although I haven't tried it)

Kill A Watt - Wikipedia

en.wikipedia.org

KILL A WATT Electric Monitor

Amazing deals on this Kill-A-Watt™ Electric Monitor at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

For your fridge, search for a consumer energy label on-line. I've found them for many models, with typical home fridges shown at about 1500 Wh/day.

I have some test equipment so I logged AC amps and watched the cycle. Discovered I had the icemaker enabled even though no water was connected, so it continuously tried to make ice out of thin air, never stopped because the container never filled up.

Kill-a-Watt would be simpler to use but wouldn't have necessarily helped me find my "operator error".

With a scope I was able to capture start-up surge amps. Only checked a window A/C, which showed 5x the nameplate rating.

 

[Hedges]

I really like the idea of orienting the panels in at different angles. I certainly hadn't thought of that. Simple to do with my method of mounting my panels on poles with satellite dish mounts as this allows me to adjust my degree of angle accurately.

Now to decide the wattage of panels I can safely add to my controller without overloading it.

I think this is your charge controller

Amazon.com : Global Solar Supply presents the LMS series intelligent solar charge controller 12/24 VDC 30 Amps with LCD display, 2 USB ports and load controler model # LMS2430 : Garden & Outdoor

Amazon.com : Global Solar Supply presents the LMS series intelligent solar charge controller 12/24 VDC 30 Amps with LCD display, 2 USB ports and load controler model # LMS2430 : Garden & Outdoor

www.amazon.com

"System voltage of PV: 40V Maximum voltage of PV: 30A Maximum discharge current: 30A Maximum output voltage: 12V/24V Maximum output power: 360W/720W"

Because it is PWM, it should only be used with "12V" panels if 12V battery, or "24V" panels if 24V battery.

The 40V max input may not let you use some "24V" panels that you could consider getting.
So you may just pick up panels and measure them but not connect to PWM, select MPPT to purchase next.

This panel for instance is 44 VOC

SunTech 285W | SanTan Solar

store.santansolar.com

This one is 37.6 VOC, but that is so close to 40V that on a cold day the Voc could rise above 40V and kill the charge controller.

Used SanTan 250W Solar Panel | SanTan Solar

store.santansolar.com

 

[Eot]

I think this is your charge controller

Amazon.com : Global Solar Supply presents the LMS series intelligent solar charge controller 12/24 VDC 30 Amps with LCD display, 2 USB ports and load controler model # LMS2430 : Garden & Outdoor

Amazon.com : Global Solar Supply presents the LMS series intelligent solar charge controller 12/24 VDC 30 Amps with LCD display, 2 USB ports and load controler model # LMS2430 : Garden & Outdoor

www.amazon.com

"System voltage of PV: 40V Maximum voltage of PV: 30A Maximum discharge current: 30A Maximum output voltage: 12V/24V Maximum output power: 360W/720W"

Because it is PWM, it should only be used with "12V" panels if 12V battery, or "24V" panels if 24V battery.

The 40V max input may not let you use some "24V" panels that you could consider getting.
So you may just pick up panels and measure them but not connect to PWM, select MPPT to purchase next.

This panel for instance is 44 VOC

SunTech 285W | SanTan Solar

store.santansolar.com

This one is 37.6 VOC, but that is so close to 40V that on a cold day the Voc could rise above 40V and kill the charge controller.

Used SanTan 250W Solar Panel | SanTan Solar

store.santansolar.com

That is my SCC. My understanding is that I'm not going to be able to add very much wattage to my system before I max my SCC?

 

[Hedges]

If you have two of these 100W "12V" 6.4A Isc panels

https://www.renogy.com/template/files/Specifications/RNG-100D-R.pdf

You could probably add two more.
With PWM, the panels will never deliver rated wattage. Rather, something between Imp and Isc.
Four panels would deliver up to 25.6A, which is within the capability of the SCC.

But, I think you're better off getting higher wattage, higher voltage second hand PV panels and an MPPT charge controller.

 

[Eot]

Thanks for that info. Yes, shipping fairly steep. Doubles the price. By the way, how do you turn off defroster on fridge? By disconnecting it internally?

 

[Hedges]

Might be a switch.
I saw one switch labeled for frost between doors. That seems to be an additional heater, but maybe combined with defrost. "Power Save/Moisture Control". You could try turning off such a switch when running on battery during power failures. Off-grid we would rather have it controlled by a light sensor or something like that.

My upright freezer has a mechanical timer underneath in the back that switches on heater, could probably be unplugged there.
But in general good to have defrost cycle, runs indefinitely without icing up.
Big pocket of ice between my top freezer and fridge, I defrosted extensively and jacked up front wheels so door closes itself and water might drain back.

