CHT solar (photovoltaic) system

< DRAFT+ >

Solar-related information and open questions CHT collected while starting out in DIY systems.

    xxx stub
    2015-10-11 couture
    2016-03-06 quick sketch of cht4c situation, should prep doc for release
    2017-08-17 restyle
    2017-09-22 update to cht5a state
    2020-08-17 moving over + overviewing ...
    2021-03-28 (some updates)

Ties to:
    * 🔗stuff - under "Energetics"
    * parts of 🔗ordering for currently provisioned gear
    * parts of 🔗tech-tree (and other infrastructures)

Table of Contents
1 SETUP 2021→
2 SETUP 2017-2019
3 SETUP 2015-2017
4.1 Hacker-scene projects
4.2 Solar panel materials (mono/poly/?)
4.3 Charge controllers
4.4 Branded gear "for nomads" is expensive
4.5 Motorised sun trackers
4.6 DIY solar recipes
4.7 Charge-up in public inconspicuously
4.8 Powering RPi from batteries
4.9 Charging curve, State of charge, for lead-based batteries (flooded, AGM, gel)
4.10 Lithium batteries
4.11 Mixing random solar panels ("punk solar systems")
4.12 Wire types & sizing (gauge)
4.13 Proper wiring (connectors, junction boxes, fusing, guides, ...)
4.14 Grounding / Earthing
4.15 Conduits
4.16 Solar Thermal plants
4.17 ... have potential for storage / "latent use" (molten salt, etc)
4.18 Free software
5.1 Wire charge controllers per-panel ?
5.2 Charging AGM off the alternator ?
5.3 Which battery to pick? (AGM? Gel? Lithium?)
5.4 Laptops and dirty power (input voltage tolerance)
5.5 Better than off-the-shelf
5.6 Using truck battery to charge laptops
5.7 Deep-cycle batteries
5.8 Microinverters
5.9 Concentrated water heating -> hot water (heating, bathing, power)
5.10 Solar ovens !!!
5.11 Calculate our price per watt
5.12 Questioning DIY solar "sustainability"
6 *** PAD
6.1 [!] ask corps for sponsorship (Voltaic, etc)
6.2 [!] document types, prices and availability of batteries
6.3 Solar in Canaria
6.4 ARCHIVE: Historic primitive, and imagined designs
6.4.1     Main coordinates (2015)
6.4.2     System 0 (CHT4b):
6.4.3     System 1 (imagined):
6.4.4     System 2 ("DC straight to battery"):
6.4.5     System 3a ("DC straight to laptop"):
6.4.6     System 3b
6.4.7     System 4 ("standard solar"):
6.4.8     Cht4b Status (June 2015)
6.4.9     Cht4c Status (March 2016)
6.4.10     Test setup Germany (Gerrit)
6.5 PROJECT "hyperbattery": own battery system based on 18650s 
6.6 nice solar BMS for LiFePO4
6.7 (L:) Battery / system enclosures
6.8 "Grid defection"

SETUP 2021→

Within 🔗hackbase-type4.

Quick gear & financials
150... solar panel (Sharp 460Wp)
150... regulator (Epever Tracer A 40A 12/24V → 480/960W)
250... battery (Victron AGM 12V 120Ah → ~600Wh useful)
220... inverter (Edecoa 12V 1500W pure continuous)
30... cables

More details → 🔗ordering

SETUP 2017-2019

Panels are tied (!) to top of 🔗trucko.
Chain similar to below.

    2x 60Wp nomadic foldable solar panels
    1x 50Wp glass/alu panel
    (==170Wp all together)
    500W (cont) MSW Inverter
    DC-DC 20V (direct charging Lenovos)
    Small AGM battery
    Independent Thinkpad X220/X230 battery charger hold
    Li-ion power banks

