Solar and small appliances

[carolanded]

We have a new DRV Mobile Suites equipped with two 190 watt Solar panels, and a 2000 watt inverter. No generator.
This is our second time out in it and our first time dry camping for a weekend. We rarely dry camp in the 30 years we’ve been using RVs, maybe only once or twice. Solar is new to us. Should the solar be able to power my hairdryer, Keurig coffee maker, toaster, etc.? Right now we’re not able to use any of that.

[John Hilley]

A lot depends on your battery capacity. With fully charged batteries and full sun you should be able to use those types of things for a few minutes. A battery monitor that can keep track of amps in and out is necessary to let you know what you can power at any one time.

[phfkef]

You have to be careful with respect to the current that you draw. For instance your 1200 watt hair dryer ( look it's label to get actual wattage) at 12 volts will draw 100 amps. That amounts to a lot of heat. Make sure that your 12 volt side right up to the inverter has very heavy gauge wiring.

[2Yung2 Quit]

Does your inverter power the whole panel, and all the outlets, or just a limited number of circuits? Our 1k watt inverter only powers the refrigerator outlet.

[Persistent]

Originally Posted by carolanded

We have a new DRV Mobile Suites equipped with two 190 watt Solar panels, and a 2000 watt inverter. No generator.
This is our second time out in it and our first time dry camping for a weekend. We rarely dry camp in the 30 years we’ve been using RVs, maybe only once or twice. Solar is new to us. Should the solar be able to power my hairdryer, Keurig coffee maker, toaster, etc.? Right now we’re not able to use any of that.

380 watts of solar panel cannot power the heat producing devices you listed. Watts are watts whether 12 or 120 volts. The panel is 1600 watts short of enough.
The inverter draws 12 volt power from the battery, charger, and the solar. To produce 2000 watts of 120 volt power, it needs about 170 amps at 12 volts. Most or all of that would have to come from the battery bank. A 350 amp hour battery bank could provide that for an hour or so.
A 100 amp hour battery bank probably cannot deliver enough current to power a 2000 watt inverter under heavy load. The inverter will probably trip out due to low voltage from the battery. What size is your battery bank in amp hours?

A 380 watt solar panel may take 3 or 4 days to replace that one hour of use providing no other 12 volt appliances are used during that period.

I wish you good luck and happy trails ahead.

[1bigmess]

Some really good info here on batteries, power, and recharging.

The 12volt Side of Life (Part 1)

[Mark_K5LXP]

I would offer that most people don't spend an hour drying their hair, making coffee or toast. These are loads you might see for what, 5 minutes? There still is the issue of if the batteries have the "guts" to supply this amount of current for even 5 minutes but from a watt hour point of view this isn't a huge amount of power.

Efficiencies aside, 1200W is 100A at 12V, which for an hour would be 100Ah. But just 5 minutes of that load is 8.3Ah. Even applying worst case efficiencies that might be 10Ah, which is not a huge amount to recover.

You'll find out in a hurry if your batteries are up to it, depending on their merit and cabling you'll see the voltage dip when the load is applied and how far it dips will determine how long that load can be sustained before the inverter low voltage setpoint trips. In my view there's no reason to not at least try it.

Mark B.
Albuquerque, NM

[followingsea]

Originally Posted by carolanded

..... Should the solar be able to power my hairdryer, Keurig coffee maker, toaster, etc.? Right now we’re not able to use any of that.

I can do all those things one at a time with my 4 GC2 batteries assuming they they are charged and I have clean battery terminals.

However, I do not do those things when dry camping. For example, I use a French press when dry camping.

You have just learned the practical lesson of solar. The reason to have solar is to tell people you have solar.

I have a list of expensive things they sell at CW that others well tell you need while sitting around the campfire.

I am full time and do not need them. I watch the week end warriors pull in and unpack and then pack up again. It is an interesting ritual.

