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   "source": [
    "# Solar Energy Potential Analysis\n",
    "\n",
    "This is an introduction to solar radiation modeling in *GRASS GIS* in *Jupyter Notebook*. In addition to common *Python* packages, it demonstrates the usage of `grass.script`, the *Python* API for GRASS GIS, and `grass.jupyter`, an experimental *Jupyter Notebook* specific package that helps with the launch of *GRASS GIS* and with displaying maps.\n",
    "\n",
    "This interactive notebook is available online thanks to the [https://mybinder.org](Binder) service. To run the select part (called a *cell*), hit `Shift + Enter`."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2b47cfa6-312b-4db9-873d-7e2333589411",
   "metadata": {},
   "source": [
    "## Starting GRASS in Jupyter Notebooks"
   ]
  },
  {
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   "execution_count": null,
   "id": "66e65bb3-6401-448f-bc1e-475ac5fcf1ad",
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   "outputs": [],
   "source": [
    "# Import Python standard library and IPython packages we need.\n",
    "import os\n",
    "import subprocess\n",
    "import sys\n",
    "\n",
    "# Ask GRASS GIS where its Python packages are.\n",
    "sys.path.append(\n",
    "    subprocess.check_output([\"grass\", \"--config\", \"python_path\"], text=True).strip()\n",
    ")\n",
    "\n",
    "# Import the GRASS GIS packages we need.\n",
    "import grass.script as gs\n",
    "import grass.jupyter as gj\n",
    "\n",
    "# Start GRASS Session\n",
    "gj.init(\"../../data/grassdata\", \"nc_basic_spm_grass7\", \"user1\")\n",
    "\n",
    "# Set computational region to elevation raster\n",
    "gs.run_command(\"g.region\", raster=\"elevation@PERMANENT\", flags=\"pg\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "70a1e6ee-39a0-4936-b656-95976c3cce44",
   "metadata": {
    "tags": []
   },
   "source": [
    "## Solar radiation analysis"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "8a7d0768-80ca-4190-ba8c-d19b4719e7d2",
   "metadata": {},
   "source": [
    "Prepare input maps (slope and aspect):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "bca26a9a-126b-41d0-a8db-c58e4ac9c58d",
   "metadata": {},
   "outputs": [],
   "source": [
    "gs.run_command(\"r.slope.aspect\", elevation=\"elevation\", aspect=\"aspect\", slope=\"slope\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f3567f03-624b-4a17-8463-6715f86e6b75",
   "metadata": {},
   "source": [
    "### Incidence angles and cast shadows\n",
    "\n",
    "Compute the sun position on Dec. 22 at 4:15pm, EST (no map output expected):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0d01b59b-2c2e-440b-886d-bb484451a8ba",
   "metadata": {},
   "outputs": [],
   "source": [
    "gs.run_command(\"r.sunmask\", elevation=\"elevation\", year=\"2001\", month=\"12\", day=\"22\", hour=\"16\", minute=\"15\", sec=\"0\", timezone=\"-5\", flags=\"s\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "311fe6d4-a2d4-4295-9e86-798f0debe28d",
   "metadata": {},
   "source": [
    "Calculate incidence angles including cast shadows."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "116f5f2c-48e0-483b-b49d-3595196d8714",
   "metadata": {},
   "outputs": [],
   "source": [
    "gs.run_command(\"r.sun\", elevation=\"elevation\", aspect=\"aspect\", slope=\"slope\", incidout=\"incident\", day=\"356\", time=\"16.25\")\n",
    "gs.parse_command(\"r.info\", map=\"incident\", flags=\"g\")\n",
    "gs.run_command(\"r.colors\", map=\"incident\", co=\"bcyr\", flags=\"e\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "8374778c-339f-410a-a2c7-099cabef20f3",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Display incident angles\n",
    "solar_map = gj.GrassRenderer()\n",
    "solar_map.d_rast(map=\"incident\")\n",
    "solar_map.d_legend(raster=\"incident\", fontsize=12, at=\"25,75,1,5\")\n",
    "solar_map.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b0f211b3-e5d7-4051-9a80-0f5ce0cf9665",
   "metadata": {},
   "source": [
    "Extract the cast shadow area for 4:15pm."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "d64db7b3-c22a-4a26-a32b-fccc7eb0858d",
   "metadata": {},
   "outputs": [],
   "source": [
    "gs.mapcalc(\"shadow = if(isnull(incident), 1, null())\")\n",
    "gs.run_command(\"r.colors\", map=\"shadow\", color=\"grey\")\n",
    "gs.run_command(\"r.colors\", map=\"elevation\", color=\"elevation\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2ccf0d4e-633f-463c-bb12-6fe151a03fb1",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Display 4:15pm Shadows\n",
    "shadow_map = gj.GrassRenderer()\n",
    "shadow_map.d_shade(shade=\"shadow\", color=\"elevation\")\n",
    "shadow_map.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "30758fb8-7658-41d3-ad25-199bf8e8e4e7",
   "metadata": {},
   "source": [
    "### Solar radiation\n",
    "Compute global (beam+diffuse+refl) radiation for entire day during summer and winter solstice. This may take a minute to run.\n",
    "\n",
    "Display the radiation maps."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "753dcb19-a2f1-4329-ba39-912e709ff85e",
   "metadata": {},
   "outputs": [],
   "source": [
    "gs.run_command(\"r.sun\", elevation=\"elevation\", aspect=\"aspect\", slope=\"slope\", day=\"356\", glob_rad=\"winter\", insol_time=\"its356\")\n",
    "gs.run_command(\"r.colors\", map=\"winter\", co=\"gyr\", flags=\"e\")\n",
    "\n",
    "gs.run_command(\"r.sun\", elevation=\"elevation\", aspect=\"aspect\", slope=\"slope\", day=\"172\", glob_rad=\"summer\", insol_time=\"its172\")\n",
    "gs.run_command(\"r.colors\", map=\"summer\", co=\"gyr\", flags=\"e\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0a27993b-126a-44c8-8102-dd85ee9aee96",
   "metadata": {},
   "outputs": [],
   "source": [
    "rad_map = gj.InteractiveMap()\n",
    "\n",
    "# Set opacity to 1.0 (default is 0.8) so that we can see colors clearly\n",
    "rad_map.add_raster(\"winter\", opacity=1.0)\n",
    "rad_map.add_raster(\"summer\", opacity=1.0)\n",
    "rad_map.add_layer_control()\n",
    "\n",
    "rad_map.show()"
   ]
  }
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