SETUP 2015-2017

Within 🔗hackbase-type2.
a 50W portable solar panel

{{1}}->LED lights {{1}}->DC regulator, ~18-20V out DC regulator, ~18-20V out->AC inverter (220V) DC regulator, ~18-20V out->laptops (Lenovo-type, macbooks, etc) DC regulator, ~18-20V out->sound systems built-in USB 5V out->Lithium 5V battery packs built-in USB 5V out->Mobile phones built-in USB 5V out->tiny WLAN built-in USB 5V out->tiny sound Lithium 5V battery packs->Guitar effect pedals (via 5V->9V regulator) Lithium 5V battery packs->Raspberry Pi built-in 18V semi-regulated output->charge controller charge controller->load 12V out charge controller->AGM battery (12V) 50W solar panel->charge controller 50W portable solar panel->built-in USB 5V out 50W portable solar panel->built-in 18V semi-regulated output AC inverter (220V)->(any 220V load) load 12V out->DC regulator, ~18-20V out load 12V out->WLAN router load 12V out->3.5" external HDD AGM battery (12V)->{{1}} to ignore controller's load disconnect, when battery is not really completely empty AGM battery (12V)->charge controller SUN->50W solar panel SUN->50W portable solar panel SUN->SUN SUN->SUN SUN->SUN LED lights LED lights DC regulator, ~18-20V out DC regulator, ~18-20V out built-in USB 5V out built-in USB 5V out Lithium 5V battery packs Lithium 5V battery packs Mobile phones Mobile phones tiny WLAN tiny WLAN tiny sound tiny sound built-in 18V semi-regulated output built-in 18V semi-regulated output charge controller charge controller 50W solar panel 50W solar panel 50W portable solar panel 50W portable solar panel AC inverter (220V) AC inverter (220V) (any 220V load) (any 220V load) load 12V out load 12V out WLAN router WLAN router 3.5" external HDD 3.5" external HDD AGM battery (12V) AGM battery (12V) Guitar effect pedals (via 5V->9V regulator) Guitar effect pedals (via 5V->9V regulator) Raspberry Pi Raspberry Pi laptops (Lenovo-type, macbooks, etc) laptops (Lenovo-type, macbooks, etc) sound systems sound systems SUN SUN

Parts specifics: 🔗stuff and 🔗ordering

^ not the CHT system ;-)

Hacker-scene projects
ties to 🔗real-hacks
    * AltPwr:
        * [...]

    * +chrono:
        designing own solar charge controller @

    * check "open hardware charge controller":

    * [...] ###

Solar panel materials (mono/poly/?)

2021 Update:
    It seems price & performance of both have pretty much converged
    So it doesn't seem like it's a defining factor anymore.


Read this first:

For prices, I took a random look through
Not sure if they deliver to Canarias and what the price would be!!!

poly 145Wp 18V 240€ (1.5€/W)
mono 45Wp 21V 150€ (3€/W)
thin film 50Wp 21V 100€ (2€/W)
mono 50Wp 12V 60€
mono 160W 200€ (folding portable 2x80W halves zip together)

For more prices etc, see 🔗ordering!

this is prob for @@ordering

Charge controllers

Looks like they're 30€. Example:

    * "up to 40% improvement"
    * can charge higher-voltage panels (?):
        (case with big Sharp panels @Fuerteventura)

Problem of fake MPPT chargers:
    A giveaway ~6:00min:
        Should be ~100V.

Branded gear "for nomads" is expensive

(List not updated in a while.)

    * Voltaic systems
        * $400 for 10W + 72Wh batt
        * $400 for 18W 18V + 72Wh batt
        * $170 for 20W , 18V
    * Goal Zero :
        * expensive ~ $10/W
        * Nomad series:
    * [...]

Motorised sun trackers

    We move our 50W solar panel to 3 positions in day (morning, mid-day, evening), and approximate 30-50% improvement

We've seen one built (+Tila @arreita):
    I think mostly because they look cool.
It's not a giant improvement in efficiency, I've heard "20%".
But it feels like you could get more.


DIY solar recipes

    * :
        going to waste, asking for used "garden lights"
    * :
        lots of awesome links
    * [...]

Charge-up in public inconspicuously


    * put chargers, devices and possibly extra batteries in a bag + 220v splitter, to be inconspicuous
    * just plug that one cable from the bag while #squatworking

    * problem: heat? maybe
    * what's the fastest (W) one can expect to charge?
    * how not to destroy ports?

### not really solar

Powering RPi from batteries

#rpi #solar #energetics

(this is for rpi1/rpi2? ###)

    Max: 2.5A @ 5V, Expected: ~500mA -> 2.5W
    Didn't work from an 550mA Alcatel USB charger, but exits on powerbanks are usually 1A, 2.1A
    Frequent unexpected poweroffs can corrupt SD card
    Roughly (made up :)): hours ~= cap / ( draw - charge/2or3{night} * 0.8or0.9{losses}) >> what's your experience?
    Solar 7W + 5000mAh(=~10h) battery min could work
    Could get a few days on the 3W+10000mAh below maybe (survives ~2nights + 0.5Wcharging)

Less power:
        Have a 5min circuit breaker + OS that takes one measurement, then shuts down (but security won't work that way, just sensors)
        RPi 1 or 2, or zero (zero is hard to get)
        Arduino? base is ~50mA, but at more than 5V... can it easily work with sense hat?