[astrocamper]

It can be done with much a larger system. I have four 100 amp-hour LiFePO4 BattleBorn batteries and a 2200 Spartan pure sine wave inverter that can surge to 6600 watts. I installed 1405 watts of solar on the roof. I replaced my 13500 air conditioner with a 11000 power saver version that can run on much less wattage.

LiFePO4 batteries are capable of sustaining much larger inverter loads for a longer period. My four batteries can surge to 800 amps for 30 seconds and sustain 100 amps for about an hour.

We run our microwave and toaster at the same time. We don't run an hair blower because we don't use one. We run our Vitamin for fruit shakes and blended drinks.

After changing out my air conditioner for a more efficient version we can run our air conditioner from about 11 AM until about 6PM with out running down our batteries.

LiFePO4 batteries are capable of sustaining much larger inverter loads for a longer period. My four batteries can surge to 800 amps for 30 seconds and sustain 400 amps for about an hour. My batteries are slightly discharging when the air conditioner compressor is running and quickly recharging when the compressor cycles off.

LiFePO4 batteries also waste less energy during the charging cycle and charge faster all the way to 100% state of charge compared to lead acid.

With your smaller system, you probably should use a generator for the times you are using the microwave, toaster or hair dryer for more than a couple of minutes.

My previous trailer had 240 watts of solar, two Trojan T105 batteries and a 1000 watt pure sine wave inverter. I would use it to run the blender and vacuum. All the rest of my loads ran directly on 12 volts.

[creativepart]

Basically what everyone is saying is that it’s your battery bank that powers those devices through your inverter. Not your solar cells. All your solar does is charge your batteries.

So no, you can’t run those items off of your solar cells.

IF you have 400aH of battery bank available AND those batteries are fully charged, then sure, you can run those items one at a time for short periods. Unless you have other large loads running at the same time - things like the electric water heater, coffee maker or microwave also running at the same time.

Your solar charge controller doesn’t count as a load, it just takes power from your panels and applies it to your battery bank.

Also some inverters will only allow large load (read heat) appliances to run for short periods and then cut out so they don’t draw too much power too fast.

[steve52]

Originally Posted by followingsea

You have just learned the practical lesson of solar. The reason to have solar is to tell people you have solar.

And here I thought it was so I could charge batteries without running a genny...

[richard5933]

I've got four L16 six volt batteries, with a total of 780 Ah. We have a 1500 watt element in our water heater. I can run it for about 10-15 minutes before the voltage drops below the cut off on the inverter. It is enough to warm up enough water to wash up in the morning if absolutely necessary.

I really set this up as a test of the system. It does work, but I wouldn't want to rely on it. Even with 560 watts of solar capable of charging at 30 amps, it's a stretch to get the batteries fully charged again during the day if I use the inverter for heavy loads like this for more than a few minutes. And if it's a cold night and I used the batteries to power the furnace blower (plus our 12v fridge) I start the day with a deficit.

In my opinion, to run heavy loads like this requires a system built for it with a high-capacity battery bank and enough solar to recharge with the sun & time available. It's also necessary to use very heavy cables to between the battery and the inverter, like the 2-0 we're running.

[whiterhino]

Originally Posted by astrocamper

It can be done with much a larger system. I have four 100 amp-hour LiFePO4 BattleBorn batteries and a 2200 Spartan pure sine wave inverter that can surge to 6600 watts. I installed 1405 watts of solar on the roof. I replaced my 13500 air conditioner with a 11000 power saver version that can run on much less wattage.

LiFePO4 batteries are capable of sustaining much larger inverter loads for a longer period. My four batteries can surge to 800 amps for 30 seconds and sustain 100 amps for about an hour.

We run our microwave and toaster at the same time. We don't run an hair blower because we don't use one. We run our Vitamin for fruit shakes and blended drinks.

After changing out my air conditioner for a more efficient version we can run our air conditioner from about 11 AM until about 6PM with out running down our batteries.

LiFePO4 batteries are capable of sustaining much larger inverter loads for a longer period. My four batteries can surge to 800 amps for 30 seconds and sustain 400 amps for about an hour. My batteries are slightly discharging when the air conditioner compressor is running and quickly recharging when the compressor cycles off.

