Adding a 3rd Solar panel running out of power!

[chunkytfg]

Hi,

First time poster so go easy please.

I have a simple Van based Solar system with Renogy parts. DCC50S charger, 2kw inverter and a pair of 100W Renogy Panels I've turned into a suitcase style setup with a home made hinges and stand wired in parallel due to max input voltage of DCC50S. Plus 2 50ah Lithium batteries.

We went away for a long weekend and found our system to be a little less than ideal.

The things it mostly powers is

Low watt induction hob(800W)
small Kettle(850W)
Halfrods Fridge cool box(55W Claimed on 240V).
USB outlet for phones etc.
A single 12v LED strip light thats a few Watts I think but barely got switched on.


Obviously the fridge is on all the time and the hob is used once for dinner mainly pasta type food so not used for ages.

I was finding the batteries were not substantial enough to do what I thought was a relatively small amount of use and after the first evening of cooking and boiling the kettle once I resorted to the backup portable gas stove. I'm assuming as much as the Hob and Kettle are big power users the fridge is the issue. We were waking up in the morning to it all being off as the batteries were dead. I was moving the Solar around throughout the day to try and maximise the Watts but once it clouded over a bit I was getting maybe 80W with peaks around 180W.

I was thinking beyond having to leave the Van Idling for a while each day to top it up my options are more solar or more Batteries.

I dont believe the battery bank ever really fully recovered from the first use of the kettle and hob.

If I add more Solar I have the option of 1 panel on the van roof(roof top tent so limited space) which would give another 100W potentially and budget would maybe stretch to a 3rd 50Ah battery.

If I add the 3rd panel it would be paralleled with the first 2 but I would have to wire it direct to the DCC50S and not with the other 2 panels. Would that be an issue?

Extra battery is easy enough as I just add it to the Bank in parallel so I know thats not too much of an issue.

Thoughts?

Youre answers/help is appreciated in advance

 

[MisterSandals]

not substantial enough to do what I thought was a relatively small amount of use

Have you done an energy audit to see how many Wh you need each day?

2 50ah Lithium batteries.

100Ah x 13.3V = 1320Wh

Halfrods Fridge cool box(55W Claimed on 240V).

55W x 24h = 1320Wh ( all of your battery capacity)

200W solar x 5h = 1000Wh (not enough to power the fridge)

 

[chunkytfg]

Thanks for the Reply. Makes things alot clearer. I didnt do an audit but clearly my guess was underestimated by quite a bit.

So looks like I need more of everything!

The Fridge has a 12v cigarette lighter connection too which has a draw of 44W so that will need to be used as it will reduce the usage by 300Wh each day.

So if we assume 13.3v x 150ah thats ~2kWh.

300W solar will give me 1500Wh per day of charge. I can top up with the engine which isnt ideal but its an option.

Usage would be around 1k Wh for the fridge maybe less if I put it on a timer overnight when its colder.

that leaves me 500wh(on solar alone) or 1000Wh assuming fully charged batteries(with the vans help) each day so thats about 35/70mins of hob/kettle usage each day minus extras for phone charging, lights etc.

does that seem right?

 

[MisterSandals]

does that seem right?

There is a link to an energy audit tool in my signature. Doing an audit will be the most informative step in this process.

 

[chunkytfg]

There is a link to an energy audit tool in my signature. Doing an audit will be the most informative step in this process.

Thanks you.

I've filled it in and as my system stands now I need 150ah of battery and 470w of Solar.

My system is capable of handling that but I lack the roof space to fit the Solar. I will likely end up having to cope with 300w and assume I'll need to top it up with the alternator a bit each day.

So lastly in terms of wiring the extra panels, because they wont be part of the briefcase setup I will need to wire them separately. Am I right in thinking I'm okay to wire them direct to the Charger in parallel with the other 2?

 

[MisterSandals]

Am I right in thinking I'm okay to wire them direct to the Charger in parallel with the other 2?

Probably but you have not revealed your panel specs. DCC50 accepts only 25V max right? (this is a terrible design and limitation)

 

[NWC100]

I have a similar set up in some ways, 24v AIO from vevor to manage hook up and inverting, 400w solar (I think one panel not playing nicely though) victron mppt 100/15, victron 24/12 converter, ultramax 24v 60ah lithium battery.

I run a similar fridge to the one below on 24/7, every day 25 mins 800w water heater and a little reheat as required, 1000w induction hob, 1500w air fryer, TV, lights,charging etc..

