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lifestyle:faq_solar_generator

Words of wisdom: “These aren't aimed at people that know what they are doing.” – LastTreeStar

The self contained units are overpriced, underperforming “power for dummies”. – Somebodyelse1)

Solar generators

images-na.ssl-images-amazon.com_images_i_51ug3iif-zl._ac_us218_.jpg “Solar Generators” (power stations, power packs) are self-contained devices that contain:

These devices are packaged for convenience and are usually much more expensive than the components bought separately. Sometimes manufacturers use non-standard panel connectors to keep customers in an expensive “walled garden”, referring to normal, non-proprietary panels as "off_brand".2)

Less expensive “solar generators” may cut corners by using more basic batteries (AGM vs Lithium), cheaper inverters (Modified sine wave instead of pure sine wave), or less efficient solar charge controllers (PWD instead of MPPT).

The overall proposition can be summed up by the title of a Bob Wells video, Should you Buy a Jackery Power Station? Super Easy but Super Expensive.

The terms solar generator and generator alternative are marketing terms with no real meaning: the units do not generate power.

Sometimes the term jump pack is used for portable battery packs in general, but it often means packs intended to jump start a vehicle. Battery pack usually means small, pocketable “bricks” for charging phones and other small devices.


Best case scenario

The best use of these “generators” is someone who:

  • Has little technical knowledge of electricity and battery chemistries, and no interest in obtaining any
  • Is short on time and needs a solution very quickly
  • Has plenty of disposable income
  • Camps on relatively short outings
  • Has small to medium power needs, or does not need long run time.
  • Can charge from shore power when away from the camper
  • May need to bring their power source well outside of their vehicle for recreational or work reasons

A solar generator may also be useful for people who want to move the battery between different vehicles.


Specifications

Specs for these devices are often given in nonstandard or even misleading ways. The following discussion will use the Yeti shown above, although their product description is better than most.

capacity

Ah are often expressed as mAh. Which is more impressive, 33Ah or 33,000mAh? They are the same capacity expressed in different ways.

The 33Ah capacity lead-acid battery in the example above is stated as 400Wh. This is technically correct but mixes units in a way that consumers may not understand. Consumers may also not realize that lead-acid chemistries are usually only drawn down to 50% depth of discharge, giving an actual usable capacity of 16.5Ah. In addition, lead-acid battery capacities are measured over 20hrs. With our example this means a 10w continuous DC load in this case, or 9w from the built-in inverter. Loads greater than those will decrease usable capacity due to the peukert effect.

Nefarious marketers sometimes multiply each cell's Ah rating times the number of cells, resulting in a 3x inflation of Ah rating.
On the upside, they have almost no peukert effect and therefore can support heavier loads (at the expense of running time). Also, higher end units run 4S or higher voltages then downconvert them for a ~13v output much closer to what nominal 12v devices expect.

You could run run a load at the inverter's 300W normal rating for ~36 minutes.3) Some manufacturers will list the inverter's peak output (600w in this case) in the title as if it were the amount of power the unit could deliver over time. New folk sometimes read this as “I can run 600w of appliances off the unit forever!”, forgetting this is a peak load and that the unit has a finite capacity.

cell chemistry

The cell chemistry is likely 3.6v Li-NMC4) unless LiFePO4 is stated. The chemistry has significant impact on both battery cycle life and solar charging behavior.5)

Li-NMC are typically 3.6v cells arranged three in a row (3S) for nominal 10.8v. Actual voltage will vary from 9v-12.6v.6) Li-NMC are rated ~500 cycles to 20% depth of discharge.

LiFePO4 are typically 3.2v cells arranged four in a row (4S) for nominal 12.8v and actually ~12.1v - 14.0v. LiFePO4 are ~2000-3000 cycles to 80%.

SLA (lead) batteries aren't used much anymore, but if present they are nominal 12v and actually ~12.1-14.6v. Properly charged SLA are capable of ~500 cycles to 50%.

inverter

The inverter will usually be pure sine wave, but lower-priced units that do not specify may be modified sine wave. See the linked article for information about MSW and electronics.

Inverters are typically rated on their continuous output but unscrupulous marketers may list the peak load, which is a temporary overload.

solar charging limits

Many smaller units have quite restrictive solar input limits.

