diy solar

diy solar

Small home hybrid setup... but hit a snag

benfox.bf

New Member
Joined
Jun 4, 2022
Messages
3
I've been researching residential solar for several months now. I wish I'd reached out to this forum earlier... I was told by a friend to DIY a system that an installer would sell me on. Use the installers as the brain behind my needs and just do it myself. I used https://www.energysage.com/ to get a bunch of quotes.

Then I mimic'd those quotes.

The request:
I'd like to have solar that is a backup whole home for a short amount of time. 24 hrs is probably sufficient. My home is not large, nor do I have too much consumption (I don't think).

The set up:
* Live in sunny Northern-ish California near Stockton (lots of sun hours)
* No nearby trees for hundreds of feet
* 1200 sq ft manufactured home fed from a 100amp breaker on a 200amp subpanel attached to my home. The 100amp breaker goes to the manufactured home's sub panel to distribute out to all the parts of my home (heavy electric uses would be Water heater, Clothes dryer, space heater)
* I live on 5 acres and have plenty of land for solar. but put it on my roof for ease of wiring to my home.

The Issue:
I was almost ready to buy the materials and begin working, but I had a place draw up my solar plans to submit to my county and noticed that if I went with a 7.8kw solaredge inverter that it would only feed 40amps back to my subpanel. That was when I realized that this was not a whole home backup but an essential backup. One issue is that I have a 100amp circuit that goes to my manufactured home about 10 ft. I don't really want to mess with pulling circuits out of my homes 100amp breaker box and putting it into my backup breaker box.

I'd like to have the whole 100amp service to my manufactured home be able to be backed up. I'm sure I don't use all 100 at the same time. And if the power is out, I can opt to not use my dryer or A/C (not water heater). I was really hoping to do a whole home solar, because the power goes out several times a year, sometimes for 24 hrs.

I'll attach a picture from the plans i paid someone to draw up. I'm not sold on any specific manufacturer of inverters. From reading the forums here, there is likely a better solution than solaredge than what I was quoted by people selling solar.

Also, if this question has been asked elsewhere or I should post elsewhere, please let me know. I tried to read through most of this forum before asking.
 

Attachments

  • solar wire diagram.png
    solar wire diagram.png
    191.5 KB · Views: 31
In September I use the most power. I used 51 kwh in a single day in September. On average it's about 35kwh.
 
In September I use the most power. I used 51 kwh in a single day in September. On average it's about 35kwh.

35kWh is about $10,000 in batteries alone. That doesn't consider if they're compatible with whatever grid-tie system you select.

I'm not sure what your concern is about the 40A vs. 100A.

Placing panels on a roof may require additional cost for code compliance for NEC 2017 or NEC 2020, and CA is not known for it's lax code. I would be concerned with the structural integrity of panels mounted to a manufactured home's roof as well. Consider ground mounts.
 
Based on your described layout it sounds like your home is ALL electric including a cook top or range which was not mentioned in your list of high usage appliances. I have 1,200 sq ft rental house in So. Cal. that is electrically about the same. When I added up all the name plate electrical consumption data it came was just over 30kW when including a microwave, coffee maker, toaster oven, bathroom space heater all of which are only 120V but I consider them to be high usage also.
If you wish to back up your entire 100Amp manufactured home subpanel I would do the following.
1) Consider ways to reduce electrical consumption. Heat Pump water heater(or at least install inexpensive water heating panels to preheat water in the electic WH tank), Inverter type high eff. mini split heat pump.
2) Choose a different Inverter with a bigger internal disconnect. Example, Schneider Conext XW Pro that handle a 60A input breaker and feed the Inverter output directly to your 100A subpanel.
 
A couple of Quick Back of the Envelope Calculations. (no corrections for line losses & inefficiencies).
240 Volts @ 100A = 24,000 Watts. this would require 2x 12,000W Inverters in Parallel, each drawing a MAX of 250A from a 48VDC battery bank.