I think the issue is mainly the fridge drawing so much power, maybe consider changing that first, I presume that it's always drawing power and is of the peltier type cooling? A proper compressor fridge would likely massively reduce the power usage ours runs about 10 -15 mins max every hour in a few 5 min runs, I sleep on top of it sometime and never woken up by it's start up, and definitely better to run on 12v than 240v lots of power lost in having the inverter running all the time as well probably, best to save that for when it's needed and keep it turned off otherwise.

A simple upgrade to a compressor fridge may solve all the woes, prior to fitting my panels we camped by charging the battery on hook up and rarely got below 45% in a 24hr period close to the equivalent of half your bank's available power. This was over winter and running a diesel heater for 2-3 hrs each night.

We have something very similar to the below and works brilliantly, ours runs direct off 24v but can do mains and 12v if required.



I'm not an expert but my thoughts on a similar kind of set up in some ways!

Nick

 

[Tomthumb62]

Our setup is similar to yours, but in a small camp trailer. We're near the Canadian border, so temperate climate compared to places like southern Arizona and we have looong days of sun in the summer.

1000W inverter powers AC fridge, drawing about 1300Wh per day
Other loads are minimal, about 100-200Wh per day
Inverter operates on ECO mode, idle-consumption is about 75Wh per day
We heat and cook 100% with propane

Solar:
400W of panels (now is 300W due to poor installation and we lost one panel and haven't replaced it yet)
30A Renogy Rover solar charge controller MPPT
200Ah LiFePO4
(200W of folding panels but haven't needed to use them yet)
30A AC shore power charger but don't need it unless more than 3 days without good sun

This system finally powers our needs beautifully. Battery is at 70-80% SOC in the morning and fully charged by mid-day. It produces enough power to run the fridge and charge our battery and power the other minimal power needs (water pump, LED lights, couple small fans, charge phones, laptops). Even though we're down a rooftop panel to 300W, it's still keeping up, provided we're in full sun and not shaded. We'll use the folding 200W of panels for when we park the trailer in the shade put the folding ones in the sun or if were in cloudy weather and need to produce more power. I'm guessing that 600W in cloudy weather should produce at least 250W, which would run our fridge and provide a small charge.

Like you, we started out with an underpowered system. We hemmed and hawed over installing alternator charging, even to the point of buying a Renogy 40A DC-DC charger but ended up not doing it due to the complexity of the install and high cost of 45 feet round trip of 2AWG cable. At this point, I'm glad we didn't install the DC-DC charger, because our 300-400W of solar is producing all we need.

Our first system just sucked. It never worked right. The short version of why not is it was a combo of not enough panels period to power our loads and this meant our AGM battery bank received a very very poor charge. AGM are much more finicky about how they are charged compared to lithium. So our AGM bank lost capacity on probably a daily basis to the point that it couldn't run our fridge through the night without sending the inverter into low voltage alarms and shutdown (we came to dread the loud BEEP BEEP BEEP the inverter would spit out every night).

The upgraded system not only has more panels, more/better battery but I also upgraded ALL the wiring to beefier ones. The wiring I had in there would "pass code", but it was the bare minimum. Also, I found a critical loose connection from the SCC to battery on the old system that may have also been contributing to our charging problems.

So that's all to say that were I in your shoes, I would add at least another 50Ah of battery, but another 100Ah would be even better. And 400-700W of panels would be ideal. Since you already have alternator charging, then you know you can always count on a charge no matter what during driving. We also added some insulation throughout our trailer during our upgrade and this has made a huge difference. It's much cooler in there (we have no A/C) and so the fridge isn't running as often.

 

[chunkytfg]

Probably but you have not revealed your panel specs. DCC50 accepts only 25V max right? (this is a terrible design and limitation)

So current panels are 2x 100W

23V OC voltage
19.2V optimum operating V

11.05A SC current
10.42A optimum operating Current

19% efficiency

https://uk.renogy.com/200-watt-12-volt-monocrystalline-solar-panel/. These ones

What I'm looking to add to it with has

21.6V OC Voltage
18.1V Optimum V

10.3A SC Current
9.67A optimum operating Current.

https://uk.renogy.com/175-watt-monocrystalline-solar-panel/. This one.

I'm aware from what I've found online the new panel will drag the current ones down to the lower operating voltage/current thus reducing there efficiency but I'm thinking its a very marginal amount.

I'm restricted by Budget so while I appreciate Renogy isnt the best equipment out there it does serve a purpose.

I'm now realising the restriction the Charger/MPPT has by only having a 25V OC max input and having a separate Charger and Solar controller would be a much better solution but again, restricted to what I've got and what I can do to make It work better.