  • voltage - 22Voc is a common voltage limit, effectively limiting one to 12v nominal panels.
  • current limit - 3A is a common input current limit on smaller, less-expensive units. With PWM controllers the max power harvestable will be 3A x [internal battery voltage], which can be as low as 9v. 9v x 3A 27w. MPPT controllers with the same limit might run the panels at 18v: 18v x 3A = 54w.7)

pass-through charging

Pass-through charging is an important feature, as it allows you to run DC/USB/AC while charging the unit8) While passing-through keep an eye on the unit's temperature and discontinue one or the other if it gets too warm.

A unit with pass-through would maximize charging while driving. The SG and attached devices would charge.

  12v ciggy port -> SG -> other devices
  

A unit without pass-through could only charge the SG because the power cannot be “passed through” the SG.

  12v ciggy port -> SG
  
  

The situation with solar would be even worse, because it might take all day to charge from solar and the SG could not power other devices for that day.

regulated DC output

Since many of the devices don't run at 12v-friendly voltages some of the nicer ones have voltage regulation. This means the output would be a steady 12.8v or 13.4v9) no matter the voltage level of the internal battery pack.

Unregulated 3S packs can drop to 9v, causing some devices to misbehave.

Charging

Using the Yeti above as our example again, the charging requirements are:

5 hours from a wall outlet with the included AC charger; in 13 hours with the available car charger*; or as fast as 8 hours from Goal Zero’s monocrystalline solar panels*

Things to consider:

Charging from solar panels

Charging these devices from solar panels will probably be slower than you might expect:

  • in the absence of an mppt controller10) panel output will be hamstrung by battery voltage. You may see a device listing 60w max input but specifying a 100w panel for use with it, and now you know why.
  • devices with 3S lithium cells will hamstring the panels even worse11)
  • long wire runs (as seen with portable panels set outside) result in voltage drops
  • sunlight is limited to a certain number of hours. Some units require more hours of charging than there are hours of sunlight in a day.
  • it is common for smaller units to have low input current limits for DC charging (Wall adapter, car adapter, or panel). This is particularly restrictive on panel input. Consider these examples using a 3A input limit and 100w panel with 18Vmp.
    • 100w panel on MPPT controller - 18v x 3A = 54W12)
    • 100w panel on PWM controller - With typical 3S Li-Po batteries input would typically be limited to something like 36w (12v x 3A). Less-common internal AGM batteries would make a bit more since voltage is higher, ~39W (13v x 3A).

Poly panels will typically make slightly more power on normal (non-MPPT) devices due to poly's lower voltage / higher current. Devices with internal MPPT controllers will use both panels equally well because they decouple battery and panel voltages.

Adding MPPT charging

Some of the newer Goal Zeros have MPPT chargers built into them, which does increase their usability. To older models, it can sometimes be added.

goal zero optimizer

Goal Zero makes an optional MPPT controller that installs seamlessly into selected models. Will Prowse damns it with faint praise, noting the 22v solar input voltage limit and relatively modest yield improvements:

It does work better than the PWM on the goal zero… it's worth the money but not as good as a DIY system13) (see below)

Although the DIY mppt setup makes somewhat more than the Optimimizer, the sleek install of the GZ Optimizer may result in a better appearance and portability. The GZ display will not show the charge rate from external controllers.

standalone mppt

It may be possible to run the output of a standalone MPPT controller into a charging port of the device. Remember to configure the controller to put a max voltage in line with what the AC charging adapter puts out.

See this video by Will Prowse.

buck converter

It is possible to place a small DC-DC converter between the panel and input port to get the panel up near max power. Doing so will make it even more important to manually disconnect the panel when charging is complete.

Units that do not mention solar charging in their specs can likely still take solar charging through the DC charging port. Since there may be no controller, manually disconnect the panel when battery voltage creeps up too high. For lead this would be ~15v, and for lithium ~12.3v14). Another rule of thumb is that the cutoff voltage should be no higher than the voltage on the stock DC charger – read its label. Be certain not to exceed the maximum input charging voltage.15)

Another approach might be to place a shunt charge controller between the panel and DC input and limit the voltage automatically that way. This will not work if the DC port does not “show” the controller the battery voltage.

Charging from wall socket

Wall charging is typically fastest because the manufacturer gets total control over the adapter's voltage and current output. Note that they might not include a fast charger to reduce cost or heat stress on the battery.16)

charging from car outlet

Car charging is typically slow because alternator voltage tends to be fairly low17) and ciggy outlet current limited to 10A. Unless one is on a road trip there is probably not enough time spent driving the vehicle to charge the device fully.