NOTE that it is FAR cheaper to conserve energy than it is to Generate & Store it !
Electric Water Tanks: like leaving car running ALL day long just in case you want to go for a ride... On-Demand Water Heater is far cheaper.
Electric Stoves "Coil Type" are the worst ! Induction Stoves are much more efficient.
Clothes Dryers are also very inefficient but there are some pretty good one, nothing beats a Clothes Line for costs. ;-)
Older Refrigeration / Freezers are massive energy pigs ! Same applies to many AC Systems. Several options exist.
Electric "Resistance" Heating such as baseboard, electric furnace etc are "Evil" when it comes to energy use. Several options exist depending on your structure.

1x 48V 280AH Battery Pack = 14,336 Watt Hours / 14.3Kw (Formula for LFP: 16 Cells X 3.2V (nominal voltage) X AmpHrs of battery. [51.2V*280])
* 48V is a generalization, for LFP the calculation is based on the Norminal Voltage which is 3.200V per cell and 16 Cells are required for a standard Straight 16S Battery Pack.

A DIY 48V/280AH battery requires 16 Cells, One 16S BMS, A Case/box, and a Fuse. Every Battery must be fused.
16 EVE 280ah Grade A Matched & Batched cells. $2,368.00, Shipping $1,043.00, Total $3,411.00
1 JKBMS [JK-B2A24S20P] Smart BMS with Active Balancing, BlueTooth RS485/CanBus, 200A Capability. Total $175 USD (free shipping)
1 Fuse (Class T 250A with Holder) approx $50 (prices vary a lot)
Cost -Casing = $3,636.00 USD

** NOTE: Prebuilt Battery Packs are typically in 100AH & 200AH capacities. This is largely due to size & weight of each unit.
Example: a single EVE 280AH cells weigh 5kg/11lbs each. 16=175lbs, plus casing etc. 100AH cell=2kg/4.4lbs, 200AH=4kg/8.8lbs. +/- a bit.

Will Prowse has tested and listed server rack type batteries, see his information here:
Here is a link to his YT Channel that covers most everything.
Look at his Playlists for reviews on a lot of things including Inverters & All-In-One units and do look at his DIY Solar Blueprints for further options & details.

I hope this helps, Good Luck.
 
Thank you all for your wonderful comments. This helps immensely! I did not mention but I have a 250gal propane tank that feeds my stove and furnace and that is all. I use about 250 gallons (1 tank) a year.

My home was built in 2019 so I do not have too old of appliances although I bet the fridge is not very energy efficient. The passive water heating panels is good idea, I'll need to look into it more to see how to best cover that base.

Also, I will look into a larger inverter because I would like to be able to power a little more of my home. Although you make great points on reducing consumption instead of keeping a car running all day.

Thank you again!
 
Split your fuse box,
Lighting and sockets to the solar.
Hot water, cooker, air con to the grid.
 
I've been researching residential solar for several months now. I wish I'd reached out to this forum earlier... I was told by a friend to DIY a system that an installer would sell me on. Use the installers as the brain behind my needs and just do it myself. I used https://www.energysage.com/ to get a bunch of quotes.

Then I mimic'd those quotes.

The request:
I'd like to have solar that is a backup whole home for a short amount of time. 24 hrs is probably sufficient. My home is not large, nor do I have too much consumption (I don't think).

The set up:
* Live in sunny Northern-ish California near Stockton (lots of sun hours)
* No nearby trees for hundreds of feet
* 1200 sq ft manufactured home fed from a 100amp breaker on a 200amp subpanel attached to my home. The 100amp breaker goes to the manufactured home's sub panel to distribute out to all the parts of my home (heavy electric uses would be Water heater, Clothes dryer, space heater)
* I live on 5 acres and have plenty of land for solar. but put it on my roof for ease of wiring to my home.

The Issue:
I was almost ready to buy the materials and begin working, but I had a place draw up my solar plans to submit to my county and noticed that if I went with a 7.8kw solaredge inverter that it would only feed 40amps back to my subpanel. That was when I realized that this was not a whole home backup but an essential backup. One issue is that I have a 100amp circuit that goes to my manufactured home about 10 ft. I don't really want to mess with pulling circuits out of my homes 100amp breaker box and putting it into my backup breaker box.