Charging curve, State of charge, for lead-based batteries (flooded, AGM, gel)

Notable resources:
    * [...]

Lithium batteries

    * ###
    * [..]

    * do not charge to 100%
    * consider lifepo4 (greater cycles)
    * you can build your own BNC
    * [..]

Mixing random solar panels ("punk solar systems")

Though mixing different solar panels is not recommended, it’s not forbidden and things would be ok as long as each panel’s electrical parameters (voltage, wattage, amps) are carefully considered.

    ? max input voltage
    * [...]


PWM could be better than MPPT !
In systems with multiple solar panels of different voltages (e.g. 32 cell panels mixed with 36 cell or 40 cell panels), PWM charge controllers are preferable to MPPT controllers because their operation algorithms are less finicky. 



    * in SERIES:
        * VOLTAGES add up
        * CURRENT is limited to minimum panel
        * TOTAL is multiplication !
        """if you connect in series solar panels with different voltage and current ratings, the total output power is determined mostly by the solar panel of the lowest rating!"""

    * in PARALLEL:
        "For this reason, parallel connection is more typical for off-grid systems."

    * [...]


    How to evauate clearly if you have gained (or lost) by adding a random panel?
    How to measure amp outs with a multimeter?

Wire types & sizing (gauge)
### #tomerge ... i looked into this 2020/10 but can't find it right now ...
Great intro.

"Wire gauges are designated by the American Wire Gauge (AWG) system. Although it seems counter-intuitive, the smaller the number, the fatter the gauge"

"Most home PV is wired with AWG 10 on the DC side (AWG 6 or 8 if you're using a combiner box), and AWG 10 or 8 on the AC side. The bare copper equipment ground for the array is usually AWG 6, which is sturdy enough to withstand the elements."

Generally, either PV wire or USE-2 wire is used for the array, and is not run inside conduit. USE stands for "underground service entrance". It's not, however, restricted to subterranean applications. Both USE-2 and PV wire can handle high ambient heat. Their jackets will not degrade from ultraviolet exposure and they're both moisture resistant. PV wire has an extra layer of insulation. Most installers then switch to a less expensive building wire, typically THWN-2 Copper, on the other side of the junction or combiner box. Since this wire is run through conduit, it does not need to be UV resistant [...]

At any rate, here's what the letters (and number) stand for in THWN-2:
T - thermoplastic insulation around the copper
H - rated for 75 degrees Celsius
W - suitable for wet conditions 
N - Nylon jacket
-2 - rated for 90 degrees C (canceling out the H coding above.) 

(Also remember that THWN-2 is not UV- resistant. That's why it must always run in conduit when used outdoors.)


* Thickness calculators, etc ... How to be sure? How to measure / try?

* ... how to work with found wires?

* If wire thickness is not enough, does doubling work? Does double wire increase current flow?
Useful when you don't have a thick enough wire, can you just combine? (to escape resistence)
Where used as parallel conductors, the circular-mil areas of these conductors are added together to provide the total cross-sectional area for the overall size of the parallel conductors.
All of the paralleled conductors in each phase, neutral or grounded set must be the same length and be made from the same conductor material. They must be the same circular mil area and have the same type of insulation. Finally, all parallel conductors must be terminated in the same manner. This ensures that each conductor in the parallel set will carry the same amount of current.
However, one-phase, neutral or grounded circuit conductors are not required to have the same physical characteristics as those of another phase, neutral or grounded conductor. For example, in a 400A, single-phase, 120/240V parallel run, Phase A could be composed of two 3/0 copper conductors in parallel and Phase B composed of two 250 kcmil aluminum conductors in parallel with the neutral being two 3/0 copper conductors.

There will be the normal electro-magnetic effects (counter leads will oppose, co-leads attract).

Proper wiring (connectors, junction boxes, fusing, guides, ...)

"Electrical equipment shall be installed in a neat and workmanlike manner..."

    * wires
    * fuses / "disconnectors" / circuit breakers / fuse box
    * "plug-in N terminal"
    * junction boxes / "combiner" / "terminal block" / "Protective Conductor Terminal"
    * conduit / cable channel, cable guides, etc
    * ground rod ?
    * [...]