LiFePO4 batteries also waste less energy during the charging cycle and charge faster all the way to 100% state of charge compared to lead acid.

With your smaller system, you probably should use a generator for the times you are using the microwave, toaster or hair dryer for more than a couple of minutes.

My previous trailer had 240 watts of solar, two Trojan T105 batteries and a 1000 watt pure sine wave inverter. I would use it to run the blender and vacuum. All the rest of my loads ran directly on 12 volts.

Admittedly I have not started running AH and wattage numbers so I'm new at this.
We have always had an on-board genny and a dual 110/propane fridge but just sold our RV and are looking at 5ers with residential fridges and no genny. When on vacation we frequently spend the nights in a rest stop. Knowing that the tow rig will be charging the batteries while driving, I know that the fridge will sustain overnight. But what about needing AC on hot summer nights?

Doing a quick search on the LifePO4 batteries, those puppies are expensive! I'm wondering which ones you have?

Would you share a budgetary number of what you have invested in your system? inverter, batteries, solar, etc?

[astrocamper]

It's my solar charging that sustains the air conditioning. The four BattleBornBatteries are 100 amp hour and can sustain high charging and discharging rates efficiently. My original 13500 air conditioner pulled about 160 amps DC out of my system through the inverter. I replaced it with a 11000 power saver unit that only pulled about 110 amps.

I am adding another 300 watts of portable power for those times were I am parked for 4 - 8 nights at an astronomy event without shade. The 300 watts + 160 watts on truck roof + 1405 watts on trailer roof will give me more charging capability. The 300 watts tilted towards the sun after 5PM will help improve my solar charging when the sun is lower in the sky but hasn't yet set. I have a 25 foot 4 AWG power pole cable that can go from my trucks solar to my trailer battery bus bars. The 300 watt solar array will be running as two parallel banks of three 50 watt 12 volt panels in series. The higher voltage will reduce voltage drop until the cable reaches the MPPT controller next to the trailer battery bus bars. I will rotate the portable array a few times a day to keep it facing the sun at about 40 degrees tilt.

When I am camped at an astronomy event under full sun for several days I will put up a 20 foot long 14 foot wide Alluminet 70% shade fabric on the south side (fridge) of the trailer. My awning and door is on the north side. This keeps my fridge and the south wall of the trail in the shade all day so even less air conditioning is needed. I have a cable attached to my solar panel brackets the full length of the roof. I use bungee balls to secure the grommeted fabric to the vinyl clad steel cable. The other side of the 14 wide fabric is tied to rope staked in the ground every 4 feet. This gives me a shaded area but the fabric allows the wind to blow through so it don't pull on the trailer in high winds.

The batteries are slightly discharging when the air conditioner compressor is on with only the 1405 of roof top solar. I run the air conditioner in low power auto mode. The blower will stop shortly after the compressor stops. With the air conditioner stopped I am getting 90-100 amps back into my batteries. With a well insulated trailer and my sunny side of the trailer windows with light block I can run all day under full sun. I don't setup the shade fabric at a normal campsite were we are moving day to day.

Once the sun is down my batteries would discharge within about 3 hours running the air conditioner without solar input. Fortunately we camp at 5000+ elevation in the very dry Great Basin and don't need air conditioning after sunset.

If I lived where it was humid and required overnight air conditioning I wouldn't attempt running it without a generator or full hookups. I would probably use full hookups and not camp off grid until I arrived a location that wasn't as hot or humid.

I paid $950 per 100 amp-hour battery and have four of them. The efficiency of the charging and discharging of LiFePO4 batteries is what makes my high load system work so well. Each battery can sustain 100 amps of charging or discharging plus 200 amps at 30 seconds for peak discharge. My inverter can surge to 6600 watts which is 550 DC 12 volt amps. I went with four batteries to sustain my ability to camp for several days in cold weather months when my panels may become snow covered and I need power for the furnace.