I'd like to have the whole 100amp service to my manufactured home be able to be backed up. I'm sure I don't use all 100 at the same time. And if the power is out, I can opt to not use my dryer or A/C (not water heater). I was really hoping to do a whole home solar, because the power goes out several times a year, sometimes for 24 hrs.

I'll attach a picture from the plans i paid someone to draw up. I'm not sold on any specific manufacturer of inverters. From reading the forums here, there is likely a better solution than solaredge than what I was quoted by people selling solar.

Also, if this question has been asked elsewhere or I should post elsewhere, please let me know. I tried to read through most of this forum before asking.
Use an Emporia energy monitor to track your electric usage. They work great.
I am a huge proponent in how Will Prouse has his setup built, as it is very cost effective, and works flawless as a whole home backup. MPP inverters work great, as long as your not going to do grid tie. I say use the GRID as backup only, and just use as little power as you can from them.
Here is a link to a guy who did it right also. My setup almost mirrors his, but I have SEPLOS batteries.

Here is a pic of my setup:
 

Attachments

  • 20210920_163750.jpg
    20210920_163750.jpg
    169.6 KB · Views: 12
A couple of Quick Back of the Envelope Calculations. (no corrections for line losses & inefficiencies).
240 Volts @ 100A = 24,000 Watts. this would require 2x 12,000W Inverters in Parallel, each drawing a MAX of 250A from a 48VDC battery bank.

NOTE that it is FAR cheaper to conserve energy than it is to Generate & Store it !
Electric Water Tanks: like leaving car running ALL day long just in case you want to go for a ride... On-Demand Water Heater is far cheaper.
Electric Stoves "Coil Type" are the worst ! Induction Stoves are much more efficient.
Clothes Dryers are also very inefficient but there are some pretty good one, nothing beats a Clothes Line for costs. ;-)
Older Refrigeration / Freezers are massive energy pigs ! Same applies to many AC Systems. Several options exist.
Electric "Resistance" Heating such as baseboard, electric furnace etc are "Evil" when it comes to energy use. Several options exist depending on your structure.

1x 48V 280AH Battery Pack = 14,336 Watt Hours / 14.3Kw (Formula for LFP: 16 Cells X 3.2V (nominal voltage) X AmpHrs of battery. [51.2V*280])
* 48V is a generalization, for LFP the calculation is based on the Norminal Voltage which is 3.200V per cell and 16 Cells are required for a standard Straight 16S Battery Pack.

A DIY 48V/280AH battery requires 16 Cells, One 16S BMS, A Case/box, and a Fuse. Every Battery must be fused.
16 EVE 280ah Grade A Matched & Batched cells. $2,368.00, Shipping $1,043.00, Total $3,411.00
1 JKBMS [JK-B2A24S20P] Smart BMS with Active Balancing, BlueTooth RS485/CanBus, 200A Capability. Total $175 USD (free shipping)
1 Fuse (Class T 250A with Holder) approx $50 (prices vary a lot)
Cost -Casing = $3,636.00 USD

** NOTE: Prebuilt Battery Packs are typically in 100AH & 200AH capacities. This is largely due to size & weight of each unit.
Example: a single EVE 280AH cells weigh 5kg/11lbs each. 16=175lbs, plus casing etc. 100AH cell=2kg/4.4lbs, 200AH=4kg/8.8lbs. +/- a bit.

Will Prowse has tested and listed server rack type batteries, see his information here:
Here is a link to his YT Channel that covers most everything.
Look at his Playlists for reviews on a lot of things including Inverters & All-In-One units and do look at his DIY Solar Blueprints for further options & details.

I hope this helps, Good Luck.
WOW, killed it! Wonderful, thorough reply, I learned a lot.
Thanks much.
 
How much do you want to spend?
The system I put in would do it, but only 14kWh usable battery. So small loads at night, lots of power during the day.

You can decide how much you want to power and spend accordingly.
Gas generator for some loads is a reasonable way to make it more economical.
PV is a good deal if you use the power produced all the time, not for 2 days per year.
 
Back
Top