Random examples:
    * "SODIAL(R) 5 Pcs Dual Row 5 Position Screw Terminal Strip 600V 15A" (5€)
    * "Haudang Connector DK2.5N-BL 10-Way Power Splitter Dk2.5N-BL 10-Way Box Connector DIN Rail Terminal Blocks, 12-22 AWG, 20 A, 600 V Solar Connector, Blue"
    * "Pollmann 202 02 53 POLL Junction Terminal A14-S Grey Plug-In"
    * [...]

__________________ !
Whichever component you choose, the junction box or combiner should be placed near the array because you'll be switching to a less expensive wire type at that spot.  The NEC requires that any wire transition take place inside an electrical enclosure. You can't just splice your connecting wires together, wrap them with electrical tape and leave them out in the elements. 

"For residential solar electric systems, always use copper wire. Aluminum wire is less expensive but breaks easily and corrodes. It's also less efficient in conducting electricity"

Run the wiring from the solar source to a junction box, then transition to your conduit run. The wiring must remain in the conduit run until it reaches the inverter (for grid-tie systems) or charge controller (for battery-based systems). 
Properly grounding the electrical components of your solar system is an essential step. For one, grounded electrical connections reduce the risk of shock, power surges, and build-up of static electricity. Moreover, if the circuit fails, grounding allows a safe pathway for fault current.
Labeling strings, DC and AC circuits within junction boxes is another good practice allowing for better troubleshooting by future maintenance personnel.
Simple 101 writeup on fuses!
Though charge controller and inverter have inbuilt fuses for protection, you can put switches and fuses in the following places for additional protection and isolation.
1. In between solar panel and charge controller
2. In between the charge controller and battery bank
3. In between battery and inverter

Grounding / Earthing

How is off-grid grounding?
Does it make sense?
What specific cases does it protect me against (think: water pump VS
Most people are unaware that circuit grounding involves more than just the third wire and neutral grounded conductor mentioned above. While those wires connected to a grounding terminal at the main panel, more wiring may be necessary to protect your PV system. In addition to a ground fault, a few other hazards are possible, including:                                
  • lightining strike
  • trauma to utility grid (typically storm-related or a vehicular collision with an electric pole)
  • solar flare                                 
To truly protect electrical equipmens, appliances and home electronics, the NEC and building inspectors may require you to do the following:
  • install a lightning or surge arrestor
  • run a "grounding electric conductor" (GEC) directly from your inverter to the home's main GEC (which runs between to the main panel and a buried grounding rod).
  • bury a suppementary grounding rod and run a GEC from there to the PV array.

Solar Thermal plants

Many different designs. Example: mass of motorized mirrors concentrate heat to towers powering turbines.
High-temperature collectors concentrate sunlight using mirrors or lenses and are generally used for fulfilling heat requirements up to 300 deg C / 20 bar pressure in industries, and for electric power production.  Two categories include Concentrated Solar Thermal (CST) for fulfilling heat requirements in industries, and Concentrated Solar Power (CSP) when the heat collected is used for electric power generation.  CST and CSP are not replaceable in terms of application. 
Ivanpah ~400MW !
... but fries birds to "streamers"! wow!
DIY project?

first one built, in Spain (Sevilla), 2007
The solar receiver at the top of the tower produces saturated steam at 275 °C. The energy conversion efficiency is approximately 17%.[5]

... have potential for storage / "latent use" (molten salt, etc)

Another possibility is to use a phase-change material as thermal storage where latent heat is used to store energy.
However, there are many considerations for using molten salt as an energy storage medium due to the great capability of storing energy for long periods without substantial losses (see Concentrated solar power). Another possibility is to use a phase-change material as thermal storage where latent heat is used to store energy. 

Free software

<------------------------- (new) INFO/TIPS/MINI PROJECTS ↑


Wire charge controllers per-panel ?

I'd suggest getting an MPPT per panel, that way you'll get the most efficient charging all the time.

Charging AGM off the alternator ?

Heard: not a good idea at all


    * measure alternator output (should NOT exceed 15V, be within 13.5V - 15V)
    * ~ you "should" use a "smart charger"
    * [...]

    * cheap DC-DC battery charger ....... #ordering
    * ... that can handle alternator outputs ... prob around 60A ? :
        #trucko !!!
    * [...]


Great resource, check more:
    * !!!
    * [...]

Which battery to pick? (AGM? Gel? Lithium?)