My icemaker I had left the bail down. Raising it turned it off. I had been stuffing things into the area to store, have now removed the icemaker.

 

[Eot]

Might be a switch.
I saw one switch labeled for frost between doors. That seems to be an additional heater, but maybe combined with defrost. "Power Save/Moisture Control". You could try turning off such a switch when running on battery during power failures. Off-grid we would rather have it controlled by a light sensor or something like that.

My upright freezer has a mechanical timer underneath in the back that switches on heater, could probably be unplugged there.
But in general good to have defrost cycle, runs indefinitely without icing up.
Big pocket of ice between my top freezer and fridge, I defrosted extensively and jacked up front wheels so door closes itself and water might drain back.

My icemaker I had left the bail down. Raising it turned it off. I had been stuffing things into the area to store, have now removed the icemaker.

So I purchased a Kill A Watt meter and determined that my freezer used 0.82KW/day and my fridge used 0.97 KW/day which I'm rounding up to approx 2 KW/day. I'm considering due to my storage batteries being AGMs and several years old that at bare minimum I need to upgrade to deep cycles and purchase additional panels. Question, any recommendations on battery and number of batteries as well as panels and wattage of panels while staying with my inverter and charge controller?

 

[Hedges]

I suggest power the freezer and fridge only during the day, when sun and PV can power them. No reason to try to supply them at night from a battery.
Maybe your existing AGM batteries will still do fine, if they can feed any nighttime loads you have.
But if they've been deeply cycled many times and don't supply what you want, then could replace.

If you did run the fridge/freezer at night, 2kWh/day would be 1 kWh/night or 80 Ah at 12V (plus something for inverter inefficiency).
The 155Ah AGM on SanTan's site would be drained 50% every night, so that's the minimum size and its life would be shortened.
Having 200 Ah to 300 Ah would last longer with that much drain (but not necessarily be any cheaper per year of life.)
I use SunXtender which has longer cycle life than some.
Rolls and other names, some wet-cell FLA, have much longer life.

You can check websites for insolation/weather estimates. Typically, 5.5 hours/day average effective sun throughout the year, 2 hours/day in winter. Panels might put out 80% of their STC rating. So 1200W of panels could make 2000 Wh/day in winter, 5000 to 6000 Wh in summer.

A PWM charge controller is most appropriate for a smaller system. I suggest getting MPPT, with current rating for any planned expansion.
Santan has charge controllers and panels (which would have to ship by truck on a pallet.) For a small order of 3 to 5 panels you may get a lower total price somewhere local, check Craigslist and eBay for sellers.

Affordable Solar Panels & Accessories: New & Used Available!

Discover our affordable solar panels & accessories! Explore our range of new & used solar options to power your sustainable lifestyle efficiently. Shop now!

www.santansolar.com

Your sine wave inverter 1500 continuous/3000 surge should be able to start and run both.

 

[Eot]

I suggest power the freezer and fridge only during the day, when sun and PV can power them. No reason to try to supply them at night from a battery.
Maybe your existing AGM batteries will still do fine, if they can feed any nighttime loads you have.
But if they've been deeply cycled many times and don't supply what you want, then could replace.

If you did run the fridge/freezer at night, 2kWh/day would be 1 kWh/night or 80 Ah at 12V (plus something for inverter inefficiency).
The 155Ah AGM on SanTan's site would be drained 50% every night, so that's the minimum size and its life would be shortened.
Having 200 Ah to 300 Ah would last longer with that much drain (but not necessarily be any cheaper per year of life.)
I use SunXtender which has longer cycle life than some.
Rolls and other names, some wet-cell FLA, have much longer life.

You can check websites for insolation/weather estimates. Typically, 5.5 hours/day average effective sun throughout the year, 2 hours/day in winter. Panels might put out 80% of their STC rating. So 1200W of panels could make 2000 Wh/day in winter, 5000 to 6000 Wh in summer.

A PWM charge controller is most appropriate for a smaller system. I suggest getting MPPT, with current rating for any planned expansion.
Santan has charge controllers and panels (which would have to ship by truck on a pallet.) For a small order of 3 to 5 panels you may get a lower total price somewhere local, check Craigslist and eBay for sellers.

Affordable Solar Panels & Accessories: New & Used Available!

Discover our affordable solar panels & accessories! Explore our range of new & used solar options to power your sustainable lifestyle efficiently. Shop now!

www.santansolar.com

Your sine wave inverter 1500 continuous/3000 surge should be able to start and run both.

Thanks HEDGES for the quick response and helpful info. I must admit, I'm a little slow in my absorption rate these days. Will take a bit for me figure what questions I may still have.

 

[Eot]

I did think of 1 question. Is there a sure fire way to test my batteries short of connecting the freezer/fridge on full charge batteries?