It's not *efficient* in the normal sense, but if ciggy charging is running <100w it might make sense to charge the device with the AC adapter running on an inverter rather than from the car charging adapter.

12v ciggy port → small inverter → AC adapter → device

Example: the Bluetti AC50S charges about 2x as fast from the inverter than from the car adapter, due to the AC adapter's higher 27.5v output.18)

charging from isolator

If >120w charging is required while mobile, one solution might be to install an isolator as one would when charging an auxilliary battery. The isolator will pass heavier current into the cabin of the vehicle:

alternator --> isolator –> inverter –> SG's high power wall adapter

As with the ciggy lighter setup above, it's not particularly efficient but while driving the alternator has power to waste.

internal AGM batteries

Some units use AGM batteries. This will greatly reduce cost and provide more normal voltage19) but requires diligent charging or the batteries will fail prematurely. All lead-chemistry batteries need to be fully charged then kept charged as much as possible.

manufacturers

The most common “premium” brands are Jackery and Goal Zero (Yeti). Bluetti is also gaining traction with a loyal following, and there are less-famous brands like Rockpals, ExpertPower, Aimtom, Nexpow, etc.20) They tend to be named after the watt-hours21) of battery capacity22), or sometimes by the inverter output rating.

The manufacturers often sell proprietary panels (Jackery Solar Saga, etc) which are needlessly expensive. Do the homework and find out which normal panels can work with your device;23) most will require an adapter. Will Prowse recommends devices with MPPT controllers.

Notes: inverter ratings below are the continuous rating, not peak/startup rating. Lithium packs are typically duty-cycle rated to 80% of capacity. Inverter runtime estimates are 100% of continuous rating at 80% DoD and 10% inversion losses.24) Inverters described below are pure sine wave (PSW) unless described as electrical:inverter#modified_sine_wave (MSW).

Jackery

  • Explorer 160 - 167Wh. 100w MSW inverter (~72 minutes practical runtime25) at full inverter load). 1x AC outlet. 2x USB. 1x USB-C outlet.26) 6mm DC output jack.27). PWM controller. 14.4v internal.
  • Explorer 240 - 240Wh. 200w inverter (~52 minutes). 1x AC outlet. 2x USB. Ciggy port. Some specs mention MPPT controller.28)
  • Explorer 300 - 293Wh. 300w inverter (~42 minutes). 2x AC outlet. 2x USB. 1x USB-C29). Covered ciggy port. Used by caratank30).
  • Explorer 440 - cannot use Solar Saga panels
  • Explorer 500 - 518Wh. 500w inverter (~45 minutes). 3x USB. 2x DC. ciggy port. Original version has a PWM controller; version 2 has MPPT.31)
  • Explorer 1000 - 1002Wh @ 21.6v(regulated). 1000w inverter (~43 minutes). 3x AC outlet. 2x USB. 1x USB-C32). Covered ciggy port. DC jack and Anderson33) inputs. MPPT controller. 1000 charge cycles to 80% DoD.

Goal Zero (GZ)

  • Yeti 200x - 187Wh @ 14.4v (regulated). 120w inverter (~67 minutes). 1x AC outlet. Ciggy outlet. DC jack outlet. 2x USB. 2x USB-C. MPPT controller. 500 cycles.
  • Yeti 400 - 428Wh @ 10.8v (regulated to 12v). 300w inverter (~62 minutes). 2x AC outlets. Ciggy outlet. 1x DC outlet port. 3x USB.
  • Yeti 500x - 505Wh @ 10.8v (regulated). 2x AC outlets. Ciggy outlet. 1x DC jack outlet. 2x USB. 2x USB-C34). 500 cycles.
  • Yeti 1500x - 1516Wh @ 10.8v (regulated). 2000w inverter (~33 minutes). 2x AC outlets. Ciggy outlet. 2x DC jack outlets. 1x DC Anderson outlet. 2x USB. 2x USB-C. 500 cycles. DC input jack and DC input Anderson jack.
  • Yeti 3000x - 2982Wh @ 10.8v (regulated). 2000w inverter (~64 minutes). 2x AC outlets. Ciggy outlet. 2x DC jack outlets. 1x DC Anderson outlet. 2x USB. 2x USB-C. DC input jack and DC input Anderson jack. 500 cycles.