2020 update:
    it seems lithium is now price-viable, even if you don't build it yourself.
    ... accounting you can only use 50% of AGMs rated capacity ...
    ... but, what about cycles? 

Laptops and dirty power (input voltage tolerance)

    * What happens with a Lenovo X220 if you provide it with wrong voltage / current if it's turned off?
    * ... and if it's turned on?
    * why do laptops actually physically "whir" with the wrong voltage?
  • "Voltages slightly below 19V can be used but 19V is a useful standard voltage that will meet most eventualities."
  • "It is usual for a charger to use a switch mode power supply (SMPS) to convert the available voltage to required voltage. A SMPS can be a Boost converter (steps voltage up) or Buck converter (steps voltage down) or swap from one to the other as required. In many cases a buck converter can be made more efficient than a boost converter. In this case, using a buck converter it would be possible to charge up to 4 cells in series. "

Better than off-the-shelf

Looking at Voltaic etc (below) it seems that we could get by with much less?
maybe a 20W panel + 100Wh (~8.33Ah @12V) battery system (per laptop)?

Using truck battery to charge laptops
  • good info on deep cycle batteries
    • truck batteries only made for short usage (start the truck) and not for deep cycles so don't use it ;)

Deep-cycle batteries
= lead battery designed for repeated discharges + recharges

Cost ~0.5€/W ?
Inverter per panel

Concentrated water heating -> hot water (heating, bathing, power)


Solar ovens !!!


Calculate our price per watt


Questioning DIY solar "sustainability"

I've got several currently unused panels here, and I'm wondering:
    how many ever pay themselves off in carbon terms, and how many are carbon sources
even though this place from Berlin for example sells actual products:
    its claims about "sustainability" for these marketing gizmos and "solar backpacks" is basically a greenwashing scam
i was wondering what is the hidden price of these distributed grids:
    basically chinese coal burning converted to underutilized and inefficient distributed EU systems,
    inculding all the labour & tinkering, logistics, marketing, etc,

What are the simple totals on solar industry's current and expected emissions, offset by what's produced?

    * :
        brilliant <
    * :
        via (more like "deceptive")
    * ### [M!]

<------------------------- (new) OPEN QUESTIONS  ↑↑↑

*** PAD

[!] ask corps for sponsorship (Voltaic, etc)

asked so far:
    * giga turbines (insta)
    * germans (that gave 50% off ot influencers)
    * [...]

[!] document types, prices and availability of batteries

update 2020: we have a direct source on @lanzarote

update 2020:
    (see above, about batteries)

Solar in Canaria

    * Sol-Lar (Canarsol - Lar):
        * at Puerto in Arrecife, Lanzarote
        * pics: [img:IMG_20150416_140426974.jpg]
        * 12V 85W 155€ poly (~1.5€/W)
        * 629 16 12 09 (Open Mon-Friday 9-13h)
    * Sun-Telco @Lanzarote:
    * people suggest buying from Gran Canaria and shipping in!
    * guy we've met that has a direct link:
        50% off prices!
        see XXX🔗contacts
    * [...]

ARCHIVE: Historic primitive, and imagined designs

    Main coordinates (2015)

We are moving along with our project, and have some funds available for dive into solar.

Need info around the following basic coordinates:
    * start small and cheap.
    * Looking for:
        * 200W out
        * 5h (1kWh) of battery
        * size & weight optimisation not a must, but would be nice
        * optimizing around price
    * Devices to power are all DC:
        * 2 laptops ~20V 50-90W <-- data via what chargers are rated at 220V ac charger label, not consumption
        * 3 smartphones ~5V 10W
    * That would make it maybe 250Wp (?), but could live with half of that too (?)

Main idea currently:
    * Do it without DC->AC inversion
    * Just pure DC system, with a voltage regulator
    * can build it ourselves

    System 0 (CHT4b):
        -> solar panel
        -> directly to an old Samsung 19V / 40W laptop with broken screen

It turned on and worked as a regulator to charge USB devices.
Can't verify the laptop worked stable, because broken screen.

    * what could possibly go wrong?

    System 1 (imagined):
        -> solar panel with higher wattage
        -> DC conversion, no battery
        -> directly to laptop

        * CONTRA: You'd need a big panel, probably 100W size (X220 takes 65W)

    System 2 ("DC straight to battery"):
        -> solar panel
        -> DC convert to 11.1V (X220 battery voltage)
        -> charge batteries directly with some contraption to connect them like
        -> switch batteries in laptop

        * is possibly higher / fluctuating current a problem?