 

[chunkytfg]

I have a similar set up in some ways, 24v AIO from vevor to manage hook up and inverting, 400w solar (I think one panel not playing nicely though) victron mppt 100/15, victron 24/12 converter, ultramax 24v 60ah lithium battery.

I run a similar fridge to the one below on 24/7, every day 25 mins 800w water heater and a little reheat as required, 1000w induction hob, 1500w air fryer, TV, lights,charging etc..

I think the issue is mainly the fridge drawing so much power, maybe consider changing that first, I presume that it's always drawing power and is of the peltier type cooling? A proper compressor fridge would likely massively reduce the power usage ours runs about 10 -15 mins max every hour in a few 5 min runs, I sleep on top of it sometime and never woken up by it's start up, and definitely better to run on 12v than 240v lots of power lost in having the inverter running all the time as well probably, best to save that for when it's needed and keep it turned off otherwise.

A simple upgrade to a compressor fridge may solve all the woes, prior to fitting my panels we camped by charging the battery on hook up and rarely got below 45% in a 24hr period close to the equivalent of half your bank's available power. This was over winter and running a diesel heater for 2-3 hrs each night.

We have something very similar to the below and works brilliantly, ours runs direct off 24v but can do mains and 12v if required

I'm not an expert but my thoughts on a similar kind of set up in some ways!

Thanks for that info. I'm going to check out the fridge. I looked and changing that as the obvious source of the problem but purely looking are specs the expensive proper fridges draw the same 40-50W. I guess I didnt take into account the fact mines drawing it 100% of the time and not 20% of the time!

 

[chunkytfg]

Our setup is similar to yours, but in a small camp trailer. We're near the Canadian border, so temperate climate compared to places like southern Arizona and we have looong days of sun in the summer.

1000W inverter powers AC fridge, drawing about 1300Wh per day
Other loads are minimal, about 100-200Wh per day
Inverter operates on ECO mode, idle-consumption is about 75Wh per day
We heat and cook 100% with propane

Solar:
400W of panels (now is 300W due to poor installation and we lost one panel and haven't replaced it yet)
30A Renogy Rover solar charge controller MPPT
200Ah LiFePO4
(200W of folding panels but haven't needed to use them yet)
30A AC shore power charger but don't need it unless more than 3 days without good sun

Snip

So that's all to say that were I in your shoes, I would add at least another 50Ah of battery, but another 100Ah would be even better. And 400-700W of panels would be ideal. Since you already have alternator charging, then you know you can always count on a charge no matter what during driving. We also added some insulation throughout our trailer during our upgrade and this has made a huge difference. It's much cooler in there (we have no A/C) and so the fridge isn't running as often.

Thanks for that. My system is set up so it can be removed. I have a 5ft 'coffin' with a 3ft pull out draw/counter top on it that comes out the side door of my small Van with the roof top tent providing cover over it. The remaining 2ft behind the drawer has all the electrical bits in it. its been designed so I can remove it in one go from the van leaving it as a bare normal van when I dont need it.

This means I have very limited amounts of space to place panels hence making a fold up system I can plug in and put to the side of the van on the ground.

I have room for maybe 150-200W of panel behind the roof tent laying flat so hopefully thats going to help along with another 50ah of battery

 

[Tomthumb62]

I'm now realising the restriction the Charger/MPPT has by only having a 25V OC max input

Ouch. That’s a very low max input. If you wrote your 100W panels all in parallel, you’ll be fine except in cold weather. Use a solar temperature calculator to determine how cold the panels can get before they produce more than 25V. If you go over that amount, you’ll fry your MPPT.

 

[Tomthumb62]

Thanks for that. My system is set up so it can be removed. I have a 5ft 'coffin' with a 3ft pull out draw/counter top on it that comes out the side door of my small Van with the roof top tent providing cover over it. The remaining 2ft behind the drawer has all the electrical bits in it. its been designed so I can remove it in one go from the van leaving it as a bare normal van when I dont need it.

This means I have very limited amounts of space to place panels hence making a fold up system I can plug in and put to the side of the van on the ground.

I have room for maybe 150-200W of panel behind the roof tent laying flat so hopefully thats going to help along with another 50ah of battery

I understand small spaces! We're fortunate for a large-ish roof, so we can fit 4x100W up there, could probably fit another one or two as well, but 400W seems plenty for us. But we have no alternator charging. All the equipment except the SCC is in a 12" x 22" x 23" space, including a massive 200Ah lithium battery. Would I do it over again, I would buy one of the SunFunKits batteries and either build my own from that or their pre-built as they are quality builds in a compact package.