Bluetti

Bluetti provides more information than usual about their specs, outlets, etc. [bravo! – secessus]

  • Maxoak AC20 - 200Wh. 120w inverter (~72 minutes). 1x AC outlet. 1x DC jack outlet. 2x USB. 1000 cycles. MPPT controller.35)
  • Maxoak AC100 - 1000Wh @ 14.8v (regulated to 13.4v). 600w inverter (~72 minutes). 2x AC outlets. Ciggy outlet.36) 4x usb. 1x USB-C. “Up to” 2500 cycles. MPPT controller.37)
  • AC200P - 2000Wh LiFePO4 @14.8v. 2000w inverter (~43 minutes). 6x AC outlets. Ciggy outlet. 3x DC jack outlets. 2x USB. 1x USB-C. MPPT controller.38)
  • AC200 Max.

Note: check polarity on models with 30A outlet before use; there are reports the outlet may be wired incorrectly.

Note: check

Ecoflow

  • Ecoflow River Pro - 720Wh. 600w inverter (~52 minutes). 3x AC outlets. Ciggy outlet. 2x DC jack outlets. 3x USB. 1x USB-C. Specs do not list MPPT, but website does.39)

Some Ecoflow models have an inverter function they call “X-boost” that appears to drop voltage in order to increase current for heavy loads:

The X-Boost mode is not applicable for all electrical devices. Some devices with a rated power of 600W-1200W that have strict voltage requirements are still not compatible. Please conduct a full test to confirm before usage, so it will not to affect your work. It is recommended to use electrical equipment with heating elements and with a rated power between 600-1200W, such as hair dryers, electric kettles, coffee

Note that the loads mentioned in X-Boost docs are resistance loads (heating coils).

Heads up: there are at least two issues that may affect the Delta Pro: "explosive" failure and reverse polarity.

DIY solar generator

m.media-amazon.com_images_i_71lfkh8w4al._ac_ul320_.jpg People who want portability or an all-in-one solution can build their own solar generator out of a trolling battery box or milk crate.

In this approach the battery, inverter, solar charge controller, and DC power ports are installed in or on the carrier.

quirks

The Jackery Explorer 1000 flashlight appears to activate one of the USB ports even when the USB panel is switched off.

The Jackery Explorer 500 solar charge controller is PWM40) while the 500 version 2 appears to be MPPT and capable of handling up to 30v.41)

Some units are tightly focused on inverter (AC) output, and don't have big DC outlets. The Bluetti EB150, for example, maxes out at 9A DC and that is through the ciggy outlet.

2)
COUGH inergy COUGH
3)
including 10% efficiency loss on inversion, but not including peukert effect
4)
“Li-Po”. Some are even SLA
5)
when PWM charge controllers are used (see below).
6)
Some more expensive models use 4S for 12v-14.4v but this is uncommon.
7)
minus DC-DC conversion losses of ~5%
8)
some units will pass through DC but not power the inverter for AC. Check the specs and reviews carefully/
9)
whatever they decide
10)
sometimes present on higher-end devices
11)
3S Li voltage can be as low as 9v, and maxxes around 12.5v.
12)
In practice it will be even lower due to cell temperature derating. 10% derating would put max input around 49w.
13)
ie, external charge controller. See https://www.youtube.com/watch?v=rqXscD69RvM
14)
assuming 3S
15)
typically 20-25v for built-in MPPT controllers. Standalone controllers typically can handle much higher input voltages – check the specs.
16)
particularly for Li
17)
particularly for charging lead
19)
compared to 3parallel_serial lithium
20)
Cheaper units may be high-value rebadged units, or they may be lacking features. Read and understand the specs so you know what you are buying.
21)
Wh
22)
at 100% DoD, unrealistic
23)
voltage and amps
24)
Jackery advises 15% inverter losses in the Amazon listings, but 10% is used here for consistency
25)
to 80% DoD
26)
discharge only
27)
no ciggy port but port-to-ciggy adapter included
28)
newer model?
29) , 32)
charge/discharge
31)
“You want the one that states 'Jackery' and underneath 'Explorer 500'.” - from an Amazon review
33)
for use with included parallel panel adapter
34)
one will also charge
35)
“Input Voltage must be 14V-40V”
36)
9A
37)
“working voltage is >16V,Open circuit voltage(OCV) <45V, the Max. output current is max.10A,Max. 170W”
38)
“Open Circuit Voltage between 35V-150V, Max.12A, Max.700W”, so at least 24v of nominal panel
39)
“You can connect 1 110W solar panel or 2 sets of 110W solar panels in parallel”
40)
maybe shunt
lifestyle/faq_solar_generator.txt · Last modified: 2022/09/05 11:33 by frater_secessus