        * PRO: awesome because using standard and Li-Pol batteries
        * PRO: can bring with you away, split weight, etc

    System 3a ("DC straight to laptop"):
        -> solar panel
        -> DC convert to standard battery voltage (12V / 24V)
        -> AGM battery ~50€
        -> DC convert to 20V / even better, manual dial-in any DC voltage
        -> plug in laptop

        * CONTRA: two DC converters needed

    System 3b
        -> solar panel
        -> charge controller (12V / 24V)
        -> AGM battery ~50€
        -> notebook power adapter (cigar lighter) ~30€
        -> plug in laptop
        -> all stuff stored in an IKEA box (samla)
        -> battery protector 12€ like]

        * PRO: could be extended by an USB cigar lighter adapter like
            * what happens if the battery becomes almost empty? Is it better to use a constant current source?

    System 4 ("standard solar"):
        -> solar panel
        -> DC convert to battery
        -> AGM 12V battery / series of batteries
        -> inverter to AC 220V
        -> laptop adapter to 20V DC

        * inverters to AC 220V are / seem expensive (~150€ for 300W):
            UPDATE: not really. see 🔗ordering
        * Q: how much do you lose with DC -> AC -> DC conversion?:
            Probably least 20-30%.
        * but you can plug in anything which is handy!

    Cht4b Status (June 2015)
    * Bought:
        * 50W SolarWorld panel (for 90€):
            (classic poly-crystal panel)
            outputs ~18-21V
            ~1x1m, ~5-6kg
        * DC-only, to charge laptop (Lenovo X220)
        * laptop accepts 20V 3.25A / 4.5A. Unsure about tolerances / dangers?
        * Battery in laptop 11.1V
        * can charge devices on 5V USBs via laptop

    Cht4c Status (March 2016)
    * Bought:
        * Battery
        * Charge controller
        * Step-Up voltage regulator
    * Powering with up-regulator:
        * (Cinch-based connector setup (temporary hack))
        * Lenovo X220 ~20.5V
        * sound system ~15V, takes 20V
        * Apple Macbook cable (16V, still works ~18V)
    * Powering direct from battery:
        * LAN + WLAN direct from battery (12V)
        * 3.5" disk drive (unstable!)

    Test setup Germany (Gerrit)

Instance of 3b (above).

        * 12V x 12Ah = 144Wh AGM battery (for 28€):
        * 20Wp mono solar panel (for 32€):
        * 12V cigar ligher (for 8€):
        * charge controller (for 26€):
        * notebook power adapter (cigar lighter) ~30€:
        * battery protector 12€:
   included in this charge controller      

PROJECT "hyperbattery": own battery system based on 18650s 


nice solar BMS for LiFePO4:

BMS = Solar Battery Management System

        * Shipping, Ready to buy
        * LiFePO4 is cheaper long term:
            ~2000 (even "up to 8000" cycles, compared to ~500 for Lipo for 2-3x price (or lead acid "250 to 1200")
            however perhaps easier to damage if you're experimenting, and a bigger upfront investment
        * Copyleft hardware designs & firmware !:
            ### looks like @@real-hacks

(L:) Battery / system enclosures

"essentially a vented box made from aluminum or fiberglass or steel.  This product is perhaps more commonly called a "solar battery box" but is also referred to as a "pole mount battery box"."

AGM battery don't normally emit gasses / fumes etc, but they are a lot less accepting of improper charging. IF you're sure your charge controller can properly handle and is properly adjusted for AGM, they are maintenance free, no water needs to be added, nor indeed can be added. However, like mentioned, they are relatively easily damaged compared to flooded. 
As long as the AGMs are never overcharges, the electronics should be OK in the box - - as long as the inverter and controller do not overhead in the enclosed box. They usually require free airflow for cooling.
Best practice, and often, code, is to maintain 500mm seperation between any kind of lead battery and your electronics
DESERTEC: Sustainable Wealth for Every Human on Earth
 → The DESERTEC Foundation makes the biggest idea of the 21st Century real: green Desert-Energy, that advances the Decarbonization of Europe, guaranties Africa clean prosperity and makes the Middle East independent from oil-income. For this process, we have gathered governments, businesses and experts/scientists for years. We are the Lobby for Desert-Energy. Everyone talks about Nuclear Fusion and Superbatteries… we present a solution already tested in the harsh environment of reality. We want to scale this idea to a global solution!

"Grid defection"

<-------------------------- ((new))