On Grid, Off Grid Project Results

Solar PowerHouse. the modules in the background are gridtied and some can be switched to DC

Battery wiring is a temporary set up to be upgraded

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Back on June 20th, I posted about a fairly simple yet sophisticated solar battery system. I finally got the last of the wiring done last week. In the top picture is the "PowerHouse" which I designed and had local Mennonites make as a prototype two years ago. The idea was to build finished solar systems either gridtied or offgrid battery. The slope of the roof is 38 degrees which is the latitude of southern West Virginia. It fits 6) 230 watt modules, although today you can get 250 watters at less price.
The next picture is inside the PowerHouse showing the batteries, charge controller, combiner and inverter. For a full description and a link for the schematic drawing go to my June 20th post "Sensible Solar Battery System".

Two of the three series relays. Note Enphase microinverter behind timber

On July 5th I posted a schematic of a method of switching gridtied modules to DC so additional power can be collected for the battery system. I was a bit concerned the points in the relays might get damaged by under-load switching. I saw no visible arcing switching back and forth, so I suppose it will work for a long time.
The relay and it's socket are under the middle of the PV module and well protected, None the less, I used silicon dielectric grease on the wires, blade slots, and around the base edge of the relay since it didn't look like it was hermetically sealed. Then on top of that, I sprayed an anti-corrosive into the wire sockets and clamp screws. Ought to last for a while. Please note: I used "touch safe" sockets for added safety.
Basically, I doubled my collection power from 1380 watts to 2760 watts. Theoretically, I could charge the battery pack in 4 sunny hours. So yea, now I'm thinking of another set of 4) 220 A/hr batteries for winter conditions. Cha Ching..but that's the nature of the beast and human nature.

Close up of DPDT relay, socket and wiring

Different way to have battery backup on gridtie

This idea came directly from my previous post on a practical PV backup system. I have some grid tied modules nearby my battery backup shed and wanted to employ the grid tied modules to help out when the power was down. I decided to switch 6 modules into a 2 x 3 panel series string to feed the charge controller. The above diagram represents one string. It will deliver >100 VDC @ ~8A. My charge controller, an Outback FM80, can take in up to 150 VDC.
By using 120 VAC for the relay coils, it will automatically switch to DC mode if the grid goes down or you turn off the supply switch. Care should be taken switching in full sun/load conditions. It could shorten the life of the contacts in the relays. Disconnect the AC and DC sides of the system when practical.  You could install 4 RC snubbers on each relay or buy solid state relays. Either is kinda expensive. There may be no problem at all.
I'll be installing this over the next few days and I'll let you know how it works, or not...

Sensible Solar Battery System

It's been awhile since I last posted on this blog. We have been quite busy with our PV and electronics businesses, not to mention all the chores.
Anyhow, now that we are fully gridtied with more than our annual electric needs, I decided to develop a DIY kit for either grid backup or totally offgrid use. I knew it had to be kept simple, conservative, yet as a high performance system with quality parts. It is a 1500 watt PV rating, 48 volt 10KWh battery pak, and a 120VAC 2400 watt continuous inverter. We supply the solar specific parts, you supply the muscle and commonly available wire, gear, and hardware. It will provide about 5KWh per day on an annualized basis here in West Virginia. That may sound not like much, but if you are in survival mode or never had grid power, you'll manage. I have installed a six circuit transfer switch to run critical loads. For us, that's preserving food, a few lights, and satellite tv. Others may have different priorities. But how about water with only having 120VAC? In our case we have a spring fed cistern just below grade. This allows use of a 120 RV-type pump hooked in parallel to our regular 240 pump. If you have a deep well or city supply, you too could bury a cistern or two and fill 'em up when things are rosy. When things go down, use a similar parallel pump system. If you have a site that allows the tank to be planted up hill, you could rely on gravity to return the pumped water. Think of it as a hydraulic battery system.
This kit allows you to get involved in some fun stuff and you may be amazed how easy you could make such a useful infrastructure. We intend on using some fraction of the power every day to keep our batteries exercised and in good shape. We'll also reduce our power demand to boot. If you are interested in learning more go to diy-solar-kit  We also will provide technical resources to help you through the project or to evaluate if this deal is for you.